SHOULDER

The shoulder is formed by three joints:

1 & #8211; Sternoclavicular

2 & #8211; Acromioclavicular

3 & #8211; Glenoumeral

Some authors still consider another joint in the shoulder complex: the joint back-scapular, between the ribs and the scapula, very important in the physiological biomechanics of the shoulder.

 

1- Sternoclavicular Joint

This joint is formed by joining the sternal end in the collarbone and the sternal manubrium. It has the following joint structures:

Articular Capsule & #8211; Circles the joint and varies in thickness and strength.

Anterior Sternoclavicular Ligament & #8211; It is a broad bundle of fibers covering the anterior face of the joint.

Posterior Sternoclavicular Ligament & #8211; It is an analogous bundle of fibers that covers the posterior face of the joint.

Interclavicular Ligament & #8211; It is a flat beam that joins the upper faces of the sternal ends of the clavicles.

Costoclavicular Ligament & #8211; It is small, flat and sturdy. It is fixed to the upper and medial part of the cartilage of the first rib and the inferior face of the collarbone.

Articular Disc & #8211; It is flat and interposed between the articular surfaces of the sternum and collarbone.

 

2- Acromioclavicular Joint

It is a flat joint between the acromial end of the clavicle and the medial edge of the acromion. It is formed by the following structures:

Articular Capsule & #8211; It involves the entire acromioclavicular joint.

Acromioclavicular Ligament & #8211; It consists of parallel fibers that extend from the acromial end of the clavicle to the acromion.

Articular Disc & #8211; It is usually absent in this joint.

Coracoclavicular Ligament & #8211; joins the clavicle to the coracoid process of the scapula. It is formed by two ligaments: Ligament Trapezoid and Ligament Conoid.

We can still identify two more important ligaments in the shoulder complex: the Coracoacromial Ligament it's the Superior Transverse Ligament.

Coracoacromial Ligament & #8211; It is a strong triangular beam extended between the coracoid process and the acromion. It is an important ligament for stabilization of the humeral head in the glenoid cavity, as it avoids its elevation in abduction movements above 90 degrees.

Superior Transverse Ligament & #8211; It is a thin flat fascicle inserted into the coracoid process and scapular notch.

 

3- Glenohumeral Joint

This is a multiaxial spheroid joint with three degrees of freedom. The articular faces are the hemispheric head of the humerus (convex) and the glenoid cavity of the scapula (concave).

The glenohumeral joint is formed by the following structures:

Articular Capsule & #8211; It involves the entire glenoid cavity and the humeral head.

Coracohumeral Ligament & #8211; It is a broad beam that strengthens the top of the capsule.

Glenoumeral Ligaments & #8211; They are robust thickening of the joint capsule over the ventral part of the joint. It consists of three ligaments:

1 – Glenoumeral Superior

2 – Middle Glenoumeral Ligament

3 – Lower Glenoumeral Ligament

Transverse Ligament of Humerus & #8211; It is a narrow blade of short and transverse fibers joining the largest and smallest tubercle, keeping the long tendon of the biceps brachii in the intertubercular groove.

Glenoidal Labrum & #8211; It is a fibrocartilaginous border inserted around the glenoid cavity. It has an important function in glenohumeral stabilization and when broken provides joint instability facilitating anterior or posterior dislocation of the humerus (dislocation).

 

 

PREVIOUS VIEW OF SHOULDER JOINT STRUCTURES
 Anterior View of Shoulder Joint Articular Structures
Source: NETTER, Frank H .. Atlas of Human Anatomy. 2 ed. Porto Alegre: Artmed, 2000.

 

PREVIOUS VIEW OF SHOULDER JOINT STRUCTURES
 Anterior View of Shoulder Joint Articular Structures
Source: NETTER, Frank H .. Atlas of Human Anatomy. 2 ed. Porto Alegre: Artmed, 2000.

 

CORONAL (FRONT) SHOULDER SECTION
 Coronal Shoulder Section
Source: NETTER, Frank H .. Atlas of Human Anatomy. 2 ed. Porto Alegre: Artmed, 2000.

 

SEE MORE

Synovial Joints
ATM
Spine
Elbow
Fist
Hip
knee
Ankle