A N A T 
pula. It is inferted into the upper and middle part of the 
large protuberance on the head of the os humeri. Its ufe 
is to roll the humerus outwards; to aflift in railing, and in 
fupporting it when raifed ; and to pull the ligament from 
between the bones. 3. Teres minor, arifes from the round 
edge of the inferior coda of the fcapula, and runs forwards 
along the inferior edge of the infrafpinatus mufcle, and 
adheres to the ligament. It is inferted into the back-part 
of the large protuberance on the head of the os humeri, 
a little behind, and below the termination of the laft- 
named mufcles. Its ufe is to roll the humerus outwards; 
to draw the humerus backwards; and to prevent the liga¬ 
ment from being pinched between the bones. 
Along the inferior coda of the fcapula is, teres major, 
■which arifes from the inferior angle of the fcapula, and 
from all that portion of it's inferior coda that is rough and 
thicker than the red; its flediy fibres are continued over 
part of the infrafpinatus mufcle, to which they firmly ad¬ 
here. It is inferted into the ridge at the inner fide of the 
groove for lodging the tendon of the head of the biceps, 
along with the latiffimus dorfi. Its ule is to roll the hu¬ 
merus, inwards, and to draw it backwards and downwards. 
The two before the fcapula are, 1. Deltoides, arifes from 
the pofterior part of the clavicle that the peCtoralis major 
does not poffefs; from the acromion, and lower margin of 
alntod the whole fpine of the fcapula; from thefe origins 
it runs in three different directions, and is contpofed of a 
number of fafciculi, which form a drong flefny mufcle that 
covers the anterior part of the joint of the os humeri. It 
is inferted into a rough protuberance in the outer fide of 
the os humeri, near its middle, where the fibres of this 
mufcle intermix with forne part of the brachialis externus,. 
Its ufe,is to pull the arm directly outwards and upwards, 
and a little forwards and backwards, according to the dif¬ 
ferent directions of its fibres. 2. Coraco-brachialis , arifes 
from the fore-part of the coracoid procefs of the fcapula; 
adhering, in its defcent, to the diort head of the biceps. 
It is inferted about the middle of the internal part of the 
os humeri, near the origin of the third head of the triceps, 
called brachialis externus, wdiere it fends down a thin ten¬ 
dinous expanfion to the internal condyle of the os humeri; 
and ferves to raife the arm upwards and forwards. There 
palfes a nerve through this mufcle, called mifcula cutancus. 
The one beneath the fcapula is , fubfcapularis, arifes from 
the bafe Of the fcapula internally, and from its fuperior 
and inferior coftae, being compofed of a number of ten¬ 
dinous and flediy fafciculi, which make prints on the 
bone; it is inferted into the upper part of the internal 
protuberance at the head of the os humeri. It ferves to 
roll the humerus inwards, and to draw it to the fide of 
the body; and to prevent the capfular ligament from being 
pinched. 
Muscles on the Os Humeri. —Thefe are called 
Mufcles of the cubit or fore-arm. They confift of two before 
and two behind. Before are, 1. Biceps fexor cubiti , which 
arifes by two heads. The firft and outermoft, called lon¬ 
gus, begins from the upper edge of the glenoid cavity of 
the fcapula; paffes over the head of the os humeri within 
the joint; and, in its defcent without the joint, is inclofed 
in a groove near the head of the os humeri, by a membra¬ 
nous ligament that proceeds from the capfular ligament 
and adjacent tendons. The fecond, or innermoft head, 
called brevis, arifes from the coracoid procefs of the fca¬ 
pula, in common with the coraco-brachialis mufcle. A 
little below the middle of the fore-part of the os humeri, 
thefe heads unite. It is then inferted into the tubercle 
of the upper end of the radius internally, and ferves to 
turn the hapd fupine, and to-bend the fore-arm. 2. Bra- 
c hi alls internus, arifes from the middle of the os humeri, 
at each fide of the infertion of the deltoid mufcle; and is 
inferted into the coronoid procefs of the ulna. Its ufe is 
to bend the fore-arm, and to prevent the capfular liga¬ 
ment of the joint from being pinched. Behind are, 1. 
