On the myology of the sciuromorphine and hystricomorphine rodents / by F.G. Parsons.
- Frederick Gymer Parsons
- Date:
- 1894
Licence: Public Domain Mark
Credit: On the myology of the sciuromorphine and hystricomorphine rodents / by F.G. Parsons. 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.
15/48 page 263
![In the Caviidfo the arrangement is the same as in Ccelogeuys (C. cohay a, Ceredon rupestris). Teres Minor.—The teres minor rises from the humeral third to half of the axillary border of the scapida, and is inserted just below the insertion of tho infraspinatus. It is sometimes a perfectly distinct muscle, but in most cases is so closely united to the infraspinatus that, were it not for its being supplied by the circumflex nerve, it would be most conveniently described with that muscle. The teres minor was seen most distinctly in Layostomus, in which animal a fibrous band was found running from the metacromial process to the origin of the long head of the triceps, covering the infraspinatus and teres minor near their insertions. In the Sciuromorpha the muscle is specially indistinct. Biceps Cubiti.—The biceps always rises by a strong tendon from the margin of the glenoid cavity at the base of the coracoid process ; it may or may not have a second head rising from the tip of that process, or from the surface of the coraco-brachialis. Its insertion is into the radius, ulna, or both bones just below the sigmoid cavity, occasionally, however, it is prolonged farther down the bones. The semilunar fascia from the inner side of its tendon to the fascia of the forearm is very indistinct, but by careful dissection a few fibres may be traced. In the Dipodidfe there is only one head, and the insertion is almost entirely into the ulna (Dipus (egyptius, Alectaga indica). In the Octodontidse there are two heads; the insertion is into both radius and ulna (Myopotamus, Aidctcodus, Capromys, Octodori). In the ITystrickhe there is only one head in Hystrix, but two in Sphingurus and Erethizon dorsatus1; it is inserted largely into the radius in the Tree-Porcupines, but chietly into the ulna in Hystrix. In the Chinchillidre there are two heads; the insertion is into the coronoid process of the ulna and the oblique line of the radius (Chinchilla, Layostomus). In the Yiscacha 1 dissected there were three heads to the biceps on the left side, the extra one rising from the front of the great tuberosity of the humerus. In the Dasyproctidse there is only one head, and the insertion is entirely into the ulna (Dasyprocta, Ccelogeuys). In the Caviidm the arrangement is the same as that in the Dasyproctidae (Cavia cohaya, Ceredon rupestris, Dolichotis2). In the Sciuromorpha, Sciurus, Pteromys, Arctomys, and Xerus have the muscle rising chiefly by the glenoid or long bead, but also by some fibres from the front of the coraco-brachialis (representing a short head). The insertion is almost entirely into the tubercle of the radius so as to act as a supinator. Spermophilus differs in the absence of the short head. Castor has only one head and the insertion is entirely into the ulna. Coraco-brachialis.—The three parts of this muscle described by 1 Mivart, P. Z. S. 1882, p. 271. 2 Beddard, P. Z. S. 1891, p. 236. IS* [13]](https://iiif.wellcomecollection.org/image/b2238635x_0017.jp2/full/800%2C/0/default.jpg)
