Dudley Robinson MBBS MD MRCOG

• Consultant Urogynaecologist/Honorary Senior Lecturer,
• Department of Obstetrics and Gynaecology, King? College
• Hospital, London

The shape of the articular surfaces ensures that flexion is always accompanied by medial rotation blood pressure medication lack of energy coreg 6.25 mg purchase otc, and extension by lateral rotation blood pressure medication morning or evening order coreg in united states online. One of the most specific thumb movements is that of opposition blood pressure medication valsartan purchase coreg with visa, in which the tip of the thumb is brought into contact with the tips of the fingers blood pressure bracelet cheap coreg online american express. It requires a combination of flexion blood pressure medication young adults buy generic coreg 12.5 mg, medial rotation and adduction of the thumb, and is very much a human attribute: the carpometacarpal joints of the fingers are synovial plane joints. The second and third are less mobile than the fourth and fifth, and all are less mobile than that of the thumb; the metacarpal heads articulate with the cupped bases of the proximal phalanges. Superficial veins and cutaneous nerves lie in the superficial fascia, the terminal branches of the radial nerve crossing the tendon of abductor pollicis longus. Beneath it pass the long extensor tendons and their synovial sheaths, each being retained by fibrous septae within fibro-osseous tunnels. Flexion/medial rotation ­ flexor pollicis longus and brevis and opponens pollicis Extension/lateral rotation ­ abductor pollicis longus and extensor pollicis longus and brevis Abduction ­ abductor pollicis longus and brevis Adduction ­ adductor pollicis Opposition ­ opponens pollicis. The metacarpophalangeal joints the metacarpophalangeal joints are synovial joints, the metacarpal heads articulating with the cupped bases of the proximal phalanges. Flexion, extension, abduction and adduction and circumduction are possible, except for the thumb, whose metacarpophalangeal joint is limited to flexion and extension: Flexion ­ long digital flexors and flexor pollicis longus, assisted by the interossei, lumbricals, flexor pollicis brevis and flexor digiti minimi Extension ­ in the fingers, extensor digitorum, extensor indicis and extensor digiti minimi; in the thumb, extensor pollicis longus and brevis Abduction ­ in the fingers, the dorsal interossei and abductor digiti minimi; in the thumb, abductor pollicis longus and brevis Adduction ­ palmar interossei and adductor pollicis. Its proximal apex is continuous with the flexor retinaculum and receives the attachment of the tendon of palmaris longus; distally its base divides into four digital slips, which bifurcate around the long flexor tendons to be attached to the deep transverse ligaments of the palm. Its cause is unknown, but it results in shortening and thickening of the digital bands, which then pull the fingers into flexion, especially the ring and little fingers. Eventually the metacarpophalangeal and proximal interphalangeal joints become permanently flexed. Medially it is attached to the pisiform and hamate, and laterally to the scaphoid and trapezium. Thenar and hypothenar muscles arise from its superficial surface, and the ulnar artery and nerve and its palmar branches cross it. Beneath it the carpal tunnel conveys the long flexor tendons, the radial and ulnar bursae and the median nerve and its digital branches. Whenever the size of the tunnel is reduced, as it may be following the tissue swelling of rheumatoid arthritis or pregnancy, symptoms are produced by compression of the median nerve deep to the retinaculum (carpal tunnel syndrome). Compression of its cutaneous digital branches produces pain, tingling (paraesthesia) and anaesthesia over the lateral 3½ digits. If the motor branches are affected then weakness, eventual paralysis and wasting of those small muscles of the hand supplied by the median nerve results. There will be progressive loss of coordination and strength in the thumb, and a loss of muscle bulk in the thenar eminence may be noted. The tendons are confined within osseofascial tunnels that arch over the tendons and are attached to the sides of the phalanges. These potential fascial spaces may become infected, either by direct trauma from a puncture wound or by spread from a tendon sheath infection, and in these circumstances the infection can spread proximally deep to the flexor retinaculum to reach the lower forearm. The thick palmar fascia usually prevents the signs of infection appearing in the palm. The painful swelling is generally most evident on the dorsum where the fascia is thinner. It is attached to the scaphoid and adjacent flexor retinaculum, and its tendon passes to the radial side of the base of the proximal phalanx of the thumb. Opponens pollicis is attached proximally to the trapezium and adjacent flexor retinaculum and distally to the radial side of the 1st metacarpal. It flexes, adducts and medially rotates the thumb (otherwise known as opposing the thumb) to bring the pulp of the thumb tip into contact with the tips of the flexed fingers. The hypothenar muscles are small mirror images of the thenar muscles and are supplied by the deep branch of the ulnar nerve. They each arise from the medial side of the flexor retinaculum and pisiform or hamate bones. Abductor digiti minimi and flexor digiti minimi gain distal attachment to the base of the proximal phalanx of the little finger; opponens digiti minimi is attached distally to the ulnar margin of the 5 metacarpal shaft. Proximally these are attached to the shafts of the metacarpals: the palmar to the palmar surfaces of the 1, 2, 4 and 5 bones; the larger, more powerful dorsal muscles are attached by two heads to adjacent metacarpals. Both groups, acting with the lumbricals, flex the proximal phalanx and, by their attachment to the extensor expansion, help to extend the middle and distal phalanges. Each is attached distally to the radial side of the extensor expansion of its tendon. Their action is similar to that of the interossei, but it is in the finer control of the upstroke in writing that they are most important. The two lateral lumbricals are supplied by the median nerve, the two medial by the ulnar nerve. The power grip involves the long finger flexors and intrinsic flexors of the four fingers, locked down and reinforced by thumb flexion and adduction. A precision grip is much more a combination of mainly the interossei and lumbricals with assistance from the thenar and hypothenar opponens. In all hand movements it is a combination of ulnar, median and radial nerves as there is normally synergism between the wrist extensors and finger flexor groups. The superficial palmar branch of the ulnar artery passes laterally deep to the palmar aponeurosis to join the terminal branch of the radial artery superficial to the long flexor tendons. It provides four palmar digital branches which, by bifurcating, supply adjacent sides of the fingers and also join with the deep palmar arch, another anastomosis, formed largely by the radial artery and a smaller branch from the ulnar artery. It lies deep to the long flexor tendons and provides palmar metacarpal arteries and perforating arteries to the dorsum of the hand. Upper limb sensory testing (with eyes closed) of dermatomes and individual nerves Lumbricals (a) Touch (cotton wool); pain (sterile needle); temperature (side of finger versus cold side of tuning fork); vibration (base