Muscles of the Hand

Question 1

Thenar muscles

Answer 1

Opponens pollici, abductor pollicis brevis, flexor pollicis brevis

Question 2

Opponens pollicis

Answer 2

Origin - tubercle of the trapezium and associated flexor retinaculum
Attachment - lateral margin of the metacarpal of the thumb
Action - opposes the thumb by medially rotating and flexing the metacarpal on the trapezium
Innervation - median nerve

Question 3

Abductor pollicis brevis

Answer 3

Origin - tubercles of the scaphoid and trapezium and associated flexor retinaculum
Attachment - lateral side of the proximal phalanx
Action - abducts the thumb
Innervation - median nerve

Question 4

Flexor pollicis brevis

Answer 4

Origin - tubercle of the trapezium and associated flexor retinaculum
Attachment - base of proximal phalanx of the thumb
Action - flexes the metacarpophalangeal joint of the thumb
Innervation - median nerve

Question 5

Hypothenar muscles

Answer 5

Opponens digiti minimi, abductor digiti minimi, flexor digiti minimi brevis

Question 6

Opponens digiti minimi

Answer 6

Origin - hook of the hamate and associated flexor retinaculum
Attachment - medial margin of metacarpal V
Action - rotates the metacarpal of the little finger toward the palm, producing opposition
Innervation - ulnar nerve

Question 7

Abductor digiti minimi

Answer 7

Origin - pisiform and tendon of flexor carpi ulnaris
Attachment - base of the proximal phalanx of the little finger
Actions - abducts the little finger
Innervation - ulnar nerve

Question 8

Flexor digiti minimi brevis

Answer 8

Origin - hook of the hamate and adjacent flexor retinaculum
Attachment - base of the proximal phalanx of the little finger
Action - flexes the metacarpophalangeal joint of the little finger
Innervation - ulnar nerve

Question 9

Lumbricals

Answer 9

4 lumbricals each associated with a finger (I-IV)
Origin - each lumbrical originates from a tendon of the flexor digitorum profundus
Attachment - extensor hood of each finger
Action - flex metacarpophalangeal joint and extend at interphalangeal joint of each finger
Innervation - medial two (little and ring finger) = ulnar nerve
Innervation lateral two (index and middle) = median nerve

Question 10

Dorsal interossei

Answer 10

Origin - lateral and medial surface of the metacarpal
Attachment - extensor hood and proximal phalanx of each finger
Action - abduct the fingers at the metacarpophalangeal joint
Innervation - ulnar nerve

Question 11

Palmar interossei

Answer 11

Origin - medial or lateral surface of a metacarpal
Attachment - extensor hood and proximal phalanx of same finger
Action - adducts the fingers at the metacarpophalangeal joint
Innervation - ulnar nerve

Question 12

Palmaris brevis

Answer 12

Origin - palmar aponeurosis and flexor retinaculum
Attachment - dermis of skin on the medial margin of the hand
Action - wrinkles skin of the hypothenar eminence and deepens the curvature of the hand, improving grip
Innervation - ulnar nerve

Question 13

Adductor pollicis

Answer 13

Origin - metacarpal III and the capitate and adjacent areas of metacarpals II and III
Attachment - base of the proximal phalanx of the thumb
Action - adductor of the thumb
Innervation - ulnar nerve