Flexor and Extensor Compartments of Arm

Proximal and Distal Attachment

Coracobrachialis

P: coracoid process of scapula

D: middle third of medial humerus

Proximal and Distal Attachment

Biceps Brachii

P:

Short Head: coracoid process of scapula

Long Head: supraglenoid tubercle of scapula

D: tuberosity of radius and (fascia of forearm via) bicipital aponeurosis

Proximal and Distal Attachment

Brachialis

P: distal portion of anterior surface of humerus

D: coronoid process and tuberosity of ulna

Proximal and Distal Attachment

Triceps Brachii

P:

Long Head: infraglenoid tubercle of scapula

Lateral Head: posterior surface of humerus, superior to radial groove

Medial head: posterior surface of humerus, inferior to radial groove

D: olecranon of ulna

Innervation

Coracobrachialis

Peripheral: musculocutaneous nerve

Innervation

Biceps Brachii

Peripheral: musculocutaneous nerve

Segmental: C5, C6, C7

Innervation

Brachialis

Peripheral: musculocutaneous and radial nerve

Innervation

Triceps Brachii

Peripheral: radial nerve

Segmental: C6, C7, C8

Action

Coracobrachialis

assists in shoulder flexion and adduction

adds stability to GH joint

Action

Biceps Brachii

forearm supination; elbow flexion especially when forearm is supinated

short head adds stability to GH joint

Action

Brachialis

elbow flexion (independent of forearm position)

Action

Triceps Brachii

elbow extension, shoulder extension

long head stabilizes GH joint during abduction