Triceps extenfor cubiti, arifes by three hea ds; the firft, called 
longus, from the inferior cofta of. the fcapula, near its cer- 
O JVI Y. 575- 
vix. The fecond, called brevis, from the back-part of tie 
os humeri, and a little below its head, outwardly. The 
third, called brachialis externus, from the back-part of the 
os humeri. Thefe three heads unite lower than the infer¬ 
tion of the tere's major, and cover the whole pofterior part 
of the humerus; and are inferted into the upper and ex¬ 
ternal part of the procefs of the ulna, called olecranon, and 
partly into the condyles of the os humeri, adheriug firmly 
to the ligament; and ferve to extend the fore-arm. 3. An¬ 
coneus, arifes from the pofterior part of the external con¬ 
dyle of the os humeri; is inferted into a ridge on the 
outer and pofterior edge of the ulna, and aftifts in extend¬ 
ing the fore-arm. 
Muscles on the Cubit or Fore-Ari^.—T hefe may 
be divided into three claffes: firft, flexors and extenfors 
of the whole hand; fecond, flexors and extenfors of the 
fingers; and third, fupinators and pronators, or thofe that 
roll the radius on the ulna. The firft ciafs coniifts of three 
flexors, and three extenfors. Flexors are, 1. Palmaris 
longus, arifes from the internal condyle of the os humeri; 
and is inferted into the ligamentum carpi annulare, and 
into a tendinous membrane that is expanded on the palm 
of the hand, named aponcurofs palmaris ; which, above, 
begins at the tranfverfe or annular ligament of the -Wrift, 
and, below, is fixed to the roots of the fingers. Its ufe 
is to bend the hand, and to ftretch the membrane that is 
expanded on the palm. This mufcle is fometimes want¬ 
ing; but the aponeurofis palmaris is always to be found, 
and a fmall mu fcle named palmaris brevis, which arifes from 
the ligamentum carpi annulare, and tendinous membrane 
that is expanded on the palm of the hand; and is inferted 
into the I kin and fat that covers the abductor minimi di- 
giti, and into the os pififorme. Its ufe is to aflift in con¬ 
tracting the palm of the hand. 2. Flexor carpi radialis , 
arifes from the internal condyle of the os humeri, and 
from the anterior part of the upper end of the ulna ; it 
is inferted into the fore and upper part of the metacarpal 
bone that fuftains the fore finger; and ferves to bend the 
hand, and to aflift in its pronation. 3. Flexor carpi ulnaris t 
arifes from the internal condyle of the os humeri. It has 
likewife a fmall flefhy beginning from the outer fide of the 
olecranon ; between which and the condyle the ulnar 
nerve palfes to the fore-arm; and a number of its flefhy 
fibres arife from the tendinous membrane which covers 
the fore-arm. It is inferted into the os pififorme ; at a 
little diftance from its infertion, a fmall ligament is fent 
off to the metacarpal bone that fuftains the little finger. 
It aflifts the former in bending the arm. 
The extenfors are, 1. Extenfor carpi radialis longior, ari¬ 
fes immediately below the fupinator radii longus, from the 
lower part of the external ridge of the os humeri, above 
its external condyle. It is inlerted into the pofterior and 
upper part of the metacarpal bone that fuftains the fore¬ 
finger; and ferves to extend and bring the hand backwards. 
2. Extenfor carpi radialis brevior, arifes from the external 
condyle of the os humeri, and from the ligament that con¬ 
nects the radius to it, and runs along the outfide of the 
radius. It is inferted into the upper and back part of the 
metacarpal bone that fuftains the middle finger, and ferves 
as an affiftant to the lad-mentioned mufcle. 3. Extenfor 
carpi ulnaris, arifes from the external condyle of the os 
humeri; and, in its progrefs, paffes over the ulna. Its 
round tendon is encloled by a membranous ftieath, in a 
groove which is fituated at the extremity of the ulna. It 
is inferted into the pofterior and upper part of the meta¬ 
carpal bone that fuftains the little finger; and aflifts.the 
former in extending the hand. 
Second Ciafs. —The flexors and extenfors of the four 
fingers are two long, and one fmall, flexor to each finger, 
and one extenfor. 1. FlexorJ'ublbnis peforatus, arifes from 
the internal condyle of the os humeri; from the coronoid 
procefs of the ulna, near the edge of the cavity that -re¬ 
ceives the head of the radius ; from the tubercle of the 
radius; and from the middle of the-fore-part of the radius, 
where the flexor pollicis longus arifes, It is inferted into 
