In the name of Allah, Most gracious, Most merciful

Transcription

1 In the name of Allah, Most gracious, Most merciful This lecture includes the following: The Palmer Oponeurosis. The Carpel tunnel. The palmaris brevis muscle. The anatomical snuffbox. The Fibrous flexor Sheath. The Small muscles of the Hand. Fascial spaces of the Palm. Arteries of the palm. Allen's test. Veins of the palm. The lymph drainage of the palm. Nerves of the palm. The dorsum of the hand. The dorsum venous arch. To start with; The deep fascia of the wrist and palm is thickened to form the flexor retinaculum and the palmar aponeurosis. The Palmer Oponeurosis: The palmar aponeurosis is triangular and occupies the central area of the palm. It's a thickened layer of deep fascia on the palm of the hand. The apex of the palmar aponeurosis is attached to the distal border of the flexor retinaculum and receives the insertion of the palmaris longus tendon. The distal part of the palmar aponeurosis gives slits of fibers. They begin two; one goes superficially to the skin while the deep divides into two which attach to the sides of the phalanges. Function of the palmar aponeurosis: 1. Protection of deep structures.

2 2. Helps with the contraction of the palm especially when a fist is made or when our hand assumes a position of trying to catch a rounded object. Muscles of the hand involve the thenar and hypothenar muscles. Superficially, a muscle called the palmaris brevis muscle can be seen when one contracts his hand in a certain way it can be seen on the ulnar side of the skin it also helps in the gripping action of the hand. The Carpel Tunnel: Contains the median nerve and lies between the tendons of flexor digitorum superficialias and flexor carpi radialis. Because of the concavity of the carpel bones that face anteriorly with the flexor retinaculum this tunnel is formed. In a case known as synovitis which is the inflammation of the synovial sheath around the long tendons such as those for flexor digitorum superficialis and profundus, this tunnel becomes very narrow and starts to add pressure on the median nerve. This is a very common clinical manifestation in ladies that are dependent on their wrist joint while working making them more disposed to synovitis and thus the carpal tunnel syndrome. The resulting inflammatory state results in edema which results in a consequent build up of pressure and compression of the median nerve. The inflicted nerve like in any other nerve lesion will show both sensory and motor deficits of the involved nerve. The muscles supplied by the median nerve in the hand are (3) thenar muscles(abductor pollicis brevis, flexor pollicis brevis and opponens policis). So a case of carpal tunnel syndrome will cause weakness in the movement of the thumb. The median nerve also supplies two lumbrical muscles which are L1 and L2. From this it is evident that maintaining a writing position of the hand is weakened. The sensory innervations of the superficial branch of the median nerve supply the skin of three and a half fingers (thumb, index, middle and half of the ring finger) of the palmer surface and only till the middle phalanx at the dorsum of the hand. Pressure on the median nerve, will cause what is known as parasthesia which is a sort of tingling and numbness felt in the affected area, a type of abnormal sensation. To distinguish between carpal tunnel syndrome and injury to the median nerve above the level of the tunnel we make use of a branch called the palmar cutaneous branch of the median nerve that arises superficially to the flexor retinaculum and is sparred from entering the carpal tunnel. This nerve supplies the lateral two thirds of the palm. Meaning that sensation of the lateral two thirds of the palm will be normal unless the median nerve is injured at a level above the tunnel whereby sensation of the lateral two thirds of the hand will be lost. To recap; a case of carpal tunnel that causes compression and hence damage to the median nerve will cause abnormal sensation of three and a half fingers mentioned above with the sensation of the lateral third of the palm left intact.

