Shoulder Joints and Ligaments

Question 1

Sternoclavicular Joint

Answer 1

Articulation: sternal end of the clavicle with manubrium and 1st costal cartilage

Type: synovial saddle joint

Movements:

• Moves in response to the scapula (because it’s attached to the scapula at the acromial end)
• Sternal end of clavicle will move in opposite direction of scapula
• Ex: scapula is protracting, SC joint is retracting

Question 2

Anterior and Posterior Sternoclavicular Ligaments

Answer 2

Reinforce joint capsule anteriorly and posteriorly

Question 3

Interclavicular Ligaments (SC Joint)

Answer 3

Runs from sternal end of one clavicle to sternal end of the other, serving to strengthen joint capsule superiorly

Question 4

Costoclavicular Ligaments (SC Joint)

Answer 4

Anchor inferior surface of sternal end of clavicle to 1st rib and its costal cartilage strengthening joint inferiorly

Question 5

Articular Disc of SC Joint

Answer 5

• Within the joint capsule that is attached to the anterior and posterior sternoclavicular ligaments and to the interclavicular ligament
• Serves to provide further strength and support to the joint
• Exists b/w sternal end of clavicle and manubrium

Question 6

Acromioclavicular Joint

Answer 6

Articulation: acrominal end of the clavicle articulating with the acromion of the scapula

Type: synovial plane joint

Movements: acromion of the scapula glides on the acrominal end of the clavicle as the scapula moves (since this is a plane joint, there is little movement that occurs here other than slight gliding)

Question 7

Acromioclavicular Ligament (AC Joint)

Answer 7

Runs from the acromion to the clavicle and strengthens the joint superiorly

Question 8

Coracoclavicular Ligament (AC Joint)

Answer 8

-Consists of 2 separate ligaments usually separated by a bursa that serve to anchor the clavicle to the coracoid process of the scapula, helping the joint to be stable by resisting separation of the clavicle and the acromion (conoid and trapezoid)

Question 9

Glenohumeral Joint

Answer 9

Articulation: large, round head of the humerus articulates with the relatively shallow glenoid cavity of the scapula

A ring like fibrocartilaginous glenoid labrum encircles the glenoid cavity and serves to deepen the socket, thereby, improving the congruency of this articulation

Type: synovial ball and socket

Movements:

• GH joint has more freedom of movement than any other joint in body due to laxity in its joint capsule and large size of humeral head in relation to the small, shallow glenoid cavity
• Movement is allowed around 3 axis and includes flexion- extension, abduction-adduction, medial-lateral rotation
• Unless they are being performed in a very small ROM, none of these movements occur at the GH joint in isolation-they are accompanied by scapular movement as well as movement at the SC and AC joints

Question 10

Glenohumeral Joint Ligaments

Answer 10

Both intrinsic (part of the joint capsule) and extrinsic (outside the joint capsule) ligaments help support this joint

Intrinsic ligaments include the glenohumeral ligaments (3), and coracohumeral ligament

Extrinsic ligaments include the coracoacrominal arch, coracoacrominal ligament and the transverse humeral ligament

Question 11

Glenohumeral Ligaments (GH Joint)

Answer 11

• 3 fibrous bands that reinforce the joint capsule anteriorly
• Superior, middle and inferior parts
• Radiate laterally and inferiorly from the glenoid labrum at the supraglenoid tubercle and blend with the joint capsule as it attaches to the anatomical neck of the humerus
• Help to prevent anterior dislocation of the head of the humerus

Question 12

Coracohumeral Ligament (GH Joint)

Answer 12

• A strong band that passes from the base of the coracoid process to the anterior aspect of the greater tubercle of the humerus
• Strengthens superior portion of capsule and helps to prevent superior displacement of the head of the humerus

Question 13

Transverse Humeral Ligament (GH Joint)

Answer 13

• A broad fibrous band that runs from the greater tubercle to the lesser tubercle of the humerus bridging the intertubercular groove
• Serves to create a canal which holds the long head of the biceps tendon in place during movement of the shoulder

Question 14

Coracoacromional Arch and Coracomacrominal Ligament (GH Joint)

Answer 14

• The coracoacrominal arch is an extrinsic protective structure formed by the inferior surface of the acromion and coracoid process and the coracoacrominal ligament that spans between them
• Forms a protective arch that overlies the humeral head and prevents superior dislocation of the humeral head
• This arch is so strong that forceful superior thrust of the humerus will not fracture it-the humerus or clavicle will fracture first