Demonstrations of anatomy : being a guide to the knowledge of the human body by dissection / by George Viner Ellis.

  • Ellis George Viner, 1812-1900.
Date:
1882
Catalogue details

Licence: Public Domain Mark

Credit: Demonstrations of anatomy : being a guide to the knowledge of the human body by dissection / by George Viner Ellis. 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.

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    muscles to tlie ossicles. Tensor tym- pani. Origin. Insertion. Use. Laxator tympani. Origin. Insertion. Use. Stapedius attached to stapes. Use. Lining of tyinpaniun. transversely striated fibres are connected witli the chain of bones ; two of these are attached to tlie malleus, the other to the stapes. The tensor tympani (fig. 240, internal muscle of the malleus) is the largest and most distinct of the muscles of the tympanum, and takes the shape of its containing tube, which must be laid open to see it completely. The muscle arises from the surface of its bony canal, also slightly in fi-ont fi-om the cartilage of the Eustachian tube. Posteriorly it ends in a tendon wliich is reflected over the end of the cochleariform process. Fig. 240.* and is inserted into the inner border of the handle of the mal- leus near its base. Action. The muscle draws in- wards the handle of the malleus towards the inner wall of the tympanic cavity, and tightens the membrane of the tympanum; and as the long process of the incus is moved inwards with the malleus the base of the stapes will be pressed into the fenestra ovalis. Laxator tympani (iig. 240, g, external muscle of the malleus). It is connected externally with the spinous process of the sphe- noid bone ; and passing through the Glaserian fissure, it is at- tached to the neck of the malleus above the processus gracilis. Action. The muscle draws inwards and forwards the upper end of the malleus, and tilts outwards the handle, so as to relax the merabrana tympani ; and on the cessation of the contraction of the tensor, it can move out the bony chain. The stapedius (fig. 240, i) is lodged in the canal hollowed in the interior of the pyramid. Arising inside the tube, the muscle ends in a small tendon, which issues from the pyramid, and is inserted into the back of the neck of the stapes. Action. By directing the neck of the stapes backwards the muscle raises the fore part of the base out of the fenestra ovalis, diminish- ing the pressure on the fluid in the vestibule; and supposing it to contract simultaneously with the tensor, it would prevent the sudden jar of the stapes on that fluid. Mucous memhrane of the tympanum. The mucous lining of the tympanic cavity adheres closely to the wall; it is continuous with * Plan of the ossicles in position in the tympanum with their muscles. a. Cavity of the tympanum. 6. Membrana tympani. c. Eustachian tube. d. Malleus, e. Incus. /. Stapes, g. Laxator tympani muscle. Ii. Tensor tympani. i. Stapedius.