William P. Fay, MD

• JW and Lois Winifred Stafford Distinguished
• Chair in Diabetes and Cardiovascular Research
• Professor of Internal Medicine
• Medical Pharmacology and Physiology
• Director, Division of Cardiology
• University of Missouri
• Columbia, Missouri

All bones of the foot proximal to the metatarsophalangeal joints are united by dorsal and plantar ligaments muscle relaxant drugs medication best mestinon 60 mg. The bones of the metatarsophalangeal and interphalangeal joints are united by lateral and medial collateral ligaments muscle relaxant radiolab generic 60 mg mestinon visa. Joint Capsule Rbrous layer of joint capsule is attached to margins of articular surfaces L ig am ents Medial spasms during pregnancy order mestinon 60 mg amex, lateral muscle relaxant education purchase discount mestinon line, and posterior talocalcaneal ligaments support capsule; Interosseous talocalcaneal ligament binds bones together muscle relaxant 1 order 60 mg mestinon with mastercard. Movements Inversion and eversion of foot Blood Supply Posterior Ubial and fibular arteries Nerve Supply Talocalcaneonavicular Synovial joint; talonavicular part is ball and socket type Joint capsule incompletely encloses joint. Gliding and rotatory move menis· possible Plantar aspect: medial or i<~teral plantar nerve Dorsal aspect: deep fibular nerve Calcaneocuboid Plane synovial joint Rbrbus capsule encloses joint. Dorsal calcaneocuboid ligament, plantar calcaneocuboid, and long plantar ligaments support joint capsule. Dorsal and plantar cuneonavicular ligaments Inversion and eversion of loot, circumduction Anterior tibial artery via lateral tarsal artery, a bra. Dorsal, plantar, and interosseous lntermetatarsal ligaments bind lateral four metatarsal bones together. Gliding or sliding Deep fibular: medial and lateral plantar nerves; sural nerve lntermetatarsal Plane synovial joint Bases of metatatSal bones articulate with each other. Metatarsophalangeal Condyloid synovial joint Heads of metata rsal bones articulate with bases of proximal phalanges. Flexion, extension and some abduclion, adduolion, and circumduction Lateral metatarsal artery (a branch of dorsalis pedis artery) Digital nerves Interphalangeal Hinge synovial joint Head of one phalanx articulates with base of one distal to it. The anatomical subtalar joint is a single synovial joint between the slightly concave posterior calcaneal articular surface of the talus and the convex posterior articular facet of the calcaneus. The joint capsule is weak but is supported by medial, lateral, posterior, and interosseous talocalcaneal ligaments. Orthopedic surgeons use the term subtalar joint for the compound functional joint consisting of the 1830 anatomical subtalar joint plus the talocalcaneal part of the talocalcaneonavicular joint. The two separate elements of the clinical subtalar joint straddle the talocalcaneal interosseous ligament. Structurally, the anatomical definition is logical because the anatomical subtalar joint is a discrete joint, having its own joint capsule and articular cavity. Functionally, however, the clinical definition is logical because the two parts of the compound joint function as a unit; it is impossible for them to function independently. The subtalar joint (by either definition) is where the majority of inversion and eversion occurs, around an axis that is oblique. The transverse tarsal joint is a compound joint formed by two separate joints aligned transversely: the talonavicular part of the talocalcaneonavicular joint and the calcaneocuboid joint. Transection across the transverse tarsal joint is a standard method for surgical amputation of the foot. Sequential stages of a deep dissection of the sole of the right foot showing the attachments of the ligaments and the tendons of the long evertor and invertor muscles. The spring ligament supports the head of the talus and plays important roles in the transfer of weight from the talus and in maintaining the longitudinal arch of the foot, of which it is the keystone (superiormost element). Some of its fibers extend to the bases of the metatarsals, thereby forming a tunnel for the tendon of the fibularis longus. The long plantar ligament is important in maintaining the longitudinal arch of the foot. It extends from the anterior aspect of the inferior surface of the calcaneus to the inferior surface of the cuboid. Because the foot is composed of numerous bones connected by ligaments, it has considerable flexibility that allows it to deform with each ground contact, thereby absorbing much of the shock. Furthermore, the tarsal and metatarsal bones are arranged in longitudinal and transverse arches passively supported and actively restrained by flexible tendons that add to the weight-bearing capabilities and resiliency of the foot. Thus, much smaller forces of longer duration are transmitted through the skeletal system. The arches distribute weight over the pedal platform (foot), acting not only as shock absorbers but also as springboards for propelling it during walking, 1833 running, and jumping. Then, it is transmitted posteriorly to the calcaneus and anteriorly to the "ball of the foot" (the sesamoids of the 1st metatarsal and the head of the 2nd metatarsal), and that weight/pressure is shared laterally with the heads of the 3rd­5th metatarsals as necessary for balance and comfort. Between these weight-bearing points are the relatively elastic arches of the foot, which become slightly flattened by body weight during standing. Body weight is divided approximately equally between the hindfoot (calcaneus) 1834 and the forefoot (heads of the metatarsals). The forefoot has five points of contact with the ground: a large medial one that includes the two sesamoid bones associated with the head of the 1st metatarsal and the heads of the lateral four metatarsals. The 1st metatarsal supports the major share of the load, with the lateral forefoot providing balance. Functionally, both parts act as a unit with the transverse arch of the foot, spreading the weight in all directions. The medial longitudinal arch is higher and more important than the lateral longitudinal arch. The medial longitudinal arch is composed of the calcaneus, talus, navicular, three cuneiforms, and three metatarsals. The fibularis longus tendon, passing from lateral to medial, also helps support this arch. The lateral longitudinal arch is much flatter than the medial part of the arch and rests on the ground during standing. The medial longitudinal arch is higher than the lateral longitudinal arch, which may contact the ground when standing erect. The transverse arch is demonstrated at the level of the cuneiforms, receiving stirruplike support from a major invertor (tibialis posterior) and evertor (fibularis longus). The components of the medial (dark gray) and lateral (light gray) longitudinal arches are indicated. The medial arch is primarily weight bearing, whereas the lateral arch provides balance. The active (red lines) and passive (gray) supports of the longitudinal arches are represented. The medial and lateral parts of the longitudinal arch serve as pillars for the transverse arch. The tendons of the fibularis longus and tibialis posterior, crossing under the sole of the foot like a stirrup. The integrity of the bony arches of the foot is maintained by both passive 1836 factors and dynamic supports. Passive factors involved in forming and maintaining the arches of the foot include: the shape of the united bones (both arches, but especially the transverse arch). Four successive layers of fibrous tissue that bowstring the longitudinal arch (superficial to deep): 1. Dynamic supports involved in maintaining the arches of the foot include: Active (reflexive) bracing action of intrinsic muscles of foot (longitudinal arch). Active and tonic contraction of muscles with long tendons extending into foot: Flexors hallucis and digitorum longus for the longitudinal arch. Of these factors, the plantar ligaments and the plantar aponeurosis bear the greatest stress and are most important in maintaining the arches of the foot. Surface Anatomy of Joints of Knee, Ankle, and Foot the knee region is between the thigh and the leg. Superolateral to the knee is the iliotibial tract, which can be followed inferiorly to the anterolateral (Gerdy) tubercle of the tibia. The patella, easily palpated and moveable from side to side during extension, lies anterior to the femoral condyles (palpable to each side of the middle of the patella). Extending from the apex of the patella, the patellar ligament is easily visible, especially in thin people, as a thick band attached to the prominent tibial tuberosity. The plane of the knee joint, between 1837 femoral condyles and tibial plateau, may be palpated on each side of the junction of patellar apex and ligament when the knee is extended. Laterally, the head of the fibula is readily located by following the tendon of the biceps femoris inferiorly. The fibular collateral ligament may be palpated as a cord-like structure superior to the fibular head and anterior to biceps tendon, when the knee is fully flexed. The prominences of the lateral and medial malleoli provide an 1839 approximation of the axis of the ankle joint. When the ankle is plantarflexed, the anterior border of the distal end of the tibia is palpable proximal to the malleoli, providing an indication of the joint plane of the ankle joint. The sustentaculum tali, approximately 2 cm distal to the tip of the medial malleolus, is best felt by palpating it from below where it is somewhat obscured by the tendon of the flexor digitorum longus, which crosses it. On the lateral side, when the foot is inverted, the lateral margin of the anterior surface of the calcaneus is uncovered and palpable. The calcaneal tendon at the posterior aspect of the ankle is easily palpated and traced to its attachment to the calcaneal tuberosity. The transverse tarsal joint is indicated by a line from the posterior aspect of the tuberosity of the navicular to a point halfway between the lateral