We investigated the structure of the myotendinous rotator cuff in
thirty-two grossly intact cuffs from thirty fresh cadavera of subjects who
had been seventeen to seventy-two years old at the time of death. We
studied the gross anatomy of the capsule and ligaments of the cuff, as well
as histological sections of the tendons of the subscapularis,
supraspinatus, and infraspinatus muscles. The tendons were found to splay
out and interdigitate to form a common, continuous insertion on the
humerus. The biceps tendon was ensheathed by interwoven fibers derived from
the subscapularis and supraspinatus tendons. The anterior margin and bursal
surface of the supraspinatus tendon were enveloped by a thick sheet of
fibrous tissue derived from the coracohumeral ligament. Fibers from the
coracohumeral and glenohumeral ligaments were found concentrated in a plane
between the capsule and the tendons of the cuff. Microscopically, in the
region of the supraspinatus and infraspinatus tendons, the cuff was
composed of five layers defined by the attachments and orientations of the
fibrous elements in each of these layers.