3 Note: From Wikipedia. Edema is swelling caused by fluid retention - excess fluid is trapped in the body's tissues. Swelling caused by edema commonly occurs in the hands, arms, ankles, legs and feet. It is usually linked to the venous or lymphatic systems. The palmaris brevis muscle: Origin: Deep fascia in the flexor retinaculum. Insertion: Skin of the palm, on the ulnar side. Nerve Supply: Superficial branch of the ulnar nerve. Function: Improves the grip of the hand when holding an object. The anatomical snuffbox: A triangular depression formed on the posterolateral side of the wrist and metacarpal I by the extensor tendons passing into the thumb. The lateral border is formed by the tendons of the abductor pollicis longus and extensor pollicis brevis. The medial border is formed by the tendon of the extensor pollicis longus. Content: Radial artery, where we can feel the pulse. Floor: The scaphoid and trapezium bones. Roof: The Superficial branch of the radial nerve and the origin of the cephalic vein. The Fibrous Flexor Sheath: The anterior surface of each finger, from the head of the metacarpal to the base of the distal phalanx, is provided with a strong fibrous sheath that is attached to the sides of the phalanges. The proximal end of the fibrous sheath is open, whereas the distal end of the sheath is closed and is attached to the base of the distal phalanx. The sheath and the bones form a blind tunnel in which the flexor tendons of the fingers lie. In the thumb, the osteo -fibrous tunnel contains the tendon of the flexor pollicis longus. In the case of the four medial fingers, the tunnel is occupied by the tendons of the flexor digitorum superficialis and profundus. Note: As there is an extensor expansion there is also a flexor expansion. Synovioal flexor sheath: The tendons of the flexor digitorum superficialis and profundus muscles invaginate a common synovial sheath from the lateral side. The medial part of this common sheath extends distally without interruption on the tendons of the little finger. The lateral part of the sheath stops abruptly on the middle of the palm, and the distal ends of the long

4 flexor tendons of the index, the middle, and the ring fingers acquire digital synovial sheaths as they enter the fingers. The flexor pollicis longus tendon has its own synovial sheath that passes into the thumb. These sheaths allow the long tendons to move smoothly, with a minimum of friction, beneath the flexor retinaculum and the fibrous flexor sheaths. Note: The synovial sheath of the flexor pollicis longus (sometimes referred to as the radial bursa) communicates with the common synovial sheath of the superficialis and profundus tendons (sometimes referred to as the ulnar bursa) at the level of the wrist in about 50% of subjects. The Small Muscles of the Hand: 4 Lumbrical muscles. 8 Interossei muscles. 3 Thener muscles. 3 Hypohenar muscles. 1 Adductor pollicis. The Lumberical Muscles: Origin: The First and Second ( Lateral Two Lumbricals or the Radial Lumbricals): The lateral side of the Flexor Digitorum Profundus tendons associated with the index and middle fingers in the palm. The Third and Fourth (Medial Two Lumbricals or the Ulnar Lumricals): Adjacent to the second, third and fourth tendon of the flexor digitorum profundus.. Associated with the middle and ring fingers and the ring and the little fingers, respectively. All four tendons of the lumbricals pass dorsally around the lateral side of each finger (proximal phalanx) and insert into the dorsal digital expansion (extensor expansion). Nerve Supply: The first and second lumbricals: Median nerve. The third and fourth lumbricals: Ulnar nerve. Function: Because all four insert in the lateral side they help in the writing position meaning: Flection at the metacarpophalangeal joints. Extension at the interphalangeal joints.

5 The Interossei Muscles: Generally, they originate from the metacarpal bones. 4 dorsal and 4 palmer. Sometimes only 3 Palmer Interossei muscles are present as the first palmar interosseous muscle is often absent, depending on its relationship with the metacarpal bone of the thumb. Palmer Interossei: Origin: 1. First palmer interosseous muscle (if present): The medial side of the first metacarpal bone. 2. Second palmer interosseous muscle : The medial side of the second metacarpal bone. 3. Third and fourth palmer interosseous muscles: The lateral sides of the third and fourth metacarpal bones, respectively. Insertion: All in all insert in the extensor expansion of 2,4 and 5 th digits. Function: Dorsal interossei muscles: Origin: Adjacent sides on the posterior aspect of the metacarpal bones. 1. The first dorsal interosseous muscle: Lateral head: Ulnar side of 1 st metacarpal bone. Medial head: Radial side of 2 nd metacarpal bone. 2. The second, third and fourth dorsal interosseous muscle: The space between metacarpal bones. Insertion: 1. The first dorsal interosseous muscle: Radial side of 2 nd proximal phalanx. 2. The second dorsal interosseous muscle Radial side of 3 rd proximal phalanx. 3. The third dorsal interosseous muscle: Ulnar side of the 3 rd proximal phalanx. 4. The fourth dorsal interosseous muscle: Ulnar side of the 4 th proximal phalanx. Palmar Interossei Muscles: Adduction of the fingers. Dorsal Interossei Muscles Abduction of the fingers.

