ANATOMY. 
576 
i ."c anterior and tipper part of the fecond bone of each 
being, near the extremity of the'firft bone, divided 
' 10r the paflage of the perforaris.. Its life is to bend the 
fecond joint or phalanx of the fingers. 2. Flexor profun¬ 
dus pcrjbrans, arifes from the external fide and upper part 
of the ulna, and ironi a large (hare of the interofieous li¬ 
gament. It fplits into four tendons, and is inferted into 
the tore and upper part of the third or laft bone of all the 
four fingers; and ferves to bend the laft joint of the fingers. 
The tour final! flexors are named lumbrkalis. They 
arife from the outfide ot the tendons of the flexor pro¬ 
fundus, a little above the lower edge of the ligamentum 
carpi annulare ; and are inferted into the outer (ides of the 
broad tendons of the interoflei mufcles, about the middle 
ot tite firft joint. They increafe the flexion of the fingers, 
while the long flexors are in full adtion. 
I he extentors are, Extenfor digitorum communis, arifes 
from the external condyle of the os humeri, where it ad¬ 
heres to the fupinator radii brevis. Before it paffes under 
the ligamentum carpi annulare externum, it fplits into four 
tendons; tome of which may be divided into feveral 
(mailer: and about the fore-part of the metacarpal bones 
they remit tendinous filaments to each other. They are 
inferted into the- pofterior part of all the bones of the four 
fingers, by a tendinous expanfion; and ferve to extend all 
the joints of the fingers. 
The Third Clafs confifts of four mufcles, viz. two fupi¬ 
nator s, and two pronators. The fupinators are, 1. Supinator 
radii longus, arifes from the external ridge of the os hume¬ 
ri, above the external condyle; and is inferted into the 
outer-tide of the inferior extremity of the radius. Its life 
is to roll the radius outwards, and confequently the palm 
of the hand upwards. 2. Supinator radii brevis, arifes from 
the external condyle of the os humeri; and from the ex¬ 
ternal and upper part of the ulna, and adheres firmly to 
the ligament that joins thefe two bones. It is inferted in¬ 
to the head, neck, and tubercle, of the radius, near the 
infertion of the biceps ; and ferves to roll the radius out¬ 
wards, and fo bring the hand fupine. 
The pronators are, 1. Pronator radii teres, arifes from 
the internal condyle of the os humeri, and from the co- 
r oho id procefs of the ulna; and is inlerted into the middle 
ot the pofterior part of the radius. Its life is to roll the 
radius, together with the hand, inwards. 2. Pronator ra¬ 
dii quadratics, arifes from the lower and inner part of the 
ulna; and is inferted into the lower and anterior part of 
the radius, oppolite to its origin. Its life is to turn the 
radius, together with the hand, inwards. 
Muscles on the Hand. —Thefe may be divided into 
four claffes, viz. mufcles of the thumb, fore-finger, little- 
finger, and metacarpal bones. The mufcles of the thumb 
coniift of three flexors, three extenfors, one abduElor, and one 
adduElor. The flexors are, 1. Flexor longus pollicis manus, 
arifes from the upper part of the radius, immediately be¬ 
low its tubercle, and is continued down for fome fpace on 
the fore-part of this bone. It has likewife generally ano¬ 
ther origin from the internal condyle of the os humeri, 
which forms a diftindf flefliy flip that terminates near the 
upper part of the origin from the radius. It is inferted in¬ 
to the laft joint of the thumb, after having palled its ten¬ 
don under the ligament of the wrift, and ferves to bend 
the laft joint of the thumb. 2. Flexor brevis pollicis manus, 
arifes from the os trapezoides, magnum, and unciforme, 
of the carpus, and is divided into two portions by the ten¬ 
don of the flexor pollicis longus. It is inferted into the 
offa fefamoidea and firft bone of the thumb. 3. Flexor 
ojjis metacarpi pollicis, or opponens pollicis, arifes from the os 
trapezium and ligamentum carpi annulare, lying under the 
abdudfor pollicis; and is inferted into the under and ante¬ 
rior part of the metacarpal bone of the thumb. Its ufe 
is to bring the thumb inwards, oppofite to the other fingers. 
