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.
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![couies from the spine of the scapula and fascia over the infra- spinatus. Mivart and Murie, in their description of the myology of the Agouti', prefer to describe the clavicular portion as part of the pectoralis, but I have been able to satisfy myself that its nerve- supply is derived from the circumflex and not the anterior thoracic. The insertion of the deltoid is into the pectoral ridge close to that of the pectoralis. The clavicular fibres are often prolonged to t he elbow and in all cases are inserted lowest, while the part from the spine is inserted deep to the acromial slip. In the Dasyproctidse the clavicular portion is continued down almost to the external condyle. In Sciurus and Pteromys the clavicular and acromial fibres are closelv united owing to the development of the clavicle. Sphin- gurus has the same arrangement. In Arctomys and Spennophilus the clavicular part divides into a superficial and deep portion; the latter has the usual insertion, but the former is continued down to the coronoid process of the ulna. In Castor, owing to the great development of the muscle, the intervals between the three parts are slight. The other animals examined present nothing remarkable in this muscle. Supraspinatus, Infraspinatus, and Su,bscapularis.—These muscles have the human attachments and, except in their comparative size, do not vary at all. Teres Major.—This muscle rises from the posterior quarter (more or less) of the axillary border of the scapula, and is inserted either into the tendon of the latissimus clorsi or into the humerus close to the insertion of that muscle. In the Dipodidie the insertion is posterior to that of the latis- simus dorsi as in Man (D. cegyptius, D. hirtipes, Alectaga inelica). In the Octodoutidae it is inserted into the front of the tendon of latissimus dorsi (Aulacoclus, Myopotamus, Octodon, Capromys pilorides and C. melanurus)1 2. In Lagostomus among the Chinehillidse, owing to the great size of the infraspinatus, the muscle only rises from about gth of the axillary border of the scapula and from the surface of the infra- spinatus and subscapularis, which overlap the bone. The insertion is into the rudimentary bicipital groove somewhat above the latissimus dorsi tendon, with which it is closely connected. Chinchilla has very much the same arrangement, but the muscle rises from more of the axillary border. In the llystricidse the lower border of the muscle is wrapped round by the latissimus dorsi close to the insertion (vide latissimus dorsi) (Hystrioc, Sphingurus). In the Dasyproctidse it was inserted nearer the shoulder than the latissimus dorsi in my specimen of Dasyprocta, but according to Mivart and Murie 3 the two muscles are inserted together. In Coelogenys it is inserted with, and in front of, the latissimus dorsi. 1 P. Z. S. 1866, p. 383. 2 Dobson, P. Z. S. 1884, p. 234. 3 P. Z. S. 1866, p. 383. [12]](https://iiif.wellcomecollection.org/image/b2238635x_0016.jp2/full/800%2C/0/default.jpg)