malleolus and the tuberosity of the 5th metatarsal. The metatarsophalangeal joint of the great toe lies distal to the knuckle formed by the head of the 1st metatarsal. Gout, a metabolic disorder, commonly causes edema and tenderness of this joint, as does osteoarthritis (degenerative joint disease). The weight-bearing iliac portion of the acetabular rim overlies the femoral head, which is important for transfer of weight to the femur in the erect 1840 (standing/walking) position. Consequently, of the positions commonly assumed by humans, the hip joint is mechanically most stable when a person is bearing weight, as when lifting a heavy object, for example. Decreases in the degree to which the ilium overlies the femoral head (detectable radiographically as the angle of Wiberg;. Because of the anterior direction of the axis of the acetabulum and the posterior direction of the axis of the femoral head and neck as it extends laterally (owing to the torsion angle-discussed earlier), there is an angle of 30­ 40° between their axes. Consequently, the articular surfaces of the head and acetabulum are not fully congruent in the erect (bipedal) posture. The anterior part of the femoral head is "exposed" and articulates mostly with the joint capsule. Nonetheless, rarely is >40% of the available articular surface of the femoral head in contact with the surface of the acetabulum in any position. Fractures of Femoral Neck Fractures of the neck of the femur (unfortunately referred to as "fractured hips," 1841 implying that the hip bone is broken) are uncommon in most contact sports because the participants are usually young and the femoral neck is strong in people <40 years of age. When they do occur in this age group, these fractures usually result from high-energy impacts. For example, if the foot is firmly braced against the car floor with the knee locked, or if the knee is braced against the dashboard during a head-on collision, the force of the impact may be transmitted superiorly and produce a femoral neck fracture. Femoral neck fractures are especially common in individuals >60 years, especially in women, because their femoral necks are more often weak and brittle, as a result of osteoporosis. Fractures of the femoral neck are often intracapsular, and realignment of the neck fragments requires internal skeletal fixation. Fractures of the femoral neck often disrupt the blood supply to the head of the femur. Most of the blood to the head and neck of the femur is supplied by the medial circumflex femoral artery. The retinacular arteries arising from this artery are often torn when the femoral neck is fractured or the hip joint is dislocated. Following some femoral neck fractures, the artery to the ligament of the femoral head may be the only remaining source of blood to the proximal fragment. This artery is frequently inadequate for maintaining the femoral head; consequently, the fragment may undergo aseptic vascular necrosis (tissue death). Surgical Hip Replacement 1842 Although the hip joint is strong and stable, it is subject to severe traumatic injury and degenerative disease. Osteoarthritis of the hip joint, characterized by pain, edema, limitation of motion, and erosion of articular cartilage, is a common cause of disability. Fractures that result in separation of the superior femoral epiphysis (the growth plate between the femoral head and neck) are also likely to result in an inadequate blood supply to the femoral head and in posttraumatic avascular necrosis of the head of the femur. As a result, incongruity of the joint surfaces develops, and growth at the epiphysis is retarded. Such conditions, most common in children 3­9 years of age, produce hip pain that may radiate to the knee. Dislocation of Hip Joint Congenital dislocation of the hip joint is common, occurring in approximately 1. Dislocation occurs when the femoral head is not properly located in the acetabulum. In addition, the affected limb appears (and functions as if it is) shorter because the dislocated femoral head is more superior than on the normal side, resulting in a positive Trendelenburg sign (hip appears to drop on one side during walking). Approximately 25% of all cases of arthritis of the hip in adults are the direct result of residual defects from congenital dislocation of the hip. Acquired dislocation of the hip joint is uncommon because this articulation is so strong and stable. Nevertheless, dislocation may occur during an automobile accident when the hip is flexed, adducted, and medially rotated, the usual position of the lower limb when a person is riding in a car. A head-on collision that causes the knee to strike the dashboard may dislocate the hip when the femoral head is forced out of the acetabulum. The joint capsule ruptures inferiorly and posteriorly, allowing the femoral head to pass 1844 through the tear in the capsule, and over the posterior margin of the acetabulum onto the lateral surface of the ilium, shortening and medial rotating the limb. This kind of injury may 1845 result in paralysis of the hamstrings and muscles distal to the knee supplied by the sciatic nerve. Sensory changes may also occur in the skin over the posterolateral aspects of the leg and over much of the foot because of injury to sensory branches of the sciatic nerve. Anterior dislocation of the hip joint results from a violent injury that forces the hip into extension, abduction, and lateral rotation.

Furthermore muscle relaxant no drowsiness mestinon 60 mg buy on-line, the arteries or their derivatives are relatively superficial muscle spasms xanax effective 60 mg mestinon, underlying skin that is capable of sweating so that excess heat can be released spasms esophageal purchase mestinon online. To prevent undesirable heat loss in a cold environment spasms diaphragm hiccups cheap mestinon 60 mg on-line, the arterioles of the hands are capable of reducing blood flow to the surface and to the ends of the fingers muscle relaxant succinylcholine buy mestinon 60 mg mastercard. The ulnar and radial arteries and their branches provide all the blood to the hand. The carpal bones are fully ossified in this teenage hand, but the epiphysial plates (growth plates) of the long bones remain open. The artery divides into two terminal branches, the superficial palmar arch and the deep palmar branch. The superficial palmar arch, the main termination of the ulnar artery, gives rise to three common palmar digital arteries that anastomose with the palmar metacarpal arteries from the deep palmar arch. Each common palmar digital artery divides into a pair of proper palmar digital arteries, which run along the adjacent sides of the 2nd­4th digits. It enters the palm by passing between the heads of the 1st dorsal interosseous muscle and then turns medially, passing between the heads of the adductor pollicis. The radial artery ends by anastomosing with the deep branch of the ulnar artery to form the deep palmar arch, which is formed mainly by the radial artery. It usually arises from the radial artery, but it may originate from the princeps pollicis. Veins of Hand 627 Superficial and deep venous palmar arches, associated with the superficial and deep palmar (arterial) arches, drain into the deep veins of the forearm. The dorsal digital veins drain into three dorsal metacarpal veins, which unite to form a dorsal venous network. Superficial to the metacarpus, this network is prolonged proximally on the lateral side as the cephalic vein. In addition, branches or communications from the lateral and posterior cutaneous nerves may contribute some fibers that supply the skin of the dorsum of the hand. A distal skin incision was made along the transverse wrist crease, crossing the pisiform bone. The skin and fasciae are removed proximally, revealing the tendons and neurovascular structures. A circular incision and removal of the skin and thenar fascia 629 reveals the recurrent branch of the median nerve to the thenar muscles, vulnerable to injury when this area is lacerated because of its subcutaneous location. The tendons of the flexor digitorum superficialis and profundus are numbered in B according to the digit of insertion. Transverse section of the distal forearm demonstrating the long flexor and extensor tendons and neurovascular structures en route from forearm to hand. The ulnar nerve and artery are under cover of the flexor carpi ulnaris; therefore, the pulse of the artery cannot be easily detected here. Nerves of Hand In the hand, these nerves convey sensory fibers from spinal nerves C6­C8 to the skin, so that the C6­C8 dermatomes include the hand. The median and ulnar nerves convey motor fibers from spinal nerve T1 to the hand; the intrinsic muscles of the hand make up myotome T1. The carpal tunnel is the passageway deep to the flexor retinaculum between the tubercles of the scaphoid and trapezoid bones on the lateral side and the pisiform and hook of the hamate on the medial side. Distal to the carpal tunnel, the median nerve supplies two and a half thenar muscles and the 1st and 2nd lumbricals. It also sends sensory fibers to the skin on the entire palmar surface, the sides of the first three digits, the lateral half of the 4th digit, and the dorsum of the distal halves of these digits. Note, however, that the palmar cutaneous branch of the median nerve, which supplies the central palm, arises proximal to the flexor retinaculum and passes superficial to it. Here the ulnar nerve is bound by fascia to the anterior surface of the flexor retinaculum as it passes between the pisiform (medially) and the ulnar artery (laterally). Just proximal to the wrist, the ulnar nerve gives off a palmar cutaneous branch, which passes superficial to the flexor retinaculum and palmar aponeurosis and supplies skin on the medial side of the palm. The dorsal cutaneous branch of the ulnar nerve supplies the medial half of the dorsum of the hand, the 5th finger, and the medial half of the 4th finger. The ulnar nerve ends at the distal border of the flexor retinaculum by dividing into superficial and