THE POSTERIOR LIMBS 



91 



Fig. 57. 



row The three first of the upper row articulate with the radius ; the fourth responds 

 to the ulna. In the bones of the lower row, the trapezium responds to Ihe metacarpal 

 of the thumb and that of the index the trapezoides to the latter only, the os magnum 

 and unciform to the metacarpals of the medius, annularis, and little finger. The 

 pisiform bone and the cuneiform process of the unciform convert the posterior face of the 

 carpus into a channel. 



'2. Metacarpus. The five metacarpals of Man are parallel to each other, and articulate 



by their superior extremities with the bones of the cur- 

 pus ; by their inferior extremities with the phalanges. 

 They are all concave in their middle portion, and 

 thickened at their ends. The metacarpal of the thumb 

 is the shortest and strongest. The others diminish In 

 volume from the fourth to the first. 



3. Digital Region. Here we find five digits, each 

 composed of three bony columnettes, with the exception 

 of the thumb, in which only the second and third pha- 

 langes are present. They decrease in length from the 

 third to the first, and the third to the fifth. The first 

 and second phalanges are small semicylindrical bones, 

 slightly thickened at their extremities. The ungueal 

 phalanges are constricted in their middle, and widened 

 like a horse-shoe at their inferior extremity ; the palmar 

 face is roughened, the dorsul face smooth. 



ARTICLE V. POSTERIOR LIMBS. 

 Each of these is divided, as already noted, 

 into four secondary regions : the pelvis, thigh, 

 leg, and/ooJ. 



PELVIS. 



PALMAR SURFACE OF LEFT 

 HUMAN HAND. 



The pelvis is a kind of bony cavity formed 



, , * . / . -i "jr j_ 1 i 1 HUJM.AJN HAJNU. 



by the union of the sacrum with two lateral l 2,Semilunare; 



pieces, the coxas, which are consolidated with ' 

 each other in the inferior median line. The 

 description of the sacrum having been already 

 given, it now remains to speak of the coxa. 



3, Cuneiform ; 4, Pisiform ; 5, 

 Trapezium ; 6, Groove in tra- 

 pezium for tendon of flexor 

 carpi radialis j 7, Trapezoides ; 

 8, Magnum ; 9, Unciform ; 10, 



10, The five metacarpal bones; 



11, 11, First row of phalanges; 



12, 12, Second row; 13, 13, 

 Third row; 14, First phalanx 

 of the thumb; 15, Second and 

 last phalanx. 



A. Coxa. 



The coxa, also designated os iliacum, os inno- 

 minatum, is a very irregularly-shaped flat bone, 

 double (with its fellow on the opposite side), 

 and directed obliquely from above to below and 

 before to behind. It is contracted in its middle part, which presents exter- 

 nally an articular cavity, the cotyloid ; anteriorly, where it rests on the 

 sacrum, it becomes widened, as it also does in its posterior portion, which 

 is inflected inwards to be united, on the median line, with the bone of 

 the opposite side. 



It is divided, in the foetus, into three distinct pieces, joined by cartilage 

 in the centre of the cotyloid cavity, which the three concur in forming. 

 Although they soon become consolidated into a single piece, it is customary 

 to describe them as so many separate bones by the names of ilium, pubis, and 

 ischium. 



ILIUM. The ilium, a flat and triangular bone, curved on itself, directed 

 obliquely from above to below, before to behind, and within outwards, forms 

 the anterior portion of the coxa which corresponds with the sacrum. It is 

 the most considerable of the three divisions, and has two faces, three borders, 

 and three angles. 



