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Book One -- The things that sustain and support the entire body, and what braces and attaches them all. [the bones and the ligaments that interconnect them] |
[Figures and figure legend]
The next page shows the index of the three figures which are set
forth here, and their characters.
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page 95 |
| A, B 1 , 2 | Depression [cavitas glenoidalis] of the scapula into which the head of the humerus [caput humeri] is articulated. 5 In the second figure, the lower portion of the depression, which is more or less round, is marked B. A is the narrower upper part, and the contracted A in the first figure illustrates the protruding part [tuberculum supraglenoidale] of the depression or neck of the scapula [collum scapulae] from which two ligaments [ll. glenohumeralia et l. coracohumerale] peculiar to this joint originate together with the outer head of the anterior of the muscles [m. bicipitis brachii, caput longum] that flex the forearm. |
| C, D 1 , 2 | Cervix or neck of the scapula [collum scapulae]. 6 C also marks the root of the scapula’s interior process [processus coracoideus], marked E, f, and F. C in the first figure also marks a certain depression 7 visible beneath the inner process of the scapula. |
| E, f and F[ 1 , 2 ] | in the first figure, and E and F in the second, mark the inner process [processus coracoideus] of the scapula, where F designates the protuberant part to which the clavicle is attached and by which it is all but supported. 8 E shows the epiphysis of this process, and f the rough area from which the ligament [l. coraco-acromiale] originates that extends from here to the acromion 9 (which will be marked K). |
| G, H 2 | Root of the spine of the scapula, or the actual spine of the scapula, which in man puts forth the acromion, marked K, in the first, second, and third figures and L in the first and third. 10 Thus the longitude of the spine’s source is G and H. What runs from H to K is the acromion. Where H is seen is the point where we shall say the spine leaves the back of the scapula. The epiphysis of the acromion is separately marked K. |
| L 1 , 3 | Depression [facies articularis acromii] quite lightly carved in the acromion, prepared for the admission of the clavicle. |
| I 2 , 3 | Thicker part 11 of the spine of the scapula, sometimes with an epiphysis. 12 Around G, I, and H, the spine of the scapula is thicker than elsewhere. From G through I to K the rough part of the spine and the acromion is labeled. What lies between I and H in the second figure and in the first between L and a is smooth and not at all rough. |
| M, M, etc. 1 | Tubercles resembling oblique lines, 13 forming depressions that look as if they had been impressed in the hollow of the scapula by the curvature of the ribs. |
| N, O 1 | Hollower areas [fossa subscapularis] in the inner region of the scapula, corresponding to the letters G and H in the second figure. |
| P 1 | Protruding, thicker portion of the lower side, 14 which bulges into the inner surface of the scapula. |
| p 1 | Here 15 the lower edge or side of the scapula is made sharper and thereby protrudes further, so that the third of the muscles [m. subscapularis] that move the arm may more readily originate from here. |
| Q 1 | Rough depression [margo lateralis] of the scapula’s lower side, from whence originates the inner muscle [m. triceps brachii, caput longum] of those that extend the forearm. R was accidentally left out. |
| S 2 | Protruding part [tuberculum infraglenoidale] of the lower side near the outer surface of the scapula. |
| T 2 | Depressed, wide area of the lower side, from which originates the third of the muscles [m. teres major] that move the arm. |
| V, V 2 | Here the outer surface [fossa infraspinata] of the scapula is particularly concave because of the thickness of the lower side. 16 What lies between V, V and G, H is very thin and extremely fine and solid. |
| X 1 , 2 , 3 | Epiphysis [margo medialis] of the base of the scapula, fused to the beginning of the spine itself. |
| Y 1 , 2 , 3 | Epiphysis of the lower angle [angulus inferior] of the base of the scapula. |
| F 1 | Portion of the upper angle that protrudes slightly into the inner region of the scapula. |
| Z 1 , 2 , 3 | As previously stated, this marks the upper angle [angulus superior] of the base. |
| a 1 , 3 | Semicircular foramen or depression [incisura scapulae] visible in the upper side of the scapula. |
| b, c 3 | Area [fossa supraspinata] in the outer region of the scapula between the spine and the higher side of the scapula. Here b marks an extremely thin, slender, and somewhat transparent portion of the scapula, while c identifies the small foramen that often appears here, providing a path for the small vein to nourish the scapula at this point. |
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FOURTH FIGURE OF THE TWENTY-FIRST CHAPTER
In this figure we have illustrated the outer or posterior
surface of a dog’s scapula so that the difference in the acromion or upper
process of the scapula between the human scapula and that of a dog or sheep may
readily be considered.