6 Note: These four dorsal interossei muscles help the lumbricals in the writing position. Nerve Supply: All eight interossei muscles are supplied by: The deep branch of the ulnar nerve. The thenar muscles: 1. Abductor pollicis brevis. 2. Flexor pollicis brevis. 3. Opponens pollics. These form the thenar eminence. Remember: Abduction: Forward movement of the thumb. Adduction: Backward movement of the thumb. 1. Abductor pollicis brevis: Origin: Lateral border of the flexor retinaculum on the scaphoid and trapezium bones. Insertion: Lateral side of the first proximal phalanx. Nerve Supply: Median nerve. Function: Abduction of the thumb at the carpometacarpal and metacarpophalangeal joints. 2. Flexor pollicis brevis: Origin: Lateral border of the flexor retinaculum. Insertion: Base of the first phalanx. Nerve Supply: Median nerve. Function: Flexion of the thumb at the carpometacarpal and metacarpophalangeal joints. 3. Opponens pollicis: Origin: Lateral border of the flexor retinaculum. Insertion: Radial side of the first metacarpal bone, on the shaft. Nerve Supply: Median nerve. Function: Opposition: the movement of the thumb against another finger. When we move our thumb especially in the writing position there is a movement besides flexion and adduction which is medial rotation. The Opponens pollicis is responsible for it. Note: A suggested question in the test may ask which nerve is injured due to the disability of shaping the letter (O) or ( C) using one's hand. The answer is the median nerve. Hypothenar muscles: 1. Abductor digiti minimi. 2. Opponens digiti minimi.

7 3. Flexor digiti minimi brevis. 1. Abductor digiti minimi: Origin: The medial side of the flexor retinaculum. On the pisiform and the hook of the hamate. Insertion: Ulnar side of the base of the proximal fifth phalanx. Nerve supply: Deep branch of the ulnar nerve. Function: Abduction of the little finger at the metacarpophalangeal joint. 2. Opponens digiti minimi: Located between the abductor digiti minimi and the flexor digiti minimi brevis. Origin: Medial side of the flexor retinaculam. Insertion: The ulnar border of the entire fifth metacarpal bone. Nerve supply: Deep branch of the ulnar nerve. Function: Flexion at the metacarpophangeal joint and lateral rotation of the fifth digit. 3. Flexor digiti minimi brevis: Origin: Medial side of the flexor retinaculam. Insertion: Ulnar side of the base of the proximal fifth phalanx. Nerve supply: Deep branch of the ulnar nerve. Function: Flexion at the metacarpophangeal joint. Each muscle functions according to its name. Note: All three hypothenar muscles are supplied by the deep branch of the ulnar nerve. Adductor Pollicis: Origin: Oblique Head: 1. Capitate bone. 2. Bases of 2-3 metacarpals. Transverse Head: Proximal 2/3 of palmar surface of 3 rd metacarpal. Function: Adduction of the thumb.

