-A ball and socket jt.
-A mobile jt.
1. Articulation of the ball that is spherical to a shallow glenoid
2. Weak ligaments
3. Shoulder capsule is loose and redundant
4. There is an intimate relationship bet. Bursa, tendons, capsule
5. Forms mobile base of the shoulder jt. the SCAPULA (only
connection via coracoacromial ligament and acromioclavicular
- Bones of the shoulder complex are the humerus, which articulates
with the scapula at the glenoid fossa, the clavicle, which originates
at the sternum and follows and S shape to the tip of the shoulder
where it articulates with the acromion process of the scapula which
is a somewhat flat triangular bone with two bony projections called
the spine of the scapula and the coracoid process.
- The spine of the scapula divides the posterior aspect of the scapula
into two unequal parts called the supraspinatus fossa, which holds
the supraspinatus muscle and the infraspinatus fossa which holds
the infraspinatus muscle
- The shoulder or pectoral girdle consists of articulations between
the clavicle, scapula and the proximal end of the humerus.
- The sternoclavicular articulationis the only bony link between the
upper limb and the axial skeleton.
- Movements at this joint are largely passive in that the occur as a
result of active movements of the scapula.
- Through the acromioclavicular articulation, the clavicle can act as a
strut maintaining the upper limb away from the thorax permitting a
greater range of upper limb motion.
- This joint also helps provide static stability to the upper limb
reducing the need to use muscle energy to keep the upper limb in
its proper alignment.
- The glenohumeral articulation (shoulder joint) has the
greatest range of motion of any joint in the body.
- The mobility of the shoulder joint is necessary for placement of
the hand to maximize manipulation.
- The scapula is suspended on the thoracic wall by muscle
forming a "functional joint" called the scapulothoracic joint.
- These muscles act to stabilize and/ or to actively move the scapula.
- Active movements of the scapula help increase the range of motion
of the shoulder joint.