A
and
B
will therefore signify the convexity or dorsum of the scapula, A
its lower area
[fossa infraspinata] and B its upper
[fossa supraspinata], closer to the
animal’s neck or head.
C
and
D
will identify the spine of the scapula
[spina scapulae], which does not
extend above the neck of the scapula.
E
marks the scapular neck
[collum scapulae].
Position and attachments of the scapula
The scapulae, one on each side (R in the three skeletal figs.), rest
upon the posterior region of the thorax near the top; they are attached to the
occipital bone, the cervical and thoracic vertebrae, the ribs, and the hyoid
bone by muscles alone. The scapula is attached to the occipital bone with the
help of the second of the muscles that move the scapula (G, D in the 9th table
of muscles),
17
which also
joins it to the spines of several vertebrae,
18
as does the third agent of scapular motions
[m. levator scapulae] (G in the 12th
table of muscles), which binds it to the neck vertebrae
19
[vertebrae cervicales]. The fourth
of the muscles that move the scapula
[m. rhomboideus major] (G in the
10th table) braces it on several spines of the thoracic and cervical vertebrae.
The first of the muscles that move the scapula
[m. pectoralis minor] (G in the 5th
table) and the second of the muscles that move the thorax
[m. serratus anterior] (L in the 7th
table) join the scapula to the ribs. The scapula is linked to the hyoid bone by
the seventh
[m. omohyoideus] of that bone’s
particular muscles. In humans, monkeys, squirrels, and whatever other animals
have clavicles, the scapula is articulated with the clavicles (Q to l in the
complete skeletons) by a mass of ligaments
[l. acromioclaviculare, l.
coracoclaviculare] and is
conterminous with the clavicle.
Use of the scapula
20
In all animals the arm bone or humerus is articulated to the scapula (S
to R of the skeletons); if you imagined a human without scapulae, you could in
no way describe the shoulder joint. It is essential to the construction of this
joint that the head of the humerus go into the socket of some other bone: and
for it to be mobile, that it be braced in another bone as in a kind of base.
21
For the sake of such a socket, a neck
protrudes — the cervix of the scapula
[collum scapulae] (C, D in figs. 1
and 2) — in the end of which a socket is carved as wide and deep as is useful
to the shoulder joint for various quite different motions. This is judged to be
without doubt the first and foremost use of the scapulae; another immediately
follows, itself not a regrettable one, to wit the fortification and protection
of the parts of the thorax covered by the ribs. We watch out for the anterior
parts of the thorax and forsee well ahead of time things that are about to
strike and wound it, jumping aside in anticipation to avoid what is coming at
us, putting up something to shield the chest, or picking up something in our
hands with which to defend ourselves. Indeed, we often risk even our bare
hands, judging it better that these should be hurt, fractured, crushed, or cut
off than allow what could damage the chest to reach it. For the thorax is the
organ of respiration, as the lung is also surrounded by it; moreover, the heart
is considered the nurturer of innate heat and the seat of an irascible nature,
therefore also requiring sturdier defenses. Since the same danger of blows
threatens the back of the thorax as the front, but there is not the same
foreknowledge of things which can harm it from the rear as in front, there
being no eyes in the posterior region, it was quite fitting that Nature fashion
some artifice here too and not neglect the posterior surface of the thorax.
Whence, as a kind of wall and marvellous rampart she fitted there the vertebrae
of the thorax, and she threw up the scapulae like two shields, bucklers, or
mighty battlements. She was not unaware that from this yet another use would
accrue to man, by which several muscles
22
controlling motions of the arm acquire a
place of support where they may best take their origin. Surely it is a work of
supreme justice that the same bone is used for such various and quite necessary
functions, and that the scapulae are everywhere so formed that they could be
thought made exclusively for each of these employments.
23
The triangular shape of the scapula
The scapula is quite irregular, and is different in every part. Not
counting its various processes, depressions, protrusions, epiphyses, and other
such features from which we have picked out the distinguishing characteristics
of bones, the scapula looks more or less like a triangle formed by its several
sides.
