Muscles of the Hand - Origin, Insertion, Nerve Supply | Anatomy Tutorial

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There are nineteen muscles of the hand arranged in various groups.

Having origin from the tubercle of scaphoid , crest of trapezium and flexor retinaculum we have the abductor policis brevis. This muscles inserts into the lateral side of the base of the proximal phalanx of the thumb.
Next muscle to be indicated is the flexor policis brevis. This muscle has two heads; a superifical and a deep head. The superifical head arises from the flexor retinaculum, while the deep head arises from the trapezoid and capitates bones. Both heads become tendinous and insert together into the lateral side of the base of the proximal phalanx of the thumb. A sesamoid bone is located at the junction of the two tendinous heads of flexor policis brevis. Keep in mind that between the two heads of flexor polics brevis is passing the tendon of flexor policis longus. This tendon arrives in the palm from under the flexor retinaculum , passes between the two heads of flexor policis brevis then finally inserts into the base of the distal phalanx of the thumb.
The third and the last musle of the thenar eminence is the opponens policis. This musle is the deepest muscle of the group and originates from theflexor retinaculum and crest of trapezium and inserts into the lateral side of the first metacarpal bone.
Even though is not a muscle of the thenar muscles group , The adductor policis muscle is also responsible for controlling the fine movements of the thumb. This muscle has two heads of origin.
The next group of muscles to be indicated is the hypothenar muscles group which are responsible for fine movements of the little finger. We will indicate this muscles using the blue colour.
Having origin from the tendon of flexor carpi ulnaris and pisiform bone is the Abductor digiti minimi. This muscle inserts into the medial side of the base of the proximal phalanx of little finger.
Having origin from the flexor retinaculum and hook of hamate is the flexor digiti minimi. This muscle inserts also into the medial side of the base of the proximal phalanx of little finger.
Next muscle to be indicated originates also from the flexor retinaculum and hook of hamate and inserts into the medial surface of the shaft of fifth metacarpal bone. This muscle is the opponens digiti minimi.
The fourth muscle of the hypothenar muscles goup is the Palmaris brevis. This is a thin quadrilateral muscle having origin from the flexor retinaculum and palmar aponeurosis. Its insertion is into the into the skin on the ulnar border of the palm of the hand.
The next group of muscles of the hand are the interossei muscles. There are seven interossei muscles. Three of them are palmar interossei and are unipennate muscles. The first palmar interosseous muscle originates from the medial side of second metacarpal bone and inserts into the medial side of the proximal phalanx of the second finger. The second palmar interosseous muscle originates from the lateral side of the fourth metacarpal bone and intserts into the lateral side of the base of the proximal phalanx of fourth finger. The third palmar interosseous muscle originates from the lateral side of the fifth metacarpal bone and inserts into the lateral side of the base of the proximal phalanx of little finger. An important observation is that origins and insertions of the palmar interossei muscles are facing the midline of the hand.
The other four interossei muscles are the dorsal interossei. These muscles are bipennate muscles. Each of them is placed in the corresponding intermetacarpal space and originates from the adjanced sides of the metacarpal bones. The first dorsal interosseous muscle inserts into the lateral side of the base of proximal phalanx of second finger. The second interosseous inserts into the lateral side of the base of the proximal phalanx of the middle finger. The third interosseous inserts into the medial side of the base of proximal phalanx of middle finger. The fourth interosseous mucle inserts into the medial side of the base of proximal phalanx of fourth finger.
The last group of muscles of the hand are the lumbricals. The lumbricals are four in number and arise from the tendons of flexor digitorum profundus in the palmar region.
As you know we have four tendons of flexor digitorum profundus , each of them inserts into the base of distal phalanges of the last four fingers. The first two lumbricals are unipennate muscles and arise from the lateral side of the first two tendons of flexor digitorum profundus. The third and fourth lumbricals are bipennate muscles and arise from the adjacent sides of the last three tendons of flexor digitorum profundus. The insertions of lumbricals muscles are into the lateral side of dorsal digital expansion of the corresponding digit from second to fifth.

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