On the scapula, the capsule has two lines of attachments. Extending only at its medial margin, where the fibers protrude by around 1 cm. On the humerus, the capsule attaches to its anatomical neck. The internal surface of the capsule is lined by a synovial membrane. It extends from the scapula to the humerus, enclosing the joint on all sides. The shoulder joint is encircled by a loose fibrous capsule. Instead, joint security is provided entirely by the soft tissue structures the fibrous capsule, ligaments, shoulder muscles and their tendons. This incongruent bony anatomy allows for the wide range of movement available at the shoulder joint but is also the reason for the lack of joint stability. The surface of the humeral head is three to four times larger than the surface of glenoid fossa, meaning that only a third of the humeral head is ever in contact with the fossa and labrum. The labrum acts to deepen the glenoid fossa slightly, it is triangular in shape and thicker anteriorly than inferiorly. Congruency is increased somewhat by the presence of a glenoid labrum, a fibrocartilaginous ring that attaches to the margins of the fossa. The concavity of the fossa is less acute than the convexity of the humeral head, meaning that the articular surfaces are not fully congruent. The glenoid fossa is a shallow pear-shaped pit on the superolateral angle of scapula. Being a synovial joint, both articular surfaces are covered with hyaline cartilage.

The glenohumeral joint is the articulation between the spherical head of the humerus and the concave glenoid fossa of the scapula. Glenoid cavity of scapula, Cavitas glenoidalis scapulae This article will discuss the anatomy and function of the glenohumeral joint. Mnemonic: Rotator cuff SITS on the shoulder Supraspinatus, infraspinatus, teres minor, subscapularis Subscapular nerve (joint) suprascapular nerve, axillary nerve, lateral pectoral nerve (joint capsule)Īnterior and posterior circumflex humeral, circumflex scapular and suprascapular arteriesįlexion, extension, abduction, adduction, external/lateral rotation, internal/medial rotation and circumduction Superior glenohumeral, middle glenohumeral, inferior glenohumeral, coracohumeral, transverse humeral Glenoid fossa of scapula, head of humerus glenoid labrum Synovial ball and socket joint multiaxial Because of this mobility-stability compromise, the shoulder joint is one of the most frequently injured joints of the body. Instead the surrounding shoulder muscles and ligamentous structures offer the joint security the capsule, ligaments and tendons of the rotator cuff muscles. This shoulder function comes at the cost of stability however, as the bony surfaces offer little support. In fact, it is the most mobile joint of the human body.

It is a ball-and-socket joint, formed between the glenoid fossa of scapula (gleno-) and the head of humerus (-humeral).Īcting in conjunction with the pectoral girdle, the shoulder joint allows for a wide range of motion at the upper limb flexion, extension, abduction, adduction, external/lateral rotation, internal/medial rotation and circumduction.

The glenohumeral, or shoulder, joint is a synovial joint that attaches the upper limb to the axial skeleton. Glenohumeral joint (Articulatio glenohumeralis)

Abduction of shoulder