deep branches. The superficial branch of the ulnar nerve supplies cutaneous branches to the anterior surfaces of the medial one and a half digits. The ulnar nerve is often referred to as the nerve of fine movements because it innervates most of the intrinsic muscles that are concerned with intricate hand movements (Table 3. It pierces the deep fascia near the dorsum of the wrist to supply the skin and fascia over the lateral two thirds of the dorsum of the hand, the dorsum of the thumb, and proximal parts of the lateral one and a half digits. Surface Anatomy of Hand the radial artery pulse, like other palpable pulses, is a peripheral reflection of cardiac action. The palmaris longus tendon serves as a guide to the median nerve, which lies deep to it. The radial artery crosses the floor of the snuff box, where its pulsations may be felt. The scaphoid and, less distinctly, the trapezium are palpable in the floor of the snuff box. The skin covering the dorsum of the hand is thin and loose when the hand is relaxed. The looseness of the skin results from the mobility of the subcutaneous tissue and from the relatively few fibrous skin ligaments that are present. Hair is present in this region and on the proximal parts of the digits, especially in men. If the dorsum of the hand is examined with the wrist extended against resistance and the digits abducted, the tendons of the extensor digitorum to the fingers stand out, particularly in thin individuals. These tendons are not visible far beyond the knuckles because they flatten here to form the extensor expansions of the fingers. The knuckles that become visible when a fist is made are produced by the heads of the metacarpals. Under the loose subcutaneous tissue and extensor 635 tendons on the dorsum of the hand, the metacarpals can be palpated. The skin on the palm is thick because it must withstand the wear and tear of work and play. The superficial palmar arch lies across the center of the palm, level with the distal border of the extended thumb. The deep palmar arch lies approximately 1 cm proximal to the superficial palmar arch. The palmar skin presents several more or less constant flexion creases, where the skin is firmly bound to the deep fascia, that help locate palmar wounds and underlying structures. The longitudinal creases deepen when the thumb is opposed; the transverse creases deepen when the metacarpophalangeal joints are flexed. Proximal (transverse) palmar crease: commences on the lateral border of the palm, superficial to the head of the 2nd metacarpal; it extends medially and slightly proximally across the palm, superficial to the bodies of the 3rd­5th metacarpals. The distal palmar crease begins at or near the cleft between the index and middle fingers; it crosses the palm with a slight convexity, superficial to the head of the 3rd metacarpal and then proximal to the heads of the 4th and 5th metacarpals. Each of the medial four fingers usually has three transverse digital flexion creases: Proximal digital crease: located at the root of the finger, approximately 2 cm distal to the metacarpophalangeal joint. Distal digital crease: lies over or just proximal to the distal interphalangeal joint. The proximal digital crease of the thumb crosses obliquely, at or proximal to the 1st metacarpophalangeal joint. The skin ridges on the pulp (pads) of the digits, forming the fingerprints, are used for identification because of their unique patterns. The physiological function of the skin ridges is to reduce slippage when grasping objects. The 637 fibrous degeneration of the longitudinal bands of the palmar aponeurosis on the medial side of the hand pulls the 4th and 5th fingers into partial flexion at the metacarpophalangeal and proximal interphalangeal joints. Gradually, progressive contracture of the longitudinal bands produces raised ridges in the palmar skin that extend from the proximal part of the hand to the base of the 4th and 5th fingers. Treatment of Dupuytren contracture usually involves surgical excision of all fibrotic parts of the palmar fascia to free the fingers (Salter, 1999). Hand Infections Because the palmar fascia is thick and strong, swellings resulting from hand infections usually appear on the dorsum of the hand, where the fascia is thinner. The potential fascial spaces of the palm are important because they may become infected. The fascial spaces determine the extent and direction of the spread of pus formed by these infections. Depending on the site of infection, pus will accumulate in the thenar, hypothenar, midpalmar, or adductor compartments. Antibiotic therapy has made infections that spread beyond one of these fascial compartments rare; however, an untreated infection can spread proximally from the midpalmar space through the carpal tunnel into the forearm, anterior to the pronator quadratus and its fascia. Tenosynovitis Injuries such as a puncture of a finger by a rusty nail can cause infection of the digital synovial sheaths. When inflammation of the tendon and synovial sheath occurs (tenosynovitis), the digit swells and movement becomes painful. Because the tendons of the 2nd, 3rd, and 4th fingers nearly always have separate synovial sheaths, the infection is usually confined to the infected finger. If the infection is untreated, however, the proximal ends of these sheaths may rupture, allowing the infection to spread to the midpalmar space. Because the synovial sheath of the little finger is usually continuous with the common flexor sheath. How far an infection spreads from the fingers depends on variations in their connections with the common flexor sheath. Excessive friction of these tendons on their common sheath results in fibrous thickening of the sheath and stenosis of the osseofibrous tunnel. The excessive friction is caused by repetitive forceful use of the hands during gripping and wringing. This condition, called Quervain tenovaginitis stenosans, causes pain in the wrist that radiates proximally to the forearm and distally toward the thumb. Local tenderness is felt over the common flexor sheath on the lateral side of the wrist. Thickening of a fibrous digital sheath on the palmar aspect of the digit produces stenosis of the osseofibrous tunnel, the result of repetitive forceful use of the fingers. This condition is called digital tenovaginitis stenosans (trigger finger or snapping finger). Laceration of Palmar Arches Bleeding is usually profuse when the palmar (arterial) arches are lacerated. It 641 may not be sufficient to ligate only one forearm artery when the arches are lacerated, because these vessels usually have numerous communications in the forearm and hand and thus bleed from both ends. To obtain a bloodless surgical operating field for treating complicated hand injuries, it may be necessary to compress the brachial artery and its branches proximal to the elbow. This procedure prevents blood from reaching the ulnar and radial arteries through the anastomoses around the elbow. Ischemia of Digits (Fingers) Intermittent bilateral attacks of ischemia of the digits, marked by cyanosis and often accompanied by paresthesia and pain, are characteristically brought on by cold and emotional stimuli. When the cause of the condition is idiopathic (unknown) or primary, it is called Raynaud syndrome (disease). Postsynaptic fibers from the sympathetic ganglia enter nerves that form the brachial plexus and are distributed to the digital arteries through branches arising from the plexus. When treating ischemia resulting from Raynaud syndrome, it may be necessary to perform a cervicodorsal presynaptic sympathectomy (excision of a segment of a sympathetic nerve) to dilate the digital arteries. Lesions of Median Nerve Lesions of the median nerve usually occur in two places: the forearm and the wrist. Fluid retention, infection, and excessive exercise of the fingers may cause swelling of the tendons or their synovial sheaths. The median nerve has two terminal sensory branches that supply the skin of the hand; hence, paresthesia (tingling), hypoesthesia (diminished sensation), or anesthesia (absence of sensation) may occur in the lateral three and a half digits. The palmar cutaneous branch of the median nerve arises proximal to , and does not pass through, the carpal tunnel; thus, sensation in the central palm remains unaffected. The nerve also has terminal motor branches: the recurrent branch, which serves the three thenar muscles, and branches to lumbricals 1 and 2. They have difficulty buttoning a shirt or blouse, as well as gripping things such as a comb. Symptoms of compression can be reproduced by compression of the median nerve with your finger at the wrist for approximately 30 seconds. To relieve both the compression and the resulting 644 symptoms, partial or complete surgical division of the flexor retinaculum, a procedure called carpal tunnel release, may be necessary. The incision for carpal tunnel release is made toward the medial side of the wrist and flexor retinaculum to avoid possible injury to the recurrent branch of the median nerve. In attempted suicides by wrist slashing, the median nerve is commonly injured just proximal to the flexor retinaculum. This results in paralysis of the muscles of the thenar eminence (except the adductor pollicis and deep head of the flexor pollicis brevis) and the first two lumbricals. Hence opposition of the thumb is not possible, and fine control movements of the 2nd and 3rd digits are impaired. Undoubtedly, injuries to the nerves supplying the intrinsic muscles of the hand, especially the median nerve, have the most severe effects on this complex movement. If the median nerve is severed in the forearm or at the wrist, the thumb cannot be opposed. Median nerve injury resulting from a perforating wound in the elbow region results in loss of flexion of the proximal and distal interphalangeal joints of the 2nd and 3rd digits. The ability to flex the metacarpophalangeal joints of these fingers is also affected because digital branches of the median nerve supply the 1st and 2nd lumbricals.

