Copy 1

The Dublin dissector or manual of anatomy / By R. Harrison.

  • Robert Harrison
Date:
1847
Catalogue details

Licence: Public Domain Mark

Credit: The Dublin dissector or manual of anatomy / By R. Harrison. Source: Wellcome Collection.

    42/956 page 8
    somewhat analogous to the spasmodic constriction of the sphincter ani muscle. In the operation of opening the lachrymal sac, the incision should commence immediately below this tendon, so as to avoid imjuring it, and be carried obliquely downwards and outwards, to the extent of about half an inch. Separate the orbicularis from the occipito-frontalis over the internal half of the superciliary arch, the tensor tarsi and the corrugator su- percilii muscles will be exposed. Tensor Tarst arises tendinous from the posterior edge of the os unguis, where it joins the os planum, passes forwards between the conjunctiva and the expansion of the tendo oculi which covers the lachrymal sac, divides into two portions, which are inserted into-the la- chrymal ducts, along which the fibres extend, nearly as far as the puncta. Use, to draw the puncta and eyelids into close contact with the eye, also to press the puncta towards the nose, to compress the lachrymal sac, and to force out the secretion from the follicles of the caruncula lachrymalis. This muscle is also named HoRNER’s muscle, from its discoverer; it will be better seen if the two tarsi be divided about their middle, and their inner portions turned towards the nose without injuring the tendo oculi. CoRRUGATOR SUPERCILII arises fleshy and tendinous from the internal angular process of the os frontis, passes upwards and out~ wards, and is inserted into the middle of the eyebrow, mixing with the orbicularis and occipito-frontalis muscles. Use, to depress and approximate the eyebrows, throwing the skin of the forehead into ver- tical wrinkles, as in the act of frowning; this pair of muscles is vo- luntary, but they cannot act separately; they directly oppose the occipito-frontalis and shade the eye. They are covered by the orbi- cularis and occipito-frontalis, and lie on the os frontis and on the fron- tal nerve and vessels. PyRAMIDALIS NAsI, superficial, long, thin, often wanting, arises from the occipito-frontalis, descends close to its fellow between the aponeurotic, and is zxserted into the compressor nasi muscle. Use, it raises the skin covering the ossa nasi, when the occipito-frontalis is in action, but if the latter be relaxed, it can then draw down the inner end of the eyebrow. ComprEssorR Nast is thin and triangular, placed on the side of the nose, between the skin and the cartilage; it arises from the inner side of the canine fossa, in the superior maxilla; the fibres pass for- wards, expanding over the ala nasi, and are inserted by a thin apo- neurosis into the dorsum of the nose, joining some fibres from the from it, so that it may alternately enlarge or diminish the anterior naris; its action will partly depend on the form of the cartilage ; if convex, it may compress, if concave it may expand the ala nasi; in
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