Deltoid

Action: shoulder abduction, flexion, and extension

Innervation: Axillary nerve

Supraspinatus

Action: abduction of arm (first 15 degrees), stabilization of humerus

Innervation: Suprascapular nerve

Infraspinatus

Action: Lateral rotation of arm, stabilize humerus

Innervation: Suprascapular nerve

Teres major

Action: Internal rotation (medial) of the humerus

Innervation: Lower subscapular nerve

Teres minor

Action: Laterally rotates the arm, stabilizes humerus

Innervation: Axillary nerve

Serratus anterior

Action: protracts and stabilizes scapula, assists in upward rotation

Innervation: Long thoracic nerve

Pectoralis major

Action: adducts and medially rotates the humerus. Draws the scapula anteriorly and inferiorly

Innervation: Lateral and medial pectoral nerves

Pectoralis minor

Action: stabilizes the scapula by drawing it inferiorly and anteriorly against the thoracic wall

Innervation: medial pectoral nerve

Biceps brachii

Action: Flexes elbow, supinates forearm

Innervation: Musculocutaneous nerve

Coracobrachialis

Action: adducts humerus, flexes arm at glenohumeral joint

Innervation: Musculocutaneous nerve

Brachialis

Action: Elbow flexion

Innervation: Musculocutaneous nerve

Brachioradialis

Action: Elbow flexion

Innervation: radial nerve

Triceps brachii

Action: Extends forearm, long head adducts shoulder

Innervation: Radial nerve and axillary nerve (long head)

Deltopectoral triangle

Contains cephalic vein

Triangular space

Contains scapular circumflex arteries

Quadrangular space

Contains axillary n. and posterior circumflex humeral a.