The root canal (pulp canal) transmits the nerves and vessels to and from the pulp cavity through the apical foramen spasms under breastbone discount mestinon online amex. In living people muscle relaxant drugs medication buy 60 mg mestinon overnight delivery, the pulp cavity is a hollow space within the crown and neck of the tooth containing connective tissue muscle relaxant safe in breastfeeding buy mestinon 60 mg without prescription, blood vessels muscle relaxant on cns buy mestinon with amex, and nerves spasms foot order mestinon 60 mg with amex. The cavity narrows down to the root canal in a single-rooted tooth or to one canal per root of a multirooted tooth. Bite-wing radiograph of maxillary premolar and molar teeth demonstrating features shown and described in part A. Within the alveolus, the roots of teeth with more than one root are separated by interradicular septa. The bone of the socket has a thin cortex separated from the adjacent labial and lingual cortices by a variable amount of trabeculated bone. Therefore, the labial surface commonly is broken to extract incisors and the lingual surface is broken to extract molars. The roots of the teeth are connected to the bone of the alveolus by a springy suspension forming a special type of fibrous joint called a dento-alveolar syndesmosis or gomphosis. The periodontium (periodontal membrane) is composed of collagenous fibers that extend between the cement of the root and the periosteum of the alveolus. Pressoreceptive nerve endings are capable of receiving changes in pressure as stimuli. The alveolar veins have the same names and distribution 2113 accompany the arteries. Lymphatic vessels from the teeth and gingivae pass mainly to the submandibular lymph nodes. Palate the palate forms the arched roof of the mouth and the floor of the nasal cavities. It separates the oral cavity from the nasal cavities and the nasopharynx, the part of the pharynx superior to the soft palate. The superior (nasal) surface of the palate is covered with respiratory mucosa, and the inferior (oral) surface is covered with oral mucosa, densely packed with glands. The palate consists of two regions: the hard palate anteriorly and the soft palate posteriorly. The soft palate acts 2114 as a valve, elevating to seal the pharyngeal isthmus connecting the nasal cavity and nasopharynx with the oral cavity and oropharynx. The anterior two thirds of the palate have a bony skeleton formed by the palatine processes of the maxillae and the horizontal plates of the palatine bones. The incisive fossa is a depression in the midline of the bony palate posterior to the central incisor teeth into which the incisive canals open. The nasopalatine nerves pass from the nose through a variable number of incisive canals and foramina that open into the incisive fossa. The palatine aponeurosis is formed by the merging of the flattened tendons of the right and left tensor veli palatini muscles. Before they become flattened, each tendon uses the pterygoid hamulus as a trochlea or pulley, redirecting its line of pull approximately 2116 90°. Medial to the 3rd molar tooth, the greater palatine foramen pierces the lateral border of the bony palate. The greater palatine vessels and nerve emerge from this foramen and run anteriorly on the palate. The lesser palatine foramina posterior to the greater palatine foramen pierce the pyramidal process of the palatine bone. These foramina transmit the lesser palatine nerves and vessels to the soft palate and adjacent structures. The soft palate has no bony skeleton; however, its anterior aponeurotic part is strengthened by the palatine aponeurosis, which attaches to the posterior edge of the hard palate. The aponeurosis is thick anteriorly and thin posteriorly, where it blends with a posterior muscular part of the soft palate. Postero-inferiorly, the soft palate has a curved free margin from which hangs a conical process, the uvula. When swallowing, the soft palate is initially tensed to allow the tongue to press against it, squeezing the bolus (masticated mass) of food to the back of the mouth. The soft palate is then elevated posteriorly and superiorly against the wall of the pharynx, thereby preventing passage of food into the nasal cavity. Laterally, the soft palate is continuous with the wall of the pharynx and is joined to the tongue and pharynx by the palatoglossal and palatopharyngeal arches, respectively. A few taste buds are located in the epithelium covering the oral surface of the soft palate, the posterior wall of the oropharynx, and the epiglottis. The fauces is bounded superiorly by the soft palate, inferiorly by the root of the tongue, and laterally by the pillars of the fauces, the palatoglossal and palatopharyngeal arches. The isthmus of the fauces is the short, constricted space that establishes the connection between the oral cavity proper and oropharynx. The isthmus is bounded anteriorly by the palatoglossal folds and posteriorly by the palatopharyngeal folds. The palatine tonsils, often referred to as "the tonsils," are masses of lymphoid tissue, one on each side of the oropharynx. Each tonsil is in a tonsillar sinus (fossa), bounded by the 2117 palatoglossal and palatopharyngeal arches and the tongue. The superior lingual gingiva, the part of the gingiva covering the lingual surface of the teeth and the alveolar process, is continuous with the mucosa of the palate. Therefore, injection of an anesthetic agent into the gingiva of a tooth anesthetizes the adjacent palatal mucosa. The orifices of the ducts of the palatine glands give the mucous membrane an orange-skin appearance. The palatine glands form a thick layer in the soft palate and a thin one in the hard palate; they are absent in the region of the incisive fossa and the anterior part of the palatine raphe. The openings of the ducts of these glands give the palatine mucosa a pitted (orange-peel) appearance. In the midline, posterior to the maxillary incisor teeth, is the incisive papilla. This elevation of the mucosa lies directly anterior to the underlying incisive fossa. Radiating laterally from the incisive papilla are several parallel transverse palatine folds or rugae. Passing posteriorly in the midline of the palate from the incisive papilla is a narrow whitish streak, the palatine raphe. The palatine raphe marks the site of fusion of the embryonic palatal processes (palatal shelves) (Moore et al. You can feel the transverse palatine folds and the palatine raphe with your tongue. This closes the isthmus of the pharynx, requiring that one breathes through the mouth. The soft palate may also be drawn inferiorly so that it is in contact with the posterior part of the tongue. This closes the isthmus of the fauces, so that expired air passes through the nose (even when the mouth is open) and prevents substances in the oral cavity from passing to the pharynx. Tensing the soft palate pulls it tight at an intermediate level so that the tongue may push against it, compressing masticated food and propelling it into the pharynx for swallowing. The five muscles of the soft palate arise from the base of the cranium and descend to the palate. Note that the direction of pull of the belly of the tensor veli palatini is redirected approximately 90° because its tendon uses the pterygoid hamulus as a pulley or trochlea, allowing it to pull horizontally on the aponeurosis. The greater 2120 palatine artery passes through the greater palatine foramen and runs anteromedially. The lesser palatine artery, a smaller branch of the descending palatine artery, enters the palate through the lesser palatine foramen and anastomoses with the ascending palatine artery, a branch of the facial artery. In this 2121 dissection of the posterior part of the lateral wall of the nasal cavity and the palate, the mucous membrane of the palate, containing a layer of mucous glands, has been separated from the hard and soft regions of the palate by blunt dissection. The posterior ends of the middle and inferior nasal conchae are cut through; these and the mucoperiosteum are pulled off the side wall of the nose as far as the posterior border of the medial pterygoid plate. The perpendicular plate of the palatine bone is broken through to expose the palatine nerves and arteries descending from the pterygopalatine fossa in the palatine canal. The mucosa has been removed on each side of the palatine raphe, demonstrating a branch of the greater palatine nerve on each side and the artery on the lateral side. There are four palatine arteries, two on the hard palate (greater palatine and the terminal branch of posterior nasal septal/sphenopalatine artery) and two on the soft palate (lesser palatine and ascending