Book One -- The things that sustain and support the entire body, and what braces and attaches them all. [the bones and the ligaments that interconnect them] | Chapter 21 On the Scapuli

The depression made to receive the humerus

The neck continues to be extended considerably outward, and is widened; being itself oblong, it forms an oblong depression [cavitas glenoidalis] (A, B in figs. 1 and 2), ending with a circular edge in the lower part but extended more to a point in the upper part. This happens because of an impression (C in fig. 1) made here in the inner surface of the neck to make room for the tendon of the muscle [m. subscapularis] (G in the 7th table of muscles, H in the 8th) which rotates the arm inward and anteriorly. The upper part (A in fig. 1) of the scapular neck and socket extends higher so that two very strong ligaments of this joint [ll. glenohumeralia] (e in the 5th table of muscles and V in the 13th) may better take their origin from this point, and so that the outer head (m in the 6th table of muscles) of the muscle [m. biceps brachii, caput longum] that will be considered the anterior of those that flex the forearm may conveniently take its origin hence. This scapular cavity is covered with cartilage like the other joint sockets, and is not carved very deeply. Its length and breadth do not match the length and breadth of the head of the humerus (A, B, C in figs. 1 and 2, ch. 23) with which it is articulated. 34 Nature devised this feature in quite a peculiar way in this joint. In other joints, the heads match the sockets perfectly, unless you wish to make an exception of the joint of the femur with the tibia [articulatio genus] (join E, F, I of fig. 1 ch. 30 with G, F, I of fig. 7 ch. 31 and consult fig. 8 of the same ch.), where you will understand the sockets of the tibia do not match the heads [condylus medialis, c. lateralis] of the femur, and that Nature was making some separate arrangement in that joint as well. We shall explain in the appropriate place where the knee differs from the system of the other joints, but now we must explain the shoulder joint.



Book One -- The things that sustain and support the entire body, and what braces and attaches them all. [the bones and the ligaments that interconnect them] | Chapter 21 On the Scapuli