Carla Ann Martinez, MD

• Assistant Professor
• Division of Maternal Fetal Medicine
• Department of Obstetrics and Gynecology
• Texas Tech University Health Science Center at Houston
• El Paso, Texas

The pyloric arteries are branches of the right gastric and right gastroepiploic arteries skin care yogyakarta order cleocin 150 mg. They pierce the duodenal wall around its entire circumference just distal to the sphincter and reach the submucosa acne prevention cheap cleocin 150 mg with mastercard. The pyloric arteries anastomose with submucosal arteries in the duodenum and gastric antrum close to their origin and termination acne makeup cheap cleocin 150 mg with visa, respectively skin care 29 year old cheap cleocin online american express. The pyloric sphincter muscle is supplied by gastric and pyloric arteries via branches that leave their parent vessels in the subserosal and submucosal levels to penetrate the sphincter acne off buy cleocin 150 mg with amex. It passes inferiorly towards the midline just below the pylorus and then runs laterally along the greater curvature between the layers of the gastrocolic omentum about 1­2 cm from the greater curvature of the stomach. It ends by anastomosing with the left gastroepiploic artery (although this anastomosis is variably developed (Ndoye et al 2006) and may be absent). The right gastroepiploic artery gives off gastric branches that ascend on to the anterior and posterior surfaces of the antrum and lower body of the stomach; epiploic branches that descend into the greater omentum; and branches that contribute to the supply of the inferior aspect of the first part of the duodenum. A rich submucosal and intramural venous network gives rise to veins that usually accompany the corresponding named arteries and drain into either the splenic or superior mesenteric veins, although some pass directly into the portal vein. The course and distribution of the veins is highly variable even up to the level of the major named vessels. Oesophageal arteries originating from the thoracic aorta anastomose with vessels supplying the fundus of the stomach in the region of the cardiac orifice. At the pyloric orifice, the extensive network of vessels supplying the duodenum allows for some anastomosis between branches of the superior mesenteric artery and pyloric vessels derived from arteries arising from the coeliac trunk. The major named vessels left gastroepiploic vein the left gastroepiploic vein drains both anterior and posterior surfaces of the body of the stomach and the adjacent greater omentum via multiple tributaries. It runs superolaterally along the greater curvature, between the layers of the gastrocolic omentum, and drains into the splenic vein within the gastrosplenic ligament. The right gastroepiploic artery has been used for coronary artery revascularization in some centres and this may pose a particular hazard if the patient subsequently requires surgery for gastric cancer. Abnormalities of the intramural vascularity of the stomach are a rare cause of acute upper gastrointestinal haemorrhage. It runs medially along the greater curvature in the upper part of the gastrocolic omentum. Just proximal to the pylorus, it passes posteriorly to drain into the superior mesenteric vein below the neck of the pancreas. A variety of neurotransmitters have been identified within pyloric muscle, including acetylcholine, nitric oxide, enkephalins and vasoactive intestinal polypeptide. Inhibition of the sphincter is mediated by nitrergic fibres whilst basal tone is mostly cholinergic (although it should be noted that many other factors, including acid and luminal nutrients, influence pyloric contraction; Ramkumar and Schulze (2005)). It ascends along the lesser curvature to the oesophageal opening, where it receives several lower oesophageal veins. It then curves posteriorly and medially behind the posterior peritoneal surface of the lesser sac, passing either anterior or posterior to the common hepatic artery. It usually drains into the portal vein at the level of the upper border of the first part of the duodenum, which corresponds to 1­2 cm from the origin of the portal vein (Rebibo et al 2012). In up to one-third of individuals, the left gastric vein terminates in the splenic vein. On rare occasions, it drains into the left portal vein within the liver (Ohkubo 2000), which may be clinically important in portal hypertension. Sympathetic innervation Right gastric vein the right gastric vein is typically small and runs along the medial end of the lesser curvature, passing under the peritoneum as it is reflected from the posterior aspect of the pylorus and first part of the duodenum on to the posterior wall of the lesser sac. It drains directly into the portal vein at the level of the first part of the duodenum. It receives the prepyloric vein as it ascends anterior to the pylorus at the level of the pyloric opening. Rarely, the right gastric vein drains directly into a branch of the portal vein within the liver. The sympathetic supply to the stomach originates from the fifth to twelfth thoracic spinal segments, and is mainly distributed via the greater and lesser splanchnic nerves and the coeliac plexus. Additional innervation comes from fibres of the hepatic plexus, which pass to the upper body and fundus via the lesser omentum and by direct branches from the greater splanchnic nerves. Sympathetic activity causes vasoconstriction, inhibits gastric motility and constricts the pylorus. Afferent sensory pathways, including pain, travel with sympathetic efferent nerves. Parasympathetic innervation posterior gastric veins One or more distinct posterior gastric veins may be present, draining the middle of the posterior surface of the stomach into the splenic vein. They may become particularly prominent in portal hypertension (Kimura et al 1990). In the abdominal oesophagus, the perforating veins drain into tributaries of the left gastric vein, whereas, in the lower thoracic oesophagus, they drain into tributaries of the azygos and hemiazygos systems. Bidirectional flow is possible in this region, and accommodates pressure changes that occur during breathing and Valsalva manoeuvres. Oesophageal and gastric varices are abnormally dilated veins that occur in the submucosal plexus of the distal oesophagus and gastric fundus when portal venous pressure is chronically elevated (typically greater than 15 mmHg). This may develop as a consequence of liver fibrosis or cirrhosis, or portal vein thrombosis, or from a variety of other causes. Portal hypertension leads to the recanalization of occluded embryonic venous channels between venous tributaries of the portal system and the systemic venous circulation. Valves within these veins become incompetent, permitting retrograde flow and causing the development of varices. Gastric varices may also be present on the inferior aspect of the cardiac orifice. Lymphatic drainage the stomach has a rich network of lymphatics that connect with lymphatics draining other viscera within the upper abdomen. At the gastrooesophageal junction, the lymphatics are continuous with those draining the lower oesophagus; in the region of the pylorus, they are continuous with those draining the duodenum and pancreas. Pancreatic and hepatic lymphatics play a significant role in draining the stomach during disease. The anterior vagal trunk (formed mainly from fibres from the left vagus nerve within the oesophageal plexus) is often double or even triple, and supplies filaments to the cardiac orifice. The nerve is closely applied to the anterior surface of the outer muscle of the abdominal oesophagus and usually divides near the gastro-oesophageal junction into gastric, pyloric and hepatic branches (Jackson 1949). Upper gastric branches radiate on the anterior surface of the upper body and fundus but the main gastric branch (also known as the anterior nerve of the lesser curvature or greater anterior gastric nerve) lies in the lesser omentum near the lesser curvature. The hepatic branch runs almost transversely between the peritoneal layers of the lesser omentum towards its free edge to reach the hilum of the liver, where hepatic branches ramify. From here, some fibres descend adjacent to