palatine). The greater palatine nerve supplies the gingivae, mucous membrane, and glands of most of the hard palate. The nasopalatine nerve supplies the mucous membrane of the anterior part of the hard palate. The palatine nerves accompany the arteries through the greater and lesser palatine foramina, respectively. The tongue is also involved with mastication (chewing), taste, and oral cleansing. The root of the tongue is the attached posterior portion, extending between the mandible, hyoid, and the nearly vertical posterior surface of the tongue. The body of the tongue is the anterior, approximately two thirds of the tongue between root and apex. The apex (tip) of the tongue is the anterior end of the body, which rests against the incisor teeth. The anterior free part constituting the majority of the mass of the tongue is the body of the tongue. The posterior attached portion with an oropharyngeal surface (2) is the root of the tongue. The anterior (two thirds) and posterior (third) parts of the dorsum of the tongue are separated by the terminal sulcus (groove) and foramen cecum. Brackets, indicate parts of the dorsum of the tongue and do not embrace specific labels. The more extensive, superior and posterior surface is the dorsum of the tongue ("top" of the tongue). The inferior surface of the tongue (commonly referred to as its "underside") usually rests against the 2123 floor of the mouth. The margin of the tongue separating the two surfaces is related on each side to the lingual gingivae and lateral teeth. The dorsum of the tongue is characterized by a V-shaped groove, the terminal sulcus of the tongue, the angle of which points posteriorly to the foramen cecum. This small pit, frequently absent, is the nonfunctional remnant of the proximal part of the embryonic thyroglossal duct from which the thyroid gland developed. The terminal sulcus divides the dorsum of the tongue transversely into a presulcal anterior part in the oral cavity proper and a postsulcal posterior part in the oropharynx. A midline groove divides the anterior part of the tongue into right and left parts. The mucosa of the anterior part of the tongue is relatively thin and closely attached to the underlying muscle. It has a rough texture because of numerous small lingual papillae: Vallate papillae: large and flat topped, lie directly anterior to the terminal sulcus and are arranged in a V-shaped row. They are surrounded by deep circular trenches, the walls of which are studded with taste buds. Filiform papillae: long and numerous, contain afferent nerve endings that are sensitive to touch. Fungiform papillae: mushroom-shaped pink or red spots scattered among the filiform papillae, but most numerous at the apex and margins of the tongue. The vallate, foliate, and most of the fungiform papillae contain taste receptors in the taste buds. It has no lingual papillae, but the underlying lymphoid nodules give this part of the tongue an irregular, cobblestone appearance. The pharyngeal part of the tongue constitutes the anterior wall of the oropharynx. The inferior surface of the tongue is covered with a thin, transparent 2124 mucous membrane. This surface is connected to the floor of the mouth by a midline fold called the frenulum of the tongue. On each side of the frenulum, a deep lingual vein is visible through the thin mucous membrane. A sublingual caruncle (papilla) is present on each side of the base of the frenulum of the tongue that includes the opening of the submandibular duct from the submandibular salivary gland. As with the orbital muscles, it is traditional to provide descriptions of the actions of tongue muscles (1) ascribing a single action to a specific muscle or (2) implying that a particular movement is the consequence of a single muscle acting. This approach facilitates learning but greatly oversimplifies the actions of the tongue. The muscles of the tongue do not act in isolation, and some muscles perform multiple actions. Parts of a single muscle are capable of acting independently, producing different, even antagonistic actions. In general, extrinsic muscles alter the position of the tongue, and intrinsic muscles alter its shape. The four intrinsic and four extrinsic muscles in each half of the tongue are separated by a median fibrous lingual septum.

Excess pressure is placed on the medial aspect of the knee joint muscle relaxant 8667 discount mestinon 60 mg buy on-line, which results in arthrosis (destruction of knee cartilages) bladder spasms 4 year old cheap mestinon 60 mg buy line, and the fibular collateral ligament is overstressed spasms vs fasciculations purchase cheap mestinon line. A lateral angulation of the leg (large Q-angle infantile spasms 8 months mestinon 60 mg visa, >17°) in relation to the thigh (exaggeration of the knee angle) is called genu valgum (knock-knee) muscle relaxant antidote cheap mestinon 60 mg on-line. Because of the exaggerated knee angle in genu valgum, the weightbearing line falls lateral to the center of the knee. Consequently, the tibial collateral ligament is overstretched, and there is excess stress on the lateral meniscus and cartilages of the lateral femoral and tibial condyles. The patella, normally pulled laterally by the tendon of the vastus lateralis, is pulled even farther laterally when the leg is extended in the presence of genu valgum so that its articulation with the femur is abnormal. Children commonly appear bowlegged for 1­2 years after starting to walk, and knock-knees are frequently observed in children 2­4 years of age. Persistence of these abnormal knee angles in late childhood usually means congenital deformities exist that may require correction. Any irregularity of a joint eventually leads to wear and tear (arthrosis) of the articular cartilages and degenerative joint changes (osteoarthritis [arthrosis]). Patellar Dislocation When the patella is dislocated, it nearly always dislocates laterally. Patellar dislocation is more common in women, presumably because of their greater Qangle, which, in addition to representing the oblique placement of the femur relative to the tibia, represents the angle of pull of the quadriceps relative to the axis of the patella and tibia (the term Q-angle was actually coined in reference to the angle of pull of the quadriceps). The tendency toward lateral dislocation is normally counterbalanced by the medial, more horizontal pull of the powerful vastus medialis. In addition, the more anterior projection of the lateral femoral condyle and deeper slope for the larger lateral patellar facet provide a mechanical deterrent to lateral dislocation. An imbalance of the lateral pull and 1847 the mechanisms resisting it result in abnormal tracking of the patella within the patellar groove and chronic patellar pain, even if actual dislocation does not occur. This syndrome may also result from a direct blow to the patella and from osteoarthritis of the patellofemoral compartment (degenerative wear and tear of articular cartilages). In some cases, strengthening of the vastus medialis corrects patellofemoral dysfunction. This muscle tends to prevent lateral dislocation of the patella resulting from the Q-angle because the vastus medialis attaches to and pulls on the medial border of the patella. Hence, weakness of the vastus medialis predisposes the individual to the patellofemoral dysfunction and patellar dislocation. Knee Joint Injuries Knee joint injuries are common because the knee is a low-placed, mobile, weight-bearing joint, serving as a fulcrum between two long levers (thigh and leg). The knee joint is essential for everyday activities such as standing, walking, and climbing stairs. It is also a main joint for sports that involve running, jumping, kicking, and changing directions. To perform these activities, the knee joint must be mobile; however, this mobility makes it susceptible to injuries. The most common knee injury in contact sports is ligament sprain, which occurs when the foot is fixed in the ground. If a force is applied against the knee when the foot cannot move, ligament injuries are likely to occur. Hyperextension and severe force directed anteriorly against the femur with the knee semiflexed. This injury causes the free tibia to slide anteriorly under the fixed femur, known as the anterior drawer sign. These injuries can also occur in head-on collisions when seat belts are not worn and the proximal end of the tibia strikes the dashboard. Pain on lateral rotation of the tibia on the femur indicates injury of the lateral meniscus. Peripheral meniscal tears can often be repaired, or they may heal on their own because of the generous blood supply to this area. Knee joints from which a meniscus has