Shoulder Joint - EXAM 2: Upper Extremity (Fall 2025)

Shoulder Joint/Glenohumeral Joint

Articulation of head of humerus with the glenoid fossa for scapula

• Synovial joint

• Ball and socket

• Three degrees of freedom

• More mobility than stability

Arthrokinematic Motion

Surface area of head of humerus is greater than surface area of glenoid fossa

• Head of humerus convex, glenoid fossa concave

• Roll, spin, and glide

Glenohumeral Joint

reinforce capsule

Coracohumeral ligament

dorsal lateral side of coracoid process and greater and lesser tubercles

Transverse humeral ligament

lips of bicipital groove

Glenoid labrum

• Fibrocartilaginous ring

• Attached to rim of glenoid fossa

• Deepens fossa to increase stability of joint

Rotator Cuff

 Tendinous band forms ”cuff” around head of humerus

 Maintains head of humerus in glenoid fossa

 SITS muscles comprise the tendinous band

SITS muscles

 Comprise the tendinous band (Subscapularis, infraspinatus, teres minor, and suprasinatus)

Anterior Deltoid Muscle

O: Lateral third of the clavicle

I: Deltoid tuberosity

A: Shoulder abduction, flexion, medial rotation, and horizontal adduction

Middle Deltoid Muscle

O: Acromion process

I: Deltoid tuberosity

A: Shoulder abduction

Posterior Deltoid Muscle

O: Spine of scapula 

I: Deltoid tuberosity

A: Shoulder abduction, extension, lateral rotation, horizontal abduction

Biceps Brachii Muscle

O: Long head: supraglenoid tubercle of scapula

     Short head: coracoid process of scapula

I: Radial tuberosity of radius

A: Shoulder flexion, elbow flexion, forearm supination

Coracobrachialis Muscle

O: Coracoid process of the scapula

I: Medial surface of the humerus near the midpoint

A: Shoulder flexion, adduction.

Pectoralis Major Clavicular Portion

O:Medial third of clavicle

I: Bicipital groove of humerus (inferior to the sternal portion)

A: Shoulder flexion—first 60 degrees, medial rotation, adduction Horizontal adduction

Pectoralis Major Sternal Portion

O: Sternum, costal cartilage of first six ribs

I: Bicipital groove of humerus (superior to the clavicular portion)

A: Medial rotation, adduction, horizontal adduction shoulder extension from full flexion (180 degrees) when shoulder extension is resisted

Latissimus Dorsi Muscle

O: Thoracolumbar fascia, the spinous processes of T7 through L5, posterior surface of iliac crest & sacrum, and lower three ribs

I: Floor of bicipital groove

A: Shoulder extension, adduction, medial rotation

Teres Major Muscle

O: Inferior axillary border of scapula

I: Medial lip of bicipital groove

A: Shoulder extension, adduction, and medial rotation

Triceps Brachii Muscle

O: Long head: infraglenoid tubercle of scapula

     Lateral head: posterior humerus

     Medial head: posterior surface of humerus

I: Olecranon process of ulna

A: Shoulder extension. Elbow extension.

Supraspinatus Muscle

O: Supraspinous fossa of the scapula

I: Greater tubercle of the humerus

A: Shoulder abduction Stabilizes shoulder

Infraspinatus Muscle

O: Infraspinous fossa of scapula

I: Greater tubercle of humerus

A: Shoulder lateral rotation, horizontal abduction Stabilizes shoulder

Teres Minor Muscle

O: Axillary border of scapula

I: Greater tubercle of humerus

A: Shoulder lateral rotation, horizontal abduction Stabilizes shoulder

Subscapularis Muscle

O: Subscapular fossa of the scapula

I: Lesser tubercle of the humerus

A: Shoulder adduction, medial rotation Stabilizes shoulder

Flexion, major

Anterior deltoid, pectoralis (clavicular)

Extension

Pectoralis deltoid, latissimus dorsi, teres major, pectoralis major (sternal)

Hyperextension

Latissimus dorsi, posterior deltoid

ABduction

Deltoid, supraspinatus

ADduction

Pectoralis major, teres major, latissimus dorsi

Horizontal, ABduction

Posterior deltoid, infraspinatus, teres minor

Horizontal, ADduction

Pectoralis major, anterior deltoid

Lateral Rotation

Infraspinatus, teres minor, posterior deltoid

Medial Rotation

Latissimus dorsi, teres major, subscapularis, pectoralis major, anterior deltoid