of tuning fork on head of ulna); graphaesthesia (writing numbers on the forearm with a blunt instrument); stereognosis (recognizing a coin by touch); position sense (recognizing direction of movement ­ hold the sides of the index finger). Motor testing Power (grip); tone (passive flexion and extension of a relaxed elbow joint); coordination (finger to tip of nose ­ eyes open and then closed); reflexes (biceps C5/6; supinator, triceps C6/7); note wasting and abnormal movements; individual muscles ­ active and passive movements, and against resistance. They extend the interphalangeal joints by traction on the extensor tendons and flex the metacarpophalangeal joints by releasing tension in the digital aspect of the long flexor tendons. The characteristic deformity of wrist drop occurs and there is loss of sensation over the radial side of the dorsum of the hand and lateral 3½ fingers and a variable part of the posterior surface of the forearm. Wrist-drop and sensory loss over the radial side of the palm and lateral fingers result. In the forearm, superficial injuries cause no more than a small area of diminished sensation over the radial side of the dorsum of the hand because the radial nerve contains no muscular branches. Deeper forearm injuries or fractures of the radial neck may damage the posterior interosseous nerve and result in inability to extend the thumb and the metacarpophalangeal joints of the fingers, because of the paralysis of the long extensors. Extension of the wrist is maintained because extensor carpi radialis is supplied by a branch of the radial nerve that arises above the elbow. In this case there is no sensory loss because the posterior interosseous nerve is entirely motor. The consequent pull of the long digital extensors produces hyperextension of the metacarpophalangeal joints. The following muscles contribute to the extensor expansions of the fingers: a extensor digitorum longus b extensor indicis c palmar interossei d extensor pollicis longus e the two medial lumbricals T/F ( ) ( ) ( ) ( ) ( ) Answers 1. The following structures pass superficial to the flexor retinaculum: a palmar branch of the ulnar nerve b palmar branch of the median nerve c anterior interosseous nerve d the tendon of palmaris longus e the tendon of flexor pollicis longus T/F ( ) ( ) ( ) ( ) ( ) 3. Palpation of the wrist reveals that: a the palmaris longus tendon is present only in a minority of people b the median nerve can usually be rolled under the fingers over the tendons of flexor digitorum superficialis c the superficial branches of the radial nerve can be rolled over the flexor pollicis longus d the radial pulse is usually medial to the tendon of flexor carpi radialis e the scaphoid bone lies in the floor of the anatomical snuffbox T/F ( ) ( ) ( ) ( ) ( ) 4. A mid-term pregnant patient presents with a complaint of numbness in the middle three fingers of her right hand and some difficulty in grasping objects with that hand. He has no obvious deformity but exhibits tenderness in the anatomical snuffbox of the affected hand. The median nerve supplies motor fibres to the muscles of the thenar eminence and sensation to the thumb, index and middle finger and to the lateral half of the ring finger. Answer b the anatomical snuffbox on the posterolateral aspect of the hand is a triangular space walled by the tendons of extensor pollicis brevis, abductor pollicis longus and extensor pollicis longus. The scaphoid bone forms its floor and tenderness suggests that it is the bone fractured. An old woman falls downstairs and sustains a midshaft fracture of the humerus, damaging the radial nerve in the spiral groove. Wrist drop is the most noticeable injury, owing to loss of action of all finger and wrist extensors. The median nerve lesion is the most disabling because thumb opposition is lost, as well as the sensation over the thumb, index and middle fingers. An infection in the pulp might readily spread proximally where, in some people, it joins the ulnar bursa, both of them passing deep to the retinaculum and extending for 2­3 cm to the level of the wrist. The median nerve lies just deep to palmaris longus, and the ulnar nerve lies between the ulnar artery and the pisiform bone. To test the median nerve, the patient is asked to abduct his thumb against resistance (note that thumb opposition can be mimicked by the long flexor tendons). To test the ulnar nerve, the hand is placed palm downwards and the fingers straightened, and then abducted and adducted against resistance. How might a swelling proximal to the wrist joint be connected with infection in the tip of the thumb (tenosynovitis) After repair of the arteries, which other important structures would you also wish to test and how would you do this The foot Bailey & Love · Essential Clinical Anatomy · Bailey & Love · Essential Clinical Anatomy Essential Clinical Anatomy · Bailey & Love · Essential Clinical Anatomy · Bailey & Love Chapter Bailey & Love · Essential Clinical Anatomy · Bailey & Love · Essential Clinical Anatomy 15 the hip and thigh · · · · · · · the fascia. During its development there is rotation medially on its long axis, so that the flexor surface lies posteriorly and the sole of the foot faces backwards and then downwards. In the standing position the centre of gravity passes behind the hip and in front of the knee and ankle joints. The weight is distributed between the heel and the balls of the toes, most of it being carried by bones and ligaments, with only a minimal amount of muscle activity being required to maintain balance. The deep fascia of the gluteal region and thigh forms a firm investing layer, the fascia lata. Proximally it is attached in a continuous line to the inguinal ligament, iliac crest, posterior sacrum, sacrotuberous ligament, ischiopubic ramus and body of the pubis. Gluteus maximus and tensor fasciae latae gain attachment to the tract and, because of this attachment, assist in extension and stabilization of the knee. It is attached to bone around the margins of the patella, to the medial surface of the tibia and, inferiorly, to both malleoli. It ensheaths the muscles and contributes to intermuscular septa that separate the anterior, lateral and posterior muscle compartments. The posterior muscles are further divided by a fascial envelope into superficial and deep compartments, the former enclosing gastrocnemius and soleus. Around the ankle the fascia thickens to form the retinacula, restraining the tendons as they enter the foot. On the dorsum of the foot the fascia is thin, but on the sole it is thickened to form the plantar aponeurosis. Throughout the leg and thigh, the fascia is pierced by perforating (communicating) veins joining the superficial to the deep veins, and by cutaneous nerves, arteries and lymph vessels. The fascial compartments of the leg are rather rigid envelopes for the soft tissues contained within them; trauma and bleeding, such as may follow a leg fracture, can cause compartmental swelling and rise in pressure of sufficient severity to compromise the arterial supply to the contents of the compartment. It is essential in these circumstances that close observation is maintained on the pulses in the leg, and if the circulation is found to be threatened, a fasciotomy (incision along the length of the fascial sheath) must be urgently undertaken to relieve the pressure in that compartment. Valves are present in the larger veins and all the communicating veins; they direct blood flow towards the heart