Anatomical variations : an account of a few of the more interesting abnormalities that have occurred in the dissecting-rooms during the last seven years : with remarks on their morphological significance, and their bearing on the practice of surgery / by W.J. Walsham.

  • William Walsham
Date:
[1880]
Catalogue details

Licence: Public Domain Mark

Credit: Anatomical variations : an account of a few of the more interesting abnormalities that have occurred in the dissecting-rooms during the last seven years : with remarks on their morphological significance, and their bearing on the practice of surgery / by W.J. Walsham. 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.

    3/38 page 71
    insertion. Its middle third was quite suppressed. Its lowermost portion consisted of a few fibres, forming a thin muscle, about an inch and a half in length, and arose from the back of the sternum just external to the abnormal origin of the right muscle, and ended on the carotid sheath. Its uppermost portion, about a quarter of an inch in breadth and an inch and a half in length, was attached to the oblique line on the ala of the thyroid car- tilage, and was inserted into the left lobe of the thyroid body on its antero-internal aspect. A levator glandulae thyroidoae, arising from the body of the hyoid bone and inserted into the isthmus of the thyroid gland, was also present. This is the only abnormality of the kind that I have seen. Macalister relates a case in which the sterno-thyroid was absent, and this Professor Humphry1 states to be the only example of the absence of the sterno-thyroid or sterno-hyoid that he has seen recorded. A slip from the outer edge of the sterno-thyroid has been noticed, extending to the sheath of the vessels; but I know of no case in which the sterno-thyroid has been seen cross- ing the middle line of the neck, and in which the middle of the muscle has been suppressed. In the great ant eater the sterno- thyroids decussate across the middle line, but this decussation takes place behind the sternum, the sterno-thyroid in this animal arising in the interior of the thorax as far back ns the eighth bone of the sternum (Owen); and it is noteworthy that at the place of decussation a tendinous intersection exists. The rudimentary condition of the left sterno-thyroid is of con- siderable importance. In the sterno-thyroid as well as in the sterno-hyoid, a transverse tendinous intersection is often observed just above the sternum, “ a remnant,” says Professor Hum- phry,2 “of the transverse septa of the primitive ventral muscle.” Occasionally a similar but less marked intersection is seen a little higher in these muscles; whilst, as is well known, in animals with long necks, as the giraffe, the depressors of the hvoid consist of alternate tendinous and muscular portions. These tendinous intersections, which are serially homologous with the transverse inscriptions in the rectus abdominis and the rectus sternalis, when present, would thus seem to indicate that the muscle was developed from a number of distinct verte- bral segments. The explanation of the abnormality (absence of the middle portion of the left sterno-thyroid) would seem to be, that one or more of the primitive segments from which the middle part of the muscle is developed, i.e., the part between two or more trans- 1 Brit. Med. Journal, 1873, yol. i. 2 Ibid., 1873, yol. i.
    digitised image 1
    digitised image 2
    digitised image 3