ANATOMY. 



connected by adhering cartilaginous sur- 

 faces and immense ligaments. Such is 

 the streiKVii of this union, that it will yield 

 to no force but one that would destroy 

 and crush the whole fabric. 



Joints of the lower extremity. In the hip, 

 which supports the whole body ,and which 

 is the centre of motion of the whole in 

 moving from place to place, we find an 

 apparatus, admitting of extensive motion, 

 but at the same time most carefully guard- 

 ed and strengthened. There is a very 

 large rounded head of the thigh received 

 into a deep cup of the os innominatum. 

 Here it can revolve freely, and is prevent- 

 ed from escaping by thick and strong 

 rising edges, that guard the brim of the 

 cavity. From these edges there springs 

 a very tough and stout orbicular ligament, 

 which is firmly stretched over the head of 

 the bone, and implanted into a contracted 

 part called the neck. In order to provide 

 still further for the security of so impor- 

 tant a joint as the hip, there is a short, 

 strong ligament arising from the head of 

 the bull, and implanted in the bottom of 

 the cup. This affords a very great obsta- 

 cle to any force tending to displace the 

 bone; but at the same time lies in the 

 bottom of the cavity, so as not to interfere 

 with any of the ordinary motions. 



The knee-joint is formed by three 

 bones : the head of the tibia, the condyles 

 of the femur, and' the patella. It is a gin- 

 glymus, and its motions are accordingly 

 restrained by two strong lateral ligaments, 

 and it is secured still further by two im- 

 mense ligamentous ropes within the ca- 

 vity of the joint, called the crucial liga- 

 ments. 



The ankle is a ginglymoid joint, formed 

 by the tibia and fibula, together with the 

 astragalus. This joint, which is an im- 

 portant one, as bearing the weight of the 

 whole body, is strengthened at its sides 

 by two bony processes, called the inter- 

 nal and external malleoii or ankles. 



The bone?, of the tarsus, metatarsus, 

 and toes, are articulated, like those of the 

 hand. 



Muscles consist of bundles of red fi- 

 bres ; but the colour is not essential, since 

 it can be removed by repeated washings 

 ftiul maceration. 



The threads composing a muscle are 

 enveloped by cellular substance, which 

 connects it to the surrounding parts. 

 Each bundle consists of numerous fibres, 

 i>o small, that ottr instruments of research 



cannot arrive at the ultimate or original 

 fibre ; hence, any perceivable fibre, how- 

 ever small, is formed by the juxta-position 

 of numerous fibrillx ; and, as we employ 

 magnifying instruments of greater power, 

 a fibre, which before seemed simple, re- 

 solves itself into a congeries of still more 

 minute threads. We pass over in silence 

 the dreams of various investigators, who 

 have busied themselves in looking for the 

 ultimate muscular fibre ; these researches 

 do not assist us in explaining the pheno- 

 mena of muscular action. The cohesion 

 of the constituent particles of the moving 

 fibre is maintained by the vital power : 

 hence, a dead muscle will be torn by a 

 weight of a few ounces, which in the 

 living body would have supported many 

 pounds. The muscular fibre receives a 

 copious supply of vessels and nerves. 



Tendons are formed by an assemblage 

 of logitudinal parallel fibres. They are 

 extremely dense and tough, of a splendid 

 white colour, which is beautifully con- 

 trasted with the florid red of a healthy 

 muscle. The muscular fibres terminate 

 in these bodies, and they are connected 

 to the bones. They possess no apparent 

 nerves, and very few and small blood- 

 vessels. 



There is always an exact relation be- 

 tween the joint and the muscles that move 

 it. Whatever motion the joint, by its me- 

 chanical construction, is capable of per- 

 formingjthat motion the annexed muscles, 

 by their position, are capable of produc- 

 ing. For example, if there be, as at the 

 knee and elbow, a hinge joint, capable of 

 motion only in the same plane, the muscles 

 and tendons are placed in directions pa- 

 rallel to the bone, so as by their construc- 

 tion to produce that motion, and no other. 

 If these joints were capable of freer mo- 

 tion, there are no muscles to produce it. 

 Whereas, at the shoulder and hip, where 

 the ball and socket joint allows by its 

 construction a rotatory or sweeping mo- 

 tion, tendons ^are placed in such a posi- 

 tion, and pull in such a direction, as to pro* 

 duce the motion of which the joint admits. 

 In the head and hand, there is a specific 

 mechanism in the bones for rotatory mo- 

 tion ; and there is accordingly, in the ob- 

 lique direction of the muscles belonging 

 to them, a specific provision for putting 

 this mechanism of the bones into action. 

 The oblique muscles would have been in- 

 efficient without that particular articula- 

 tion, and that particulararticulation would 

 have been useless without the muscles. 



As the muscles act only by contraction, 

 it is evident that the recirocal e 