or from the superficial to the deep veins. The superficial veins drain skin and superficial fascia into two main channels, the great and small saphenous veins. It receives tributaries from the small saphenous vein and connects by communicating branches to the deep veins of the thigh and calf just behind the medial border of the tibia. It receives cutaneous tributaries and communicates with the deep veins of the calf by perforating veins. The deep veins comprise those of the foot and the soleal plexuses of veins, the popliteal and the femoral vein (p. The superficial veins drain to them by communicating veins that perforate the deep fascia. All the veins of the lower limb possess valves that permit blood flow only up the limb or from superficial veins to deep veins. This is one of the factors that accounts for the high frequency of deep vein thrombosis postoperatively. Note the swelling and skin changes Lymphatic drainage There are two groups of lymph nodes in the lower limb, superficial and deep. The upper superficial (horizontal) inguinal group is in the femoral triangle, just below the inguinal ligament. It receives lymph from the lower abdominal wall, perineum, external genitalia, anal canal and gluteal region, and drains to the lower superficial inguinal group and the deep nodes. The lower superficial inguinal (vertical) group lies around the saphenous opening and receives lymph from the upper group and the skin of the thigh and the medial leg and foot. Its efferent vessels drain through the saphenous opening to the deep inguinal or external iliac group. The popliteal group, a small group, lies in the popliteal fossa around the small saphenous vein and drains the skin of the lateral foot and calf and the deep tissues of the leg. The deep inguinal group lies around the femoral canal and receives the lymph of all the superficial nodes and deep lymphatic vessels of the lower limb. Cancers arising in the external genitalia or anal canal may spread to and enlarge these inguinal nodes. Maldevelopment of the lymph vessels, or blockage of the vessels or nodes by disease, produces soft tissue swelling because of the interference with lymph flow. Levator ani (puborectalis part) Sphincter (b) urethrae Obturator foramen the lateral surface of the hip bone the gluteal surface of the ala of the ilium is smooth and faces laterally; it is bounded by the iliac crest above and by the greater sciatic notch and the acetabulum below. It gives attachment to gluteus medius and minimus centrally and to gluteus maximus posteriorly. The ischial spine separates the greater and lesser sciatic notches; below the lesser notch is the ischial tuberosity.

Accompanying these vessels connexin 43 arrhythmia cheap 25 mg coreg, the nerve leaves the gluteal region by passing through the lesser sciatic foramen hypertension prognosis order coreg 12.5 mg without a prescription, and enters the pudendal canal blood pressure medication used to treat anxiety buy generic coreg pills. It runs forwards below the internal pudendal vessels arteria gastroepiploica dextra generic 25 mg coreg with mastercard, and terminates by dividing into: a blood pressure medication sore joints buy discount coreg 12.5 mg. Muscular branches to the urogenital muscles, and to anterior parts of external anal sphincter and the levator ani. The nerve to the bulbospongiosus also gives off the nerve to bulb which supplies corpus spongiosum, penis and the urethra. The dorsal nerve of the penis or clitoris is the smaller terminal branch of the pudendal nerve. It runs forwards first in the pudendal canal above the internal pudendal vessels; and then in the deep perineal space between these vessels and the pubic arch. Therefore, in vaginal operations, general anaesthesia can be replaced by a pudendal nerve block. Course the course of internal pudendal artery is similar to the course of pudendal nerve. It enters the gluteal region through greater sciatic notch, leaves it through lesser sciatic notch to enter the pudendal canal. In the deep perineal space, the artery of the penis or clitoris, which is continuation of internal pudendal artery, runs forwards close to the side of pubic arch, medial to the dorsal nerve of penis or of clitoris. Branches In the pelvis, the artery runs downwards in front of the piriformis, the sacral plexus and the inferior gluteal artery. It leaves the pelvis by piercing the parietal pelvic fascia and passing through the greater sciatic foramen, below the piriformis, thus entering the gluteal region. In the gluteal region, the artery crosses the dorsal aspect of the tip of the ischial spine, under cover of the gluteus maximus. Here it lies between the pudendal nerve medially and the nerve to the obturator internus laterally. In the pudendal canal, the artery runs downwards and forwards in the lateral wall of the ischioanal fossa, about 4 cm above the lower margin of the ischial tuberosity. The artery gives off the inferior rectal artery in the posterior part of the canal, and the perineal artery in the anterior part. The internal 1 the inferior rectal artery arises near the posterior end of the pudendal canal, and accompanies the nerve of the same name. Here it divides into the transverse perineal and the posterior scrotal or posterior labial branches. All of them pierce the perineal membrane and reach the superficial perineal space. The urethral artery supplies the corpus spongiosum and the anterior part of the urethra. The deep artery of the penis or the clitoris traverses and supplies the crus and the corpus cavernosum. The dorsal artery of the penis or the clitoris supplies the skin and fasciae of the body of the penis and of the glans or the glans clitoridis. In the deep fascia lie deep dorsal vein of penis, two dorsal arteries and two dorsal nerves of penis. Main difference in male and female perineum about the structures piercing the perineal membrane is the additional vaginal opening in female. Muscles attached here are external 1­5 · · · · anal sphincter, fibres of longitudinal muscle coat of anal canal, pair of levater ani, bulbospongiosus and superficial and deep transversus perinei. Bulbspongiosus of two sides is separate in female and overlie the bulb of vestibule. Inferior rectal nerve supplies mucous membrane of the lower part of the anal canal, external anal sphincter and the skin around anal opening. The internal pudendal artery and pudendal nerve course through the pudendal canal, lying in the lateral wall of the fossa. The swelling occurred due to disruption of a small branch of internal pudendal artery, probably as a result of infection during childbirth or infection in the episiotomy area. Section 2 From Medical Council of India, Competency based Undergraduate Curriculum for the Indian Medical Graduate, 2018;1:44­80. Section · · · · · · · · · Name the structures piercing perineal membrane in female. It chiefly lodges the genital system, the only system different in the male and female. The greater pelvis is comfortably occupied by the abdominal viscera, leaving only the lesser pelvis for the pelvic viscera. Urinary bladder lies behind pubic symphysis; rectum and anal canal are close to the sacrum and coccyx. The bones are the two hip bones in front and on the sides, and the sacrum and coccyx behind. The joints are the two sacroiliac joints, the pubic symphysis and the sacrococcygeal joint. The pelvis is divided by the plane of the pelvic inlet or pelvic brim, or superior aperture of the pelvis into two parts: a. Upper part