the hepatic artery to supply the pylorus, duodenum and pancreas. An additional pyloric branch often arises from the greater anterior gastric nerve during its course; this runs inferomedially to the pyloric antrum, where it gives off branches to the pylorus before running superiorly to contribute to the hepatic plexus. Variations in the anterior nerve include accessory pyloric branches and high and low courses of the hepatic and pyloric branches in the lesser omentum. The posterior vagal trunk usually lies within loose connective tissue immediately posterior and to the right of the oesophagus. Gastric branches run behind the cardiac orifice and body of the stomach and extend to the proximal antrum, but do not normally reach the pyloric sphincter. The largest gastric branch (also known as the posterior nerve of the lesser curvature or the greater posterior gastric nerve) descends posteriorly near the lesser curvature. The coeliac branch arises from the posterior vagal trunk and carries the majority of fibres contributing to the coeliac plexus. One or two small hepatic branches may also originate from the coeliac division of the nerve. The parasympathetic nerve supply is secretomotor to the gastric mucosa and motor to the gastric musculature. It is responsible for coordinated relaxation of the pyloric sphincter during gastric emptying. However, the majority of fibres within the vagus nerves are afferent; these convey gut sensation, including fullness, nausea and probably pain. Pain arising from the gastro-oesophageal junction is commonly referred to the lower retrosternal and subxiphoid areas. B, Fundal varices seen from within the stomach after retroflexion of the gastroscope. C, Portal gastropathy (gastric antrum) due to venous congestion of the gastric mucosa. Hence, gastrectomy with meticulous lymphadenectomy can be curative in a proportion of patients with gastric cancer and nodal involvement. The extent of potential/actual nodal involvement by the tumour is classified as N1 (locoregional nodes specific to the tumour site); N2 (regional and major named vessel nodes draining the tumour); and N3 (wider-draining nodes, including para-aortic nodes). Gastrectomies can be classified according to the node groups excised with the tumour: D1 (removal of the affected portion of the stomach and en bloc resection of N1 nodes); D2 (total gastrectomy, including all N1 and N2 nodes); and D3 (total gastrectomy plus extensive lymphadenectomy that includes the associated upper abdominal lymph nodes: namely, pancreatic, superior mesenteric, coeliac, hepatic and transverse colic) (Japanese Gastric Cancer Association 1998, Japanese Research Society for Gastric Cancer 1998). The sagittal relationships of the node groups around the neck of the pancreas are shown bottom right. The para-aortic nodes are among the highest nodes for these viscera but have been removed for clarity. Key: A, multiple main trunks; B, low origin of the hepatic/pyloric branch lying close to the lesser curvature. The microstructure reflects the functions of the stomach as an expandable muscular sac lined by secretory epithelium, although there are local structural and functional variations in this pattern. Mucosa the mucosa is a thick layer with a soft, smooth surface that is mostly reddish brown in life but pink in the pyloric region. In the contracted stomach, the mucosa is folded into numerous folds, or rugae, most of which are longitudinal. The rugae represent large folds in the submucosal connective tissue (see below) rather than variations in the thickness of the mucosa covering them, and they are obliterated when the stomach is distended. As elsewhere in the gut, the mucosa is composed of a surface epithelium, lamina propria and muscularis mucosae. Epithelium When viewed microscopically at low magnification, the internal surface of the stomach wall appears honeycombed by small, irregular gastric pits: there are approximately 60 to 100 gastric pits per square millimeter of gastric mucosa, each pit having a diameter of approximately 70 µm and a depth of about 0. The base of each gastric pit receives several long, tubular gastric glands that extend deep into the lamina propria as far as the muscularis mucosae. Simple columnar mucus-secreting epithelium covers the entire luminal surface, including the gastric pits, and is composed of a continuous layer of surface mucous cells that release gastric mucus from their apical surfaces to form a thick, protective, lubricant layer over the gastric lining. This epithelium commences abruptly at the Z line at the cardiac orifice, where there is a sudden transition from oesophageal stratified squamous epithelium. Parietal (oxyntic) cells are the source of gastric acid and of intrinsic factor, a glycoprotein necessary for the absorption of vitamin B12. Parietal cells occur intermittently along the walls of the more apical half of the gland but can reach as far as the isthmus; they bulge laterally into the surrounding connective tissue. They have a unique ultrastructure related to their ability to secrete hydrochloric acid. The latter actively secrete hydrogen ions into the lumen; chloride ions follow along the electrochemical gradient. The mitochondria-rich cytoplasm facing these channels contains a tubulo-vesicular system of abundant fine membranous tubules directed towards the canalicular surface. The precise structure of the cell varies with its secretory phase: when stimulated, the number and surface area of the microvilli increases up to five-fold, probably as a result of the rapid fusion of the tubulovesicular system with the plasma membrane. This process is reversed at the end of stimulated secretion, when the excess membrane retreats back into the tubulo-alveolar system and microvilli are lost. Mucous neck cells are numerous at the necks of the glands and are scattered along the walls of the more basal regions. They are typical mucus-secreting cells, displaying apical secretory vesicles, containing mucins, and basally displaced nuclei; their products are distinct histochemically from those of the superficial mucous cells. Stem cells are relatively undifferentiated mitotic cells from which the other types of gland cell are derived. They are relatively few in number, and are situated in the isthmus of the gland and the bases of the gastric pits. They periodically undergo mitosis; their progeny migrate either apically, to differentiate into new surface mucous cells, or basally, to form mucous neck, parietal, chief or neuroendocrine cells. All of these cells have a limited lifespan, especially the mucus-secreting types, and so they are constantly replaced. The typical replacement period for surface mucous cells is 3 days, and that for mucous neck cells is 1 week. Neuroendocrine (enteroendocrine) cells occur in all types of gastric gland but more frequently in the body and fundus of the stomach. They are situated mainly in the deeper parts of the glands, among the chief cells. They are basally situated, pleomorphic cells and display irregular nuclei surrounded by granular cytoplasm that contains clusters of large (0. Neuroendocrine cells synthesize a number of biogenic amines and polypeptides that are important in the control of gut motility and glandular secretion. Cardiac glands Cardiac glands are confined to a small area near the cardiac orifice; some are simple tubular glands, others are compound branched tubular glands. Mucus-secreting cells predominate; parietal and chief cells are present but sparse. The glands are populated mainly by mucus-secreting cells but they also contain neuroendocrine cells, especially G cells, which secrete gastrin when activated by appropriate mechanical stimulation (causing increased gastric motility and secretion of gastric juices). Although parietal and chief cells are scarce, parietal cells are always present in both fetal and postnatal pyloric glands, and may also appear in the duodenal mucosa, proximally near the pylorus, in adult tissue. Principal gastric glands the principal glands are found in the body and fundus, three to seven opening into each gastric pit. Their junction with the base of the pit is the isthmus; immediately basal to this is the neck; and the remainder is the base.

