Glenohumeral Joint Muscles

Coracobrachialis

Origin: - coracoid process of the scapula, at the apex Insertion: - middle third of the medial shaft of the humerus Action: - flexion of the arm at the GH joint - Adduction of the arm at the GH joint Innervation: - Musculocutaneous nerve - C5, C6, C7 To Stretch: - abduct and extend arm

Pectoralis Major

Origin: - from the costal cartilage of rib seven up along the sternum to 1/2 way along the clavicle ( costal cartilage of ribs one - seven, sternum, and medial 1/2 of the clavicle) Insertion: - lateral lip of the intertubercular groove of the humerus. Action: - adduction of arm at the glenohumeral joint - flexion of the arm at the glenohumeral joint - medial rotation of the arm at the glenohumeral joint Innervation: - Medial and Lateral Pectoral Nerves - C5 and C7 (main); C6, C8, and T1 (lesser) To Stretch: - abduct, extend, and laterally rotate arm.

Teres Major

Origin: - inferior lateral border of the scapula and inferior angle of the scapula, dorsal surface Insertion: - medial lip of the intertubercular groove of the humerus (between greater and lesser tubercles), posterior to the insertion of the latissimus dorsi. Action: - medial rotation of the arm at the glenohumeral joint - adduction of the arm at the glenohumeral joint - extension of the arm at the glenohumeral joint - (same as Lat. dorsi muscle) Innervation: - Lower Subscapular Nerve - C6 (main); C5, C7 (lesser) To Stretch: - flex, abduct, laterally rotate arm

Deltoid

Origin: - lateral 1/3 of clavicle (anterior) - acromion process - scapular spine (posterior) Insertion: - deltoid tuberosity of the humerus (whole muscle) Action: - abduction of the arm at the GH joint (whole muscle) - flexion of the arm at the GH joint (anterior) - extension of the arm at the GH joint (posterior) - medial rotation of the arm at the GH joint (anterior) - lateral rotation of the arm at the GH joint (posterior) - horizontal flexion of the arm at the GH joint (anterior) - horizontal extension of the arm at the GH joint (posterior) Innervation: - Axillary Nerve To Stretch: - extend and laterally rotate arm in an adducted position (anterior) - flex and medially rotate arm in an adducted position (posterior) Clinical Notes: - General Notes: -

Infraspinatus

Origin: - medial two thirds of the infraspinous fossa of the scapula Insertion: - middle facet of the greater tubercle of the humerus (just below the Supraspinatus insertion and just above the Teres minor insertion) Action: - lateral rotation of the arm at the glenohumeral joint Innervation: - Subscapular Nerve - C5 (main); C6 To Stretch: - medially rotate and horizontally flex arm

Supraspinatus

Origin: - medial two thirds of the supraspinous fossa of the scapula Insertion: - superior facet of the greater tubercle of the humerus (just above the Infraspinatus insertion) Action: - abduction of the arm at the glenohumeral joint - flexion of the arm at the glenohumeral joint - only rotator cuff muscle that does not rotate the arm Innervation: - Subscapular Nerve - C5 (main); C6 (lesser) To stretch: - adduct and extend arm

Latissimus Dorsi

Origin: - spinous processes of T7 to L5 - posterior sacrum - posterior iliac crest - (T7 all the way down to the sacrum and across to the posterior iliac crest) Insertion: - medial lip of the intertubercular groove (between greater and lesser tubercles) of the humerus Action: - extension of the arm at the glenohumeral joint - adduction of the arm at the glenohumeral joint - medial rotation of the arm at the glenohumeral joint Innervation: - Thoracodorsal Nerve - C7 (main); C6, C8 (lesser) To Stretch: - flex, abduct, and laterally rotate arm

Subscapularis

Origin: - subscapular fossa of the scapula (entire medial border, ventral surface) Insertion: - lesser tubercle of the humerus Action: - medial rotation of the arm at the glenohumeral joint Innervation: - Upper and Lower Subscapular Nerves - C6 (main); C5 To Stretch: - laterally rotate arm

Teres Minor

Origin: - superior two thirds of the superior lateral border of the scapula, dorsal surface. Insertion: - inferior facet of the greater tubercle of the humerus (just below the Infraspinatus insertion) Action: - lateral rotation of the arm at the glenohumeral joint Innervation: - Axillary Nerve - C5 (main); C6 To Stretch: - medially rotate, abduct, and horizontally flex the arm

What muscles adduct the arm?

- Coracobrachialis - Pectoralis Major - Latissimus Dorsi - Teres Major

What muscles abduct the arm?

- Deltoid (whole muscle) - Supraspinatus

Rotator Cuff Muscles

- Supraspinatus - Infraspinatus - Teres Minor - Subscapularis

What muscles cause flexion of the arm?

- anterior Deltoid - Coracobrachialis - Pectoralis Major - Supraspinatus - Long head of the Biceps Brachii

What muscles medially rotate the arm?

- anterior Deltoid - Pectoralis Major - Latissimus Dorsi - Teres Major - Subscapularis

What muscles laterally rotate the arm?

- posterior Deltoid - Infraspinatus - Teres Minor

What muscles cause extension of the arm?

- posterior Deltoid - Pectoralis Major - Latissimus Dorsi - Teres Major - Long head of the Triceps Brachii