Anatomy, descriptive and surgical / by Henry Gray ; the drawings by H.V. Carter ; the dissections jointly by the author and Dr.Carter.

  • Henry Gray
Date:
1860
Catalogue details

Licence: Public Domain Mark

Credit: Anatomy, descriptive and surgical / by Henry Gray ; the drawings by H.V. Carter ; the dissections jointly by the author and Dr.Carter. Source: Wellcome Collection.

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    superincumbent pressure is well exhibited in various parts of the skeleton, such as the human foot, and more especially in the vaulted roof of the cranium. Bones are divisible into four classes: Long, Short, Flat, and Irregular. The Long Bones are found chiefly in the limbs, where they form a system of levers, which have to sustain the weight of the trunk, and to confer extensive powers of locomotion. A long bone consists of a lengthened cylinder or shaft, and two extremities. The shaft is a hollow cylinder, the walls consisting of dense compact tissue of great thickness in the middle, and becoming thinner towards the extremities; the spongy tissue is scanty, and the bone is hollowed out in its interior to form the medullary canal: The extremities are generally somewhat expanded for greater convenience of mutual connexion, for the purposes of articulation, and to afford a broad surface for muscular attachment. Here the bone is made up of spongy tissue with only a thin coating of compact substance. The long bones are, the clavicle, humerus, radius, ulna, femur, tibia, fibula, metacarpal, and meta- tarsal bones, and the phalanges. Short Bones. Where a part is intended for strength and compactness, and the motion at the same time slight and limited, it is divided into a number of small pieces united together by ligaments, and the separate bones are short and com- pressed, such as the bones of the carpus and tarsus. These bones, in their struc- ture, are spongy throughout, excepting at their surface, where there is a thin crust of compact substance. Flat Bones. Where the principal requirement is either extensive protection, or the provision of broad surfaces for muscular attachment, we find the osseous struc- ture remarkable for its slight thickness, becoming expanded into broad flat plates, as is seen in the bones of the skull and shoulder-blade. These bones are composed of two thin layers of compact tissue, enclosing between them a variable quantity of cancellous tissue. In the cranial bones, these layers of compact tissue are familiarly known as the tables of the skull; the outer one is thick and tough, the inner one thinner, denser, and more brittle, and hence termed the vitreous table. The intervening cancellous tissue is called the diploe. The flat bones are, the occipital, parietal, froiital, nasal, lachrymal, vomer, scapulce, ossa innominata, sternum, and ribs. The Irregular or Mixed bones are such as, from their peculiar form, cannot be grouped under either of the preceding heads. Their structure is similar to that of other bones, consisting of an external layer of compact, and of spongy cancellous tissue within. The irregular bones are, the vertebrce, sacrum, coccyx, temporal, sphenoid, ethmoid, superior maxillary, inferior maxillary, palate, inferior turbinated, and hyoid. Surfaces of Bones. If the surface of any bone is examined, certain eminences and depressions are seen, to which descriptive anatomists have given the following names. A prominent process projecting from the surface of a bone, which it has never been separate from, or moveable upon, is termed an apophysis (from a7r6(^v(Ti<^, an excrescence); but if such process is developed as a separate piece from the rest of the bone to which it is afterwards joined, it is termed an epiphysis (from eV/- (}>vai<^, an accretion). These eminences and depressions are of two kinds : articular, and non-arti- cular. Well-marked examples of articular eminences are found in the heads of the humerus and femur; and of articular depressions, in the glerfoid cavi- ty of the scapula, and the acetabulum. Non-articular eminences are designated according to their form. Thus, a broad, rough, uneven elevation is called a tuberosity; a small rough prominence, a tubercle; a sharp, slender, pointed eminence, a spine; a narrow rough elevation, running some way along the surface, a ridge, or line. The non-articular depressions are also of very variable form, and are described as foss£e, grooves, furrows, fissures, notches, etc. These non-articular eminences and depressions serve to increase the extent of surface for the attachment of liga- B 2
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