The first supplies the skin of the radial side of the thumb and the adjoining thenar eminence acne surgery cheap cleocin 150 mg on line, and communicates with branches of the lateral cutaneous nerve of the forearm skin care untuk kulit berminyak buy cheap cleocin 150 mg online. The second supplies the medial side of the thumb; the third skin care natural tips order generic cleocin online, the lateral side of the index finger; the fourth acne bacteria buy generic cleocin 150 mg on line, the adjoining sides of the index and middle fingers skin care tips in urdu order genuine cleocin line. The fifth communicates with a ramus of the dorsal branch of the ulnar nerve and supplies the adjoining sides of the middle and ring fingers, where it is frequently replaced by the dorsal branch of the ulnar nerve. The digital nerves of the thumb reach only to the root of the nail; those in the index finger, midway along the middle phalanx; and those to the middle and the lateral part of the ring finger may reach no further than the proximal interphalangeal joints. The remaining distal dorsal areas of the skin in these digits are typically supplied by palmar digital branches of the median and ulnar nerves. However, the superficial terminal branch of the radial nerve may supply the whole dorsum of the hand. As it crosses the hand, it supplies the interossei and the third and fourth lumbricals. Normally, the median nerve slides smoothly in and out of the carpal tunnel during flexion and extension of the wrist, but when the nerve is compressed, additional damage may be produced during these movements. The dominant hand is usually affected first, probably because this hand is used more frequently and more vigorously. Typically, the syndrome produces pain, paraesthesia and numbness in the thumb, index, middle and medial side of the ring fingers, which is worse at night and on gripping objects. The palmar branch of the median nerve is spared because it does not pass through the carpal tunnel. With time, the compression leads to wasting and weakness of abductor pollicis brevis. Treatment is usually surgical decompression of the nerve by dividing the flexor retinaculum, either as an open procedure or with endoscopic assistance. The most common hazards of decompression are: inadequate decompression because of failure to divide the most distal part of the flexor retinaculum; damage to the motor, or palmar cutaneous, or one or more terminal sensory branches; prolapse of the nerve through the gap in the retinaculum; and damage to the superficial palmar arch causing haematoma, compression, pain and, ultimately, fibrosis or even a late false aneurysm (Birch 2011). Anatomical anomalies of the median nerve occur at the level of the carpal tunnel in up to 12% of hands. The most common are variations in the course of the recurrent motor branch in relation to the flexor retinaculum: transligamentous (23%), subligamentous (31%) or extraligamentous (46%) (Kretschmer et al 2009). Damage may also occur to the palmar cutaneous branch of the median nerve and to the superficial connections between the median and ulnar nerves (the so-called Berrettini branch), division of which will leave the patient with numbness in the middle and ring fingers. Stanci et al (1999) noted that this connection was present in 81% of dissected hands and proposed that it should be regarded as a normal anatomical finding. Median nerve division at the wrist leads to paralysis of the lumbricals to the index and middle fingers and of the thenar muscles (apart from flexor pollicis brevis and adductor pollicis), as well as loss of sensation to the thumb, index, middle and radial half of the ring fingers. The radial half of the hand becomes flattened as a result of wasting of the thenar muscles and the adducted posture of the thumb. Division of the median nerve distal to the origin of its palmar cutaneous branch, which arises somewhere between 3 and 7 cm proximal to the proximal edge of the flexor retinaculum and the distal transverse wrist crease, will leave the branch intact to supply the skin over the thenar eminence and radial side of the proximal part of the hand. Careful clinical examination of the sensibility of the skin in this region should help to clarify the level of the lesion. Causes of compression at this site include a ganglion, trauma, and proximity of aberrant or accessory muscles. The symptoms include pain in the hand or forearm and sensory changes in the palmar aspect of the little and ulnar half of the ring fingers; sensation on the ulnar aspect of the dorsum of the hand is normal. In addition, there may be weakness and wasting of the intrinsic muscles of the hand supplied by the ulnar nerve, with clawing posture in extreme cases. Ulnar tunnel syndrome can be difficult to distinguish from more proximal causes of ulnar nerve compression, of which the most common is entrapment of the nerve in cubital canal at the elbow (Ch. Sensory changes may be present more proximally and, in severe cases, weakness may be noted in flexor carpi ulnaris and the ulnar part of flexor digitorum profundus. In the absence of obvious clinical indicators, local tenderness over the site of compression and nerve conduction studies may aid diagnosis. Ulnar nerve division at the wrist paralyses all the intrinsic muscles of the hand (apart from the radial two lumbricals, abductor pollicis brevis, and part of flexor pollicis brevis and opponens pollicis). The intrinsic muscle action of flexing the metacarpophalangeal joint and extending the interphalangeal joints is lost. The unopposed action of the long extensors and flexors of the fingers cause clawing, with extension of the metacarpophalangeal joints and flexion of the interphalangeal joints. The clawing is less intense in the index and middle fingers because their lumbricals are supplied by the median nerve. The skin over the ulnar aspect of the dorsum of the hand is spared because the dorsal branch of the ulnar nerve is given off approximately 5 cm proximal to the wrist joint. A combined median and ulnar nerve palsy at the wrist results in a full claw hand with thenar and hypothenar flattening and thumb adduction and flexion (a simian hand). The superficial cutaneous branches of the radial nerve are at risk of injury from any procedure or injury in their immediate vicinity. Incisions or injections in or around the radial border of the wrist are particularly implicated. The radial styloid process projects inferiorly from the distal radius along the lateral aspect of the wrist. The posterior aspect of the lower end of the radius is partly obscured by the extensor tendons but is palpable. The tendon of extensor pollicis longus in extensor compartment 3 sits medial to the tubercle, and the tendons of extensors carpi radialis longus and brevis sit lateral to the tubercle in compartment 2. It can be moved over the articular surface of the triquetrum when the wrist is passively flexed. It can be felt on deep palpation, and the superficial division of the ulnar nerve can be rolled from side to side over the tip of the hook. The tubercle of the scaphoid is situated at the base of the thenar eminence, in line with the tendon of flexor carpi radialis and, in many individuals, forms a small, visible elevation. The radial artery lies on its lateral side and crosses the anterior margin of the expanded distal end of the radius, where it is palpable. Palpation lateral to flexor carpi radialis, 3­4 cm proximal to the wrist crease, reveals the muscle belly of flexor pollicis longus (flexing and extending the thumb will confirm that the examining finger is correctly placed). The median nerve is either covered by, or situated just lateral/radial to , the tendon of palmaris longus. Near to the wrist, the median nerve lies very close to the skin and can, therefore, be injured by relatively superficial lacerations. The four tendons of flexor digitorum superficialis lie deep to the median