Encyclopaedia of the medical sciences ... forming a portion of the Encyclopaedia Metropolitana.

Date:
1847
Catalogue details

Licence: Public Domain Mark

Credit: Encyclopaedia of the medical sciences ... forming a portion of the Encyclopaedia Metropolitana. Source: Wellcome Collection.

Provider: This material has been provided by Royal College of Physicians, London. The original may be consulted at Royal College of Physicians, London.

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    ANATOMY. Anatomy. The term Anatomy, in its most correct and exten- »-»v^~/ sive sense, implies the examination of the structure and economy of the several parts and organs not only of animal but also of vegetable bodies. In its more restricted and conventional employment, however, it is applied specially to that branch of the Science which treats of the fabric of the human body, and the organs of which it consists. The description of the tissues composing the several organs has been already given in the Essay on Zoology ; it therefore remains to con- sider the form and arrangement of the organs them- selves, which is the province of Descriptive Anatomy. SECTION I. OF THE BONES AND THEIR APPENDAGES,—viz* LIGAMENTS, CARTILAGES, AND SYNOVIAL MEMBRANES. The natural junction of the Bones by ligaments, cartilages, and synovial membranes, forms the Skeleton (Anat. PI. I. and II.), which serves three purposes; Jirst, as a frame-work upon which the soft parts are at once extended and supported; second, as furnishing cavities for the entire or partial lodgment and protec- tion of the more important organs; and, third, as pro- viding a series of levers for the motions of the whole or any part or parts of the body. The first office is performed by the whole Skeleton; the second by the Head, Spine, Chest, and Basin; and the third by the Limbs. The division of the Human Skeleton into the three principal parts,—trunk, head, and limbs,—corre- sponds generally with that of the other Vertebrate Classes, but modified in reference to its special condition and economy, which is mainly influenced by the erect pos- ture, by station on the hinder, or rather lower limbs, thereby allowing free use of the fore or upper limbs without interference with the carriage or locomotion of the body, and by the great development of the cerebral portion of the brain, which produces correspondent size and form in the skull. 1 OF THE SPINE. Columna Vertebralis, Lat.; der Ruckgrat, Germ.; la Co- lonneVertebrale, Fr. (Anat. PI. III., fig. i. to xvn.) The Spine or Backbone consists of twenty-six Verte- bres, piled one above another, and forming an irregular pillar, often called the Spinal or Vertebral Column (figs. xii. xiii. xiv.). Each Vertebre (fig. i. to x.) (Ver- tebra, Lat.; Wirbel, Germ.; Vertebre, Fr.) has an irregularly-shaped short cylindrical body (a.), behind which is the spinal hole (b.) produced by the arch- like junction of the seven processes with the back of the body. Of these processes the two transverse (c. c), which stand out from each side of the arch, and the spinous (d.) from its back, serve the purpose of levers; whilst the other four, viz., two upper articular pro- cesses (e. e.) facing backwards, and two lower (f. f.) looking forwards, link the vertebral pieces together. The spinal canal, which runs from end to end of the vertebral column, results from the piling upon each other of the rings forming the spinal holes, and lodges the spinal marrow; the apertures on each side of it for the passage vol. vim. 381 of the spinal nerves are produced by the conjunction of the notches at the roots of the articular processes, with corresponding notches of the Vertebres above and below each bone. The Spine is anatomically divided into regions, com- monly known as the neck, back, loins, and rump ; to the Cervical or neck (figs. xii. xm. xiv. a.) belong seven Vertebres; to the Dorsal or back (b.), twelve ; to the Lumbar or loins (c), five; and to the rump (d. e.), two, of which the upper piece (d.) is the true rump- bone, and the lower (e.) the rudiment of the tail- bones of other Vertebrate Animals. These Vertebres in their several regions perform peculiar offices ; hence their form varies, and their specific characters easily distinguish them ; but the nearer each region approaches the other, the more nearly does one resemble the other, and therefore the special form is best developed in the central pieces of each division. Of the Neck {Cervix, Lat.; der Hals, Germ.; le. Cou, Fr.) (Figs. iv. v. vi. vn). The principal use of this region being mobility, the Vertebres of which it consists are formed specially with that object; accordingly their bodies (a.) are of small size, and their lever-like transverse (c. c.) and spinous (d.) processes large. The upper (g.) and under surfaces of their bodies are so formed as to allow greater extent of motion than in any other part of the Spine, the upper being hollowed from side to side and the under from before to behind, so that when the bones are connected by their ligaments, a chain-like motion is performed, and thereby great mobility pro- vided without loss of strength or connexion. The ar- ticular processes face obliquely the upper (e. e.) up- wards and backwards, the lower (f. f.) downwards and forwards; hence the term oblique,'sometimes applied generally but improperly to the articular processes of all Vertebres, is to these specially appropriate. They are also more or less hollowed, and permit sliding on each other in the inclination of the head forwards and backwards, or to either side. These motions are con- fined to the six lower Vertebres of this division; and although between any two they are not extensive, yet is the combined motion of all very considerable. The transverse (c. c.) and spinous (d.) processes are each 3 D