been removed suffer no loss of mobility; however, the knee may be less stable and the tibial plateaus often undergo inflammatory reactions. Arthroscopy of Knee Joint Arthroscopy is an endoscopic examination that allows visualization of the interior of the knee joint cavity with minimal disruption of tissue. The arthroscope and one (or more) additional cannula(e) are inserted through tiny incisions, known as portals. This technique allows removal of torn menisci, loose bodies in the joint (such as bone chips), and débridement (the excision of devitalized articular cartilaginous material) in advanced cases of arthritis. Although general anesthesia is usually preferable, knee arthroscopy can be performed using local or regional anesthesia. During arthroscopy, the articular cavity of the knee must be treated essentially as two separate (medial and lateral) femorotibial articulations, owing to the imposition of the synovial fold around the cruciate ligaments. When the knee joint is infected and inflamed, the amount of synovial fluid may increase. Joint effusions, the escape of fluid from blood or lymphatic vessels, results in increased amounts of fluid in the joint cavity. Because the suprapatellar bursa communicates freely with the synovial cavity of the knee joint, fullness of the thigh in the region of the suprapatellar bursa may indicate increased synovial fluid. Direct aspiration of the knee joint is usually performed with the patient sitting on a table with the knee flexed. The joint is approached laterally, using three bony points as landmarks for needle insertion: the anterolateral tibial (Gerdy) tubercle, the lateral epicondyle of the femur, and the apex of the patella. In addition to being the route for aspiration of serous and sanguineous (bloody) fluid, this triangular area also lends itself to drug injection for treating pathology of the knee joint. Bursitis in Knee Region Prepatellar bursitis is caused by excessive and repeated friction between the skin and the patella, for example, jobs associated with kneeling. However, the bursa may also be injured by compressive forces resulting from a direct blow or from falling on the flexed knee. If the inflammation is chronic, the bursa becomes distended with fluid and forms a swelling anterior to the knee. Subcutaneous infrapatellar bursitis is caused by excessive friction between the skin and the tibial tuberosity; the edema occurs over the proximal end of the tibia. Deep infrapatellar bursitis results in edema between the patellar ligament and the tibia, superior to the tibial tuberosity. The inflammation is usually caused by overuse and subsequent friction between the patellar tendon and the structures posterior to it, the infrapatellar fat pad and tibia (Anderson et al. Enlargement of the deep infrapatellar bursa obliterates the dimples normally occurring on each side of the patellar ligament when the leg is extended. Abrasions or penetrating wounds may result in suprapatellar bursitis, an infection caused by bacteria entering the suprapatellar bursa from the torn skin. The infection may spread to the cavity of the knee joint, causing localized redness and enlarged popliteal and inguinal lymph nodes. The cyst may be a herniation of the gastrocnemius or semimembranosus bursa through the fibrous layer of the joint capsule into the popliteal fossa, communicating with the synovial cavity of the knee joint by a narrow stalk. Synovial fluid may also escape from the knee joint (synovial effusion) or a bursa around the knee and collect in the popliteal fossa. In adults, popliteal cysts can be large, extending as far as the midcalf, and may interfere with knee movements. The artificial knee joint consists of plastic and metal components that are cemented to the femoral and tibial bone ends after removal of the defective areas. The combination of metal and plastic mimics the smoothness of cartilage on cartilage and produces good results in "low-demand" people who have a relatively sedentary life. In "high-demand" people who are active in sports, the bone­cement junctions may break down, and the artificial knee components may loosen; however, improvements in bioengineering and surgical technique have provided better results. A sprained ankle is nearly always 1858 an inversion injury, involving twisting of the weight-bearing plantarflexed foot. The person steps on an uneven surface and the foot is forcibly inverted or lands on an inverted foot from a vertical jump. Lateral ligament sprains occur in running and jumping sports, particularly basketball (70­80% of players have had at least one sprained ankle). The anterior talofibular ligament-part of the lateral ligament-is most vulnerable and most commonly torn during ankle sprains, either partially or completely, resulting in instability of the ankle joint. Shearing injuries fracture the lateral malleolus at or superior to the ankle joint. Avulsion fractures break the malleolus inferior to the ankle joint; a fragment of bone is pulled off by the attached ligament(s). A Pott fracture­dislocation of the ankle occurs when the foot is forcibly everted. This action pulls on the extremely strong medial ligament, often tearing off the medial malleolus. The talus then moves laterally, shearing off the lateral malleolus or, more commonly, breaking the fibula superior to the tibiofibular syndesmosis. If the tibia is carried anteriorly, the posterior margin of the distal end of the tibia is also sheared off by the talus, producing a "trimalleolar fracture. Tibial Nerve Entrapment the tibial nerve leaves the posterior compartment of the leg by passing deep to the flexor retinaculum in the interval between the medial malleolus and the calcaneus. Entrapment and compression of the tibial nerve (tarsal tunnel syndrome) occur when there is edema and tightness in the ankle involving the synovial sheaths of the tendons of muscles in the posterior compartment of the leg. The area involved is from the medial 1861 malleolus to the calcaneus, and the heel pain results from compression of the tibial nerve by the flexor retinaculum. Hallux Valgus Hallux valgus is a foot deformity caused by pressure from footwear and degenerative joint disease; it is characterized by lateral deviation of the great toe. In some people, the painful deviation is so large that the great toe overlaps the 2nd toe. Such deviation occurs especially in females, and its frequency increases with age. These individuals cannot move their 1st digit away from their 2nd digit because the sesamoids under the head of the 1st metatarsal are usually displaced and lie in the space between the heads of the 1st and 2nd metatarsals. Often, the surrounding tissues swell and the resultant pressure and friction against the shoe cause a subcutaneous bursa to form; when tender and inflamed, the bursa is called a bunion. Often, hard corns (inflamed areas of thick skin) also form over the proximal interphalangeal joints, especially of the little toe. Hammer Toe Hammer toe is a foot deformity in which the proximal phalanx is permanently 1862 and markedly dorsiflexed (hyperextended) at the metatarsophalangeal joint and the middle phalanx strongly plantarflexed at the proximal interphalangeal joint. This deformity of one or more toes may result from weakness of the lumbrical and interosseous muscles, which flex the metatarsophalangeal joints and extend the interphalangeal joints. A callosity or callus, hard thickening of the keratin layer of the skin, often develops where the dorsal surface of the toe repeatedly rubs on the shoe. Claw Toes Claw toes are characterized by hyperextension of the metatarsophalangeal joints and flexion of the distal interphalangeal joints. Callosities or corns develop on the dorsal surfaces of the toes because of pressure of the shoe. They may also form on the plantar 1863 surfaces of the metatarsal heads and the toe tips because they bear extra weight when claw toes are present. Pes Planus (Flat Feet) the flat appearance of the sole of the foot before age 3 is normal; it results from the thick subcutaneous fat pad in the sole. As children get older, the fat is lost, and a normal medial longitudinal arch becomes visible. The more common flexible flat feet result from loose or degenerated intrinsic ligaments (inadequate passive arch support). Flexible flat feet is common in childhood but usually resolves with age as the ligaments grow and mature. Rigid flat feet with a history that goes back to childhood are likely to result from a bone deformity (such as a fusion of adjacent tarsal bones). Acquired flat feet ("fallen arches") are likely to be secondary to dysfunction of the tibialis posterior (dynamic arch support) owing to trauma, degeneration