SS 2 A N A T 
its bafe, towards the fpinal procefies of the vertebrx; and 
with the angle at the upper part of this fide about three 
inches, and the lower angle at a greater difraace, from 
thefe precedes. The back-part of the fcapnla has nothing 
but the thin ends of the ferratus -anticus major and (iibfca- 
ptilaris mufcles between it and the ribs: but, as this bone 
advances forwards, its diftance from the ribs increafes. 
The upper or fnorter fide, called the fuperior cofta , of the 
fcapnla, is nearly horizontal, and parallel with the fecond 
rib. The lower fide, which Is named the inferior cofia, is 
extended obliquely from the third to the eighth rib. The 
body of this bone is concave towards the ribs, and convex 
behind, where it has the name of do fan. Three pre¬ 
cedes are generally reckoned to proceed from the fcapnla. 
The firfl is the large fpine that rifes from its convex lur- 
face behind, and divides it unequally. The fecond pro- 
cefs (lands out from the fore-part of the upper fide; and, 
from its imaginary refemblance to a crow’s beak, is named 
coracoides. T he third procefs is the whole thick bulbous 
fore-part of the bone. Into the oblique l’pace the mufcu- 
lus patientia is'inferted. At tire root of the fpine, on the 
back-part of the bafe, a triangular plain furface is formed 
by the p re flu re of the lower fibres of the trapezius. Below 
■this the edge of the fcapnla is fcabrous and rough, for the in- 
fertion of the ferratus major anticus and rhomboid mufcles. 
The back-part of the inferior angle is made fmooth by 
the latiflimus dorfi paffingover it. This mufcle alfo alters 
the direction of the inferior cofia fome way forwards from 
this angle; and l'o far it is flatted behind by the origin of 
the teres major. As the inferior cofta advances forward, 
it is of confiderable thicknefs; it is (lightly hollowed and 
made fmooth behind by the teres minor, while it has a 
folia formed into it below by part of the fubfcapularis ; 
and between the two a ridge with a fmall depreftion ap¬ 
pears, where the longus extenfor cubiti has its origin. 
The fuperior cofta is very thin; and near its fore-part there 
is a femilunar niche, from one end of which to the other a 
ligament is ftretched ; and lometimes the bone is continued 
to form one, or fometimes two, holes, for the paflage of 
the fcapular blood-veftels and nerves. Immediately behind 
this femilunar cavity the coraco-hyoid mufcle has its rife. 
From the niche to the termination of the folfa for the 
teres minor, the fcapula is narrower than any where clfe, 
and fupports the third procefs. This part has the name 
of cervix. 
The whole dorfum of the fcapula is always faid to be 
convex ; but, by reafon of the railed edges that furround 
it, it is divided into two cavities by the fpine, which is 
ftretched from behind forwards, much nearer to the iupe- 
rior than to the inferior cofta. The cavity above the fpine 
is really concave where the fupra-fpinatus mufcle is lodged ; 
while the furface of this bone below the fpine, on which 
the infra-fpinatus mufcle is placed, is convex, except a 
foffa that runs at the fide of the inferior cofta. 
The internal or anterior furface of this bone is hollow, 
except in the part above the fpine, which is convex. The 
fubfcapularis mufcle is extended over this furface, where 
it forms feveral ridges and intermediate depreflions, com¬ 
monly miftaken for prints of the ribs ; they point out the 
interftices of the bundles of fibres of which the fubfca¬ 
pularis mufcle is compofed. 
The fpine rifes fmall at the bafe of the fcapula, and 
becomes higher and broader as it advances forwards. On 
the fidcs it is unequally hollowed and crooked, by the ac¬ 
tions of the adjacent mufcles. Its ridge is divided into 
two rough flat Surfaces: into the upper one the trapezius 
mufcle is inferted; and the lower one has part of the del¬ 
toid fixed to it. The end of the fpine, called acromion, 
or top of the fhouider, is broad and flat, and is fome¬ 
times only joined to the fpine by a cartilage. The ante¬ 
rior edge of the acromion is flat, fmooth, and covered with 
a cartilage, for its articulation with the external end of 
the clavicle ; and it is hollowed below, to allow a paflage 
to the infra and fupra fpinati mufcles, and free motion 
to the os humeri. 
O M Y. 
