| XXX | (252) | XXX |
Part V. 252 A N A T O M Y. to join the intercoftal, by which a communicathird branch is difpofed in the fame way upon the fide of forward tion is made among them all; and they foon likewife the ring-finger next to the little finger. backwards-to the mufcles that raife the When we lean or prefs on the internal condyle of the give branches of the body, their principal trunk being extended os humeri, the numbnefs and prickling we frequently trunk outwards, to come at the furrow in the lower edge of feel, point out the cpurfe of this nerve. rib, in which they run toward the anterior part of 7. Radiah s accompanies the humeral artery to'the eachthorax, between the internal' and external intercoftal bending of the elbow, ferving the flexors of the cubit in its the giving off branches in their courfe to the mufway ; then palling through the pronator radii teres mufcle, mufcles, and teguments of the thorax. it gives nerves to the mufcles on the fore-part of the fore- clesThe dorfal, as was already obferved, is partiarm, and continues its courfe near to the radius, bellow- cular inFirst this, that it contributes to form the brachial ing branches on the circumjacent mufcles. Near the nerves; and that the twoxbranches of the intercoftal, Wrill, it fometimes gives oflf a nerve, which is dillribu- which come to the thorax, form a confiderable ted to the back of the hand, and the convex part of the ganglion withdown it, thumb, and feveral of the fingers, inftead of the branch The Six lower dorfal nerves give branches to the diaof the mufcular. The larger part of this nerve, palling phragm and abdominal behind the annular ligament of the wrill, gives nerves to The Twelfth joinsmufcles. with the firft lumbar, and hothe Ihort mufcles of the thumb; and afterwards fends a llows nerves on- the mufculus quadfatus lumborum and branch along each fide of the Iheath of the tendons of iliacus inter-nus. the flexors of the thumb, fore-finger, mid-finger, and As the intercoftal is larger in the thorax than any where one branch to the fide of the ring-finger, next to the elfe, and feems to diminiih gradually as it afcends and middle one, to be loll on the concave fide of thofe defcends, there is caufe to fufpeft that this is the trunk fingers. Though the radial nerve pafles through the pronator from which the fuperior and inferior pairs are fent as tpufcle, and the mufcular nerve feems to be Hill more un- branches. Lumbar nerves on each fide communicate favourably placed within the fupinator brevis; yet the. withThetheFiveintercoftal each other, and give adtion of thefe mufcles do not feem to have any effedt in branches backwards toandthewith hindering the influence of thefe nerves, for the fingers or The First communicatesloins. with the laft dorfal, fends hand can be bended while pronation is performing vigo- branches mufcles, to the pfoas and iliaroufly, and they can be extended while fupination is ex- cus, and toto thetheabdominal teguments and mufcles on the fore-part ercifed. The manner of the going olf of thefe nerves of the of the thigh; "while its principal branch joins with the nerves, to form the crural nerve. fingers, both from the ulnar and radial, is, that a fingle other branch is fent from the trunk to the fide of the thumb The Second Lumbar nerve paffes through the pfoas mufcle, and is diftributed nearly in the fame way as the and little finger, farthell from the other fingers; and all former: as is alfo the Th 1 rd. the reft are fupplied by a trunk of a nerve, which fplits of the fecend, third, and fourth, make up into two fome way before it comes as far as the end of oneBranches which runs along the fore-part of the pelvis; the metacarpus, to run along the fides of different fin- and,trunk, palling in the notch at the fore-part of the great gers that are neareft to each other. to the os pubis and ifchium, is fpent on the It might have been obferved, that, in defcribing the hole common mufcles, and on the teguments on the infide of pofterior branches of the ulnar and mufcular nerve, we addu&or the thigh. This nerve is called the Obturator, or did not mention the particular fingers, to the convex pa,rt Posterior Crural Nerve. of which they are diftributed. The reafon of this omif- By united branches from fecond, third, and fion is, the uncertainty of their dillribution; for though fourth lumbkr nerves, a nervetheisjfr/?, formed that runs along fometimes thefe pofterior branches go to the fame fingers, pfoas mufcle, iO efcape with the external iliac veffels to the concave part of which the anterior branches of the the ulnar and radial are fent, yet frequently they are diftri- out of the abdomen, below the tendinous arcade of the external oblique mufcle. This nerve, which is named buted otherwife. The fituation of thefe brachial nerves in the axilla, the Anterior Crural, is diftrihuted principally to may let us fee how a weakncfs and atrophy may be the mufcles and teguments on the fore-part of the thigh. brought on the arms by a long continued prelfure of A branch, however, of this nerve runs down the infide crutches, t>r fuch other hard fubftances on this part; of the leg to the upper part of the foot, keeping near to and the courfe of them from the neck fo the arm, may the vena faphsena; in opening of which with a lancet at the ankle, the nerve is fometimes hurt, and occafions teach us, how much better effeds veficatories, or ftimu- fharp pain at the time of the operation, and numbnefs lating nervous medicines, would have, when applied to the Ikin, covering the tranfverfe proceffes of the verte- afterwards. brae of the neck, or at the axilla, than when they are The Sixth Pair of the falfe Vertebrae confift put between the flioulders, or upon the fpinal proceffes, each of fmall pofterior branches, fent to the hips, and of in convulfions or palfies of the fuperior extremities, large anterior branches. The firf, fecond, and third, after coming through where a ftimulus is required. The Twelve Dorsal nerves of each fide, as foon the three upper holes in the fore-part of the os facrum, as they efcape from between the vertebrae, fend a branch join together with the fourth and fifth of the loins,formto