is known as the greater or false pelvis which lodges the abdominal viscera. The plane of the pelvic inlet passes from the sacral promontory to the upper margin of the pubic symphysis. The greater or false pelvis includes the two iliac fossae, and forms a part of the posterior abdominal wall. Muscles 1 the obturator internus with its fascia reinforces the lateral wall of the pelvis from the inside. It is bounded posteriorly by the sacral promontory, anteriorly by the upper margin of the pubic symphysis, and on each side by the linea terminalis. The pelvic inlet is heart-shaped in the male, and is widest in its posterior part. Pudendal nerve enters the region through the greater sciatic notch and quickly leaves it through lesser sciatic notch to enter the perineum. The lateral wall contains obturator foramen for the passage of obturator nerve which supplies adductors of the hip joint. Similarly, anterior inferior iliac spine or ischial tuberosity may get avulsed by the contraction of their attached muscles. The axis of the pelvic cavity is J-shaped Pelvic Floor the pelvic floor is formed by the pelvic diaphragm which consists of the levator ani and the coccygeus (see Chapter 34). It resembles a hammock, or a gutter because it slopes from either side towards the median plane where it is traversed by the urethra and the anal canal, and also by the vagina in the female. The muscles of the true pelvis, its blood vessels and nerves are considered in Chapter 34. The posterior part of the outlet is formed by the coccyx and the sacrotuberous ligaments. The occiput moves downwards and forwards and reaches below the 80°­85° angled pubic arch. Then the head passes through the anterior hiatus of the levator ani to reach the perineum and then deliver. Injury to pelvic floor which mostly occurs during vaginal delivery, may cause uterine, vaginal or even rectal prolapse. The 2nd to 4th sacral nerves and coccygeal nerve can be anaesthetised by the anaesthetic agent put into the sacral canal. In the female, the septum is large, and contains uterus, uterine tubes, round ligament of the uterus, ligaments of the ovary, ovaries, vagina and ureters. Site of episiotomy is also seen Pelvic Cavity the pelvic cavity is continuous above with the abdominal cavity at the pelvic brim, and is limited below by the pelvic diaphragm. The cavity is curved in such a way that it is first directed downwards and backwards, and then downwards and forwards (J-shaped). It supplies all the muscles of perineal spaces including most of the skin and mucous membrane of perineum. All the following are the characteristic features of the female bony pelvis, except: a. The external urethral sphincter is the sphincter urethrae which is placed proximally in the wall of urethra, and not at the terminal part of the urethra. In the case of pylorus and anal canal, the sphincters are placed at their terminal ends. A full bladder is ovoid in shape and has: 1 An apex, directed upwards towards the umbilicus. The detrusor muscle of urinary bladder is arranged in whorls and spirals and is adapted for mass contraction rather than peristalsis. When empty, it lies entirely within the pelvis; but as it fills it expands and extends upwards into the abdominal cavity, reaching up to the umbilicus or even higher. External Features Section 2 An empty bladder is tetrahedral in shape and has: 1 Apex, directed forwards. The triangular area between the two ductudeferens is separated from the rectum by the rectovesical fascia of Denonvilliers. It lies 3 to 4 cm behind the lower part of the pubic symphysis, a little above the plane of the pelvic outlet. In males, smooth muscle bundles surround the bladder neck and preprostatic urethra. These are arranged as distinct circular collar with their own distinct adrenergic innervations. This is the preprostatic sphincter and is devoid of parasympathetic cholinergic nerves. In females, neck is related to the pelvic fascia which surrounds the upper part of the urethra. The internal urethral orifice lies at the level of the superior border of the pubic symphysis. In females, peritoneum covers the greater part of the superior surface, except for a small area near the posterior border, which is related to the supravaginal part of the uterine cervix. In the female, the relations are same, except that the puboprostatic ligaments are replaced by the pubovesical ligaments. As the bladder fills, the inferolateral surfaces form the anterior surface of the distended bladder, which is covered by peritoneum only in its upper part. The lower part comes into direct contact with the anterior abdominal wall, there being no intervening peritoneum. Ligaments of the Bladder True Ligaments these are condensations of pelvic fascia around the neck and base of the bladder. It extends from the back of the pubic bone (near the pubic symphysis) to the prostatic sheath. In females, bands similar to the puboprostatic ligaments are known as the pubovesical ligaments. A slight elevation on the trigone immediately posterior to the urethral orifice, produced by the median lobe of the prostate, is called the uvula vesicae. The base of the trigone is formed by the interureteric ridge or bar of Mercier produced by the continuation of the inner longitudinal muscle coats of the two ureters. The ridge extends beyond the ureteric openings as the ureteric folds over the interstitial part of the ureters. Capacity of the Bladder these are peritoneal folds, which do not form any support to the bladder. They include: 1 Median umbilical fold 2 Medial umbilical fold 3 Lateral false ligament, formed by peritoneum of the paravesical fossa. Interior of the Bladder the mean capacity of the bladder in an adult male is 220 ml, varying from 120 to 320 ml. Filling beyond 220 ml causes a desire to micturate, and the bladder is usually emptied when filled to about 250 to 300 ml. Referred pain is felt in the lower part of the anterior abdominal wall, perineum and penis (T11 to L2; S2 to S4). Arterial Supply Section 2 Abdomen and Pelvis It can be examined by cystoscopy, at operation or at autopsy. In an empty bladder, the greater part of the mucosa shows irregular folds due to its loose attachment to the muscular coat. In a small triangular area over the lower part of the base of the bladder, the mucosa is smooth due to its firm attachment to the muscular coat. Venous Drainage Lying on the inferolateral surfaces of the bladder, there is a vesical venous plexus. Veins from this plexus pass backwards in the posterior ligaments of the bladder, and drain into the internal iliac veins. A few vessels may pass to the internal iliac nodes or to the lateral aortic nodes. Nerve Supply the urinary bladder is supplied by the vesical plexus of nerves which is made up of fibres derived from the inferior hypogastric plexus. The vesical plexus contains both sympathetic and parasympathetic components, each of which contains motor or efferent and sensory or afferent fibres. In the spinal cord, pain arising in bladder passes through the lateral spinothalamic tract, and awareness of bladder distension is mediated through the posterior columns. Bilateral anterolateral cordotomy, therefore, selectively abolishes pain without affecting the awareness of bladder distension and the desire to micturate. The luminal cells are well-defined dome-shaped squamous cells with prominent nuclei. These are the levator ani, obturator internus muscles; medial and lateral puboprostatic ligaments, median and medial umbilical folds.

