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(469) 232-9738Normal Anatomy of Shoulder Joint
The shoulder is the most flexible joint in the body making it the most susceptible to instability and injury. It is a ‘ball-and-socket’ joint. A ‘ball’ at the top of the upper arm bone, humerus, fits neatly into a ‘socket’, called the glenoid, which is part of the shoulder blade, scapula.
Several soft tissues and three bones make up the shoulder joint, the bones are the collarbone (clavicle), humerus, and scapula.
The humerus provides attachment to muscles of the upper arm. The scapula connects the upper arm bone with the collarbone. It is a flat bone with a triangular shape, and it provides attachment to the muscles of the back and neck.
The clavicle is an S-shaped short bone that attaches the shoulder girdle to the body (trunk). It supports the shoulder in a functional position with the axial skeleton so that the arm has maximum range of movement. It also protects nerves and blood vessels passing from the neck to the axilla.
The coracoid process extends from the front portion of the scapula, enveloping the shoulder joint. Meanwhile, the acromial process extends from the back of the scapula, forming a roof known as the acromion, encircling the shoulder joint.
The glenoid is a shallow, smooth depression located at the end of the scapula, shaping the socket of the shoulder joint.
The soft tissues of shoulder joint include:
Rotator cuff – A group of 4 tendons makes the rotator cuff, and it holds the head of the humerus in the socket.
Biceps tendon – The biceps tendon is a long cord-like structure which attaches the biceps muscle to the shoulder and helps to stabilize the joint.
Caraco Clavicular Ligament – This ligament connects the clavicle with the corocoid process of the scapula.
Acromio Clavicular Ligament – It connects the clavicle with the acromion process.
Glenoid labrum – The glenoid labrum is a ring of fibro cartilage surrounding the cavity of the scapula for stabilization of the shoulder joint.
Articular cartilage or the capsule – It is a capsule that surrounds the shoulder joint and helps to keep the ball and socket normally aligned.
