Scapulohumeral muscles (intrinsic shoulder) muscles

Muscle	Proximal attachment	Distal attachment	Innervation*	Main action
Deltoid	Lateral third of clavicle; acromion and spine of scapula	Deltoid tuberosity of humerus	Axillary nerve (C5, C6)	Clavicular (anterior) part: flexes and medially rotates arm Acromial (middle) part: abducts arm Spinal (posterior) part: extends and laterally rotates arm
Supraspinatus^¶	Supraspinous fossa of scapula	Superior facet of greater tubercle of humerus	Suprascapular nerve (C4, C5, C6)	Initiates and assists deltoid in abduction of arm and acts with rotator cuff muscles^¶
Infraspinatus^¶	Infraspinous fossa of scapula	Middle facet of greater tubercle of humerus	Suprascapular nerve (C5, C6)	Laterally rotates arm; and acts with rotator cuff muscles^¶
Teres minor^¶	Middle part of lateral border of scapula	Inferior facet of greater tubercle of humerus	Axillary nerve (C5, C6)	Laterally rotates arm; and acts with rotator cuff muscles^¶
Teres major	Posterior surface of inferior angle of scapula	Medial lip of intertubercular sulcus of humerus	Lower subscapular nerve (C5, C6)	Adducts and medially rotates arm
Subscapularis^¶	Subscapular fossa (most of anterior surface of scapula)	Lesser tubercle of humerus	Upper and lower subscapular nerves (C5, C6, C7)	Medially rotates arm; as part of rotator cuff, helps hold head of humerus in glenoid cavity

* The spinal cord segmental innervation is indicated (eg, "C5, C6" means that the nerves supplying the deltoid are derived from the fifth and sixth cervical segments of the spinal cord). Numbers in boldface (C5) indicate the main segmental innervation. Damage to one or more of the listed spinal cord segments or to the motor nerve roots arising from them results in paralysis of the muscles concerned.
¶ Collectively, the supraspinatus, infraspinatus, teres minor, and subscapularis muscles are referred to as the rotator cuff, or SITS, muscles. Their primary function during all movements of the glenohumeral (shoulder) joint is to hold the humeral head in the glenoid cavity of the scapula.

Reproduced with permission from: Clinically Oriented Anatomy, 7th ed, Moore KL, Agur AM, Dalley AF (Eds), Lippincott Williams & Wilkins, Philadelphia 2013. Copyright © 2013 Lippincott Williams & Wilkins. www.lww.com.

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Scapulohumeral muscles (intrinsic shoulder) muscles