MSK - Muscles of the Hand

Question 1

How many groups can the hand muscles be divided into?

What are the names of these groups?

Answer 1

2

Intrinsic

Extrinsic

Question 2

What is the function of the extrinsic muscles of the hand?

Where are they located?

Answer 2

Produce crude movements and a forceful grip

Located in the anterior and posterior compartments of the forearm

Question 3

What is the function of the intrinsic muscles of the hand?

Where are they located?

Answer 3

Responsible for the fine motor functions of the hand

Located within the hand

Question 4

What is the grouped name of the three short muscles located at the base of the thumb?

Answer 4

Thenar muscles

Question 5

What is the thenar eminance?

Answer 5

The bulge at the base of the thumb produced by the muscle bellies

Question 6

What is the function of the Thenar hand muscles?

Answer 6

Fine movements of the thumb

Question 7

What nerve innervates each thenar muscle?

Answer 7

All of them are innervated by the median nerve

Question 8

What is the muscle highlighted in green?

What is it’s attachments?

What is it’s actions?

Answer 8

Oppenens Pollicis

Originates from the tubercle of the trapezium and flexor retinaculum and inserts into the lateral margin of the metacarpal of the thumb

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

Question 9

What is the muscle highlighted in blue?

What is it’s attachments?

What is it’s actions?

Answer 9

Abductor Pollicis Brevis

Originates from the tubercles of the scaphoid and trapezium and from flexor retinaculum and attaches to lateral side of proximal phalanx

Abducts the thumb

Question 10

What is the muscle highlighted in red?

What is it’s attachments?

What is it’s actions?

Answer 10

Flexor Pollicis Brevis

Originates from the tubercle of the trapezium and flexor retinaculum and attaches to the base of the proximal phalanx of the thumb

Abducts the thumb

Question 11

What is the muscle highlighted in green?

What is it’s attachments?

What is it’s actions?

Answer 11

Flexor Digiti Minimi Brevis

Originates from the hook of hamata and adjacent flexor retinaculum and inserts into the base of the proximal phalanx of the little finger

Flexes the MCP joint of the little finger

Question 12

What is the muscle highlighted in blue?

What is it’s attachments?

What is it’s actions?

Answer 12

Opponens Digiti Minimi

Originates from the hook of hamate and associated flexor retinaculum and inserts into the medial margin of metacarpal V

Rotates the metacarpal of the little finger towards the palm, producing opposition

Question 13

What is the muscle highlighted in red?

What is it’s attachments?

What is it’s actions?

Answer 13

Abductor Digiti Minimi

Originates from the pisiform and the tendon of the flexor carpi ulnaris and attaches to the base of the proximal phalanx of the little finger

Abducts the little finger

Question 14

What is the grouped name for the following muscles?

Opponens Digiti Minimi

Abductor Digiti Minimi

Flexor Digiti Minimi Brevis

What are they all innervated by?

Answer 14

The **Hypothenar **Muscles

Innervate by the Ulnar nerve

Question 15

What group do these muscles belong to?

Answer 15

The Lumbricals

Question 16

What is the function of the lumbricals?

Answer 16

Crucial to finger movement, linking the extensor tendons to the flexor tendons

Question 17

How would denervation of the lumbricals clinically present?

Answer 17

Ulnar claw/Hand of benediction

Question 18

Which lumbricals are unipennate and which are bipennate?

Answer 18

I and II - unipennate

III and IV - bipennate

Question 19

What are the attachments of the lumbricals?

Answer 19

Each lumbrical originates from a tendon of the flexor digirorum profundus before passing dorsally and laterally around each finger and inserting into the extensor hood

Question 20

What are the actions of the lumbricals?

Answer 20

The flex at the MCP joint, and extend at the IP joints of each finger

Question 21

What are the innvervations of the lumbricals?

Answer 21

Medial two lumbricals (little and ring fingers) - ulnar nerve

Lateral two lumbricals (index and middle fingers) - median nerve

Question 22

What muscles are located between the metacarpals?

Answer 22

The interossei muscles

Question 23

How many groups can the interossei muscles be divided into?

Name them

Answer 23

2

Dorsal and Palmar interossei

Question 24

What else do the interossei muscles do in addition to their own actions?

Answer 24

Assist the lumbricals in flexion at the MCP joints and extension at the IP joints

Question 25

Which ones are dorsal and which ones are palmar?

Answer 25

Yellow - **Dorsal** Green - **Palmar**

Question 26

How many dorsal muscles are there? What are their attachments? What are their individual actions? What are their innervations?

Answer 26

4 Each interossei originates from the lateral and medial surfaces of the metacarpals before attaching into the extensor hood and proximal phalanx of each finger Abduct the fingers at the MCP joint **Ulnar Nerve**

Question 27

How many palmar muscles are there? What are their attachments? What are their individual actions? What are their innervations?

Answer 27

3 Each interossei originates from a medial or lateral surface of a metacarpal before attaching into the extensor hood and proximal phalanx of the same finger Adducts the fingers at the MCP joint **Ulnar Nerve**

Question 28

There are two other muscles in the palm that do not fit the hypothenar or thenar compartments. What are their names?

Question 29

Where is the **Palmaris Brevis** found?

Answer 29

Very superficially in the subsutaneous tissue of the hypothenar eminence

Question 30

What are the attachments of the **Palmaris Brevis**? What is its actions? What is it innervated by?

Answer 30

Originates from the palmar aponeurosis and flexor retinaculum before attaching to the dermis of the skin on the medial margin of the hand Wrinkles the skin of the hypothenar eminence and deepens the curvature of the hand which improves grip **Ulnar nerve**

Question 31

What structure passes anteriorly to this muscle between its two heads and what does it form? What is it's attachments? What is it's actions? What is it innervated by?

Answer 31

**Radial artery, forming palmar arch** One head originates from metacarpal III, the other from the capitate, and adjacent areas of metacarpals II and III. They both attach into the base of the proximal phalanx of the thumb Adductor of the thumb **Ulnar nerve**