Lecture 7 - Muscles in the forearm that move the forearm and hand

Question 1

Review the elbow joints and the movements of the forearm:

Elbow joint: 3 bones articulating (humerus, radius and ulna).
Movements at the elbow joint proper:
• Flexion
• Extension
Muscles:
• Bicepsbrachii • Brachialis
• Brachioradialis • Tricepsbrachii

Answer 1

Question 2

Name the joints in the Forearm (radioulnar joints).

What are the movements at the radioulnar joints?

Answer 2

1. Proximal radioulnar joint
2. Middle radioulnar joint
3. Distal radioulnar joint
   Note: Middle radioulnar joint, i.e., the interosseous membrane, is a syndesmosis. Proximal and distal joints are synovial

Movements at radioulnar joints:
• Supination

• Pronation

Question 3

What is the function of the annular ligament of the radius?

Answer 3

holds the head of radius against the radial notch of ulna, and allows radius to rotate during pronation and supination.

Question 4

What are the bones that compose the wrist joint?

Answer 4

Wrist (or radiocarpal) joint: radius, scaphoid, lunate and triquetrum

Question 5

Identify the structures on this image.

Answer 5

Question 6

What are the movements of the hand (at the wrist)?

Answer 6

Question 7

What are the functions compartments in the forearm?

1. Anterior compartment
2. Posterior compartment

Answer 7

Anterior compartment muscles = flexors of the hand and digits.
All are innervated by the Median nerve, except 1.5 muscles innervated by Ulnar nerve.
Posterior compartment muscles = extensors of the hand and digits. All innervated by the Radial nerve.

Question 8

What are the muscles in the anterior (flexor) muscle compartment of the forearm?

Answer 8

Layer 1: Pronator teres, Flexor carpi radialis, Palmaris longus, Flexor carpi ulnaris Layer

2: Flexor digitorum superficialis
Layer 3: Flexor digitorum profundus, Flexor pollicis longus
Layer 4: Pronator quadratus

Muscles in the 1st and 4th layer move the hand and forearm; muscles in the 2nd and 3rd layer move the digits.

Question 9

Palmaris longus

Answer 9

Question 10

Pronator teres

Answer 10

Question 11

Flexor carpi radialis

Answer 11

Question 12

Flexor carpi ulnaris

Answer 12

Question 13

Pronator quadratus

Answer 13

Question 14

Supinator

Answer 14

Question 15

Extensor carpi radialis longus

Answer 15

Question 16

Extensor carpi radialis brevis

Answer 16

Question 17

Extensor carpi ulnaris

Answer 17

Question 18

What are all of the muscles that are able to do flexion of the movements of the wrist/hand?

Answer 18

• Flexion: Flexor carpi radialis, Flexor carpi ulnaris, Palmaris longus

Question 19

What are all of the muscles that are able to do extension of the movements of the wrist/hand?

Answer 19

Extension: Extensor carpi radialis longus, Extensor carpi radialis brevis,
Extensor carpi ulnaris

Question 20

What are all of the muscles that are able to do the radial deviation (=abduction) of the movements of the wrist/hand?

Answer 20

Radial deviation (= Abduction): flexor + extensors on radial side:

1. Flexor carpi radialis
2. Extensor carpi radialis longus
3. Extensor carpi radialis brevis

Question 21

What are all of the muscles that are able to do the ulnar deviation (=adduction) of the movements of the wrist/hand?

Answer 21

• Ulnar deviation (= Adduction): flexor + extensor on ulnar side:

1. Flexor carpi ulnaris
2. Extensor carpi ulnaris.

Question 22

Summary – Innervation:

All extensor muscles of the forearm are supplied by the __________.
Flexor muscles in the forearm are supplied by the ___________, except:

2. Note:
   Pronation is controlled by the median nerve (Pronator teres and Pronator quadratus).
   Supination is controlled by both musculocutaneous nerve (to Biceps brachii) and radial nerve (to Supinator).

Answer 22

Summary – Innervation:
All extensor muscles of the forearm are supplied by the radial nerve.
Flexor muscles in the forearm are supplied by the median nerve, except: 1. Flexor carpi ulnaris, and
2. medial half of Flexor digitorum profundus innervated by the ulnar nerve.
Note:
Pronation is controlled by the median nerve (Pronator teres and Pronator quadratus).
Supination is controlled by both musculocutaneous nerve (to Biceps brachii) and radial nerve (to Supinator).