Week 6 - Intrinsic Muscles of the Hand

Question 1

Where are the thenar muscles located?

Answer 1

At the base of the thumb, on the palmar side.

Produce “fleshy lump”

Question 2

What muscles make up the thenar group?

Answer 2

Adductor pollicis brevis
Opponens pollicis
Flexor pollicis brevis

Question 3

What nerve innervates the thenar muscles (include nerve roots)

Answer 3

The median nerve, C5 - T1

Question 4

What is the action of opponens pollicis?

Answer 4

Opposes the thumb by flexing and medially rotating the metacarpal on the trapezium

Question 5

What is the action of abductor pollicis brevis?

Answer 5

Abducts the thumb

Question 6

What is the action of flexor pollicis brevis?

Answer 6

Flexes the MCP joint of the thumb

Question 7

Where is the hypothenar eminence? What muscles form this?

Answer 7

Fleshy lump on the ulnar side of the palm.
Formed by:
Opponens digiti minimi
Flexor digiti minimi brevis
Abductor digiti minimi

Question 8

What nerve innervates the hypothenar muscles?

Answer 8

The ulnar nerve (C8/T1)

Question 9

What is the action of flexor digiti minimi brevis?

Answer 9

Flexes the little finger at the MCP joint

Question 10

What is the action of abductor digiti minimi?

Answer 10

Abducts the little finger

Question 11

What is the action of opponens digiti minimi?

Answer 11

Opposes the little finger by rotating the metacarpal towards the thumb side of the palm.

Question 12

How many lumbricals are there?

Answer 12

4 - 1 for each finger

Question 13

What is the function of the lumbricals?

Answer 13

Link the flexor and extensor tendons - flex at MCP and extend at IP

Question 14

What is the innervation of the lumbricals?

Answer 14

Lateral 2 = median nerve

Medial 2 = ulnar nerve

Question 15

Where are the interossei located?

Answer 15

Between the metacarpals

Question 16

What nerve innervates all the interossei muscles?

Answer 16

The ulnar nerve

Question 17

How many dorsal interossei are there?

Answer 17

4

Question 18

What is the function of the dorsal interossei?

Answer 18

Abduct the fingers at the MCP joints

Question 19

How many palmar interossei are there?

Answer 19

3 - 2nd, 4th and 5th digits

Question 20

What is the action of the palmar interossei?

Answer 20

Adduct the fingers

Question 21

What are the 2 “miscellaneous” intrinsic muscles of the hand?
Are they located on the palmar or dorsal side?

Answer 21

Adductor pollicis
Palmaris brevis

Palmar side

Question 22

What nerve innervates adductor pollicis?

Answer 22

Ulnar nerve

Question 23

Is palmaris brevis innervated by the median nerve?

Answer 23

No - ulnar nerve

Question 24

What is the action of adductor pollicis? (You’ll never guess!)

Answer 24

Adducts the thumb

Question 25

Why is adductor pollicis an anatomical landmark?

Answer 25

2 heads, between which the radial artery passes

Question 26

What is the action of palmaris brevis?

Answer 26

Wrinkles the skin of the hypothenar eminence Deepens the curvature of the skin Both these improve grip

Question 27

What are the 5 groups of intrinsic muscles of the hand?

Answer 27

``` Thenar Hypothenar Lumbricals Interossei Miscellaneous ```