Articular capsule of the humerus
Encyclopedia
The articular capsule of the humerus is the articular capsule of the shoulder joint
. It completely encircles the joint, being attached, above, to the circumference of the glenoid cavity
beyond the glenoidal labrum
; below, to the anatomical neck of the humerus, approaching nearer to the articular cartilage above than in the rest of its extent.
It is thicker above and below than elsewhere, and is so remarkably loose and lax, that it has no action in keeping the bones in contact, but allows them to be separated from each other more than 2.5 cm., an evident provision for that extreme freedom of movement which is peculiar to this articulation.
It is strengthened, above, by the Supraspinatus; below, by the long head of the Triceps brachii; behind, by the tendons of the Infraspinatus and Teres minor; and in front, by the tendon of the Subscapularis.
Glenohumeral joint
The glenohumeral joint, or shoulder joint, is a multiaxial synovial ball and socket joint and involves articulation between the glenoid fossa of the scapula and the head of the humerus...
. It completely encircles the joint, being attached, above, to the circumference of the glenoid cavity
Glenoid cavity
The glenoid cavity is a shallow pyriform, articular surface, which is located on the lateral angle of the scapula. It is directed laterally and forward and articulates with the head of the humerus; it is broader below than above and its vertical diameter is the longest.This cavity forms the...
beyond the glenoidal labrum
Glenoidal labrum
The glenoid labrum is a fibrocartilaginous rim attached around the margin of the glenoid cavity in the shoulder blade. The shoulder joint is considered a 'ball and socket' joint. However, in bony terms the 'socket' is quite shallow and small, covering at most only a third of the 'ball'...
; below, to the anatomical neck of the humerus, approaching nearer to the articular cartilage above than in the rest of its extent.
It is thicker above and below than elsewhere, and is so remarkably loose and lax, that it has no action in keeping the bones in contact, but allows them to be separated from each other more than 2.5 cm., an evident provision for that extreme freedom of movement which is peculiar to this articulation.
It is strengthened, above, by the Supraspinatus; below, by the long head of the Triceps brachii; behind, by the tendons of the Infraspinatus and Teres minor; and in front, by the tendon of the Subscapularis.
Openings
There are usually three openings in the capsule.- One anteriorly, below the coracoid process, establishes a communication between the joint and a bursa beneath the tendon of the Subscapularis.
- The second, which is not constant, is at the posterior part, where an opening sometimes exists between the joint and a bursal sac under the tendon of the Infraspinatus.
- The third is between the tubercles of the humerus, for the passage of the long tendon of the Biceps brachii.