Glenohumeral Joint

Description

The glenohumeral (GH) joint is a true synovial ball-and-socket style joint that is responsible for connecting the upper extremity to the trunk.  It is one of four joints that comprise the shoulder complex. This joint is formed from the combination of the humeral head and the glenoid fossa of the scapula. This joint is considered to have both high mobility and low stability.

Motions Available

• Abduction: elevation of the humerus on the glenoid in the frontal (coronal) plane.
• Flexion: forward and upward movement of the humerus on the glenoid in the sagittal plane.
• Extension: upward movemement of the humerus on the glenoid in the sagittal plane towards the rear of the body.
• Internal Rotation: rotation of the humerus on the glenoid in a medial direction.
• External Rotation: rotation of the humerus on the glenoid in a lateral direction.
• Scaption: elevation of the humerus on the glenoid in the scapular plane, which is midway between the coronal and sagittal planes. 
• Horizontal Adduction: movement of the humerus on the glenoid in a medial direction, usually accompanied with some degree of shoulder flexion.

Ligaments and Joint Capsule

Together, the joint capsule and the ligaments of the GH joint work to provide a passive restraint to keep the humeral head in contact with the glenoid fossa.
Joint Capsule:

• The lateral attachment of the GH joint capsule attaches to the anatomical neck of the humerus.  The medial attachment of the joint capsule is the glenoid and the labrum.  According to some sources, the the overall strength of the capsule bears an inverse relationship to the patient's age; the older the patient, the weaker the joint capsule . With the arm in a resting position the inferior portion of the capsule is lax.  The anterior portion of the capsule is reinforced by the superior, middle, and inferior glenohumeral ligaments which form a Z-shaped pattern on the capsule.  The muscles of the rotator cuff act to reinforce the joint capsule superiorly, posteriorly, and anteriorly.
  

Notable Ligaments:

• Superior Glenohumeral Ligament: limits external rotation and inferior translation of the humeral head. This ligament arises from the glenoid and inserts on the anatomical neck of the humerus.
  
• Middle Glenohumeral Ligament: limits external rotation and anterior translation of the humeral head. This ligament arises from the glenoid and inserts on the anatomical neck of the humerus.
  
• Inferior Glenohumeral Ligamen: limits external rotation and superior and anterior translation of the humeral head (anterior portion); limits internal rotation and anterior translation (posterior portion). This ligament arises from the glenoid and inserts on the humerus just beyond the lesser tuberosity.
  
• Coracohumeral Ligament: split into anterior and posterior divisions by the biceps tendon.  The anterior portion limits extension while the posterior portion limits flexion.  Both divisions limit inferior and posterior translation of the humeral head.  Runs laterally from the coracoid process to the humerus, covering the superior GH ligament superiorly.
  

Closed Packed Position

The closed packed position of the GH joint is abduction and external rotation.

Other Important Information

Capsular Pattern

Labrum

Resources

• Dutton, M. (2008). Orthopaedic: Examination, evaluation, and intervention (2nd ed.). New York: The McGraw-Hill Companies, Inc.