OCR Text |
Show 1894.] MYOLOGY OF RODENTS. 275 the fibres of this converge to be attached to the acromion and spine for a variable extent, as well as to the fascia of the outer side of the arm and the pectoral ridge of the humerus. In the Caviidae these fibres to the arm are specially well developed, and in Ceredon some of them extend as far as the internal condyle. The abdominal panniculus divides about the lateral line of the body into a superficial and a deep layer, which, as they approach the ventral region, embrace the pectoral, the superficial fibres passing over the muscle to be lost on its surface, the deep being attached to the cartilages of some of the true ribs close to the sternum and deep to the pectorall. Posteriorly the panniculus Fig. 10. Panniculus of Hystrix cristata. ends in a fairly well-defined margin over the gluteal muscles ; the fibres of this part running round to the front and inner side of the thigh to terminate in the fascia there. I have never seen any attachment to the femur. Over the inguinal region there are several planes of fibres ; some of these unite in the middle line under the ventral surface of the penis, forming a sling to keep that organ close to the body ; this arrangement is well seen in Ccelogenys. The ventral and lateral parts of the panniculus of the body are supplied by the great internal anterior thoracic nerve, which runs back from the internal chord of the brachial plexus : the cervical part is supphed by the superficial cervical and facial nerves. Latissimus Dorsi.-The latissimus dorsi rises from a large number of tbe posterior thoracic spinous processes, the posterior three or 1 See author's contribution to Proc. Anat. Soc, printed in the Journal of Anatomy, xxvi. p. x (1892). |