Animal physiology / by John G. M'Kendrick.

John Gray McKendrick

Date:: 1877

Catalogue details

Licence: Public Domain Mark

Credit: Animal physiology / by John G. M'Kendrick. Source: Wellcome Collection.

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9. The Thorax, or chest, consists of the dorsal vertebras, the sternum or breast-bone (fig. 12), the ribs^zxv^ the car- tilages connecting these with the sternum, known as the costal cartilages. The sternum, C, is situated in the median line at the fore-part of the thorax, and is connected with the rest of the trunk by the costal cartilages of the seven highest pairs of ribs. The ribs are twelve in number on each side. They are long slender curved bones which extend forwards from the spine, some of them joining the breast- bone or sternum. The seven upper ribs, which join the ster- num by cartilages, are termed the ^true' ribs; while the lower five, which do not join the sternum, are termed the 'false' ribs (see fig. 1, 12). Each rib has a double attachment to the backbone posteriorly ; by its head^ which unites with the body of the vertebrae (fig. 2, ^), and by a rounded prominence, called the tubercle^ with the transverse pro- cess of the vertebra (fig. 2, d). The costal cartilages are continuations of the ribs. They give elasticity to the framework of the thorax. In advanced life they become impregnated with earthy matter, partially lose their elasticity, and thus diminish the force and depth of respiration. 10. The Bones of the Upper Extremity.—The upper extremity consists of the shoulder, the arm, the fore- arm, and the hand. The bones of the shoulder are the scapula (fig. 1, i), and clavicle or collar-bone (fig. 12, E); in the arm, is the humerus (fig. 1, 3); in the fore-arm, are the radius, 4, and ulna, 5; and in the hand, three groups of bones—the carpus, 13, metacarpus, 14, and digital phal- ig, 12-—Antero-lateral View of Thorax: A, A, vertebrae ; B, ribs ; C, sternum ; D, cartilages of ribs ; E, clavicle ; F, scapula.

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