Intrinsic Hand Muscles

Question 1

Abductor pollicis brevis

Answer 1

O: flexor reticulum and tubercles of scaphoid and trapezium
I: base of proximal phalanx of thumb
I: median nerve (recurrent branch) ( c8-t1)
A: abducts thumb at metacarpophalangeal joint

Question 2

Flexor pollicis brevis

Answer 2

O: flexor retinaculum and tubercle of trapezium
I: lateral side of base of proximal phalanx of thumb
I: median nerve (recurrent branch) (c8-t1)
A: flexes proximal phalanx of thumb

Question 3

Opponens pollicis

Answer 3

O: flexor retinaculum of tubercle of trapezium
I: lateral side of 1st metacarpal bone
I: median nerve (recurrent branch) (c8-t1)
A: opposes thumb towards center of palm and rotates it medial

Question 4

Adductor pollicis

Answer 4

O: oblique head- bases of 2nd and 3rd metacarpals and capitate
transverse head- anterior surface of body of 3rd metacarpal bone
I: medial side of base of proximal phalanx of thumb
I: ulnar nerve (deep branch) (c8-t1)
A: adducts thumb towards middle digit

Question 5

Abductor digiti minimi

Answer 5

O: pisiform and tendon of flexor carpi ulnaris
I: medial side of base of proximal phalanx of 5th digit
I: ulnar nerve (deep branch) (c8-t1)
A: abducts 5th digit

Question 6

Flexor digiti minimi

Answer 6

O: hook of hamate and flexor retinaculum
I: medial side of base of 5th proximal phalanx of 5th digit
I: ulnar nerve (deep branch0 ( c8-t1)
A: flexes proximal phalanx of 5th digit

Question 7

Opponens digiti minimi

Answer 7

O: hook of hamate and flexor retinaculum
I: palmar surface of 5th metacarpal bone
I: ulnar nerve (deep branch) (c8-t1)
A: draws 5th metacarpal bone anteriorly and rotates it, bringing it into opposition with thumb

Question 8

Lumbricals 1 and 2

Answer 8

O: lateral 2 tendons of flexor digitorum profundus
I: lateral sides of extensor expansions of 2nd to 5th digits
I: median nerve (c8-t1)
A: flex digits at metacarpophlangeal joints and extend interphalangeal joints

Question 9

Dorsal interossei

Answer 9

O: sides of two metacarpal bones
I: extensor expansions and bases of proximal phalanges of 2nd to 4th digits
I: ulnar nerve (deep branch) (c8-t1)
A: dorsal interossei abduct digits; flex digits at metacarpophlangeal joints and extend interphalangeal joints

Question 10

Lumbricals 3 and 4

Answer 10

O: medial 3 tendons of flexor digitorum profundus
I: lateral sides of extensor expansions of 2nd to 5th digits
I: ulnar nerve (deep branch) (c8-t1))
A: flex digits at metacarpophlangeal joints and extend interphalangeal joints

Question 11

Palmar interossei

Answer 11

O: palmer surfaces of 2nd, 4th, and 5th metacarpal bones
I: extensor expansions and bases of proximal phalanges of 2nd to 4th digits
I: ulnar nerve (deep branch) (c8-t1)
A: palmer interossei adduct digits; flex digits at metacarpophlangeal joints and extend interphalangeal joints