Ellis's 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:
1890
Catalogue details

Licence: Public Domain Mark

Credit: Ellis's demonstrations of anatomy : being a guide to the knowledge of the human body by dissection / by George Viner Ellis. Source: Wellcome Collection.

    37/802 (page 23)
    The ORBICULARIS PALPEBRARUM (fig. 7, ) is the sphincter muscle Orbicularis closing the opening between the eyelids. It is a flat and thin layer, ^ujj^^^^ Avhich extends from the margin of the lids beyond the cir- cumference of the orbit. From a difference in the characters of the fibres, a division has been made of them into two parts—outer and two parts, inner. The external fibres (orbital part), the best marked, are fixed only Orbital or at the inner side of the orbit. This attachment (origin) is connected with the borders of the internal tarsal ligament ; above the ligament fnternaiiy. with the nasal j^rocess of the superior maxillary, and the internal angular process of the frontal bone ; and below the ligament with the orbital margin of the superior maxillary bone. From this origin the fibres are directed outwards, giving rise to ovals, which lie side by side, and increase in size towards the outer edge of the muscle, where they project beyond the margin of the orbit. Some of the ]3eripheral fibres spread upwards to the skin of the forehead, and others downwards to that of the cheek. The internal fibres (palpebral part), paler and finer than the outer, internal or occupy the eyelids, and are fixed at both the outer and inner sides partf^^^^ of the orbit. Internally they arise from the internal tarsal liga- ment : externally they end in the external tarsal ligament, by means attached at of which they are attached to the malar bone, and a few may blend with the orbital part. Close to the cilia or eyelashes the fibres form Ciiiary a small pale bundle, which is sometimes called ciliary. bundle. The muscle is subcutaneous ; and its circumference is blended Relations. al)ove with the frontalis. Beneath the upper half of the orbicularis, as it lies on the margin of the orbit, is the corrugator supercilii muscle with the supraorbital vessels and nerve ; and beneath the lower half is jjart of the elevator of the upper lip. The outer fibres are joined occasionall}^ by slips to other contiguous muscles below the orbit. Action. The inner fibres cause the lids to approach each other, use of inner shutting the eye ; and in forced contraction the outer commissure is ^'^^^ drawn inwards. In closing the eye the lids move unequally—the upper being much depressed, and the lower slightly elevated and moved horizontally inwards. When the outer fibres contract, the eyebrow is depressed, and the outer fibres, skin over the edge of the orbit is raised around the eye, so as to protect the ball. Elevation of the upper lip accompanies contrac- tion of the outer part of the orbicularis, owing to the associated action of the levator labii superioris and zygomatic muscles. The CORRUGATOR SUPERCILII is beneath the orbicularis, near the Corrugator inner angle of the orbit. Its fibres arise from the inner part of the ^P^^^'^ superciliary ridge of the frontal bone, and are directed outwards between the bundles of the orbicularis to be inserted into the skin inserted into above the inner half of the eyebrow. It is a short muscle, and is ^^^ • distinguished by the closeness of its fibres. Action. It draws inwards and downwards the mid-part of the use. eyebrow, wrinkling vertically the skin near the nose, and stretching that outside its place of insertion.