A system of human anatomy : on the basis of the "Traité d'anatomie descriptive" of H. Cloquet / by Robert Knox.

  • Cloquet, H. (Hippolyte), 1787-1840.
Date:
1831
Catalogue details

Licence: Public Domain Mark

Credit: A system of human anatomy : on the basis of the "Traité d'anatomie descriptive" of H. Cloquet / by Robert Knox. Source: Wellcome Collection.

Provider: This material has been provided by the Francis A. Countway Library of Medicine, through the Medical Heritage Library. The original may be consulted at the Francis A. Countway Library of Medicine, Harvard Medical School.

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    OF THE ETHMOID* BONE. 129. The Ethnoid (named also the Cribriform) Bone is placed at the anterior, lower, and middle part of the cranium, in a notch of the frontal bone. It is symmetrical, has a nearly cubical form, and seems composed of the assemblage of a multitude of thin, fra- gile and semitransparent laminae, placed in all sorts of directions, and thus constituting walls of cellules, which vary in their form and size, and are more or less open externally, in different subjects. The object of these cellules seems to be the enlargement of the surfaces without increasing the bulk. This bone also, although of pretty considerable size, is very light. It is generally divided into a middle and two lateral parts, but we shall adopt Bichat's divisions, which are the following. 130. Cerebral or superior aspect. This is broad, very uneven, and covered by the dura mater ; in the middle part, and posterior- ly, there is a small notch, sometimes a process horizontally flat- tened, which is articulated with a corresponding part belonging to the orbito-nasal aspect of the sphenoid bone, (119). A little more forwards, there rises, in a graduated manner, a crest, having the form of a triangular pyramid, varying much in size, being some- times very large and bulging, sometimes depressed and thin; its direction may ]be vertical or inclined to either side. In general it is composed of cellular structure internally, but there is sometimes a small cavity, or sinus, which communicates with those of the frontal bone : this pyramidal process is the Crista Galli or Eth^ moid Crest. By its base it is continuous with the rest of the bone; its summit gives attachment to the greater falx of the dura mater; its posterior edge is elongated and oblique behind; its anterior edge short and vertical: it ends before in two small depressed eminences, which articulate with the frontal bone, and generally contribute to the formation of the foramen coecum, of which we shall speak as we proceed. Its two lateral surfaces are plain and smooth. On either side of the crista galli, there is observed a wide but not very deep channel, corresponding to the olfactory nerves, much more distinct anteriorly than posteriorly, and perforated in its whole extent, but especially at the fore part, by round and irregularly distributed holes, named the Olfactory Foramina, on account of their giving passage to the filaments of the olfactory nerves, enve- loped in small meningeal sheaths. 131. These holes are of two kinds. Some are large and distinct, and are situated on the lateral parts of the channel, to the number of ten or twelve ; the rest, which are very small and less numerous, occupy the middle region. Each of them forms the superior ori- fice of a small canal, which subdivides in its descent in the interior H^fz-o;, ctilrum ; ilSoe, forma.