Elbow & Forearm: Action, Origin, Insertion, & Nerve Innervation

Question 1

Brachialis

Answer 1

Action: flex the elbow
Origin: distal half of the anterior surface of the humerus
Insertion: ulnar tuberosity and coronoid process of ulna
Nerve Innervation: musculocutaneous, small branch from radial C5 and C6

Question 2

Brachioradialis

Answer 2

Action: flex the elbow; assist to pronate and supinate the forearm when these movements are resisted
Origin: proximal two-thirds of the lateral supracondylar ridge of the humerus
Insertion: radial styloid
Nerve Innervation: radial C5 and C6

Question 3

Biceps Brachii

Answer 3

Action: flex the elbow, supinate the forearm, and flex the shoulder.
Origin:
Short Head: coracoid process of the scapula
Long Head: supraglenoid tubercle of the scapula
Insertion: radial tuberosity and bicipital aponeurosis
Nerve Innervation: musculotaneous C5 and C6

Question 4

Triceps Brachii

Answer 4

Action:
All Heads: extend the elbow
Long Head: extend and adduct the shoulder
Origin:
Long Head: infraglenoid tubercle of scapula
Lateral Head: posterior surface of proximal half of the humerus
Medial Head: posterior surface of distal half of the humerus
Insertion: olecranon process of the ulna
Nerve Innervation: radial C6 to C8, T1

Question 5

Anconeus

Answer 5

Action: extend the elbow
Origin: lateral epicondyle of the humerus
Insertion: olecranon process and posterior, proximal surface of ulna
Nerve Innervation: radial C7 and C8

Question 6

Supinator

Answer 6

Action: supinate the forearm
Origin: lateral epicondyle of humerus, radial collateral ligament, annular ligament, and supinator crest of the ulna
Insertion: anterior, lateral surface of proximal one-third of the radial shaft
Nerve Innervation: radial C5 to C7

Question 7

Pronator Teres

Answer 7

Action: pronate the forearm, assist to flex the elbow
Origin: common flexor tendon from medial epicondyle of the humerus and coronoid process of the ulna
Insertion: middle of lateral surface of the radius
Nerve Innervation: median C6 and C7

Question 8

Pronator Quadratus

Answer 8

Action: pronate the forearm
Origin: medial, anterior surface of the distal ulna
Insertion: lateral, anterior surface of the distal radius
Nerve Innervation: median C7 and C8, T1