The slip to the sterno-mastoid, which Duvernoy found in the Orang, occurs as an accidental variety in man, as is mentioned by Theile.[1]
The Clavio-trachélien, or Acromio-trachélien, arose from the clavicle alone, and was inserted into the inner side of the transverse process of the atlas. In the Gorilla, it has the same insertion, but it arises from the acromion.[2]
The Latissimus Dorsi possessed much the same origin as in man, but scarcely reached so far up the back. The fibres which arose from the dorsal vertebrae remained distinct, and did not interlace with those of the inferior portion of the muscle; and, as they curved round the lower margin of the Teres Major, they formed a distinct head, separated from the rest of the muscle by a septum of dense tissue, which was inserted partly into the external fascia of the arm, and partly into the humerus, together with the tendon of the Teres Major. The larger and inferior portion of the muscle passed on to be inserted by a broad tendon, which curved round the humerus, and was inserted into the inner surface of that bone an inch and a half below the bicipital groove. At the distance of an inch and a half from the point of insertion, a strong muscular slip, called by Duvernoy the Dorsoepitrochlien, is given off, which passes down along the inner side of the long head of the Triceps, to be inserted into the fascia of the arm and the olecranon process of the ulna.[3]
In the Gorilla, the Dorso-epitrochlien receives a small slip from the tendon common to the Biceps and the Coraco-brachialis (Duvernoy, l.c., p. 80.) In the Cebus, the tendon of the portion coming from the dorsal vertebrae is not inserted together with that of the Teres Major, but close to it This modification of the Latissimus Dorsi appears common to all the Quadrumana, and must greatly relieve the strain thrown on the muscles of the arm and shoulder by the weight of the
- ↑ Encyclopédie Anatomique, traduit d'Allemand par A. J. L. Jourdan, tom. iii. p. 124.
- ↑ This, the Acromio-basilar muscle of Vicq. d'Azyr, is eminently characteristic of the lower Mammalia; so that M. Duvernoy (second edition of Cuvier's Leçons, tome i. p. 371) even says, "On le trouve dans tous les mammifères, l'homme excepté, ce qui semblerait prouver qu'il est une des conditions de la station quadrupède." Its upper attachment varies in the Mammalian series from the lower cervical vertebræ (camel) to the occipital bone (rabbit). The human muscular variety, which appears to make the newest approach to the development of this muscle, is that observed by R. Wagner (cited in Henle's Handbuch der Systematischen Anatomie des Menschen, Bd. I. 3te. Abtheilung, p. 24) who found an accessory fasciculus of the Trapezius inserted into the Mastoid process, and remaining separate as far as the Acromion. The numerous dissectors, who will be busy in our medical schools during the ensuing winter, might do good service by attending to the variations of the Trapezius; and indeed of all those muscles whose attachments in man differ widely from those presented by the apes—e.g. the Flexor pollicis proprius, the Extensor indicis, and the Interossei of the hand: the Tibialis anticus, Extensores digitorum brevis, commmunis digitorum, hallucis longus, Flexor brevis digitorum, Transversus pedis, and Interossei of the foot. We shall be glad to receive and to record examples of such varieties.—[Eds.]
- ↑ This muscle is clearly represented in Man by the tendinous band which, as Halbertsma has shown (Henle, l.c. p. 183) constantly connects the long head of the Triceps with the Latissimus dorsi.—[Eds.]
