Hand Muscles

Question 1

What is the anterior/lateral border of the anatomical snuff box?

Answer 1

Abductor pollicis longus and extensor pollicis brevis

Question 2

What is the posterior/medial border of the anatomical snuff box?

Answer 2

Extensor pollicis longus

Question 3

What are the contents of the anatomical snuff box?

Answer 3

Radial A deep to tendons

Superficial radial N superficial to tendons

Question 4

Which muscles form the thenar eminence of the hand?

Answer 4

Abductor pollicis brevis, Opponens pollicis, flexor pollicis brevis, adductor pollicis

Question 5

What are the attachment sites for abductor pollicis brevis?

Answer 5

O: tubercles of the scaphoid and trapezium bones and the flexor retinaculum
I: lateral aspect of the base of the proximal phalanx of the pollux

Question 6

What is the action of abductor pollicis brevis?

Answer 6

Abduct pollux and aids in opposition

Question 7

What are the attachment sites for opponens pollicis?

Answer 7

O: tubercles of the scaphoid and trapezium bones and the flexor retinaculum
I: lateral aspect of the 1st metacarpal

Question 8

What is the action of opponens pollicis?

Answer 8

Oppose pollux

Question 9

Which thenar muscles are innervated by recurrent branch of the median N?

Answer 9

Abductor pollicis brevis, opponens pollicis and superficial head of flexor pollicis brevis

Question 10

Which muscles of the thenar eminence are innervated by deep ulnar N?

Answer 10

Deep head of flexor pollicis brevis and adductor pollicis

Question 11

What are the attachments for flexor pollicis brevis?

Answer 11

O: tubercles of the scaphoid and trapezium bones and flexor retinaculum
I: lateral aspect of the base of the proximal phalanges of the pollux

Question 12

What is the action of flexor pollicis brevis?

Answer 12

Flex 1st metacarpal and proximal phalanges of the pollux at the carpometacarpal and MP joints

Question 13

What are the origins for adductor pollicis?

Answer 13

Oblique head: capitate and bases of the 2nd and 3rd metacarpal bones
Transverse head: anterior aspect of the body of the 3rd metacarpal bone

Question 14

What is the insertion of the adductor pollicis?

Answer 14

Medial aspect of the proximal phalanx of the pollux

Question 15

What is the action of adductor pollicis?

Answer 15

Adduct pollux

Question 16

Which muscles form the hypothenar eminence?

Answer 16

Abductor digiti minimi, flexor digiti minimi brevis and opponens digiti minimi

Question 17

What are the attachment sites for abductor digiti minimi?

Answer 17

O: pisiform bone
I: medial aspect of the base of the proximal phalanx of 5th digit

Question 18

What is the action of abductor digiti minimi?

Answer 18

Abduct 5th digit

Question 19

What innervates the muscles of the hypothenar eminence?

Answer 19

Deep ulnar N

Question 20

What are the attachment sites for flexor digiti minimi brevis?

Answer 20

O: hook of hamate and flexor retinaculum
I: medial aspect of the base of the proximal phalanx of the 5th digit

Question 21

What is the action of flexor digiti minimi brevis?

Answer 21

Flex proximal phalanx of 5th digit

Question 22

What are the attachment sites for opponens digiti minimi?

Answer 22

O: hook of hamate and flexor retinaculum
I: medial aspect of the 5th metacarpal

Question 23

What is the action of opponens digiti minimi?

Answer 23

Oppose 5th digit

Question 24

Which muscles are considered to be intermediate hand muscles?

Answer 24

1-4th lumbricals, dorsal and palmar interossei

Question 25

What are the attachment sites for the 1st and 2nd lumbricals?

Answer 25

O: lateral side of the lateral two flexor digitorum profundus tendons as unipennate muscles I: radial aspect of the extensor expansions of the 2nd and 3rd digits

Question 26

What is the action of the 1st and 2nd lumbricals?

Answer 26

Flex proximal phalanges of 2nd and 3rd digits | Extend intermediate and distal phalanges of the 2nd and 3rd digits by tightening extensor expansion

Question 27

What is the action of 3rd and 4th lumbricals?

Answer 27

Flex proximal phalanges of 4th and 5th digits | Extend intermediate and distal phalanges of the 4th and 5th digits by tightening extensor expansion

Question 28

What innervates most intermediate hand muscles?

Answer 28

Deep ulnar N | Exception: 1st and 2nd lumbricals

Question 29

What innervates 1st and 2nd lumbricals?

Answer 29

Median N

Question 30

What are the attachment sites for 3rd and 4th lumbricals?

Answer 30

O: between the medial three flexor digitorum profundus tendons as bipennate muscles I: radial aspect of the extensor expansions of the 4th and 5th digits

Question 31

What are the attachment sites for dorsal interossei muscles?

Answer 31

O: adjacent sites of two metacarpals as a bipennate muscle I: bases of proximal phalanges and extensor expansion of digits 2-4

Question 32

What is the action for dorsal interossei muscles?

Answer 32

Abduct digits 2-4 (DAB) Flex proximal phalanges at the MP joint Extend intermediate and distal phalanges by tightening extensor expansion

Question 33

What are the attachment sites for palmar interossei muscles?

Answer 33

O: palmar aspect of the 2nd, 4th and 5th metacarpals I: bases of proximal phalanges and extensor expansions of the 2nd, 4th and 5th digits

Question 34

What is the action of palmar interossei muses?

Answer 34

Adduct 2nd, 4th and 5th metacarpals (PAD) Flex proximal phalanges of 2nd, 4th and 5th digits at the MP joint Extend intermediate and distal phalanges of the 2nd, 4th and 5th digits by tightening extensor expansions

Question 35

What is a power grip (palm grasp)?

Answer 35

Digits acting against the palm while wrapped around an object with counter pressure from the pollux Includes involvement from the long flexors of the digits acting at the IP joint with intrinsic hand muscles acting at the MP joint

Question 36

What is a hook grip?

Answer 36

As when carrying a suitcase Consumes less energy than the power grip Involves mainly the long flexors of the digits acting at the IP joint

Question 37

What is a precision handling grip?

Answer 37

As when writing | Involves long flexor and extensor muscles in addition to the intrinsic hand muscles performing fine movements

Question 38

What is pinching?

Answer 38

Compressing on object between the distal aspect of the 1st and 2nd digits

Question 39

What is the position of rest?

Answer 39

Inactive position