nerve; the tendons to the middle and ring fingers lie anterior to those for the index and little fingers as they pass deep to the flexor retinaculum, and can be felt and usually seen to move during finger flexion/extension. The broad tendon of flexor carpi ulnaris is easily palpated passing to the pisiform on the ulnar side of the anterior wrist; the ulnar nerve, artery and venae comitantes lie along its lateral (radial) edge. Any sharp injury that cuts through the tendon usually has enough energy to sever the ulnar neurovascular bundle. Transverse skin creases cross the palmar aspect of the fingers in three places: the most proximal crease sits at the junction of the digit with the palm and lies approximately 2 cm distal to the metacarpophalangeal joint; the intermediate crease sits opposite the proximal interphalangeal joint; and the distal crease sits just proximal to the distal interphalangeal joint. The first metacarpal is both visible and palpable on the dorsolateral hand; its dorsal aspect forms the lateral border of the hand. The less prominent hypothenar eminence is located on the medial palm and is formed by the comparable muscles of the little finger. The dorsal aspects of the trapezium and of each of the metacarpal bones are partially palpable around the margins of the corresponding extensor tendons. The heads of the metacarpal bones form the prominences of the knuckles and are most obvious during digit flexion. On the dorsal hand, the metacarpophalangeal joint line forms a palpable depression lateral to the digital extensor tendon, and alternating digit flexion/extension aids identification. Palpation distal to the metacarpal head reveals the flared base of the corresponding proximal phalanx. Its proximal border is marked by a curved line, concave superiorly, which joins the tubercle of the scaphoid to the pisiform. Flexion of the wrist produces a number of transverse skin creases (usually two, sometimes three) at the wrist. The dominant, most distal, wrist crease normally sits distal to the lunate and overlies pisiform and the proximal edge of the flexor retinaculum. A horizontal line, approximately 4 cm long and running from a point just distal to the hook of the hamate, indicates the position of the deep palmar arterial arch. The snuff-box is bounded on its anterolateral (radial) side by the tendons of abductor pollicis longus (laterally) and extensor pollicis brevis (immediately medial), and on its posteromedial/ulnar side by the tendon of extensor pollicis longus. Running a finger along extensor pollicis brevis enables palpation of the superficial radial nerve, which can be rolled from side to side on the tendon. The cephalic vein passes through the roof of the snuff-box, where it is visible and palpable, and the pulsation of the radial artery can be palpated deeply on its floor. Three bones are palpable distal to the radial styloid process along the floor of the anatomical snuff-box: the convex, ovoid proximal articular surface of the scaphoid (best palpated during alternating wrist abduction/adduction), the radial aspect of the trapezium and the expanded base of the first metacarpal. The first carpometacarpal joint forms a palpable depression distal to the trapezium. When wrist stability is clinically assessed throughout its range of movements, the scaphoid may be compressed bidigitally, between index finger and thumb, along its oblique long axis between the tubercle and articular surface. Similarly, the trapezium may be compressed between its tubercle and radial aspect. Compartment 1 (containing abductor pollicis longus and extensor pollicis brevis) sits over the lateral radius. Compartment 4 (containing extensors digitorum and indicis) sits between the ulnar head and compartment 3. The tendons of extensors carpi radialis longus and brevis can be identified on the dorsal carpus when the fist is clenched and relaxed. The tendons of extensor digitorum are visible and palpable on the dorsal hand with the fingers fully extended. Note the course of the terminal branches of the superficial radial nerve and the lateral cutaneous nerve of the forearm. A review of the surface and intra-articular anatomy of the wrist, the technique of establishing a safe portal and the specific uses of the radiocarpal, metacarpal and special-use portals. It notes that a dorsal approach to the scaphoid bone is possible as there is an available blood supply from the palmar circulation. A chapter describing the various ways in which surgeons and others can injure the peripheral nerves of the body. Costa H, Pinto A, Zenha H 2007 the posterior interosseous flap ­ a prime technique in hand reconstruction. Echigo A, Aok M, Ishiai S et al 2008 the excursion of the median nerve during nerve gliding exercise: an observation with high-resolution ultrasonography. Kretschmer T, Antoniadis G, Richter H-P et al 2009 Avoiding iatrogenic nerve injury in endoscopic carpal tunnel release. An anatomical study of 12 cadaver hands which demonstrates a variety of vascular anastomoses around the scaphoid. Petrie S, Collins J, Solomonow M et al 1997 Mechanoreceptors in the palmar wrist ligaments. The closed traction lesion of the supraclavicular brachial plexus is amongst the worst of all peripheral nerve injuries because of the frequent association with injury to the spinal cord and the usual complication of severe pain. There is one common element: the violent distraction of the forequarter from the head, neck and chest so that the angle between the head and the shoulder is opened. These are often injuries of great violence and motor cyclists in high-speed accidents are particularly at risk. Associated injuries to the head, spine, chest, abdomen, pelvis, long bones and subclavian artery are common. The most common site of nerve lesion lies within the spinal canal, affecting the intradural segments of the spinal nerves. These injuries are called preganglionic because the lesion lies between the dorsal root ganglion and the spinal cord. This concept of pre- and postganglionic injury, introduced by Bonney in 1954, is fundamental to diagnosis and treatment. The preganglionic injury is the most common lesion because the union of the ventral and dorsal roots is the weakest link in the long chain between the central nervous system and the periphery. In one series of 200 patients operated on between the years 2000 and 2004, 429 spinal nerves sustained preganglionic rupture, 223 were postganglionic ruptures and the remaining 298 spinal nerves were intact or recovering. The fifth and sixth cervical nerves are somewhat protected by proximal branches to such nerves as the phrenic and long thoracic, and also by the transverse radicular ligaments. The vulnerability of C8 and T1 is enhanced by the increasing obliquity of the roots in the spinal canal and the angulated course of T1. The abrasion at the tip of the shoulder marks the point of impact against a roadside kerb. The nerve tissue at the site of the rupture showed no central nervous system features. The tip is covered by organized blood clot and erythrocytes that interweave with fibrin strands. Note the dorsal root ganglion, the dural sleeve merging into the epineurium, and the spinal nerve itself. The small pieces of tissue on the proximal ends of the dorsal rootlets (below) are probably portions of the spinal cord. A, A traction lesion of the brachial plexus accompanied by rupture of the subclavian artery; there was a weak pulse. At operation, 54 hours after injury, stimulation of the avulsed ventral roots of C7, 8 and T1 evoked strong contraction in the relevant muscles distally. This showed that there was neither critical ischaemia within the limb nor a second, more distal, lesion. B, Strong somatosensory evoked potentials were recorded through electrodes placed over the scalp, by stimulation of the postganglionic ruptured stumps of C5 and C6 (1). The dorsal root ganglia of C7, 8 and T1 (2) and their ventral roots (3) are shown.

