Anatomy Lessons From the Great Masters by Robert Beverly Hale

Author:Robert Beverly Hale [Hale, Robert Beverly]
Language: eng
Format: epub
ISBN: 978-0-307-78644-9
Publisher: Potter/TenSpeed/Harmony
Published: 2014-06-03T04:00:00+00:00

Acromioclavicular Articulation, Forward and Back

The acromioclavicular joint, where the clavicle meets the acromion process of the scapula, is active in nearly all movements of the shoulder girdle and contributes to its great mobility.

You can find this important joint of the shoulder girdle by the projection of the enlarged outer end of the clavicle (A) as it rises slightly above the acromion process of the spine (B) of the scapula.

You can find the line of the spine of the scapula by drawing a spiral line between the bulge (A) at its outer and upper end to the inner end of the origin of the posterior portion (C) of the deltoid. If you follow the edge of the bulging muscular masses of the supraspinatus (D), infraspinatus (E), and teres major (F), all of which originate in the scapula, you will find the inner or vertebral border of the scapula (G). The inferior or lower border of the scapula (H) is being pulled forward by the lower and stronger fibers of the serratus anterior (I), several fingerlike digitations of which are visible. From its insertion in the spine of the scapula, the middle portion of the trapezius (J) assists by inward and upward action to lift the shoulder. The scapula tilts on its vertical axis and follows the movement of the arm.

By way of the acromioclavicular joint (A) and its connection with the clavicle, the scapula acts as an adjustable base or platform for the humerus of the arm and, at the same time, takes part in the movement of the whole shoulder girdle.

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