We should only know: Name, action & nerve supply Layers - Skin - Superficial fascia - Deep fascia The hand is full with sweat glands, activated at times of stress. Deep fascia In Slide #2 there was a mistake where the doctor mentioned lateral septum twice. - The deep fascia is thickened to form a triangular shaped apponeurosis. - The deep fascia sends 2 septums: Lateral septum 1st metacarpal Medial septum 5th metacarpal The hand is divided into 3 muscular compartments/spaces: - Lateral (thenar compartment thumb). - Medial (hypothenar compartment little finger). - Central compartment. Thenar muscles: - 3 muscles (FAO) Flexor pollicis brevis (flexion) Abductor pollicis brevis (abduction) Opponens pollicis (opposition) - Muscles abducting the thumb (2) Abductor pollicis longus (located in the posterior compartment of the forearm) Abductor pollicis brevis (muscles of the hand) - Abductions are accompanied by extension - Supplied by the median nerve
- All small muscles of the hand are supplied by the ulnar nerve except five muscles, three of which are the thenar muscles, and the two lateral lumbricals, which are supplied by the median nerve. Hypothenar muscles: - 3 muscles (FAO) Flexor digiti minimi (flexion) Abductor digiti minimi (abduction) Opponens digiti minimi (opposition) All supplied by the ulnar nerve Lumbricals (worm-like muscles): - 4 in number - Functions: writing position/holding pencil Extension of the phalanx and flexion of the metacarpophalangeal joint - Extension from the flexor digitorium - The two lateral lumbricals; 1 st & 2 nd, are supplied by median nerve, while the two medial lumbricals; 3 rd & 4 th, are supplied by the ulnar nerve. Palmar interossei (P-ADD: Palmars add) - Interossei: between bones - 4 in number - Function: adduct all fingers to the axial line Hold cigarette Hold paper between fingers. - All supplied by the ulnar nerve Notice that: in the palmar view; we can see that there are no muscle attached to the medial finger, which is also called the axis of the hand, to be shown in the pictures below. Dorsal interossei (D-AB: Dorsals adduct): - 4 in number - They don t insert on the thumb or little finger because they have their own abductors - Every muscle here has two heads; for example the 2 nd dorsal interossei muscle originates from the second and third metacarpal
- On the middle finger, the muscles attach from both sides, pulling from both sides and therefore cancelling out and the finger remains centered - Function: Abduction of index and ring from middle finger. Adductor pollicis: - Insertion: base of proximal phalanx - Adductors of the thumb adductor pollicis. - Supplied by ulnar nerve. - It has an oblique and transverse head Q: How many muscles act on the thumb? A: 9 muscles; as the following: - Intrinsic (thenar) 1. Abductor policis brevis 2. Adductor pilicis 3. First palmar interosseous 4. Flexor policis brevis 5. Opponens policis - Extrinsic 6. Abductor policis longus 7. Extensor policis brevis 8. Extensor policis longus 9. Flexor policis longues Radial artery - Before reaching the flexor retinaculum (FR) it s located between the tendons of brachioradialis and flexor carpi radialis - Divides to two branches before FR Small superficial branch; which will join the large superficial ulnar branch to form what we call; Superficial Palmar Arch. Large deep branch: Detected at base of snuffbox Joins the deep ulnar branch to form what we call deep palmar arch.
Ulnar artery - Medial to lateral: flexor carpi ulnaris, ulnar nerve, ulnar artery - The ulnar artery crosses over the FR and divides into 2 branches Large superficial branch. Small deep branch. Notes - Arterial and nerve supply of the fingers will be from the medial and lateral sides, and not the middle. Therefore in a surgery the needle is inserted in the medial or lateral side to block the nerve, and upon bleeding, the finger should be squeezed from the sides. - The hand is supplied by branched from both radial and ulnar arteries via two arches: superficial and deep palmar arches (supply the anterior aspect of the hand [palm]). Superficial palmar arch - The superficial branches of the radial and ulnar arteries unite to form the superficial palmar arch. - Mainly from ulnar artery (because its superficial branch is large). - Gives branches called digital branches. Deep palmar arch - The deep branches of the radial and ulnar arteries unite to form the deep palmar arch - Mainly from radial artery (because its deep branch is large) - Gives branches called digital branches. Cutaneous nerve supply to the hand: - Radial nerve: Upon reaching the cubital fossa it divides into superficial branch and deep branch. The superficial branch accompanies the brachioradialis muscle and continues to supply the skin only of the hand (cutaneous). - A needle can be used to detect whether a nerve is intact or damaged.
- The Ring Finger is supplied by both the Median & Ulnar Nerves; therefore it s the line of demarcation in the skin of the hand. The following pictures will help us to recognize the information mentioned above: In the picture above we can notice how the middle finger is innervated by three nerves from the dorsal view. But from the Palmar view; we can notice how the ring finger is supplied by two nerves; so it is the line of demarcation of the nerves of the skin. The picture below helps us more!
The picture below concludes important stuff: Try to mention the names before looking at the answers below:
1- Palmaris brevis. 5- Lumbricalls. 9- Opponens digiti 2- Dorsal interossei. 6- Opponens pollicis. Minimi. 3- Palmar interossei. 7- Abductor pollicis brevis. 10- abductor digiti 4- Adductor pollicis. 8- Flexor pollicis brevis. Minimi. 11- Flexor digiti minimi brevis.