8 Insertion: Ulnar side of base of 1 st proximal phalanx. Nerve Supply: Deep branch of the ulnar nerve. It is the only muscle in the thumb that is innervated by the ulnar nerve. Fascial Spaces of the Palm: The thenar space: The thenar space contains the first lumbrical muscle and lies posterior to the long flexor tendons to the index finger and in front of the adductor pollicis muscle. Midplamer space: The midpalmar space contains the second, third, and fourth lumbrical muscles and lies posterior to the long flexor tendons to the middle, ring, and little fingers. Functions: 1. They Prevent the spreading of an infection. 2. Lubrication. Note: From Wikipedia: Lubrication is the process, or technique employed to reduce wear of one or both surfaces in close proximity, and moving relative to each another, by interposing a substance called lubricant between the surfaces to carry or to help carry the load (pressure generated) between the opposing surfaces. Arteries of the Palm: 1. The Ulnar Artery: Revision: The ulnar artery passes superficially to the flexor retinaculum. Medial to it is the ulnar nerve. When it enters the hand it is accompanied by a vein. In the wrist region it gives rise to carpel arteries; anterior and posterior carpel arteries. After entering the hand: The artery gives off a deep branch which connects with the deep branch of the radial artery to give the deep palmer arch and then continues into the palm as the superficial palmar arch. Superficial Palmer Arch: A direct continuation of the ulnar artery. Its branches: 1. Three common palmar digital arteries; which provide the principal blood supply to the lateral side of the little finger, both sides of the ring and middle fingers and the medial side of the index finger. 2. Palmar digital artery on the medial side of the little finger.

9 So every digit (thumb not included) has two separate arteries; one on each side. At the apexes of each digit an anastomosis may occur. These lie between the tendons of the flexor digitorum superficialis and profoundus. The pulse is preferred to be felt between the three fingers because there isn't any continuity for these arteries. On the other hand; the thumb is innervated by a branch from the radial artery called the princeps pollicis artery which is in continuity. That's why if the pulse is felt on the thumb it's merely the thumb's pulse not the patient's. (I didn't understand). In surface anatomy we determine where the superficial palmar arch is, by extending the thumb; the curve of the arch lies at a level with the distal border of this extended thumb. Whereas, the curve of the deep palmar arch lies at a level with the proximal border of the extended thumb. The Deep Branch of the Ulnar Artery: It arises in front of the flexor retinaculum. It passes between the abducator digiti minimi and the flexor digiti minimi muscles. Joins the radial artery to complete the deep palmar arch. 2. The Radial Artery: At the lower seven centimeters the radial artery is directly on the radius. Making the pulse easy to feel. After that it deviates laterally deep to the tendon of the flexor pollicis longus. It goes to the dorsum of the hand and by that it is a content of the snuffbox. Penetrates the first dorsal interosseous muscle; reaching the palm. Then it penetrates the adductor pollicis forming the deep palmar arch in the palm. The Deep Palmar Arch: A direct continuation of the radial artery. Is deep to the flexor digitorum profundus. Its branches: 1. Three deep metacarpal digital arteries: They join the three common palmar digital arteries of the superficial palmar arch. The arch is completed on the medial side by the deep branch of the ulnar artery. The deep palmar arch sends branches inferiorly, which take part in the anastomosis around the wrist joint. Two branches arise from the radial artery in the palm : 1. The princeps pollicis artery on the lateral side of the thumb. 2. The radialis indicis artery on the lateral side of the index. Allen's Test:

10 To test for adequate anastomoses between the radial and ulnar arteries, compress both the radial and ulnar arteries at the wrist, then release pressure from one or the other, and determine the filling pattern of the hand. If there is little connection between the deep and superficial palmar arteries only the thumb and lateral side of the index finger will fill with blood (become red) when pressure on the radial artery alone is released. Veins of the palm: Every artery is accompanied by veins. These veins end in the dorsal venous arch which is the origin of the cephalic and basilic veins. Lymph Drainage of the Palm: Can be divided into medial side and lateral side. The lymph from the medial side of the hand ascends in vessels that accompany the basilic vein. They drain into the supratrochlear nodes and then ascend to drain into the lateral axillary nodes. The lymph from the lateral side of the hand ascends in vessels that accompany the cephalic vein. They drain into the supratrochlear nodes and then ascend to drain into the lateral axillary nodes. Nerves of the palm: 1.The Ulnar Nerve: Supplies 15 muscles. Passes superficial to the flexor retinaculum. The ulnar artery is on its lateral side. Here, the nerve and artery may lie in a fibroosseous tunnel called: (The tunnel of Guyon) between the hook of the hamate and the flexor tendon, created by fibrous tissue derived from the superficial part of the flexor retinaculum. In the forearm the ulnar nerve gives rise to: 1. Palmar cutaneous nerve of ulnar supplies one third of medial side of the palm; the ulnar side of the little finger and the adjacent sides of the little and ring fingers. 2. Dorsal cutaneous nerve of ulnar also supplies one third of the medial side of the dorsal aspect of the hand. (the distal half). When the ulnar nerve enters the hand deeply, it divides into: 1. Superficial Branch: Innervates the Palmaris brevis muscle, and continues across the palm to supply skin in the palmar surface of the little and medial half of the ring finger. 2. Deep Branch: Supplies around 14 muscles: 2 lumbricals, 8 inerossei, 3 hypothenar, 1 adductor pollicis. This branch is muscular and motor.

11 2. The Median Nerve: It gives off a palmar branch superficial to the flexor retinaculum. This branch supplies the lateral two thirds of the palm. The median nerve enters the palm by passing behind the flexor retinaculum and through the carpal tunnel. It immediately divides into lateral and medial branches. The lateral branch takes a recurrent course (recurrent branch) supplying the three thenar muscles along with the first lumbrical muscle. The medial branch gives the palmar digital branches which innervate the skin on the palmar surfaces of the lateral three and one-half digits and the distal half of the dorsal aspect of the same fingers (the dorsal aspects of the distal phalanges). These branches are cutaneous meaning that they take sensation from the skin. One of these branches also supplies the second lumbrical muscle. So we conclude: The median nerve in the palm supplies three thenar muscles, two lumbricals (L1 and L2). As for the skin, it supplies three and a half fingers at the palmar surface then it goes dorsally till it reaches the proximal phalanx. The Dorsum of the hand: At the dorsum of the hand there is the dorsal branch of the ulnar and the superficial branch of the radial that supplies the lateral TWO thirds of the dorsum in addition to the proximal phalanges. But also keep in mind the palmar digital nerves innervating the dorsal aspects of the distal phalanges of the lateral three and one-half digits. The Radial Artery on the Dorsum of the Hand: In the snuff box it will pierce the first dorsal interosseous muscle and then it will peirce the adductor pollicis muscle to form the deep palmer arch. The dorsal venous arch: The dorsal venous arch receives tributaries from the digits accompanying their corresponding arteries. At the base of the thumb we find the beginning of the cephalic vein and at the base of the little finger we find the basilic vein. From this, notice how these two superficial veins start at the dorsum of the hand and move anteriorly in the forearm. During their ascent, they cross the cubital fossa and are connected by the median cubital vein. The cephalic treks the lateral aspect of the forearm (as a continuation from the thumb) while the basilic is seen at the medial aspect of the forearm. The cephalic enters the pectoral triangle and ends as in the axillary vein, the basilic vein however will pierce the deep fascia in the arm it joins the vena comitans that accompany the brachial artery to form the axillary vein at the level of lower border of teres major. The long extensor tendons give three slips. The middle slip will insert into base of middle phalanx while the two lateral slips will insert into the base of distal phalanx forming what is known as the dorsal digital expansion. In the end;

12 1.The Fibrous Flexor Sheath, fascial spaces of the Palm, Allen's test and lymph drainage of the palm were partially copied from the slides as they were better arranged and clearer to understand compared to the way they were conveyed during the lecture. 2. Any mistakes committed were highly avoided. I am truly sorry for any scientific, spelling or grammatical errors. And any misunderstandings or vague pieces of information or misleading concepts are apologized for. Thank you for giving me this opportunity to write this humble piece of work for your section. All the best, Shatha Kayed.