The four parts of quadriceps are attached to the upper border and side margins in a single musculotendinous expansion hypertension young male 25 mg coreg buy amex. From the apex of the patella the strong patellar ligament (ligamentum patellae) descends to become attached to the tibial tubercle heart attack symptoms in men cheap coreg online mastercard. On each side of the patellar tendon the capsule of the joint is strengthened by fibrous expansions (retinacula) of the quadriceps blood pressure 90 over 50 6.25 mg coreg purchase visa. Iliofemoral ligament Obturator externus Divided pectineus Relations At its origin it is deep to the inguinal ligament blood pressure chart dental treatment purchase 12.5 mg coreg, halfway between the anterior superior iliac spine and the symphysis pubis (mid-inguinal point) hypertension 4019 buy coreg 6.25 mg line. It is palpable in the femoral triangle, being covered only by deep fascia and skin; the femoral vein lies medial to it. It leaves the triangle at its apex on adductor longus and enters the adductor canal with its vein and the saphenous nerve (p. Three to four centimetres above the adductor tubercle of the femur the artery passes through the opening in the tendon of adductor magnus (adductor hiatus) to enter the popliteal fossa as the popliteal artery. Divided ends of adductor longus Adductor magnus Femoral artery passing through adductor hiatus Perforating branches of profunda femoris artery Adductor hiatus Branches Just as the artery enters the femoral triangle it gives off three small branches to the skin of the lower abdominal wall and the inguinal region. The medial and lateral circumflex femoral arteries encircle the upper femur and supply muscles and the hip joint, and contribute to the anastomoses around the femur and hip joint. The femoral artery is very accessible in the femoral triangle; its pulsation is readily found below the mid-inguinal point, and first-aiders are taught to use it as a pressure point for the control of haemorrhage from the leg. Radiologists frequently use it for arterial catheterization, and clinicians for sampling arterial blood. The decrease in blood supply affects particularly the muscles of the calf, and exercise pain (intermittent claudication) may result. The numerous branches of the femoral artery, but especially the medial circumflex femoral, with a contribution from the gluteal arteries, make a rich anastomosis around the hip joint, most branches of which pass to the head of femur via the retinacular fibres of the neck. A small branch of the obturator artery passes into the head of femur, and is considered more important in children. The femoral vein the femoral vein begins at the opening in the lower end of adductor magnus as the continuation of the popliteal vein. It ascends with the femoral artery to end under the inguinal ligament, as the external iliac vein. It is frequently used for venous access in shocked patients with a low blood pressure and collapsed veins. Tributaries the profunda femoris vein and medial and lateral femoral circumflex veins have a similar course to their arteries. The great saphenous vein, which drains the skin and subcutaneous tissues of much of the leg and thigh (p. In the femoral triangle it immediately divides into terminal branches: Cutaneous nerves ­ supply skin on the medial and anterior aspect of the thigh. Saphenous nerve ­ the longest branch of the femoral nerve (L4) accompanies the femoral artery until the adductor hiatus, at which point it emerges from the adductor canal medial to sartorius to descend on the medial side of the knee. In the leg it entwines around the great saphenous vein to pass anterior to the medial malleolus. It is often damaged when varicose veins are stripped, causing diminished and altered sensation over the medial ankle region. The obturator nerve is a branch of the lumbosacral plexus (L2, L3, L4), whose pelvic course is described on p. It enters the thigh through the obturator foramen, where it divides into anterior and posterior branches to supply all the adductors and pectineus, except the lateral half of adductor magnus (supplied by the sciatic nerve). The femoral nerve supplies: a gluteus minimus muscle b rectus femoris c the skin over the lateral malleolus d iliacus muscle e pectineus muscle T/F ( ) ( ) ( ) ( ) ( ) Answers 1. It commences at the apex of the femoral triangle and lies on adductor longus; it finishes below at the hiatus in the adductor magnus. The hip joint: a is supplied by the nerve to rectus femoris b is supplied by the obturator nerve c is supplied by the nerve to quadratus femoris d has a posterior capsule attached to the greater trochanter e is supported most strongly by the ischiofemoral ligament T/F ( ) ( ) ( ) ( ) ( ) 3. A 30-year-old man is admitted with closed mid-shaft fractures of the tibia and fibula. Three days later he complains of severe pain throughout the leg in the cast and, after removal of the cast, it is found that his foot is cold and swollen. A confused, violent patient requires an urgent intramuscular injection of a sedative. The muscle trauma and bleeding caused by a fracture may cause tissue swelling within a fascial compartment severe enough to compromise the arterial supply. Urgent surgical relief is required and lengthy incisions along the length of the lower leg (fasciotomy) are required to reduce the tissue pressure in that compartment. Answer a the sciatic nerve runs deeply through the lower medial quadrant and is sometimes injured by injections placed outside of the upper lateral quadrant. Vastus lateralis Match the following statement to the muscle(s) in the above list. Not only are the femoral artery and vein endangered as they pass down the front of the thigh towards the subsartorial canal, but so too are their branches and tributaries. Midway down the thigh a knife piercing sartorius and the femoral vessels also lacerates adductor longus, a fairly thin muscle, and may damage the profunda femoris vessels on its deep surface. The injury is therefore very bloody owing to damage to two large arteries and their accompanying veins. Lymph from the superficial tissues of the heel runs in the lymphatics that follow one or other of the saphenous veins. Those following the great saphenous vein eventually drain to the vertically disposed groups of superficial inguinal nodes around the termination of the vein, in the groin. The lymph vessels following the small saphenous vein pierce the deep fascia in the popliteal fossa and enter the popliteal nodes. From here lymph passes to the deep inguinal nodes around the femoral vein in the femoral triangle. Bailey & Love · Essential Clinical Anatomy · Bailey & Love · Essential Clinical Anatomy Essential Clinical Anatomy · Bailey & Love · Essential Clinical Anatomy · Bailey & Love Chapter Bailey & Love · Essential Clinical Anatomy · Bailey & Love · Essential Clinical Anatomy 16 the knee, leg and dorsum of the foot · · · · · Osteology. Its anterior surface is subcutaneous; the posterior is smooth, with a smaller medial and a larger lateral facet for articulation with the femoral condyles. The quadriceps tendon is attached to the upper border and the patellar tendon or ligament to the apex; muscle fibres from vastus medialis are attached to its medial border and tendinous expansions from the vastus medialis and lateralis (retinacula) are attached to the medial and lateral borders and also to the neighbouring tibial condyles. In the standing position the lower border of the patella lies slightly proximal to the level of the knee joint. The upper end is expanded by the medial and lateral condyles and flattened superiorly, forming the tibial plateau with oval medial and lateral facets articulating with the femoral condyles. Between the articular facets is a rough intercondylar area that gives attachment to the two menisci and the anterior and posterior cruciate ligaments. The prominent anterior tibial tuberosity below the superior surface provides