The head of the infant at birth. Part II / by J.W. Ballantyne.

Date:
1890
Catalogue details

Licence: Public Domain Mark

Credit: The head of the infant at birth. Part II / by J.W. Ballantyne. Source: Wellcome Collection.

Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.

    7/16 page 7
    is marked by the pituitary body. Bland Sutton goes on to state that, even at the mid-period of intra-uterine life, a narrow cavity may be detected passing from the pharynx through the basi- sphenoid so as to come into close relation with the infundibulum. This cavity is afterwards represented by a band of fibrous tissue, which disappears in the macerated sphenoid, leaving what is known as the canalis cranio-pharyngeus of Landzert. In one of my cases, a dropsical infant, in the mesial section of the head the pituitary body was seen resting on the sella turcica of the sphenoid, and in the cartilage joining the basi-occiput and basi-sphenoid was seen a narrow cavity closed both at its pharyngeal and cranial end. This cavity, I have no doubt, represented the canalis cranio-pharyngeus, and its presence in this infant supports Bland Sutton's statement that the alimentary and central spinal canals are continuous in the vertebrate embryo. Another piece of evidence in support of this view is to be derived from the well-known fact that in mon- sters with a deformed nervous system (as the auencephalic foetus) there is frequently also deformity of the alimentary canal, e.g., constriction of the stomach or intestine, an example of which I found recently in the dissection of a monster of this variety. In a coronal section of the head in one of the infants examined the vidian canal and nerve, were well shown. The vidian nerve, which passes from the spheno-palatine ganglion backwards through the vidian or pterygoid canal at the base of the pterygoid process of the sphenoid, is relatively large in the infant at birth. The vidian canal also is large at birth, so large that it was only on subsequent dissection that I was led to a correct conclusion with regard to its character. The Ear.—The ear of the infant at birth presents two peculiari- ties,—one is the very complete development of the internal ear, the tympanic cavity and ossicles, and the mastoid antrum ; the other is the rudimentary state of the external auditory meatus, the mas- toid portion of the temporal, and the Eustachian tube. The most important characters which distinguish the infantile from the adult ear are, therefore, to be found in connexion with the last-named parts. The imperfect ossification of the temporal bone, and more especially of its tympanic ring at the time of birth, explains the condition of the external auditory meatus. In the infant also the skull in the region of the ear is in a transition stage : there is ante- riorly the antero-lateral fontanelle, which becomes the region ^Jicn'on; whilst behind the ear is the postero-lateral fontanelle, the future region asterion. At and between these two foutanelles is found a medley of small bones and cartilage islands, wliich have no small importance from the point of view of the pathologist. It is not, however, within the scope of this paper to consider the develop- ment of the temporal bone, a subject upon which there is as yet no general agreement among enibryologists. Suffice it to state, tiiat it is chiefly through the imperfectly developed condition of the tym-
    digitised image 1
    digitised image 2
    digitised image 3