The coracoid procefs is crooked, with its point inclin¬ 
ing forwards; fo that a hollow is left at the lower fide of 
its root, for the paflage of the infra fcapularis mufcle. 
The end of this procefs is marked with three plain furfa¬ 
ces : into the internal, the ferratus minor anticus is in¬ 
ferted ; from the external, one head of the biceps flexor 
cubiti rifes; and from the lower one, the coraco-brachialis 
ltas its origin. At the upper part of the root of this 
procefs, immediately before the femilunar cavity, a fmooth 
tubercle appears, where a ligament from the clavicle is 
fixed. From all the external iide of this coracoid apo- 
phyfe, a broad ligament goes out, which becomes nar¬ 
rower where it is fixed to the acromion. The (harp pain, 
violent inflammation, and tedious cure, of contulions in 
this part, are probably owing to thefe tendons and liga¬ 
ments being hurt. » 
From the cervix fcapulae the third procefs is produced. 
The fore-part of this is formed into a glenoid cavity, 
which is of the fhape of the longitudinal fedtion of an 
egg, being broad below and narrow above. Between the 
brims of this hollow and the fore-part of the root of tlia 
fpine, a large fmuofity is left for the tranfmifllon of the 
lupra and infra fpinati mufcles ; and on the upper part of 
thefe brims we may remark a fmooth furface, w here the 
fecond head of the biceps flexor cubiti has its origin. The 
root of the fupercilia is rough all round, for the firmer 
adhefion of the capfular ligament of the articulation, and 
of the cartilage which is placed on thefe brims, where it 
is thick, but becomes very thin as it is continued towards 
the middle of the cavity, which it lines all over. The 
medullary veflels enter the fcapula near the bafe of the 
fpine. The fcapula is connected to the head, os hycides, 
vertebrae, ribs, and arm-bone, by mufcles, that have one 
end faftened to thefe bones, and the other to the fcapula, 
which can move it upwards, downwards, backwards, or 
forwards ; by the quick, fucceffion of thefe motions, its 
whole body is carried in a circle. But, being alfo often 
moved as upon an axis perpendicular to its plane, its cir¬ 
cumference turns in a circle wliofe centre this axis is. 
Whichever of thefe motions it performs, it always carries 
the outer end of the clavicle and the arm along with it. 
The ufe of the fcapula is, to ferve as a fulcrum to the 
arm ; and, by altering its pofition on different occafions, 
to allow always the head of the os humeri a right-fituated 
focket to move in ; and thereby to afiift and to enlarge 
greatly the motions of the fuperior extremity, and to afford 
the mufcles which rife from it more advantageous adtion, 
by altering their direction to the bone which they are to 
move. This bone alfo ferves to defend the back-part of 
the thorax, and is often employed to fuftain weights, or 
to refill: forces too great for the arm to bear. The bafe, 
acromion, coracoid procefs, and head of the fcapula, are 
all in a cartilaginous (late at birth ; and the three firfl are 
joined as epiphyfes ; while the head, with the glenoid ca¬ 
vity, is not formed into a aiftindl feparate bone, but is 
gradually produced by the ofiification of the body of this 
bone being continued forwards. 
The arm has only one bone, called os humeri ; which is 
long, round, and nearly ftraight. The upper end of this 
bone is formed in a large round fmooth head, wliofe mid¬ 
dle point is not in a ftraight line with the axis of the bone, 
but (lands obliquely backwards from it. It is diflinguifiied 
by a circular folfa Surrounding its bafe, where the head is 
united to the bone, and the capfular ligament of the joint 
is fixed. Below the fore-part of its bafe, two tubercles 
(land out : the fmalleft one has the tendon of the fubfca¬ 
pularis mufcle inferted into it. The larger is divided, at 
its upper part, into three fmooth plain furfaces ; into the 
anterior of which, the mufculus fupra-fpinatus; into the 
middle or largeft, the infra-fpinatus ; and into the one be¬ 
hind, the teres minor; is inferted. Between thefe two tu¬ 
bercles, exadtly in the fore-part of the bone, a deep long 
folfa is formed, for lodging the tendinous head of the bi¬ 
ceps flexor cubiti; which, after palling in a manner pecu¬ 
liar to itfelf through the cavity of the articulation, is tied 
a down 