attachment for the patellar tendon; semimembranosus is attached along the side of the medial condyle. The posterior surface is crossed by an oblique ridge, the soleal line, which gives attachment to soleus; attached to the surface above the line is popliteus, and to the area below the line tibialis posterior and flexor digitorum longus. The expanded lower end has a medial projection, the medial malleolus; its distal surface, together with the lateral surface of the malleolus, articulates with the talus. The posterior border of the lower end is grooved medially by the tendon of tibialis posterior. To the roughened lateral surface is attached the interosseous ligament of the inferior tibiofibular joint. The articular surface on the femur is formed of three continuous surfaces: a middle concave surface for the patella, and markedly convex medial and lateral condylar surfaces for articulation with the tibia. The posterior surface of the patella has a medial and a larger lateral facet for articulation with the femoral concavity. The expanded head has an oval articular facet for the tibia; to its apex is attached the fibular collateral ligament of the knee joint and biceps tendon. The common peroneal nerve lying within peroneus longus is in close proximity to the neck of the fibula just below the head of the bone and can be palpated here. The shaft is long and slender; attached to its narrow anterior surface are the extensor muscles, to the posterior surface the flexor muscles and to the lateral surface the peroneal muscles. Above the articular facet is the roughened area for the interosseous ligament of the inferior tibiofibular joint, and below it the bone gives attachment to the posterior talofibular ligament. It is attached to the margins of the patella and to the periphery of the tibial plateau, except for anteriorly, where it descends below the tibial tuberosity, and posterolaterally where it is pierced by the tendon of popliteus. Capsular thickenings Coronary ligaments tether the margins of the medial and lateral menisci to the nearby margin of the tibial plateau. Accessory ligaments Patellar tendon­ from the apex of the patella to the tibial tuberosity. The knee jerk reflex is demonstrated by hitting the midpoint of this tendon with a tendon hammer, often with the knee hanging flexed over the bed or with the knees crossed. This should elicit contraction of the quadriceps muscle, which extends the knee and tests the integrity of the L3 and L4 nerve roots. Articular surface for patella Lateral collateral ligament Anterior cruciate ligament Anterior capsule of superior tibio bular joint Fibula (a) Femoral condyles Posterior cruciate ligament Medial collateral ligament Patellar ligament Patella Divided quadriceps tendon Patellar retinacula ­ tendinous expansions of the vasti muscles passing to the patellar margins and to the tibial condyles. Tibial collateral ligament ­ a broad flat ligament passing from the medial epicondyle of the femur to the medial surface of the upper tibia. Fibular collateral ligament ­ a round cord passing from the lateral epicondyle of the femur to the head of the fibula. Forward displacement of the tibia on the femur is prevented by the anterior cruciate, posterior displacement by the posterior cruciate. Both cruciate ligaments lie outside the synovial cavity in the fibrous septum between the tibiofemoral joints, but a communication between the joints exists in front of the ligaments. The synovial membrane is attached proximally to the articular margins of the femur, and distally to the margins of the tibial articular facets and the front of the intercondylar area. The joint cavity communicates with this bursa and the popliteal and gastrocnemius bursae. The lump is fluctuant but not tender, but if the cyst leaks, fluid may track down the calf, which becomes swollen and tender, mimicking a calf vein thrombosis. The menisci are two crescentic pieces of fibrocartilage with thickened outer margins. The medial cartilage is larger and semicircular and its central attachments embrace those of the lateral cartilage, which is smaller and forms three-fifths of a circle. The tendon of popliteus is attached to the posterior margin of the lateral meniscus. The stability of the joint depends entirely on its ligaments and neighbouring muscles but, because it is a mobile weight-bearing joint, injuries are common, especially in sports involving running and physical contact such as soccer or rugby. Most injuries occur when a side force to the knee is applied while the leg is weight-bearing, i. The knee is particularly prone to this injury when flexed, as it is then that the collateral ligaments are slack and making little contribution to the stability of the knee. Rupture of the cruciate ligaments is the result of severe anterior or posterior force being applied to the knee. Tears of the anterior cruciate ligament are seen most frequently in young sportsmen; they are usually the consequence of violent abduction and twisting of the knee, such as may occur in a sliding football tackle. The medial meniscus is the more liable to injury because it is fixed to the tibial collateral ligament. Presenting symptoms are pain and swelling of the knee, or locking of the knee owing to the partially detached cartilage becoming wedged between the tibial and femoral condyles. Displaced fragments of the meniscus lodged between the condyles prevent full extension of the knee. The lower leg is gripped around the upper tibia, with the knee flexed, and the tibia pushed backwards and pulled forwards (arrows). There should be no movement in these planes 9 10 11 5 67 (b) Functional aspects Movements the joint is capable of flexion, extension and a little rotation: Flexion ­ by hamstrings assisted by gastrocnemius. During movement the femoral condyles roll on the tibial condyles and also glide backwards. When the leg is almost straight the capsular and cruciate ligaments become taut and stop further backward gliding of the lateral femoral condyle. Further extension is only possible by backward movement of the medial condyle around the axis of the taut anterior cruciate ligament (medial rotation of the femur on the tibia). Rotation ­ a small amount of rotation may be produced by the hamstrings when the knee is flexed. Its collateral ligaments are inextensible; the cruciate ligaments limit gliding and distraction of the bones; quadriceps anteriorly and gastrocnemius and hamstrings posteriorly stabilize the joint. Quadriceps tends to pull the patella laterally because of the obliquity of the femur, but the displacement is limited by the projection of the lateral condyle of the femur and by the resistance provided by the horizontally attached fibres of vastus medialis into the medial border of the patella. When standing on the extended knee the centre of gravity passes in front of the axis around which the femoral condyles roll; the posterior cruciate ligaments thus take the strain. It is often due to a flat lateral femoral condyle or weakness in the lower fibres of vastus medialis. Nerve supply this is by branches of the tibial, common peroneal (fibular), obturator and femoral nerves. Relations the joint is mainly subcutaneous, being separated from the skin by quadriceps, the patella and patellar ligament anteriorly, the biceps tendon laterally and semimembranosus and semitendinosus medially. To its posterior lie the popliteal vessels and, more superficially, the tibial and common peroneal (fibular) nerves in the popliteal fossa. Anteriorly are the suprapatellar, which extends into the thigh deep to quadriceps and communicates with the knee joint, and the prepatellar, superficial and deep infrapatellar, which are related to the patellar ligament. Posteriorly lie the popliteal bursa, deep to its muscle, and one associated with the gastrocnemius deep to its medial head. Both communicate with the knee joint and the semimembranosus bursa, which lies between the muscle and the medial head of gastrocnemius.