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Analysis acne popping order generic cleocin on-line, history and precise clinical examination usually permit an accurate diagnosis of the extent and the level of the neurological injury acne zapper zeno purchase cleocin uk. History An understanding of the axis of application of force to the injured limb is very important skin care untuk kulit berminyak discount 150 mg cleocin visa. A description from witnesses or the patient of the shoulder being violently arrested by an object ­ stone acne research 150 mg cleocin amex, tree skin care websites order cleocin 150 mg on line, kerb or vehicle ­ while the body is flying through the air confirms that there has been violent stretching of the structures in the posterior triangle of the neck. Pain Severe pain within a paralysed and anaesthetic limb indicates very serious injury to the spinal nerves. It may be constant, described as crushing, burning or intense pins and needles, and is usually felt in the forearm and hand. Two-thirds of conscious patients who developed such pain did so on the day of injury. More than one-half of conscious patients experienced this pain on the day of injury (Birch 2011b). Inspection Inspection of the limb may reveal linear cuts and abrasions passing from the face to the shoulder, indicating distraction of the limb when injury was sustained. Deep bruising is an important sign of tearing of prevertebral muscle or even of the subclavian artery. Increasing swelling in the posterior triangle indicates a collection of spinal fluid, either from nerves avulsed from the spinal cord or from an expanding haematoma, or both. A degenerate efferent myelinated fibre (right) compared to a non-degenerate afferent myelinated fibre (left). C4 innervates the skin of the outer aspect of the shoulder; T2 innervates the skin of the inner aspect of the arm. When these extend down the outer arm and proximal forearm, then rupture of C5 is likely. When they extend to the lateral aspect of the forearm and thumb, then a similar lesion of C6 may be anticipated. Percussion over a rupture of C7 evokes sensations into the dorsum of the hand; that over a rupture of the lower trunk evokes sensations in the inner aspect of the forearm and little fingers. It is important to advise the Investigations Radiological and imaging studies confirm or modify the clinical diagnosis, but they may also confirm or reveal associated injuries to the spinal column, the spinal cord and the chest. Plain radiographs confirm elevation of the ipsilateral hemidiaphragm and may show tilting of the cervical spine away from the side of injury, which is often associated with fracture or dislocation of the first rib. However, the incidence of injury to the subclavian artery in the operated cases remains steady over this time at about 10%. Complete lesions accounted for 141 of the cases; 52 patients sustained preganglionic injury to all five spinal nerves. Over the years, there has been a modest Treatment the direct object of treatment is rehabilitation. The return of fluid and coordinated muscle action, and of the biceps tendon jerk, suggests some regeneration into the deep afferent pathway, perhaps through myelinated afferent fibres in the ventral root. Pain relief One of the most pleasing aspects of surgical endeavour has been the finding that reinnervation of muscle is regularly successful in improving pain and this is a strong indication for securing reinnervation of a limb, no matter how limited, in even the most severe injuries (Berman et al 1996, Berman et al 1998, Kato et al 2006; see Birch 2011a, Birch 2011b, Birch 2011c). Function is shown at 96 months after repair: wrist extension was regained by transfer of flexor carpi ulnaris to extensor carpi radialis brevis. Function is shown at the shoulder and elbow 11 years after reimplantation of the ventral roots of C5, C6 and C7. Bonney G 1954 the value of axon responses in determining the site of lesion in traction lesions of the brachial plexus. Kato N, Htut M, Taggart M et al 2006 the effects of operative delay on the relief of neuropathic pain after injury to the brachial plexus. Schenker M, Birch R 2000 Intact myelinated fibres in biopsies of ventral spinal roots after preganglionic traction injury to the brachial plexus. Schenker M, Birch R 2001 Diagnosis of the level of intradural rupture of the rootlets in traction lesions of the brachial plexus. The lumbosacral plexus is at risk in fracture dislocations of the sacroiliac joints, especially when fractures extend into the sacral foramina. The anatomical arrangements of some of the peripheral nerves make them particularly vulnerable to damage from musculoskeletal injury. Fractures and dislocations In the upper limb, the cords of the brachial plexus and the axillary vessels pass in a space bounded by subscapularis (deep) and pectoralis minor (superficial). Anterior displacement of the humeral head or bone fragments forces the nerves and vessels against the deep surface of pectoralis minor, which acts as a guillotine. The proximity to bone of all three main nerves at the elbow renders them vulnerable to skeletal injuries. Tethering of nerves In the upper limb, the axillary nerve runs in loose fatty tissue in its course anterior to subscapularis. When it turns around that muscle, it enters a quadrilateral tunnel formed by the union of the fasciae of subscapularis cranially, teres major caudally and coracobrachialis laterally, which surrounds the nerve and the posterior circumflex vessels. This arrangement puts the nerve at risk during anterior dislocation of the head of the humerus and the frequent complication of bleeding from the posterior circumflex vessels, which strangles the nerve. The radial nerve is at risk from fractures of the shaft of the humerus between the two relatively fixed points of the nerves to the lateral head of triceps and the tunnel through the lateral intermuscular septum. In the lower limb, the common fibular nerve, which passes above or through piriformis in as many as 30% of cases, is tethered above in relation to piriformis and below at the neck of the fibula. The fascia surrounding biceps femoris and its tendon sweeps around to embrace the nerve; in dislocation of the knee, the muscle frequently avulses the tip of the head of the fibula and is displaced anteriorly, pulling the nerve with it. The deep fibular nerve passes rather acutely forwards to enter the anterior compartment of the leg. The ulnar nerve is accompanied by the ulnar artery in a discrete fascial compartment in the distal two-thirds of the forearm. The deep fibular nerve is accompanied by the anterior tibial artery, an end artery, throughout most of the anterior compartment of the leg; occlusion of this artery causes death of the nerves and muscles of the anterior compartment. Collateral circulation Fascial arrangements Sleeves of fascia surround main nerves and main vessels in some regions, an arrangement that predisposes the nerves to injury from ischaemia and compression from bleeding. After the ventral primary rami of C7, 8 and T1 enter the posterior triangle of the neck, they are enclosed in quite a rigid space bounded posteriorly by the dorsal part of the first rib, the transverse processes of the cervical vertebrae and the fascia of levator scapulae. The nerves are embraced by scalenus anterior and scalenus medius, both of which are invested in an unyielding fascia (this is one envelope of the prevertebral fascia that also serves to bind the phrenic nerve down to the anterior face of scalenus anterior). The prevertebral fascia is particularly well developed anterior to the vertebral column and at the base of the posterior triangle, where it envelops the ventral primary rami of C7, 8 and T1, the phrenic nerve, the cervical sympathetic chain, and subclavian and vertebral arteries. The medial brachial fascial compartment extends from the axilla to the elbow and is bounded by the tough medial intramuscular septum and the axillary sheath. The collateral circulation at the elbow depends on vessels that run with the three main nerves. This network may maintain an adequate supply to the hand and the extensor muscles of the forearm after acute loss of flow through the brachial artery