Anatomy of Proximal Humeral Physis

- Discussion:
    - proximal humerus ossifies from four centers: head, shaft, and both tubercles, which unite at age 19 to 20;
    - frx in adult life tend to occur along old epiphyseal lines;
    - depression between tubercles, bicipital groove, contains long head of biceps;
    - tubercles also serve as points of insertion for rotator cuff, w/ subscapularis inserting on lesser tubercle & supraspinatus, infraspinatus, and teres minor inserting from anterior to posterior on three facets of the greater tubercle;

- Proximal Epiphyseal Plate:
    - irregularly cone shaped with apex pointing superiorly, posteriorly and medially in relationship to shaft;
    - configuration interlocks physis and metaphysis at the plate;
    - position of apex tends to resist axial and posterior forces;
    - thickened periosteum anchors head and tuberosities to shaft
         - anterior periosteum is thinner and weaker
         - posterior periosteum is thicker
         - ensures blood supply to head by secure fixation to physis;
    - fusion of upper humeral epiphysis with the shaft takes place between 20 and 22 years of age

Original Text by Clifford R. Wheeless, III, MD.

Last updated by Data Trace Staff on Saturday, June 23, 2012 8:39 pm