AN131: Hand

Question 1

How do the long extensor tendons insert in the hand?

Answer 1

Extensor digitorum joins deep fascia’s expansion called the extensor expansion, which is the roof of the subfascial space

Question 2

Where is the extensor expansion?

Answer 2

It occupies the whole width of the hand (the base of digits 2-5)

Question 3

Where does the tendon the extensor digitorum insert?

Answer 3

At the middle and distal phalanx.
- the extensor expansion splits into 2 lateral and 1 central part at the point of PIP (proximal interphalangeal joint).
1. lateral parts converge and insert at base of distal
2. central part inserts at base of middle phalanx

Question 4

What does the extensor expansion consist of?

Answer 4

the tendon of insertion for the:
1. lateral lumbrical muscle
2. corresponding interosseous muscle
3. extensor digitorum

Question 5

What are the intrinsic muscles of the hand?

Answer 5

1. thenar ms
2. hypothenar ms
3. short muscles of hand: lumbricals and interosseous muscles
4. palmaris brevis
5. adductor pollicis

Question 6

Which muscles share a compartment with the long flexor tendons?

In which compartment?

Answer 6

The lumbrical muscles, which are considered a part of the central compartment that is shared with the flexor digitorum profundus.

Question 7

Which short muscles of the hand have their own compartment?

Answer 7

Interosseous, between the metacarpals

Question 8

What are the thenar muscles?

Answer 8

1. abductor pollicis brevis
2. flexor pollicis brevis
3. opponens pollicis

Question 9

What is the action of the thenar muscles?

Answer 9

Mainly opposition.
- opponens pollicis medially rotates carpometacarpal joint of thumb which happens when picking up an object.
- flexor pollicis brevis flexes both CMJ and MPJ of thumb.
- abductor pollicis brevis abducts thumb

APB and FPB assist in opposing thumb.

Question 10

How are the thenar muscles organized?

Answer 10

The largest is the quadrangular opponens pollicis, beneath APB and lateral to FPB.

Question 11

Which muscles that move the thumb have more than one head?

Answer 11

1. FPB thenar muscle: superficial and deep head
2. adductor pollicis muscle: transverse and oblique head

Question 12

T/F all thenar muscles are innervated by reccurent branch of median nerve (C8, T1)

Answer 12

True, but the FPB is not only innervated by the median nerve.
- deep head of FPB: ulnar nerve innervation

Question 13

T/F the origin of all thenar muscles is the tubercle of the scaphoid, the trapezium, and the adjacent flexor retinaculum.

Answer 13

True 100%. All thenar muscles: APB, FPB, and opponens pollicis share the same origins.

Question 14

T/F all thenar muscles insert in the base of the proximal phalanx.

Answer 14

False.
lateral side of base of proximal phalanx: APB and FPB
lateral side of first metacarpal: opponens pollicis

the opponens pollicis does not insert into the proximal phalanx

Question 15

thumb

Which muscle insert into the medial side of the proximal phalanx’s base?

Answer 15

Adductor pollicis

Question 16

What are the origins of adductor pollicis muscle?

Answer 16

Transverse, one origin, but oblique has multiple:
1. transerve: shaft of 3rd metacarpal’s anterior surface
2. oblique: base of metacarpals 2 & 3, the capitate, and other carpal bones.

Question 17

What is innervated by deep branch of ulnar nerve?

Answer 17

1. adductor compartment (adductor pollicis)
2. deep head of flexor pollicis brevis
3. all of the hypothenar muscles: ADM, FDM, opponens digiti minimi
4. palmar and dorsal interossei
5. lumbrical muscles 3 & 4

Question 18

What has origins in the pisiform bone?

Answer 18

the abductor digiti minimi.

Question 19

Which muscles have origins in the hook of hamate?

Answer 19

1. flexor digiti minimi brevis
2. opponens digiti minimi

Question 20

T/F all the thenar and hypothenar muscles have origins in the flexor retinaculum.

Answer 20

False, all have origins from the flexor retinaculum except for the abductor digiti minimi.

add. pollicis (not of thenar ms.) doesn’t have flexor retinac. origins.

Question 21

Which muscle gives power to grip?

Answer 21

The adductor pollicis

Question 22

What does the palmaris brevis do?

Answer 22

corrugates skin to improve grip of palm

Question 23

originates from flexor retinaculum and palmar aponeurosis:

Answer 23

palmaris brevis

Question 24

orginates from hook of hamate and flexor retinaculum:

Answer 24

flexor digiti minimi brevis and opponens digiti

Question 25

most superficial hypothenar muscle:

Answer 25

abductor digit minimi

Question 26

origin and insertion of abductor digiti minimi:

Answer 26

from pisiform to medial side of base of proximal phalanx (5th)

Question 27

Action of opponens digiti:

Answer 27

1. pulls 5th metacarpal anteriorly 2. rotates 5th metacarpal laterally action on CMJ*

Question 28

What does the aciton of the opponens digiti minimi do?

Answer 28

Deepen the hollow of the palm

Question 29

Innervation of palmaris brevis:

Answer 29

Superficial branch of ulnar nerve

Question 30

Where does the palmaris brevis insert?

Answer 30

The skin of the palm

Question 31

Action of FDMB:

Answer 31

- on MCP joint - flexion of fifth proximal phalanx

Question 32

Inserts at medial side of the proximal phalanx base:

Answer 32

- ADM - FDMB

Question 33

Worm-like muscles:

Answer 33

Lumbrical muscles: 4, one associated with each finger (2, 3, 4)