if there is no associated fracture dislocation. The situation is much worse if the ulnar or radial nerves, with their accompanying vessels, are displaced into a fracture or compressed by haematoma. Acute loss of flow through the popliteal artery, unless urgently restored, invariably leads to extensive death of muscle and nerve, and often to amputation. Two attempts to occlude the torn posterior circumflex artery by interventional radiology failed. He was seen at 8 weeks, by which time he was in right heart failure and in great pain; he had a complete infraclavicular plexopathy on the left side. B, the muscles of the deep flexor compartment were fibrosed, causing severe clawing of the toes. Several different entities are grouped under this one heading but they have little in common beyond the presumed site of the lesion. The lower part of the brachial plexus, and the lower trunk in particular, joined at the first rib by the subclavian vessels, run a regular obstacle course on their way to the lower borders of pectoralis minor. The extent of the rib, which is rarely symmetrical bilaterally, ranges from a prolongation and pointing of the seventh cervical transverse process to a complete rib in all respects like a first thoracic rib. Scalenus minimus is the muscle that sometimes replaces the deep or posterior part of the membrane; it may be up to 10 mm in diameter in its widest part but is usually much smaller than that. The posterior border of the membrane forms, with the edge of the first rib, the foramen through which the first thoracic nerve escapes. In the healthy state, the apical pleura is easily separable from the head and neck, and most of the underside of the first rib; anteriorly, it becomes rather adherent to the underside of the rib, in relation to the costochondral junction. The upper portion of the nerve to serratus anterior is usually formed in scalenus medius by branches from the ventral primary rami of C4, 5 and 6; it emerges from the lateral surface of the muscle to be joined by a contribution from C7. Anterior to scalenus medius, the surface of the rib is, in the adult, grooved by the passage of the ventral primary ramus of T1 and the lower trunk of the brachial plexus. There is a distinct tubercle at the attachment of scalenus anterior; the subclavian artery lies in a slight depression posterior to the tubercle, and the subclavian vein runs over the upper surface of the rib anterior to the tubercle. The major part of the ventral primary ramus of T1 is at first below the rib, then medial to its edge. The preganglionic (sympathetic) ramus of T1 connects it to the stellate ganglion; the postganglionic ramus is less noticeable. The size and disposition of scalenus anterior vary: it may bifurcate to include the artery; it may be bulky and its tendon may curve posteriorly round the artery to form a kind of snare. The phrenic nerve, chiefly derived from the ventral primary ramus of C4, curves round the muscle to run down anterior to it into the thorax, lying, at first, posterior to the internal jugular vein and crossing behind the subclavian vein. The thoracic duct and the right lymphatic duct enter the brachiocephalic (innominate) vein at the subclavian­jugular (triradiate) junction on the left and right, respectively. Bridges of muscle and fascia may pass between them, altering and diminishing the space available for the neurovascular bundles. A, the right lower trunk is trapped between the aponeurotic edge of scalenus medius posteriorly and the suprapleural membrane anteriorly. The left lower trunk passes over the edge of the sickle and behind the part of scalenus anterior that passes posterior to the subclavian artery. Coote (1861) reported the removal of a left seventh cervical rib causing aneurysm of the subclavian artery. Two physicians, Lewis and Pickering (1934), pointed to the mechanism of production of the arterial lesion, namely: intimal breakage with local thrombosis and distal embolization. The vessel is distorted by the bone and constricted by a leash formed by the tendon of insertion of scalenus anterior. There is commonly dilation of the artery distal to the point of constriction, and the dilation may proceed to the formation of a true aneurysm (Wickham and Martin 1962). Complete obstruction of the main vessel with distal embolization may lead to critical ischaemia. The most dangerous complication is contralateral hemiplegia, doubtless from embolization from a thrombus extending proximally to the carotid vessel (Symonds 1927). The arterial form of this outlet syndrome is a condition predominantly affecting young women; the occurrence of such symptoms in older individuals must suggest a primary diagnosis of atherosclerosis or other systemic disorder. The extremity may be cooler than the unaffected limb and there is likely to be a pulse difference, even the absence of a pulse. Even if the hands are the same colour at rest and slightly dependent, there is likely to be blanching of the affected hand on elevation. The artery is prominent, displaced upwards and anteriorly by the underlying rib; there is a loud Thoracic outlet syndromes bruit and there may be a thrill. Doppler ultrasound examination is likely to show an abnormality: principally, a clamped, monophasic velocity signal anywhere over the arterial tree of the upper limb (Parry and Eastcott 1992). Operation is required urgently in cases of critical ischaemia, and soon in cases in which ischaemia is threatened. It may be indicated when a cervical rib is present, causing no symptoms but producing deformity of the subclavian artery sufficient to cause a steady bruit over the vessel, which must surely indicate distortion of the vessel that is likely, in time, to cause intimal breakage and thrombosis. The bruit from a prominent subclavian artery associated with an underlying seventh cervical rib cannot be ignored and investigations need to be pursued to define the extent of distortion of the artery. The confusion was not resolved for more than 40 years until the application of nerve conduction studies defined the much more common disorder. Gilliatt put the annual incidence of cervical rib syndrome with muscle wasting as low as 1 in 1 million in the general population. The patients are usually young to middle-aged women and the abnormalities are usually confined to one upper limb. The symptoms are insidious and often mild; presentation is delayed for some years, and is usually occasioned by the sudden realization that the hand has become wasted. There is pain in the medial aspect of the forearm and there may also be some blunting of sensibility in that area and in the little finger. The latter is frequently shorter than it is in a normal, age-matched hand, suggesting that the affliction of the fibres in the lower trunk commenced before skeletal maturity. A, Severe wasting of the intrinsic muscles of the right hand in a 35-year-old woman. When the nerve was first exposed at operation, the zone of attenuation was, in fact, at the site of angulation. B, Complete occlusion at the thoracic outlet in a 40-year-old woman, a heavy smoker. Radiographs of the neck show rudimentary cervical ribs or elongated transverse processes of the seventh cervical vertebrae. The diagnostic electrophysiological findings were characterized by Gilliatt, Le Quesne and Logue in 1970 and include a small or absent sensory response in the ulnar nerve and the medial cutaneous nerve of the forearm; a normal sensory response in the median nerve; an attenuated compound motor action potential amplitude from abductor pollicis brevis; and a low-amplitude ulnar motor response (Smith and Knight 2011). Operation is indicated in these patients in the expectation of alleviation of pain, improvement in sensation and some improvement in strength; recovery of the wasted small muscles of the hand is rare. The urge to advise operation should be tempered with knowledge of the possibility of complications and the high rate of recurrence of symptoms as time passes (Birch 2011). Coote H 1861 Exostosis of the left transverse process of the seventh cervical vertebra, surrounded by blood vessels and nerves, successful removal. Pseudoglandular phase (5­17 weeks: development of airways and blood vessels to level of acinus).

