A text-book of anatomy / edited by Frederic Henry Gerrish.

Date:
1899
Catalogue details

Licence: Public Domain Mark

Credit: A text-book of anatomy / edited by Frederic Henry Gerrish. Source: Wellcome Collection.

    33/926 (page 29)
    the ring finger {digitus annHhiris, from annus, a ring); and the fifth (digitus quintus) is the little finger {digitus minimus, litei'ally the least finger ). Each digit has three segments, except the thumb, which has but two. The lower limb is the homologue of the upper—that is, it is built on substan- tially the same structural plan/ It has four segments : hip, thigh, log, and foot, which corresi^ond respectively to shoulder, arm, forearm, and hand. Between hip and thigh is tlie hip-joint; l)et\veen thigh and leg, the knee-joint; and between leg and foot, the ankle-joint. The hip, or haunch (coxa), is so firmly united to the back-bone that it serves as a portion of the wall of the abdomen, the greater cavity of the trunk. Behind the hip and immediately below the loin is a large mass of muscle and fat, the buttock (natis). The thigh extends from the hip to the leg, and is technically called/oh (tv, whicli name is also applied to the single bone that forms its framework. The prominence in front at its lower end is the knee {genu), and the space opposite tlie knee on the posterior aspect is the ham {poples). The mistake of calling the buttocks the hams is often made, but has no justification. From knee-joint to ankle-joint is the leg {crus). Its rear bulge is the calf {sura or gastrocueviia, literally the belly of the leg), and the sharp vertical ridge in front is the shin. At the lower end of the leg are two bony prominences, the inner ankle {malleolus internus) and the outer ankle {incdleolus externus). Malleolus means a little hammer. The foot {pes), like its homologue the hand, is divided into three parts—a hindmost, the tarsus, a middle, the mefcdarsus, and a foremost or distal, the digits {digiti). The instep of popular nomenclature has no equivalent in anatomical terminology, as it includes pai'ts of both tarsus and metatarsus; and, on the other hand, there are no vernacular words corresponding to tarsus and metatarsus. The part of the tarsus which projects to the rear is the heel (calx); the top of the foot is its back {dorsum pedis); and the entire under surface is the sole {planta). The five digits are designated numerically, like their homologues in the hand, the count beginning, however, not at the outer end of the series, but at the inner—that nearer the median line of the body. Thus, the toes or digits of the foot {digiti pjedis) arc first, second, third, fourth, and fifth {primus, seeundus, tertius, quartus, and quintus), respectively. But the first and last have other names also, the one being commonly called the great toe {pollex pedis, the thumb of the foot, or hcdlux); and the other the little toe {digitus mini inus pedis, literally the smallest digit of the foot). In giving the Latin names for the toes it is rarely necessary to employ j)(dis ( of the foot) to distinguish those of the lower extremity, as the context indicates which limb is concerned ; and it is never essential to say manus ( of the hand ), as this is understood unless the contrary is obvious. THE SYSTEMS OF ORGANS AND THEIR FUNCTIONS. In studying anatomy the thoughtful learner is almost certain to conclude that he needs to know a great deal about every other part in order to comprehend fully the one which he has in hand. No organ, h(jwever simple, is independent: every one is so related to others, perhaps to many otliers, that they are absolutely essential to its life. In the same way it is true that some knowledge of many is necessary to the complete, or even sufficient, understanding of a single one. This fact constitutes a chief obstacle in the path of the anatomical student; but it may be diminished very considerably, and its residue rendered less discour- aging, by his having pi'esented to his mind at the beginning of his course a con- ' The difference between homology and analofty must be borne in mind. Homology relates to similarity of structure, analogy to likeness of function. The two do not always go together. For example, the upper limb of a man and that of a liird are homologous, because they are constructed on the same plan ; but they are not analogous, because the one is used for prehension (grasping), and the other for locomotion (flying). The organization in the two cases is strikingly similar ; the func- tion is radically diflerent. But compare the wing of a bird with that of a butterfly ; both are devoted to the same use—namely, flying; but they are essentially diflerent in structural plan, as can be seen on the most cursory inspection. Therefore they are analogous, but not homologous.