Lower Limb Joints Quiz

Anatomy and Joints of the Scapula

• The scapula is a flat triangular bone with three borders, three angles, and two surfaces.
• The three borders are the medial, superior, and lateral borders.
• The three corners of the triangular scapula are called angles, including the lateral angle that ends in the glenoid cavity, which forms the scapulohumeral joint.
• The body of the scapula is arched for greater strength, and the anterior surface is termed the costal surface.
• The acromion is a long, curved process that extends laterally over the head of the humerus, and the coracoid process is a thick, beaklike process that projects anteriorly beneath the clavicle.
• The posterior surface of the scapula has a prominent structure called the spine that separates the infraspinous and supraspinous fossae.
• The shoulder girdle includes three joints: sternoclavicular joint, acromioclavicular joint, and scapulohumeral joint.
• The mobility type of all three joints is freely movable, or diarthrodial, characterized by a fibrous capsule that contains synovial fluid.
• The movement type of the scapulohumeral joint is a ball-and-socket joint, allowing great freedom of movement, including flexion, extension, abduction, adduction, circumduction, and medial and lateral rotation.
• The glenoid cavity is very shallow, allowing the greatest freedom in mobility but at some expense to its strength and stability.
• Dislocations at the shoulder joint occur more frequently than at any other joint in the body, creating the need for frequent radiographic examinations of the shoulder to evaluate for structural damage.
• The sternoclavicular joint is a double plane, or gliding, joint, and the acromioclavicular joint is a small synovial joint of the plane, or gliding, movement type.