A hookshaped process of bone skin care options ultrasonic cleocin 150 mg order with visa, the supracondylar process acne refresh 080 discount cleocin 150 mg line, ranging from 2 to 20 mm in length cystic acne purchase online cleocin, occasionally projects from the anteromedial surface of the shaft acne scar treatment discount cleocin 150 mg amex, approximately 5 cm proximal to the medial epicondyle korean skin care generic cleocin 150 mg buy. It is curved downwards and forwards, and its pointed apex is connected to the medial border, just above the epicondyle, by a fibrous band, to which part of pronator teres is attached. The foramen completed by this fibrous band usually transmits the median nerve and brachial artery, but sometimes encloses only the nerve, or the nerve plus the ulnar artery (in cases of high division of the brachial artery). Its proximal third forms the lateral lip of the intertubercular sulcus and is roughened for muscular attachments. The succeeding portion is also roughened and forms the anterior limit of the deltoid tubercle; the lower half of the border is smooth and rounded. Bones the lateral border is most conspicuous at the lower end of the bone, where it is thickened to form the lateral supracondylar ridge, and its sharp edge is roughened along its anterior aspect. In its middle and upper thirds, the border is barely discernible, but in a wellmarked bone it can be traced upwards to the posterior surface of the greater tubercle. A little above its middle, it is marked by a Vshaped, roughened area: the deltoid tubercle. The limbs of the V are broad; the groove for the radial nerve runs downwards and laterally behind the posterior limb and fades away on the lower part of the anterolateral surface. The lateral intermuscular septum is attached to the lateral border, and is a condensation of the fascia over the lower part of deltoid and the neigh bouring brachialis, forming a septum between the anterior and poste rior muscular compartments. The septum is most obvious in the lower threefifths of the arm, and is perforated by the radial nerve and accom panying vessels. Lateral border Fractures of the humeral shaft Humeral shaft fractures are common; the pattern of the fracture and the displacement of the fragments depend on the force of injury and on the level at which the bone is broken. If there is wide displacement at the time of fracture, closely associated nerves and vessels are at risk of direct injury. The centre for the shaft appears near its middle in the eighth week of intrau terine life, and gradually extends towards the ends. Ossification begins in the head before birth (20%) or in the first 6 months afterwards; the greater tubercle starts to ossify during the first year in females and second year in males; the lesser tubercle begins to ossify at about the fifth year. By the sixth year, the centres for the head and tubercles have joined to form a single large epiphysis, hollowed out on its inferior surface to adapt to the conical upper end of the metaphysis. This macroscopic topography provides for mechanical stability in the physis during Fuse at sixth year Medial border the medial border, although rounded, can be identified without diffi culty in the lower half of the shaft, where it becomes the medial supra condylar ridge. In its proximal third, the medial border is indistinct until it broadens out to form a triangular area. The lateral border of this area forms the medial lip of the intertubercular sulcus, and the medial border runs upwards as the calcar humerale to the anatomical neck, where it is roughened, with vascular apertures, and forms the area of attachment of the inferior part of the shoulder capsule. In its middle third, the medial border is interrupted by a wide, shallow groove, the radial (spiral) groove that crosses the bone obliquely, passing down wards and forwards from its posterior to its anterior surface. The joint on the left side is intact and the joint on the right side is shown in coronal section. The proximal humeral epiphysis fuses with the shaft of the humerus at about the thirteenth or fourteenth year in females, begin ning on the medial aspect of the physial line, and between the four teenth to sixteenth year in males. Costoclavicular ligament the costoclavicular ligament is like an inverted cone, but short and flattened. It has anterior and posterior laminae that are attached to the upper surface of the first rib and costal cartilage, and ascends to the margins of an impression on the inferior clavicular surface at its medial end. They fuse laterally and are closely related to the attachments of subclavius, particularly the tendon of origin; it can be hard to distinguish the lateral border of the ligament from the tendon. A few deep fibres of pectoralis major attach to the external surface of the ligament, adjacent first rib, first costal cartilage and manubrium sterni. It is the only skeletal articulation between the upper limb and the axial skeleton (Sewell et al 2013). The larger clavicular articular surface is covered by fibrocartilage, which is thicker than the fibrocartilaginous lamina on the sternum. The joint is convex vertically but slightly concave anteroposteriorly, and is there fore sellar; the clavicular notch of the sternum is reciprocally curved but the two surfaces are not fully congruent. Articular disc the fibrocartilaginous articular disc divides the cavity of the joint into two compartments between the sternal and clavicular surfaces. It is attached above to the posterosuperior border of the articu lar surface of the clavicle, below to the first costal cartilage near its sternal junction, and by the rest of its circumference to the capsule, and therefore adapts to the contour of the clavicular surface. It is thicker peripherally, especially superoposteriorly and inferomedially; the central part of the disc may be perforated in later life. Fibrous capsule the capsule is thickened anteriorly and posteriorly, but superiorly and especially inferiorly, it is little more than loose areolar tissue. The intrinsic ligaments are the anterior and posterior sternoclavicular ligaments; the extrinsic ligaments are the midline interclavicular ligament and the costoclavicular ligaments on each side. Anterior sternoclavicular ligament the anterior sternoclavicular liga ment is broad and attached above to the anterosuperior aspect of the sternal end of the clavicle. It passes inferomedially to the upper anterior aspect of the manubrium, spreading on to the first costal cartilage. Posterior sternoclavicular ligament the posterior sternoclavicular ligament is a weaker band posterior to the joint. It descends inferomedi ally from the posterior aspect of the sternal end of the clavicle to the posterior aspect of the upper manubrium. Vascular supply the sternoclavicular joint is supplied by branches from the internal thoracic and suprascapular arteries. Innervation the sternoclavicular joint is innervated superficially by branches from the medial supraclavicular nerve and deeply by the nerve to subclavius. Factors maintaining stability There is almost no bony articular congruence at the sternoclavicular joint. However, the strength of its associated ligaments and the articular disc produce durable stability. These factors make sternoclavicular joint dislocation rare; fracture of the clavicular shaft is far more common for the same force directed along the clavicle. Movements between the clavicle and the disc are more extensive than those between the disc and sternum. The sellar shape of the articu lar surfaces permits translation or gliding in approximately anteropos terior and vertical planes, with rotation about the long axis of the clavicle. Closepacking coincides with maximum posterior rotation associated with full scapular rotation, i. It unites the superior aspect of the Joints In this position, the tension developed in the anterior sternoclavicu lar ligament and anterior component of the costoclavicular ligament causes the clavicle to undergo an obligatory posterior translation. It also acts as a checkrein on further rotation and displacement, so protecting the relatively weaker posterior sternoclavicular ligament from overload. The common innervation of the sternocla vicular joint (the deep afferent­mechanoceptor system) and subclavius suggests an intimate functional relationship between these structures. In daily activities, in which the upper limb is used largely in front of the trunk, the sternal end of the clavicle glides on the sternal facet about the fulcrum provided by the costoclavicular ligament. All joints in which polyaxial gliding occurs, producing shear forces (rotation with translation), possess