Syndromes

• Sedation
• Poor blood supply
• Infection in the bones of the sinuses (osteomyelitis)
• The skin is almost transparent.
• You experience unexplained and excessive yawning.
• Chronic kidney failure
• Reactions to medications
• Adults: not measured

The value of surface tension for a liquid will be related to the strength of the pull between the liquid molecules pulse pressure guidelines 25 mg coreg purchase. The interfacial interactions are a consequence of long-range forces which are electrical in nature and consist of three types: dipole arrhythmia blog discount coreg 6.25 mg otc, induced dipole and dispersion forces blood pressure after exercise generic 6.25 mg coreg mastercard. Dipole forces are due to an imbalance of charge across the structure of a molecule exo heart attack 12.5 mg coreg purchase free shipping. This situation is quite common; most drugs are ionizable blood pressure kiosk order coreg 25 mg on line, and have such an asymmetric charge distribution, as do many macromolecules and proteins. Such materials are said to have permanent dipoles, and interactive forces are due to attraction between the negative pole of one molecule when it is in reasonably close contact with the positive pole of another. Hydrogen-bonding interactions are a specific sort of this type of bonding, occurring because hydrogen consists of only one proton and one electron, making it very strongly electronegative. This unique situation causes a strong attraction between the proton and an electronegative region from another atom. The strength of the hydrogen bond results in drastically different properties of interaction, exemplified by the fact that water has such a high surface tension, melting point and boiling point (in comparison with non-hydrogen-bonded materials). A bond between carbon and oxygen would be expected to be dipolar; however, if the molecule of carbon dioxide is considered (O=C=O), it can be seen that the molecule is in fact totally symmetrical, the dipole on each end of the linear molecule being in perfect balance with that on the other end. Even though these molecules do not carry a permanent dipole, if they are placed in the presence of a polarized material, a dipole will be induced on the (normally symmetrical) molecule, such that interaction can occur (dipole­induced dipole, or Debye, interactions). These dispersion forces occur between all materials, and thus even though the interaction forces are weak, they make a very significant contribution to the overall interaction between two molecules. Dispersion forces can be understood in a simplistic fashion by considering the fact that the electrons which spin around two neighbouring nonpolarized atoms will inevitably not remain equally spaced. This will result in local imbalances in charge that lead to transient induced dipoles. These induced dipoles, and the forces which result from them, will be constantly changing, and obviously the magnitude of these interactions is small compared with the permanent and induced dipole situations described previously. Dispersion forces are long range, of the order of 10 nm, which is significantly longer than a bond length. There are a number of methods by which surface tension can be measured, including the rise of a liquid in a capillary, but more usually the force experienced by the surface is measured using a microbalance. To do this, an object in the form of either a thin plate (Wilhelmy plate) or a ring (Du Nouy ring) is introduced to the surface and then pulled free, with the force at detachment being measured. For the Wilhelmy plate method, a plate (usually very clean glass or platinum) is positioned edge on in the surface whilst suspended from a microbalance arm; the force is then measured as the plate is pulled out of the liquid. The surface tension is obtained by dividing the measured force at the point of detachment by the perimeter of the plate. Water is the liquid with the highest value for its surface tension of all commonly used liquids in the pharmaceutical field (although metals have much higher surface tensions than water. Water is also of great pharmaceutical interest, being the vehicle used for the large majority of liquid formulations, and being the essential component of all biological fluids. In general, organic impurities are found to lower the surface tension of water significantly. On the basis of a linear reduction in surface tension in proportion to the concentration of methanol added, the surface tension of this mixture would be expected to be about 68. Methanol has been used as the example here, as it is one of the more polar organic liquids, containing just one carbon, attached to a polar hydroxyl group. However, it is its hydrophobicity that causes the significant reduction in surface tension. The reason for the large effect on surface tension is that the water molecules have greater attraction to each other than to methanol; consequently the methanol is concentrated at the water­air interface, rather than in the bulk of the water. The methanol here is said to be surface active (surface-active agents are discussed elsewhere in this book; in particular in Chapters 4, 5 and 27). Inorganic additives also strengthen the bonding within water, so the surface tension is increased in their presence. Solid wettability the vast majority of pharmaceutically active compounds exist in the solid state at standard temperatures and pressures. Inevitably, the solid drug will come into contact with a liquid phase, either during processing, and/or in the formulation, and also ultimately during use in the body. Here the term wettability is used to assess the extent to which a solid will come into contact with a liquid. Obviously a material which is potentially soluble but which is not wetted by the liquid. When formulating an active pharmaceutical ingredient, it is important that the powder ultimately becomes wetted by body fluids so that it will dissolve. As with liquid surfaces, there is a net imbalance of forces in the surface of a solid, and so solids will have a surface energy. The surface energy of a solid is a reflection of the ease of making new surface, and in simple terms can be considered to be the same as surface tension for a liquid. With liquids, the surface molecules are free to move, and consequently surface levelling is seen, resulting in a consistent surface tension/energy over the entire surface. However, with solids the surface molecules are held much more rigidly, and are consequently less able to move. The shape of solids is dependent upon previous history (perhaps crystallization or milling techniques). Certainly different crystal faces and edges can all be expected to have a different surface nature due to the local orientation of the molecules presenting different functional groups at the surface of different faces of the crystal ­ some more and some less polar, and therefore some regions more water loving and other regions less so. The methods that are used for liquid surface tension measurement, such as immersing a Wilhelmy plate and measuring the force as it is pulled from the liquid, cannot be used as the plate cannot gain access to the solid. This means that surface properties of solids must be derived from techniques such as contact angle measurement. Conversely, a high contact angle indicates poor wettability, with an extreme being total nonwetting with a contact angle of 180°. The contact angle provides a numerical assessment of the tendency of a liquid to spread over a solid, and as such is a measure of wettability. If a contact angle were measured on an ideal (perfectly smooth, homogeneous and flat) surface with a pure liquid, then there would be only one value for the contact angle. The contact angle of pure water on clean glass is zero, which provides the basis of surface tension experiments (as a finite contact angle would prevent such measurements). However, whenever raindrops are seen to form on a glass window, they do not spread, but rather form drops. If raindrops fall onto a plate of glass which is horizontal, each drop will have the same contact angle all around its circumference. If the glass plate is displaced from the horizontal, the drops will run down the surface, forming a tear shape. The leading edge of this drop will always have a larger contact angle than the trailing edge. The angle formed at the leading edge is termed the advancing contact angle (A) and the other angle is termed the receding contact angle (R). There are two possible reasons for contact angle hysteresis: surface roughness and contamination or variability of the composition of the surface, i. There