The Articular Capsule (capsula articularis; capsular
ligament).The articular capsule completely surrounds the
articular margins, and is strengthened above and below by the
superior and inferior acromioclavicular ligaments. The Superior
Acromioclavicular Ligament (ligamentum acromioclaviculare).This
ligament is a quadrilateral band, covering the superior part of
the articulation, and extending between the upper part of the
acromial end of the clavicle and the adjoining part of the upper
surface of the acromion. It is composed of parallel fibers,
which interlace with the aponeuroses of the Trapezius and
Deltoideus; below, it is in contact with the articular disk when
this is present. The Inferior Acromioclavicular Ligament.This
ligament is somewhat thinner than the preceding; it covers the
under part of the articulation, and is attached to the adjoining
surfaces of the two bones. It is in relation, above, in rare
cases with the articular disk; below, with the tendon of the
Supraspinatus. The Articular Disk (dis