On a group of varieties of the muscles of the human neck, shoulder, and chest : with their transitional forms and homologies in the Mammalia / by John Wood ; communicated by Dr. Sharpey.

  • Wood, John, 1825-1891.
Date:
[1869]
Catalogue details

Licence: Public Domain Mark

Credit: On a group of varieties of the muscles of the human neck, shoulder, and chest : with their transitional forms and homologies in the Mammalia / by John Wood ; communicated by Dr. Sharpey. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    fibres of insertion of a broad triangular muscular layer (Plate X. fig. 16, l), arising from the sternum under the pectorals. This is clearly the homologue of the sterno-ciavicular muscle, disguised by its connexion with the sterno-scapular. The group of muscles just described have been taken together as one m. pectoralis minor by Krause (op. cit. S. 104), and as the subclavius by Cuvier (Recueil, pi. 233), but the interposition of the clavicle between the upper and lower portions of the deeper layer points evidently to their correspondence, respectively, to the scapulo-clavicular and sterno-ciavicular of other animals; and they are, at least, as worthy of separation as the component parts of the cephalo-humeral, as distinguished by the same bone or its tendi- nous representative. Another portion of the pectorals of the Rabbit answer more closely than these to the pectoralis minor of Man. The sterno-scapular muscle in the Guinea-pig (Plate X. fig. 17, A & B, i) corresponds with a subclavius in being attached to the movable clavicle (x) by its more superficial fibres, while the deeper are continued to the outer part of the spinous process of the scapula, where it is inserted between the supraspinatus (q) and infraspinatus. In the same animal the scapulo-clavicular muscle (1c) is very considerable in size and distinct from the supraspinatus, over which it moves freely; arising from the scapular spine and supraspinous fascia, internal to the last, and inserted into the movable clavicle (x) opposite to the sterno-ciavicular (l). This last-named muscle arises from the middle of the sternum, between and partly covered by the upper and lower fibres of the pectorals, forming a triangular layer very distinct in its origin and insertion. In the Norway Rat (Plate X. fig. 19, & Plate XI. fig. 26) the subclavius proper (m) is represented by a small bundle of fibres arising to the inner side of the sterno-scapular, and inserted into the lower surface of the inner end of the clavicle (x). The sterno-scapular is a fusiform muscle (i) ending in two tendons of insertion, one with the omo-hyoid into the cervical border, and the other into the acromion process of the scapula. The scapulo-clavicular (k) in the same animal is very distinct, arising from the middle of the supraspinous fascia, and inserted into the outer end of the clavicle (x). This bone articulates directly both with the sternum and scapula, so that the action of the muscle upon it presents nearly the same conditions as in the human subject, and is necessarily more limited than in the Rabbit and other semiclaviculate animals. The sterno-scapular muscle has been described by Murie and Mivart in the Hyrax capensis as arising from the sternum in front of the origin of the pectoralis minor, and continued over the shoulder articulation to its insertion into the anterior superior angle of the scapula (op. cit. p. 338). They also found it in the Guinea pig, together with a slip from the supraspinatus to the clavicle (scapulo-clavicular), and state that Meckel describes it as a part of the subclavius in the Hare, Porcupine, and Agouti (pp. 259, 260), and that Cuvier considered it as part of the trapeziusX (Le£ons, vol. i. p. 373). In the ‘ Recueil de Planches ’ it is marked in the Rabbit as subclavius (pi. 233). In the Crested Agouti, Mivart and Murie found the sterno-scapular to have a double origin, viz. a larger, from the sternum between the pectoral bundles; and a smaller, from