The _Rotundus Minor_, or _Teres Minor_, proceeds from the lower Rib of the _Omoplata_, and adheres to the Neck of the Shoulder-Bone with the _Infra-Spinatus_ to draw it in like manner backward. The _Sub-scapularis_ or _Immersus_ is situated entirely under the _Omaplata_, proceeding from the internal Lip of the _Basis_ or Root of the same _Omoplata_, and being terminated in the Neck of the Arm-Bone, which it causeth to lie close to the Ribs. _How many Motions are there in the_ Cubitus _or Elbow, and what are its Muscles?_ The _Cubitus_ or _Ulna_ is endu'd with two sorts of Motions, _viz._ that of Flection and that of {41} Extension, the former being perform'd by the help of two Muscles, that is to say, the _Biceps_, and the _Brachiæus Internus_; and the later by eight others, which are the _Longus_, the _Brevis_, the _Brachiæus Externus_, and the _Anconeus_. The _Biceps_ is a Muscle with two Heads, one whereof proceeds from the _Apophysis Coracoides_, and the other from the Cartilaginous edge of the _Glenoid_ Cavity of the _Omoplata_ or Shoulder-Blade: These two Heads descend along the fore-part of the Arm, and are united in one and the same Body, from whence springs forth a Ligament, which is inserted in a tuberosity situated in the upper and fore-part of the _Radius_. The _Brachiæus Internus_ is a small fleshy Muscle, lying hid under the _Biceps_, which takes its rise in the upper and fore-part of the _Humerus_, and is implanted in the upper and inner-part of the _Radius_, to bend the Elbow with the _Biceps_. The first of the four Extenders is the _Longus_ having two Sources, _viz._ one situated in the lower Rib of the _Omoplata_, near its Neck, and the other descending to the hinder-part of the Arm, till it is tyed to the _Olecranum_ or _Ancon_, by a strong _Aponeurosis_, which is common thereto, with the _Brevis_, and the _Brachiæus Externus_. The _Brevis_ or short Muscle of the Elbow arising from the hinder and upper-part of the _Humerus_, is fasten'd to the _Olecranum_ with the _Longus_. The _Brachiæus Externus_ is a fleshy Muscle which proceeds from the hinder part of the {42} _Humerus_, and adheres to the _Olecranum_ with the _Brevis_ and the _Longus_. The _Anconeus_ or _Cubitalis_ being situated behind the Fold of the _Cubitus_, is the least Muscle of all; it springs from the Extremity of the Arm-Bone, at the end of the _Brevis_ and the _Longus_, and in descending is inserted between the _Radius_ and the _Cubitus_ or _Ulna_, three or four Fingers breadth below the _Olecranum_. _How many Muscles hath the _Radius_, and which are its Motions?_ The _Radius_ is endu'd with a twofold Motion by the means of four Muscles: Of these the _Rotundus_ and _Quadratus_ cause that of _Pronation_, as the _Longus_ and the _Brevis_ that of _Supination_.