Intrinsic Muscles of Hand

Question 1

Opponens pollicis

Answer 1

Origin : flexor retinaculum and tubercles of scaphoid and trapezium
Insertion : lateral side of 1st metacarpal
Innervation : recurrent branch of median nerve C8, T1
Action : to oppose thumb, it draws 1st metacarpal medially to center of palm and rotates it medially

Question 2

Abductor pollicis brevis

Answer 2

Origin : flexor retinaculum and tubercles or scaphoid and trapezium
Insertion : lateral side of base of proximal phalanx of thumb
Innervation : recurrent branch of median nerve C8, T1
Action : abducts thumb; helps oppose it

Question 3

Flexor pollicis brevis

Answer 3

Origin : flexor retinaculum and tubercles of scaphoid and trapezium
Insertion : lateral side of base of proximal phalanx of thumb
Innervation : recurrent branch of median nerve C8, T1
Action : flexes thumb

Question 4

Adductor pollicis

Answer 4

Origin : oblique head : bases of 2nd and 3rd metacarpals, capitate and adjacent carpals
transverse head : anterior surface of shaft of 3rd metacarpal
Insertion : medial side of base of proximal phalanx of thumb
Innervation - deep branch of ulnar nerve C8, T1
Action : adducts thumb towards lateral border of Palm

Question 5

Abductor digiti mini

Answer 5

Origin : pisiform
Insertion : medial side of base of proximal phalanx of 5th finger
Innervation : deep branch of ulnar nerve C8, T1
Action: abducts 5th finger; assists in flexion of its proximal phalanx

Question 6

Flexor digiti minimi brevis

Answer 6

Origin : hook of hamate and flexor retinaculum
Insertion : medial side of base of proximal phalanx of 5th finger
Innervation : deep branch of ulnar nerve C8, T1
Action - flexes pinky

Question 7

Opponens digiti minimi

Answer 7

Origin : hook of hamate and flexor retinaculum
Insertion : medial border of 5th metacarpal
Innervation : deep branch of ulnar nerve C8, T1
Action : draws 5th metacarpal anterior and rotates it; bringing 5th finger into opposition with thumb

Question 8

Lumbricals 1 & 2

Answer 8

Origin: lateral two tendons of flexor digitorum profundus as unipennate muscles
Insertion : lateral sides of extensor expansions of 2-5th metacarpals
Innervation - median nerve C8, T1
Action : flexes MC joints; extends ICP joints of 2-5th fingers

Question 9

Lumbricals 3 & 4

Answer 9

Origin : medial three tendons of flexor digitorum profundus as bipennate muscles
Insertion : lateral sides of extensor expansions of 2-5th digits
Innervation : median nerve C8, T1
Action : flexes MC joints and extends ICP joints of 2-5th fingers

Question 10

Dorsal interossei, 1-4

Answer 10

Origin : adjacent sides of two metacarpals as bipennate muscles
Insertion : bases of proximal phalanges; extensor expansions of 2-4th fingers
Innervation : deep branch of ulnar nerve C8, T1
Action : abducts 2-4 fingers from axial line; acts with lumbricals in flexing MC joints and extends ICO joints

Question 11

Palmar interossei, 1-3

Answer 11

Origin - palmar surfaces of 2nd, 4, 5th metacarpal as unipennate muscles
Insertion - bases of proximal phalanges; extensor expansions 2,4,5 fingers
Innervation : deep branch of ulnar nerve C8, T1
Action : adduct 2,4,5, fingers toward axial line; assist lumbricals in flexing MC joints and extending ICP joints