The Pedestrian's Record

THE PEDESTRIAN'S RECORD. 2 1 1 Serratus magnus is a broad, thin, four-sided muscle. It presents on its anterior aspect a serrated appearance, and from such disposition its name is derived. These digitations arise from the firsteight ribs ;one digitationis inserted oneach rib, except thesecond, upon which two occur : from these points the muscle curvesbackwards over the convexity of the ribs, and is inserted into the scapula on its costal spect. The combinedaction of these muscles is exerted upon the shoulder and arm.The pectoralis major with latissimus dorsi depresses thehumerus. If the armsbe fixed by holding firmly some object, such as corks, then every muscular effort which can elevate the ribs is brought into action. THE POSTERIOR PART OF THE TRUNK. The muscles of the back assist he respiratory effort, especially those inclose approximation to the ribs, and dorsal vertebrae ; namely, the interspinals, intertransversales, and levatores costarum. The outer muscles of the back are the trapeziusand latissimus dorsi. Trapezius arises from the occiput andfrom the white fibrous band, the ligamentum nuchas, the spinous process of the last cervical vertebras, andfrom all those ofthe dorsals, and is inserted on the clavicleand spine of the scapula. The ligamentumnuchae (which is well depicted onplate 2 ) is a dense fibrousmembrane, and lies upon the spinous processes of the vertebras, and thus forms the line of demarkation between the trapezius on the right and thaton the left. Latissimus dorsi is a muscle of considerable extent, for it occupies more than the lowerhalf of the dorsal and the whole of the lumbar region. It arises from the spinousprocesses of six lower dorsal vertebrae,and fromall those of the lumbar, and is inserted into the bottom of the bicipital groove in the humerus. The action of these muscles combined is to draw the head back- P 2