REGIONS OF THE HAND. 



523 



they are the chief agents, and of which the 

 hand is the principal organ, that of touch, 

 which may be regarded as a kind of sentinel 

 by which we ascertain the nature of bodies ; 

 which without seeing warns the hand from too 

 closely embracing what may prove hurtful to 

 itself, or admonishes it to handle gently those 

 delicate objects that would be destroyed by too 

 rude a grasp. In the blind this sense, by con- 

 stant exercise, becomes so perfect as in a great 

 measure to compensate for the loss of sight. 

 But by the combination of these two functions 

 the hand is indeed rendered an organ worthy 

 of, and admirably suited to the mind of man. 

 With the one he plans, while through the other 

 he performs and executes all that administers 

 to the pleasures, the comforts, and the conve- 

 niences of life, and that establishes his superi- 

 ority in the creation. 



(F. T. M'Dougall.) 



HAND, REGIONS OF THE. (Surgical 

 Anatomy.) In the consideration of the surgical 

 anatomy of the hand, we shall commence our 

 description from an imaginary line encircling 

 the fore-arm, at a point immediately below the 

 insertion of the pronator quadratus, or about 

 half an inch above the radio-carpal articulation. 

 From this point downwards for about a finger' s- 

 breadth, the wrist is narrow and flattened like 

 the fore-arm ; from thence the hand, gradually 

 expanding, acquires that remarkable breadth 

 and flatness so necessary to it both as a tactile 

 and prehensile organ ; it is broadest inferiorly 

 where it terminates in the fingers. In front, 

 this region is concave and hairless ; posteriorly, 

 it is convex and slightly hairy. 



In woman, the hand is smaller and more de- 

 licately shaped ; it is also rounder and smoother, 

 on account of the greater quantity of subcu- 

 taneous adipose tissue, softening down the 

 harsher outline of bone and tendon displayed 

 in the brawny hand of man. 



In order to avoid needless prolixity, we shall 

 not subdivide this inferior segment of the upper 

 extremity into the three distinct regions of wrist, 

 hand, and fingers ; which, indeed, if we were 

 considering its bony frame-work, would natu- 

 rally present themselves. But as the soft parts, 

 with which we have principally to do in the 

 present article, exhibit no such natural distinc- 

 tions in these separate parts, and are, for the 

 most part, common to them all, we shall con- 

 sider them as constituting one entire region, 

 which is naturally subdivided into palmar and 

 dorsal regions. 



I. Of the palmar region of the hand. The 

 remarkable points on the exterior of this region 

 are as follows : Commencing from the pre- 

 supposed imaginary line, and proceeding down- 

 wards, we perceive most externally a projection 

 formed by the united tendons of the short ex- 

 tensors of the thumb; next in order, proceeding 

 from without inwards, we notice a hollow, most 

 visible when the hand is flexed, corresponding 

 to the radio-carpal articulation, and in which 

 the radial artery may be felt pulsating imme- 

 diately before it passes under the tendons we 



have just noticed ; bounding this hollow, on its 

 inside, is a second eminence, formed by the 

 tendons of the flexor carpi radialis and palmaris 

 longus, and the projecting crests of the scaphoid 

 and trapezium ; more internally a second de- 

 pression, corresponding to the ulnar nerve and 

 artery, bounded internally by a third eminence, 

 that of the flexor carpi ulnaris tendon and the 

 pisiform bone, posterior to which may be felt 

 the inferior extremity of the ulna and the inter- 

 val between it and the bones of the carpus. 



Lastly, in front of the wrist, owing to the 

 thinness of the skin in this part of the palmar 

 region, we perceive a blue network of veins, 

 from which the median is formed. 



More inferiorly, in the palm proper, we notice 

 externally the thenar eminence, extending from 

 the crest of the scaphoid to the base of the first 

 phalanx of the thumb. On the inner side of 

 the palm is the hypothenar eminence, longer 

 and thinner, but less prominent than the last ; 

 it extends from the pisiform bone to the base of 

 the first phalanx of the little finger. Separating 

 these prominent parts, and extending from the 

 inner furrow of the wrist towards the root of 

 the index finger, is a deep excavation, the 

 hollow of the palm ; next may be seen or felt 

 four elevations, corresponding to the heads of 

 the four metacarpal bones, about an inch in 

 front of which the fingers free themselves from 

 the skin of the palm, which is prolonged over 

 them for that distance in a manner somewhat 

 analogous to the web in the foot of a Newfound- 

 land dog, or other swimming animals. Of the 

 fingers themselves, the middle is the longest, 

 the first and third are on a level, the little finger 

 reaches the level of the last articulation of the 

 annular, and the thumb terminates about three 

 lines behind the second articulation of the index ; 

 the phalangeal articulation of the thumb being 

 exactly on a level with the metacarpo-phalangeal 

 union of the same finger. 



There are likewise certain lines or furrows 

 caused by the folding of the skin in flexion of 

 the hand and fingers, some of which constantly 

 occur, and are worthy of notice, inasmuch as 

 they sometimes serve as guides or landmarks to 

 the surgeon in operating on this region. They 

 are as follows: two on the wrist; the superior 

 one, extending between the styloid processes of 

 the radius and ulna, corresponds to the radio- 

 carpal articulation. Another, more remarkable, 

 slightly convex downwards, projecting between 

 the palmar eminences, separates the wrist 

 from the hand, and corresponds to the articula- 

 tion between the two rows of the carpus. In 

 the palm, one commences from the metacarpo- 

 phalangeal articulation of the index finger, 

 which soon bifurcates, one of its divisions 

 bounding the thenar on its inner side ; the other 

 runs obliquely across the palm, and terminates 

 on the upper part of the hypothenar : this in a 

 measure corresponds to the superficial palmar 

 arch, having the same obliquity across the palm, 

 but being three or four lines inferior to it ; these 

 lines are caused by the opposition of the thumb. 

 There is yet another line running from the in- 

 terval between the index and middle fincrers to 



