The Shoulder
Label the Shoulder
 The shoulder is made up of three bones
 Humerus – upper arm
bone
Clavicle
 Clavicle – collar bone
Humerus
 Scapula – shoulder
blade
Scapula
Anatomy of the Shoulder
 The head of the
humerus fits into a
rounded socket in the
scapula
 A combination of
muscles and tendons
keeps the humerus
centered in the socket
The Shoulder Girdle
 The muscles of the shoulder girdle act on the scapula, primarily to
stabilize it.
 There are six major muscles that anchor the scapula.
– Four posterior muscles (Trapezius, Rhomboid Major, Rhomboid Minor, Levator
Scapulae)
– Two anterior muscles (Pectoralis Minor, Serratus Anterior)
The Shoulder Girdle
Since the scapula has no bony articulations with the rib cage it essentially
floats
The main function of the shoulder girdle muscles is to fixate the scapula
When the scapula is immobilized it serves as a point of origin for the
muscles of the humerus (upper arm bone)
Posterior Muscles of the Shoulder Girdle
Anterior Muscles of the Shoulder Girdle
Major Muscles That Act at the Shoulder Girdle
The Shoulder
 The shoulder joint is the most mobile joint in the body.
 There are a total of nine muscles that cross the shoulder joint (inserting
on the humerus).
– Seven muscles originate from each scapula.
• Supraspinatus, infraspinatus, subscapularis, teres minor, deltoid, teres major, and
coracobrachialis)
– Two muscles originate from the axial skeleton (no attachment on the scapula).
• Pectoralis major, latissiumus dorsi
The Shoulder Anterior Deltoid and Pectoralis Major
The Shoulder- Latissiumus Dorsi, Pectoralis Major and
Deltoid, Lateral View
The Shoulder – Posterior Muscle of the Shoulder
Joint
The Rotator Cuff
 Four of the muscles that act at the shoulder are commonly called the
rotator cuff.
 The rotator cuff’s primary stabilizing function is to hold the humeral
head in the glenoid fossa to prevent subluxation (dislocation).
 The muscles of the rotator cuff can be remembered using the
acronym SITS:
– Supraspinatus
– Infraspinatus
– Teres minor
– Subscapularis
The Rotator Cuff – Anterior View
The Rotator Cuff – Posterior View
Coracobrachialis
Coracobrachialis
Major Muscles That Act at the Shoulder