The glenohumeral joint
, (from ancient Greek glene
, eyeball, puppet, doll + -oid
, 'form of', + Latin humerus
, shoulder) or shoulder joint
, is a multiaxial synovial ball and socket joint
and involves articulation between the glenoid fossa
of the scapula
(shoulder blade) and the head of the humerus
(upper arm bone). Due to the very limited interface of the humerus and scapula, it is the most mobile joint of the human body.
The glenoid fossa is shallow and contains the glenoid labrum
which deepens it and aids in stability. With 120 degrees of unassisted flexion, the glenohumeral joint is the most mobile joint in the body.
Scapulohumeral rhythm helps to achieve further range of movement. The Scapulohumeral rhythm is the movement of the scapula across the thoracic cage in relation to the humerus. This movement can be compromised by anything that changes the position of the scapula. This could be an imbalance in the muscles that hold the scapula in place which are the upper and lower trapezium. This imbalance could cause a forward head carriage which in turn can affect the range of movements of the shoulder.
The rotator cuff
muscles of the shoulder produce a high tensile
force, and help to pull the head of the humerus into the glenoid fossa.
The glenohumeral joint has a loose capsule
that is lax inferior
and therefore is at risk of dislocation
inferiorly. The long head of the biceps brachii muscle
travels inside the capsule to attach to the supraglenoid......