The distribution of blood-vessels in the labyrinth of the ear of Sus scrofa domesticus / by H. Gideon Wells.

  • Shambaugh, George Elmer, 1868-1947.
Date:
1903
Catalogue details

Licence: In copyright

Credit: The distribution of blood-vessels in the labyrinth of the ear of Sus scrofa domesticus / by H. Gideon Wells. 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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    work in which each individual loop can be traced. This is especially clearly defined in the vestibule and semicircular canals, except in the regions of the maculae and cristae acusticae, where the network is too dense to allow such close analysis. A problem which is also perplexing at first is to determine which vessels are in the membranous labyrinth and which are in the osseous labyrinth or perilymphatic structures. This question can be definitely settled by a careful study of the prepa- rations. Great assistance in determining the exact outlines of the membranous labyrinth in the vestibule and semicircular canals is found in the study of preparations that have never been cleared in creosote, but have been left in 95 per cent, alcohol for several days. Such preparations become partially transparent, and the outlines of the utricle and the membranous ampullae and semicircular canals are clearly defined. Another method that will assist in determining the outlines of the membranous labyrinth is by clearing the celloidin cast in acid-glycerine.3 In preparations that have been thoroughly cleared in creosote, the utricle and the membranous ampullae and semicircular canals are definitely outlined in the incasing network of capillaries, and when viewed through the stereoscopic microscope their exact outlines can be traced. THE ARTERIES A single vessel, the labyrinthine artery, supplies the labyrinth of the ear, sending branches to the vestibule and semicircular canals, as well as to the cochlea. It reaches the labyrinth through the meatus acusticus internus, lying upon the auditory nerve. In this canal the labyrinthine artery breaks up into a number of branches. The first to be given off is a large vessel which follows along the ramus utriculo- ampullaris to the anterior surface of the vestibule, and is called the anterior vestibular artery (Plate V). The labyrinthine artery then divides into two trunks which almost immediately break up into a number of branches. These vessels are wound part way around the stem of the nervus cochleae, as if carried around it by the spiral growth of the cochlear tube (Plate VI). The branches from the two terminal trunks of the laby- rinthine artery anastomose freely with each other, and from the anastomotic loops thus formed are given off the arteries which supply the cochlea, and others which, together with the anterior vestibular artery, supply the vestibule and the semicircular canals. 1. The arterial tree of the cochlea.—In the adult labyrinth and in the labyrinth of the foetus at full term the arteries undergo a remarkable series of convolutions described by Schwalbe as “glomeruli.” These convolutions make it quite impossible in many areas of the cochlea to follow the vessels with accuracy. In the earlier embryonic stages the arteries do not possess this character, but run their entire course as practically straight vessels, free from spiral windings. This is true for all embryos of the pig measuring less than 12 cm. At about this age the arteries begin to develop much more rapidly than the surrounding structures, and, as a result, are thrown into these convolutions which, before the embryo reaches 16 cm. in length, are already well pronounced. 3 HCl 2.5, glycerine 100.