are many different methods by which it is possible to measure a contact angle formed by a liquid on a solid. The vast majority of studies deal with smooth flat surfaces, such as polymer films, onto which it is comparatively simple to position a drop of liquid. The approaches for determination of the angle for such systems include direct measurement of the angle on a video image. The Wilhelmy plate apparatus was described earlier as a method by which it is possible to measure surface tension. As mentioned already, certain polymeric systems are readily formed into smooth flat plates for contact angle studies; however, most pharmaceutical materials exist as powders, for which such a physical state is not readily achievable. A full understanding of powder surface energetics, and an ability to alter and control powder surface properties, would be a major advantage to the pharmaceutical scientist. A drug crystal will consist of a number of different faces which may each consist of different proportions of the functional groups of the drug molecule; thus a contact angle for a powder will in fact be, at best, an average of the contact angles of the different faces, with contributions from crystal edges and defects. Also, impurities in the crystallizing solvent can cause an adjustment of habit, and crystals of the same drug can exist in different polymorphic forms; such changes in molecular packing will potentially alter the surface properties. A final complication is that despite the fact that most pharmaceutical powders have a very high degree of crystallinity (and are called crystals), in reality sometimes they will have a small degree of amorphous content which is likely to be present at the surface. Thus drug powders have heterogeneous surfaces of different shapes and sizes, which can readily change their surface properties. It is clear that all contact angle data for powders and the appropriate choice of methodology must be viewed in full knowledge of the inherent difficulties of the solid sample. The most cited method of obtaining a contact angle for powders is to prepare a compact in order to produce a smooth surface, and then to place a drop on the surface in order to measure the contact angle that is formed. The first major problem with compacted samples is that the very process of compaction will potentially change the surface energy of the sample. Compacts form by processes of brittle fracture and plastic deformation; thus new surfaces will be formed during compaction, which can mask subtle differences in the original surface nature. In fact the formation of a compact is the conversion of the material from being individual particles into a single bonded mass (no longer individual particles), so a measurement of a contact angle on a compact gives information about the material generally, but cannot be expected to give information about the unique aspects of a type of particle of that material, as the compaction will have altered the material. The alternative is to not compact the powder; for example, sticking fine powder on a piece of doubled-sided adhesive tape. This presents a rough surface which gives rise to hysteresis and potentially also has a contribution from the surface property of the adhesive. There is no solution to these sample preparation difficulties, so a compromise has to be made in order to proceed with measurements. The different methods by which the contact angle is measured for powders gives rise to different results, so comparison of data should take this into account. Adsorption at interfaces Adsorption is the presence of a greater concentration of a material at the surface than in the bulk. The material which is adsorbed is called the adsorbate, and that which does the adsorbing is the adsorbent. Adsorption can be due to physical bonding between the adsorbent and the adsorbate (physisorption) or chemical bonding (chemisorption). The differences between physisorption and chemisorption are that physisorption is by weak bonds (such as hydrogen bonding, with energies up to 40 kJ mol-1), whilst chemisorption is due to strong bonding (> 80 kJ mol-1); physisorption is reversible, whilst chemisorption seldom is; physisorption may progress beyond a singlelayer coverage of molecules on the surface (monolayer formation to multilayer formation), whilst chemisorption can only proceed to monolayer coverage. Solid­liquid interfaces the usual pharmaceutical situation is to have a liquid (solvent), particles of a solid dispersed in that liquid and another component dissolved in the liquid (solute). This forms the basis of stabilizing suspension formulations, where there may be water with suspended active pharmaceutical ingredient and in order to help stabilize the suspension (keep the solid particles from joining together) there may be a surface-active agent dissolved in the water. The surface-active agent will adsorb on the surface of the powder particles and help to keep them separated from each other (steric stabilization). Kaolin is administered as a therapy to adsorb toxins in the stomach and so reduce gastrointestinal tract disturbances. As a final example, the loss of active pharmaceutical ingredient, or preservative, from a solution product to a container can be a damaging effect of adsorption from solution to a solid. The quantity of solute which adsorbs will be related to its concentration in the liquid. The adsorption will proceed until equilibrium is reached between the solute that has been adsorbed at the interface and solute in the bulk. Many factors will affect adsorption from solution onto a solid; these include temperature, concentration and the nature of the solute, solvent and solid. The effect of temperature is almost always that an increase in temperature will result in a decrease in adsorption. This can be viewed as a consequence of giving the solute molecules more energy, and thus allowing them to escape the forces of adsorption, or simply viewed as the fact that adsorption is almost always exothermic, and thus an increase in temperature will cause a decrease in adsorption. The pH is important as many materials are ionizable, and the tendency to interact will vary greatly if they exist as polar ions, rather than a nonpolar un-ionized material. In most pharmaceutical examples (chromatographic separation being an obvious exception), adsorption will be from aqueous fluids, and for these, adsorption will tend to be greatest when the solute is in its un-ionized form, i. The effect of solute solubility will influence adsorption as the greater the affinity of the solute for the liquid, the lower the tendency to adsorb to a solid. The physical form is the easiest to deal with, as it relates largely to available surface area. Materials such as carbon black (a very finely divided form of carbon) have extremely large surface areas, and as such are excellent adsorbents, both from solution. The chemical nature of the adsorbent solid is important, as it can be a nonpolar hydrophobic surface, or a polar (charged) surface. Obviously, adsorption to a nonpolar surface will be predominantly by dispersion force interactions, whilst charged materials can also interact by ionic or hydrogen-bonding processes. Solid­vapour interfaces When considering the solid­vapour interface, it is necessary to understand the processes of adsorption and absorption. Adsorption has already been defined as the presence of greater concentrations of a material at the surface than is present in the bulk. Pharmaceutically, absorption is usually considered as the passage of a molecule across a barrier membrane, and is the essential requirement for enteral drug delivery routes to the systemic circulation. However, absorption should be considered as the movement into something; for example, a gas or vapour can pass into the structure of an amorphous material, such that the uptake onto/into the solid is the sum of adsorption (to the surface) and absorption (into the bulk). If the uptake is thought to consist of both adsorption and absorption processes, it is often referred to by the general term sorption. There are many processes at the solid­vapour interface which are of pharmaceutical interest, but two of the most important are water vapour­solid interactions, and surface area determination using nitrogen (or similar inert gas)­solid interactions. For such a plot, the pressure of the gas can be varied from zero to the saturated vapour pressure of the gas at that temperature (Po), and in each case the amount adsorbed can be determined (often by monitoring of the change of weight of the sample).

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