The muscles of the fore and hind limbs in Dasypus sexcinctus / by John Charles Galton.

  • Galton, John Charles.
Date:
[1868]
Catalogue details

Licence: Public Domain Mark

Credit: The muscles of the fore and hind limbs in Dasypus sexcinctus / by John Charles Galton. 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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    be inserted into the ulnar side of the base of the metacarpal of the fifth digit, a small round sesamoid being developed in the tendon at the point of insertion. Flexor carpi ulnaris.—Is a strong fleshy muscle which arises from the internal face of the olecranon process of the ulna, immediately below the insertion of the epitrochleo- nnconeus. Its fibres blend at first with those of the flexor profundus which take origin from the inner edge of the ulna, then pass straight forward to be inserted by a broad short tendon into the free extremity of the sickle-shaped pisiform bone. Flexor carpi radialis.—This muscle arises from the inner condyle of the humerus, having a common origin with the pronator teres, but being placed lowermost. On leaving the forearm, through which it has passed as a slender fusiform slip, it runs through a smooth groove channelled out in the palmar aspect of the scaphoid bone and having an oblique direction towards the middle line of the hand, being arched over in this groove by a strong ligament which spans its channel, to be finally inserted into the rounded, nodular, palmar projection of a carpal bone which I may term, for convenience and distinctness’ sake, trapezio-trapezoid', and becomes, also, continuous with a strong ‘ The following digression on the subject of the hones of the carpus in Dasypus will not, I think, be deemed irre- levant, when it is borne in mind that accuracy in description of the attachment of muscles demands and is dependent upon a previous knowledge of the nature, at aU events, of those osseous structures which may either serve these as a starting-point when they enter upon their journey, or be to them a goal or “ meta ” on the completion of their course. “ Sieben Knochen,” says Rapp, “ finden sich auch bei den Schuppenthieien ” {op. cit. p. 42); but no further de- scription is given of these. Since, then, the number of bones falls short of the usual carpal complement by one, there must either be a complete loss, or a fusion with some other element, of the eighth unit. Careful inspection, sup- ported by the testimony of Cuvier and Owen, shows that the latter has taken place. The former anatomist remarks, in his already quoted ‘ Ossemens Eossiles’ {loc. cit. p. 127) that in D. sexcinctus (“ I’Encoubert ”), “ Un seul os tient la place du trapeze et du trapezoide; ” while the following passage occurs in the monograph upon Myloclon rohustus of the latter (Lond. 1842, p. 97 et seq.):—“ In the only species of Armadillo (Das. sexcinchis) in which two of the normal carpal bones are blended into one, it is the trapezium and trapezoides which so coalesce, not the trapezium and scaphoides.” I append a description of the carpal bones of a species of Dasypus {sexcinctus'^), which I drew up for my own use when dissecting the Armadillo which is the subject of the present paper. Dorsal aspect.— First row (beginning from radial side) :— 1. Scaphoid: carries in front trapezio-trapezoid bone; articulates on ulnar side with os lunare. 2. Lunar: articulates with preceding bone on radial side, on ulnar side with cuneiform, in front with os maynum. 3. Cuneiform : a bone of great lateral extent articulates radially with lunar, on ulnar side with a small sesa- moid, posteriorly with ulna and elongated pisiform, anteriorly with unciform. It carries, moreover, the metacarpal of the fifth digit. 4. Pisiform: is wedged in, palmad, between uhia and cuneiform. The first two bones of the above row of the carpus articulate posteriorly with the radius in the usual manner. Second row (beginning radially) :— 5. Trapezium and trapezoid : fused into one laterally elongated bone, which carries the metacarpals of the pollex and index, and articulates posteriorly with the scaphoid, and on the ulnar side with the os maynum. 6. Os maynum: carries metacarpal of middle digit only. It articulates posteriorly with the lunar principally, slightly with the scaphoid, with unciform on ulnar side, radially with trapezio-trapezoid. 7. Unciform : carries fourth digit only; articulates posteriorly with cuneiform, radially with os maynum, on ulnar side partly with cuneiform, partly, but slightly, with fifth digit, which is supported mainly by cuneiform bone.