Muscles of the hand Flashcards
Why are the muscles acting on the hand divided into extrinsic and intrinsic groups?
extrinsic- anterior and posterior compartments of the forearm
intrinsic- muscles located in the hand
what are the Thenar muscles called?
Opponens pollicis, abductor pollicis brevis, flexor pollicis brevis
(the muscle bellies produce a buldge know as the themas eminence at the base of the thumb)
origin of opponent pollicis
tubercle of the trapezium and the associated flexor retinaculum
insertion of opponens pollicis
lateral margin of the metacarpal of the thumb
innervation of opponens pollicis
median nerve
function of opponens pollicis
opposes the thumb, by medially rotating and flexing the metacarpal on the trapezium
origin of abductor pollicis brevis
tubercles of the scaphoid and trapezium and from the associated flexor retinaculum
insertion of abductor pollicis brevis
proximal phalanx of the thumb
innervation of abductor pollicis brevis
median nerve
function of abductor pollicis brevis
abducts the thumb
origin of flexor pollicis brevis
tubercle of the trapezium and the associated flexor retinaculum
insertion of flexor pollicis brevis
base of the proximal phalanx of the thumb
function of flexor pollicis brevis
flexes the metacarpophalangeal (MCP) joint of the thumb
innervation of flexor pollicis brevis
median nerve (the deep head is innervated by the deep branch of the ulnar nerve)
What are the three hypothenar muscles?
opponens digiti minimi, abductor digiti minimi and flexor digiti minimi brevis
origin of opponens digiti minimi
hook of hamate and associated flexor retinaculum
insertion of opponens digiti minimi
medial margin of metacarpal 5
innervation of opponens digiti minimi
ulnar nerve
function of opponens digiti minimi
rotates the metacarpal of the little finger towards the palm, producing opposition
origin of abductor digiti minimi
pisiform and tendon of the flexor carpi ulnaris
insertion of abductor digiti minimi
base of the proximal phalanx of the little finger
innervation of abductor digiti minimi
ulnar nerve
function of abductor digit minimi
abducts the little finger
origin of flexor digiti minimi brevis
hook of hamate and adjacent flexor retinaculum
insertion of flexor digit minimi brevis
base of the proximal phalanx of the little finger
innervation of flexor digiti minimi brevis
ulnar nerve
function of flexor digit minimi brevis
flexes the MCP joint of the little finger
what are the four lumbricals
unipennate (I), unipennate (II), bipennate (III) and bipennate (IV)
origin of the lumbricals
each tendon of the flexor digitorum profundus
insertion of the lumbricals
they pass dorsally and laterally around each finger and inserts into the extensor hood
function of the lumbricals
flexion at the MCP joint and extension at the interphalangeal joints of each digit
innervation of the lumbricals
the lateral two lumbricals (index and middle)= median nerve
the medial two lumbricals (little and ring finger)= ulnar nerve
What are the two interossei muscles called?
dorsal interossei (4) and palmar interossei (3)
origin of the dorsal interossei
lateral and medial surfaces of the metacarpals
insertion of dorsal interossei
extensor hood and proximal phalanx of each finger
innervation of dorsal interossei
ulnar nerve
function of dorsal interossei
abduct the fingers at the MCP joint
origin of palmar interossei
medial or lateral surface of a metacarpal
insertion of palmar interossei
extensor hood and proximal phalanx of the same finger
innervation of the palmar interossei
ulnar nerve
function of palmar interossei
aducts the fingers at the MCP joint
origin of palmaris brevis
palmar aponeurosis and flexor retinaculum
insertion of palmaris brevis
dermis of the skin on the medial margin of the hand
innervation of palmaris brevis
ulnar nerve
function of palmaris brevis
wrinkles the skin of the hypothenar eminence and deepens the curvature of the hand, improving the grip
origin of adductor pollicis
one head originates from metacarpal 3. the other head originates from the capitate and adjacent areas of metacarpals 2 and 3
insertion of adductor pollicis
the base of the proximal phalanx of the thumb
innervation of adductor pollicis
ulnar nerve
function of adductor pollicis
adductor of the thumb