The alligator and its allies

by A. M. Reese

Pectoralis ([Plate I.], Figs. 1 and 2, p) (Pectoralis major, Grosser Brustmuskel). A broad muscle on the under side of the breast, bounded behind by the rectus abdominis and obliquus abdominis externus muscles, with which it is united. It arises from the whole episternum, from the whole sternum, except from the median line of its posterior part, from the sternal ends of the first six thoracic ribs, from all six sternocostal ridges, and, with a small prong, from the eighth rib. It is inserted on the distal part of the convex surface of the processus lateralis humeri.

Supracoracoideus ([Plate I.], Figs. 1 and 2, spc) (Supracoracoscapularis, Deltoideus, Schlüsselbeinhälfte, Theil der Schulterblatthälfte des Hebers des Armes, Obergrätenmuskel, Hebemuskel des Oberarmes, Epicoraco-humeralis). A muscle of considerable size at the anterior region of the coracoid and the under region of the scapula, which is divided into two parts: (a) the coracoid (inferior) division is the stronger and arises from the whole anterior half of the coracoid, from its outer and inner surfaces; it is inserted, together with the second part, on the proximal, little-developed part of the processus lateralis humeri; (b) the scapularis (superior) division is the weaker of the two and is covered by the deltoides scapularis inferior muscle; it arises from the surface of the under third of the scapula, behind the spine; it unites with the preceding part to form a single muscle and inserts itself, as said above, on the proximal part of the processus lateralis humeri.

Coraco-brachialis (Brevis) ([Plate I.], Figs. 4, 5, and 6, cbb) (Theil des grossen Brustmuskels oder Hakenarmmuskel, Pectoralis II., Pectoralis minor). A fairly strong muscle. It arises from the outer surface of the coracoid, except the median edge and the anterior section, and runs to the flexor surface of the upper arm where it is inserted on the proximal third between the lateral and median processes.

Coraco-antebrachialis ([Plate I.], Figs. 2 and 5, b¹) (Biceps, Coracoideus, Langer Kopf des langen Beugers, Langer Kopf des Biceps, Biceps humeri, Biceps brachii, Coraco-radialis). A slender and rather weak muscle on the flexor side of the upper arm. It arises by a fairly broad but thin tendon from the outer surface of the coracoid immediately before the coraco-brachialis. As a weak bundle it passes between the lateral and median processes, lying medially near the brachialis inferior muscle, with which, at the end of the upper arm, it unites; after their union the two muscles continue as a broad tendon that splits into two parts, which are inserted on the proximal end of the radius and of the ulna.

Humero-antebrachialis Inferior ([Plate I.], Figs. 2 and 6, hai) (Brachialis inferior, Caput breve m. bicipitis, Kurzer Kopf des Biceps, Brachial interne, Brachialis anticus, Erster vom Oberarm ausgehender Beuger, Portion of Brachiæus). Springs from the lateral flexor side of the humerus, from the distal end of the lateral process to the distal end of the bone, except the epiphysis; at the end of the upper arm it unites with the biceps and with it is inserted, by two tendons, to the radius and ulna.

Dorso-humeralis ([Plate I.], Fig. 1, dh) (Latissimus dorsi, Breiter Rückenmuskel, Humero-dorsalis). It springs as an aponeurosis from the back at the level of the first four or five dorsal vertebræ, and passes, with converging fibers, cephalo-ventrad to unite with the teres major muscle; in common with the latter it extends along the extensor surface of the humerus to be inserted between the lateral and median processes.

Dorsalis Scapulæ ([Plate I.], Fig. 1, dss) (Deltoides scapularis superior, Unterer Theil des äusseren Schulterblattmuskels, Untergrätenmuskel, Suprascapularis, Infraspinatus, Supraspinatus). Springs from the anterior half of the outer surface of the scapula, passes between the deltoides scapularis inferior and the caput scapulare laterale externum m. anconæi, as a narrow band, to be inserted on the lateral side of the humerus.

Deltoides scapularis Inferior ([Plate I.], Figs. 1 and 2, dsi) (Deltoideus superior, Supra- and Infraspinatus, Theil der Schulterhälfte des Hebers des Armes, Theil der oberen [Schulterblatt-] Abtheilung des Deltoideus, Zweiter Hebemuskel des Oberarmes, Theil des Deltoides). A strong muscle on the side of the shoulder. It springs from the spine of the scapula, passes back with slightly converging fibers, and ends chiefly on the outer surface of the processus lateralis humeri, while a number of superficial fibers end in the humero-radialis muscle.

Scapulo-humeralis Profundus ([Plate I.], Fig. 4, shpr) (Teres minor, Erster Teres major, Scapulo-humeralis). A small muscle that springs from the posterior border of the lower third of the scapula, and passes, with converging fibers, to its insertion on the humerus just distal to the medial process.

Teres Major (Grosser runder Muskel oder kleiner Rückwärtszieher des Oberarmbein, Zweiter teres major). Springs from the posterior half of the upper region of the outer surface of the scapula. It passes down, with converging fibers, to unite with the latissimus dorsi muscle to form a strong tendon that is inserted on the extensor surface of the humerus.