with age, or denervation. In the absence of normal passive or dynamic support, the plantar calcaneonavicular ligament fails to support the head of the talus. Consequently, the head of the talus displaces inferomedially and becomes prominent. As a result, some flattening of the medial part of the longitudinal arch occurs, along with lateral deviation of the forefoot. Flat feet are common in older people, particularly if they undertake much unaccustomed standing or gain weight rapidly, adding stress on the muscles and increasing the strain on the ligaments supporting the arches. Clubfoot (Talipes Equinovarus) Clubfoot refers to a foot that is twisted out of position. Talipes equinovarus, the common type (2 per 1,000 neonates), involves the subtalar joint; boys are affected twice as often as girls. The foot is inverted, the ankle is plantarflexed, and the forefoot is 1864 adducted (turned toward the midline in an abnormal manner). A person with an uncorrected clubfoot cannot put the heel and sole flat and must bear the weight on the lateral surface of the forefoot. The main abnormality is shortness and tightness of the muscles, tendons, ligaments, and joint capsules on the medial side and posterior aspect of the foot and ankle. Knee joint: the knee is a hinge joint with a wide range of motion (primarily flexion and extension, with rotation increasingly possible with flexion). Tibiofibular joints: the tibiofibular joints include a proximal synovial joint, an interosseous membrane, and a distal tibiofibular syndesmosis, consisting of anterior, interosseous, and posterior tibiofibular ligaments. Ankle joint: the ankle (talocrural) joint is composed of a superior mortise, formed by the weight-bearing inferior surface of the tibia and the two malleoli, which receive the trochlea of the talus. Joints of foot: Functionally, there are three compound joints in the foot: (1) the clinical subtalar joint between the talus and the calcaneus, where inversion and eversion occur about an oblique axis; (2) the transverse tarsal joint, where the midfoot and forefoot rotate as a unit on the hindfoot around a longitudinal axis, augmenting inversion and eversion; and (3) the remaining joints of the foot, which allow the pedal platform (foot) to form dynamic longitudinal and transverse arches. It is the control and communications center as well as the "loading dock" for the body. The head houses the brain; therefore, it is the site of our consciousness: ideas, creativity, imagination, responses, decision making, and memory.

The intervertebral joints between the bodies of adjacent vertebrae are joined by longitudinal ligaments and intervertebral discs spasms piriformis 60 mg mestinon sale. The heads of the ribs connect so closely to the vertebral bodies that only slight gliding movements occur at the (demi)facets (pivoting around the intra-articular ligament of the head of the rib) spasms kidney area generic 60 mg mestinon amex. However muscle relaxant flexeril 10 mg mestinon 60 mg order on line, even slight movement at the joints of the heads of ribs may produce a relatively large excursion of the distal (sternal or anterior) end of a rib xanax spasms order mestinon 60 mg on-line. Abundant ligaments lateral to the posterior parts (vertebral arches) of the vertebrae provide strength to and limit the movements of these joints spasms 1983 youtube 60 mg mestinon buy, which have only thin joint capsules. A costotransverse ligament passing from the neck of the rib to the transverse process and a lateral costotransverse ligament passing from the tubercle of the rib to the tip of the transverse process strengthen the anterior and posterior aspects of the joint, respectively. A superior costotransverse ligament is a broad band that joins the crest of the neck of the rib to the transverse process superior to it. The aperture between this ligament and the vertebra permits passage of the spinal nerve and the posterior branch of the intercostal artery. The superior costotransverse ligament may be divided into a strong anterior costotransverse ligament and a weak posterior costotransverse ligament. However, the articular surfaces on the tubercles of the superior 6 ribs are convex and fit into concavities on the transverse processes. As a result, rotation occurs around a mostly transverse axis that traverses the intra-articular ligament and the head and neck of the rib. This results in elevation and depression movements of the sternal ends of the ribs and sternum in the sagittal plane (pump-handle movement). Flat articular surfaces of tubercles and transverse processes of the 7th­10th ribs allow gliding. Conformation of articular surfaces, revealed in sagittal sections of the costotransverse joints, demonstrates how the 1st­7th ribs rotate about an axis that runs longitudinally through the neck of the rib (A), whereas the 8th­10th ribs glide (B). The middle parts of the lower ribs move laterally when they are elevated, increasing the transverse dimension (bucket-handle 737 movement). The primary movement of inspiration (resting or forced) is contraction of the diaphragm, which increases the vertical dimension of the thoracic cavity (arrows). When the diaphragm relaxes, decompression of the abdominal viscera pushes the diaphragm upward, reducing the vertical dimension for expiration. The 2nd­7th pairs of costal cartilages articulate with the sternum at synovial joints with fibrocartilaginous articular surfaces on both the chondral and sternal aspects, allowing movement during respiration. The weak joint capsules of these joints are thickened anteriorly and posteriorly to form radiate sternocostal ligaments. These continue as thin, broad membranous bands passing from the costal cartilages to the anterior and posterior surfaces of the sternum, forming a feltlike covering for this bone. Movements of Thoracic Wall Movements of the thoracic wall and the diaphragm during inspiration produce increases in the intrathoracic volume and diameters of the thorax. Consequent pressure changes result in air being alternately drawn into the lungs (inspiration) through the nose, mouth, larynx, and trachea and expelled from the lungs (expiration) through the same passages. Concurrently, intra-abdominal pressure decreases and abdominal viscera are decompressed. The vertical dimension (height) of the central part of the thoracic cavity increases during inspiration as contraction of the diaphragm causes it to descend, compressing the abdominal viscera. During expiration, the vertical dimension returns to the neutral position as the elastic recoil of the lungs produces subatmospheric pressure in the pleural cavities, between the lungs and the thoracic wall. As a result of this and the absence of resistance to the previously compressed viscera, the domes of the diaphragm ascend, diminishing the vertical dimension. Movement of the ribs (primarily 2nd­6th) at the costovertebral joints around an axis passing through the necks of the ribs causes the anterior ends of the ribs to rise-the pump-handle movement. Because the ribs slope inferiorly, their elevation also results in anteroposterior movement of the sternum, especially its inferior end, with slight movement occurring at the manubriosternal joint in young people, in whom this joint has not yet synostosed (united). The transverse dimension of the thorax also increases slightly when the intercostal muscles contract, raising the middle (lateralmost parts) of the ribs (especially the lower ones)-the bucket-handle movement. The combination of all these movements moves the thoracic cage anteriorly, superiorly, and laterally. When 739 evaluating a patient with chest pain, the examination is largely concerned with discriminating between serious conditions and the many minor causes of pain. Rib Fractures the short, broad 1st rib, postero-inferior to the clavicle, is rarely fractured because of its protected position (it cannot be palpated). Consequently, a first rib fracture is commonly viewed as a hallmark of severe injury in blunt trauma. When it is broken, however, structures crossing its superior aspect may be injured, including the brachial plexus of nerves and subclavian vessels that serve the upper limb. The weakest part of a rib is just anterior to its angle; however, direct violence may fracture a rib anywhere, and its broken end may injure internal organs such as a lung and/or the spleen. Fractures of the lower ribs may tear the diaphragm and result in a diaphragmatic hernia (see Chapter 5, Abdomen). Rib fractures are painful because the broken parts move during respiration, coughing, laughing, and sneezing. Rib fractures have been surgically plated or repaired for this reason, but