The extenfors are, j. Extenfor ofis metacarpi pollicis ma¬ 
ntis, arifes from the middle and pofterior part of the ulna, 
immediately below the infertion of the anconaeus mtifcle, 
from the pofterior part of the middle of the radius, and 
from the interofieous ligament. It is inferted into the os 
trapezium, and upper back-part of the metacarpal bone 
of the thumb, and often joins with the abdudtor pollicis. 
Its ufe is to extend the metacarpal bone of the thumb out¬ 
wardly. 2. Extenfor primi internodii, arifes from the pofte¬ 
rior part of the ulna near the, former mufcle, and from 
the intereofteous ligament; is inferted into the pofterior 
part of the firft bone of the thumb; and ferves to extend 
the firft bone of the thumb obliquely outwards. 3. Ex¬ 
tenfor fecundi internodii, arifes from the middle back-part of 
the ulna, and from the interofieous ligament; its tendon 
runs through a fmall groove at the inner and back part of 
the lower end of the radius, and is inferted into the laft 
bone of the thumb. Its ufe is to extend the laft joint of 
the thumb obliquely backwards. 
AbduElor pollicis manus, arifes, by a broad tendinous and 
fle(hy beginning, front the ligamentum carpi annulare, and 
from the os trapezium. It is inferted into the outer fide 
ot the root of the firft bone of the thumb, and draws the 
thumb from the fingers. Adductor pollicis manus, arifes 
from almoft the whole length of the metacarpal bone that 
fttftains the middle fimger: and is inferted into the inner 
part of tite root of the firft bone, and ferves to pull the 
thumb towards the fingers. 
Tore-finger: Indicator, arifes from the middle of the 
pofterior part of the ulna; its tendon paffes under the fame 
ligament with the extenfor digitorum communis, with 
part of which it is inferted into the pofterior part of the 
fore-finger. AbduElor indicis manus, arilcs from the os tra- 
pezium, and from the ftiperior part and inner fide of the 
metacarpal bone of the thumb. It is inferted into the 
outer and back part of the firft bone of the fore-finger, 
and ferves to bring the fore-finger towards the thumb. 
Little-finger: AbduElor minimi digiti manus, arifes from 
the os pififorme, and from that part of the ligamentum 
carpi annulare next it. It is inferted into the inner lide of 
the upper end of the firft bone of the little finger, and 
ferves to draw this finger from the reft. AdduElor metacar¬ 
pi minimi digiti manus, arifes from the thin edge of the os 
unciforme,'and from that part of the ligament of the wrift 
next it. It is inferted into the inner fide and anterior part 
of the metacarpal bone of this finger, and ferves to bend 
and bring the metacarpal bone of this finger towards the 
reft. Flexor parvus minimi digiti, arifes from the outer fide 
of the os unciforme, and from the ligament of the wrift 
which joins with that bone. It is inlerted into the inner 
and anterior part of the upper end of the firft bone of this 
finger; and is ufed to bend the little finger, and aflift the 
addudtor. 
Between the metacarpal bones, there are four internal 
and three external mufcles, named intercJJ'ei. Interoflei in¬ 
tend are: 1. Prior indicis, arifes from the upper and outer 
part of the metacarpal bone that fttftains the fore-finger; 
and is inferted into the outfide of that part of the tendi¬ 
nous expanfion from the extenfor digitorum communis, 
which covers the pofterior part of the fore-finger. Its ufe 
is to draw the fore-finger inwards towards the thumb, and 
extend it obliquely. 2. Poflerior indicis, ariles from the 
root and inner part of the metacarpal bone that fuftains 
the fore-finger ; and is inferted into the inner fide of the 
tendinous expanfion which is fent off from tite extenfor di¬ 
gitorum communis along the pofterior part of the fore¬ 
finger. It ferves to extend the fore-finger obliquely, and 
to draw it outwards. 3. Prior annularis, arifes from the 
root of the. outfide of the metacarpal bone that fuftains the 
ring-finger; and is inferted into the outfide of the tendi¬ 
nous expanfion of the extenfor digitorum communis which 
covers the ring-finger. Its ufe is to extend and pull the 
ring-finger towards the thumb. 4. lntcroffeus auricularis , 
arifes from the root and outer fide of the metacarpal bone 
of the little finger; and is inferted into the outfide of the 
tendinous expanfion of the extenfor digitorum communis, 
which covers the pofterior part of the little finger. It 
ferves to extend and draw the little finger outwards. 
Interoflei externi, feu bicipites: 1, Prior medii, arifes 
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