either intraarticular synovial bursae or intra articular fibrocartilaginous discs; the latter degenerate over time, pro ducing characteristic exophytic degenerative arthritis. In this context, it is interesting that degeneration of the sternoclavicular joint and ossifica tion of the costoclavicular ligaments (claviculocostal synostosis) are almost exclusively found in females above the age of 50 years. The intrinsic ligaments are the acromioclavicular ligaments; the extrinsic ligaments are the coracoclavicular ligaments. Acromioclavicular ligaments the superior acromioclavicular ligament is quadrilateral. It extends between the upper aspects of the lateral end of the clavicle and the adjoining acromion. The inferior acromio clavicular ligament is thin, and often perforated in later life; it extends between the inferior surface of the lateral end of the clavicle and the adjoining acromion. It provides attachment for the intraarticular disc when this is present and complete. Though separate from the acromioclavicular joint, it is an efficient and impor tant accessory ligament because it helps to maintain the apposition of the acromion to the clavicle, and so contributes to the suspension mechanism of the scapula (see above). The trapezoid and conoid parts of the ligament, usually separated by fat or, frequently, by a bursa, connect the posterior (more horizontal) part of the coracoid process and the lateral end of the subclavian groove of the clavicle: these adja cent areas may even be covered by cartilage to form a coracoclavicular joint. The trapezoid part is anterolateral and is broad, thin and quadrilat eral, ascending slightly from the upper coracoid surface to the trapezoid line on the inferior clavicular surface. Its anterior border is free, and its posterior border is joined to the conoid part, forming an angle that projects backwards and upwards. Quadrilateral ligaments twist when the adjoined bones rotate with respect to each other, and as they twist, the apposed surfaces must approach each other; such ligaments, there fore, act to oppose excessive rotation of the adjoining bones. The conoid part is posteromedial and is a dense, almost vertical, triangular or conical band. The joint is approximately plane but either surface may be slightly convex, the other being reciprocally concave; both surfaces are covered by fibrocartilage. The clavicular surface is a narrow, oval area that faces laterally or inferolaterally and overlaps a corresponding facet on the medial acromial border. Conical ligaments are constructed to oppose distraction; the conoid ligament, therefore, helps to keep the coracoid and the clavicle closely apposed. If the trapezoid ligament is disrupted, the conoid ligament forms a vertical fulcrum around which the cora coid can rotate under the clavicle, particularly if the acromioclavicular ligaments are also disrupted. This is the anatomical basis for the spec trum of acromioclavicular joint dislocation. Articular disc the articular disc is a complete fibrocartilaginous partition in juvenile and adolescent joints, creating medial and lateral compartments; over time, the centre of the disc perforates, and in adults (more than 20 years old), it is often incomplete inferiorly. Scapular movements on the thoracic wall are facilitated by loose areolar tissue between subscapularis and serratus anterior, and between serratus an terior and the chest wall; the latter gliding plane is the scapulothoracic joint. There may be a bursa between the superior angle of the scapula and the dorsal aspect of the second rib. The following account should be read together with the description of movements of the glenohumeral joint. It is important to keep in mind the fact that the purpose of scapular motion is the appropriate positioning of the glenohumeral joint in space, and the purpose of scapular stability is to provide a foundation for glenohumeral motion. The sternal end of the clavicle, rotating about an anteroposterior axis through the bone above the medial attachment of the costoclavicular ligament, slides down over the articular disc. This is resisted by subclavius and by tension in the costoclavicular ligament and sternoclavicular joint capsule. In scapular depression, ventral rotation occurs at the acromioclavicular joint, and the clavicle slides up on the disc at the sternoclavicular joint. The move ments are checked by the cervical fibres of trapezius, the interclavicular and superior sternoclavicular ligaments and the articular disc. Usually, gravity alone is sufficient; when necessary, the lowest part of serratus anterior and pectoralis minor are active depressors. Vascular supply the acromioclavicular joint receives its arterial supply from branches of the suprascapular and thoracoacromial arteries. Innervation the acromioclavicular joint is innervated by branches from the suprascapular and lateral pectoral nerves. It has been suggested that the density of nociceptors is greatest in the inferior acromioclavicu lar ligament and capsule. Factors maintaining stability the acromioclavicular ligaments provide the greatest resistance to anteroposterior displacement of the acromioclavicular joint, while the coracoclavicular ligaments resist rota tion and vertical translation of the joint. The sternal end of the clavicle is robustly supported by strong ligaments, and a similar, but less robust, arrangement of ligaments suspends the scapula from the lateral end of the bone. The motion of the acromioclavicular joint is limited by its small surface area and the articular capsule. Protraction and retraction Protraction (forward movement) round the thoracic wall occurs in pushing, thrusting and reaching movements, usually with some lateral rotation. The lateral (acromial) end of the clavicle describes an asymmetric conical path during motion of the upper extremity. The maximal range of rotation of the clavicle (subtended by the sternoclavicular joint) is 30°; the maximal range of rotation of the scapula (sternoclavicular and acromioclavicular joints combined) is about 60° with respect to the sternum. The scapula is suspended from the distal clavicle at the acromioclavicular joint, which can be considered as the true joint (the cavity bounded by the acromioclavicular capsule and ligaments); it is also part of an extended articulation that comprises the true joint and the coracoclavicular suspensory ligaments. Arguably, the ligaments might be better 10 defined as the claviculocoracoid ligaments, to acknowledge their role as the spiroid fulcrum around which the body of the scapula, and therefore the glenoid fossa, rotate during protraction and retraction of the scapula. The action of subclavius is to resist upward displacement of the distal clavicle, or to decelerate the clavicle moving into elevation. The antagonist of trapezial power is pectoralis minor, which, rarely, has an extension or slip of tendon that joins the coraco-acromial ligament. If surgically divided, Trapezius the cut surfaces of the coraco-acromial ligament cannot be readily reapposed, suggesting a mechanical role in pre-tensioning the acromion and coracoid against the pull of trapezius. Shortening or tightness of pectoralis minor will create fixed protraction of the scapula, which then rotates ventrally around the chest wall. As a consequence, the acromion tilts and the space between it and the cranial surface of the rotator cuff below (the subacromial space) diminishes, creating the conditions in which forceful coaptation of the apposed surface of the rotator cuff and the coraco-acromial ligament may occur. Coraco-acromial ligament Coracoclavicular ligament Subclavius Pectoralis minor over the sternal facet, carrying the disc with it. Pectoralis major, together with the anterior sternoclavicular ligament and posterior lamina of the costoclavicular ligament, check backward slide of the sternal end. Ser ratus anterior and pectoralis minor are prime movers and maintain continuous apposition of the scapula, especially its medial border, in smooth gliding on the thoracic wall, with the rhomboid muscles con trolling the rate and range of motion. The upper part of latissimus dorsi also acts like a strap across the inferior scapular angle in protraction and lateral rotation. This movement is always associ ated with humeral elevation and rotation at the glenohumeral joint, and with protraction of the scapula. Scapular rotation requires move ment at both sternoclavicular and acromioclavicular joints; the sterno clavicular joint permits elevation of the lateral end of the clavicle, a movement that is almost complete when the arm is abducted to 90°.

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