the practice remains controversial. Flail Chest Multiple rib fractures may allow a sizable segment of the anterior and/or lateral thoracic wall to move freely. The loose segment of the wall moves paradoxically (inward on inspiration and outward on expiration). Flail chest is an extremely painful injury and impairs ventilation, thereby affecting oxygenation of the blood. During treatment, the loose segment may be internally fixed with plates or wires to prevent movement. An anterior thoracotomy may involve making H-shaped cuts through the perichondrium of one or more costal cartilages and then shelling out segments of costal cartilage to gain entrance to the thoracic cavity. The posterolateral aspects of the 5th­7th intercostal spaces are important sites for posterior thoracotomy incisions. In general, a lateral approach is most satisfactory for entry through the thoracic cage. This elevates and laterally rotates the inferior angle of scapula, allowing access as high as the 4th intercostal space. Most commonly, rib retraction allows procedures to be performed through a single intercostal space following rib retraction, with care to avoid the superior neurovascular bundle. If wider exposure is required, surgeons use an H-shaped incision to incise the superficial aspect of the periosteum that ensheathes the rib, 741 strip the periosteum from the rib, and then excise a wide segment of the rib to gain better access, as might be required to enter the thoracic cavity and remove a lung (pneumonectomy), for example. After the operation, the missing pieces of ribs regenerate from the intact periosteum, although imperfectly. In many cases, intrathoracic surgery can be performed using a minimally invasive endoscopic approach (see the Clinical Box "Thoracoscopy" in this chapter). Supernumerary Ribs Persons usually have 12 ribs on each side, but the number is increased by the presence of cervical and/or lumbar ribs or decreased by failure of the 12th pair to form. Resection may be required to relieve pressure on these structures, which can be performed through a transaxillary approach (incision in axillary fossa or armpit). Supernumerary (extra) ribs also have clinical significance in that they may confuse the identification of vertebral levels in radiographs and other diagnostic images. Protective Function and Aging of Costal Cartilages Costal cartilages provide resilience to the thoracic cage, preventing many blows from fracturing the sternum and/or ribs. Because of the remarkable elasticity of the ribs and costal cartilages in children, chest compression may produce injury within the thorax even in the absence of a rib fracture. In elderly people, the costal cartilages lose some of their elasticity and become brittle; they may undergo calcification, making them radiopaque. Never having been aware of their xiphoid process before, they fear they have developed a tumor. Care must be taken during high abdominal (laparotomy) incisions, to avoid injuring or cutting the xiphoid process. Such injuries of the cartilage can result in heterotropic ossification of the upper part of the incision. Sternal Fractures Despite the subcutaneous location of the sternum, sternal fractures are not common. The installation and use of air bags in vehicles has reduced the number of sternal fractures. A fracture of the sternal body is usually a comminuted fracture (a break resulting in several pieces). Displacement of the bone fragments is uncommon because the sternum is invested by deep fascia (fibrous continuities of radiate sternocostal ligaments;. The most common site of sternal fracture in elderly people is at the sternal angle, where the manubriosternal joint has fused. The concern in sternal injuries is not primarily for the fracture itself, but for the likelihood of heart injury (myocardial contusion, cardiac rupture, tamponade) and/or lung injury. The mortality (death rate) associated with sternal fractures is 25­45%, largely owing to these underlying injuries. Patients with sternal contusion should be evaluated for underlying visceral injury (Marx et al. The flexibility of ribs and costal cartilages enables spreading of the halves of the sternum during procedures requiring median sternotomy. Such "sternal splitting" also gives good exposure for removal of tumors in the superior lobes of the lungs. Recovery is less painful than when a muscle-splitting thoracotomy incision is used (see previous Clinical Box, "Thoracotomy, Intercostal Space Incisions, and Rib Excision"). Sternal Biopsy the sternal body is often used for bone marrow needle biopsy because of its breadth and subcutaneous position. The needle first pierces the thin cortical bone and then enters the vascular spongy bone. Sternal biopsy is commonly used to obtain specimens of marrow for transplantation and for detection of metastatic cancer and blood dyscrasias (abnormalities). Sternal Anomalies the sternum develops through the fusion of bilateral, vertical condensations of precartilaginous tissue, sternal bands or bars. Complete sternal cleft is an uncommon anomaly through which the heart may protrude (ectopia cordis). Partial clefts involving the manubrium and superior half of the body are V- or U-shaped and can be repaired during infancy by direct apposition and fixation of the sternal halves. Sometimes a perforation (sternal foramen) remains in the sternal body because of incomplete fusion. It is not clinically significant; however, one should be aware of its possible presence so that it will not be misinterpreted in chest X744 ray, for example, as an unhealed bullet wound. The xiphoid process is commonly perforated in elderly persons because of age-related changes; this perforation is also not clinically significant. Thoracic Outlet Syndrome Anatomists refer to the superior thoracic aperture as the thoracic inlet because noncirculating substances (air and food) may enter the thorax only through this aperture. When clinicians refer to the superior thoracic aperture as the thoracic outlet, they are emphasizing the arteries and T1 spinal nerves that emerge from the thorax through this aperture to enter the lower neck and upper limbs. Dislocation of Ribs Rib dislocation ("slipping rib" syndrome) is the displacement of a costal cartilage from the sternum-dislocation of a sternocostal joint or the displacement of the interchondral joints. Rib dislocations are common in body contact sports; complications may result from pressure on or damage to nearby nerves, vessels, and muscles. Displacement of interchondral joints usually occurs unilaterally and involves ribs 8, 9, and 10. Trauma sufficient to displace these joints often injures underlying structures, such as the diaphragm and/or liver, causing severe pain, particularly during deep inspiratory movements. Separation of Ribs "Rib separation" refers to dislocation of the costochondral junction between the rib and its costal cartilage. In separations of the 3rd­10th ribs, tearing of the perichondrium and periosteum usually occurs. As a result, the rib may move superiorly, overriding the rib above and causing pain. Paralysis of Diaphragm Paralysis of half of the diaphragm (one dome or hemidiaphragm) because of injury to its motor supply from the phrenic nerve does not affect the other half since the domes are separately supplied by the right and left phrenic nerves. One can detect paralysis of the diaphragm radiographically by noting its paradoxical movement. Instead of descending as it normally does during inspiration owing to diaphragmatic contraction. Instead of ascending during expiration, the paralyzed dome descends in response to the positive pressure in the lungs. Apertures of thoracic wall: Although the thoracic cage is complete peripherally, it is open superiorly and inferiorly. Structures passing between the thorax and abdomen traverse openings in the diaphragm. These include joints of heads of ribs and costotransverse joints, both strongly supported by multiple ligaments. Movements of thoracic wall: the movements of most ribs occur around a generally transverse axis that passes through the head, neck, and tubercle of the rib. Muscles of Thoracic Wall Some muscles attached to and/or covering the thoracic cage are primarily involved in serving other regions. Axio-appendicular muscles extend from the thoracic cage (axial skeleton) to bones of the upper limb (appendicular skeleton). Similarly, some muscles of the anterolateral abdominal wall, back, and neck have attachments to the thoracic cage. The axio-appendicular muscles act primarily on the upper limbs (see Chapter 3, Upper Limb).

Mestinon 60 mg order amex. Progressive Muscle Relaxation.

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