The base of the scapula
Its first side (from Z through X to Y in figs. 1-3),
24
which we shall invariably call the
base
[margo medialis] of the scapula, is
that area which extends along the longitude of the back closest to the spines
of the thoracic vertebrae. This base consists of a slanting line which is
inclined above and below obliquely toward the side of the body as if in a
convex arc, but in the middle is often somewhat lunate and hollow. Sometimes
the whole base of the scapula
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Epiphyses of the base
To this base two epiphyses (one is Y, the other X in figs. 1-3) are
generally attached. One, which is larger, thicker, and longer, and always
appears, is located at the lower angle [Y] of the basis: it is markedly blunt,
and more or less rounded. The other epiphysis [X] is some distance beneath the
upper angle [Z], and fuses to that point the base from which you will hear the
spine of the scapula (G, H in fig. 2, G in fig. 3) takes its beginning.
Cartilage of the base
Besides these epiphyses, there is also attached to the base a certain
soft cartilage
[c. hyalina] of the type by which
ends of bones that are unattached to another bone are accustomed to grow. In
humans, however, this cartilage is much shorter and smaller than in sheep,
cattle, and other animals
26
whose scapulae lie more upon the sides of the thorax than, as in
man, on the posterior of the thorax next to the vertebrae. This is how the
first side or base of the scapula is arranged; the two remaining sides are
different from each other.
Differences between the upper and lower sides
The lower side
[margo lateralis] (from B to Y in
figs. 1 and 2) runs from the lower part of the base quite obliquely upward
toward the anterior. The upper
[margo superior] (from Z through F
to A in figs. 1 and 2) (which is as much shorter than the lower as the lower is
shorter than the base itself)
27
runs somewhat
downward to the exterior, proceeding more or less transversely.
28
These two sides come
together at an angle (between A and B in figs. 1 and 2) and bracket at their
end a rather broad part of the scapula where the cervix of the scapula is seen
and the depression
[cavitas glenoidalis] that receives
the head of the humerus. This place, then, (if it can be thought of as an
angle) would be the third angle
[angulus lateralis] of the scapula,
since we count as the first angle
[angulus superior] (Z in figs. 1, 2,
3) the upper angle of the base, and the lower the second angle
[angulus inferior] (Y in figs. 1, 2,
3).
Three angles of the scapula; a fuller description of the sides
Those two sides which make the third angle at their ends differ not only
in the shortness of their course, but also in their thickness. The higher the
lower side
[margo lateralis] runs upward from
the base, the thicker it becomes, and noticeably more dense (at P in fig. 1 and
S in fig. 2), just as if by means of this side Nature had wished great strength
added to a scapula that is otherwise thin and weak, and in the second place had
prepared a convenient place for the origin of certain muscles.
29
For besides the fact that the
thickness of this side makes the inner part of the scapula
[facies costalis] (between N, O, P,
and p in fig. 1) more concave for the sake of certain muscles
[m. subscapularis] (as I shall soon
add) and forms a kind of depression
[facies dorsalis] (between G, H, S,
T in fig. 2) on the outer side or protuberance, this side itself also effects a
compression (T in fig. 2) in its outer surface near the lower angle of the base
of the scapula and runs some way downward to provide an origin there for the
muscle
[m. teres major] (K in the 8th table
of muscles, s in the 13th) by which the upper arm, when extended away from the
chest, is brought back. Also, on the inner surface of this side next to its
upper part where it abuts the neck of the scapula, there is also seen a
somewhat rough and uneven oblong depression
[tuberculum infraglenoidale] (Q in
fig. 1) providing a point of origin for the muscle
[m. triceps brachii, caput longum] (T in the 12th table
of muscles) which we shall state in the second book begins from the scapula and
makes the ulna extend. We shall always call this lower side of the
scapula the lower “rib,” costa, as did the ancients, who called the upper
and lower sides of the scapula pleurai/.
30
The upper side of the scapula is thin and not at all heavy all
the way to the upper region
[angulus lateralis] of the scapular
cervix
[collum scapulae] (C in figs. 1 and
2) where the inner process
[p. coracoideus] of the scapula (F
in figs. 1 and 2) originates;
31
this is where the upper side of the scapula thickens markedly.
Within this side near the base of the scapula’s interior process, a certain
depression (a in fig. 1) or half a foramen
[incisura scapulae] is carved like a
semicircle, providing a path for a twig
[n. suprascapularis] (i in fig. 3,
ch. 11, Bk. 4) of one of the fifth pair of nerves
32
of the dorsal medulla; this twig goes to the
posterior surface of the scapula
[facies dorsalis] together with a
small vein
[v. suprascapularis] and an artery
[a. suprascapularis].
The neck of the scapula
The neck of the scapula
[collum scapulae] (C, D in figs. 1
and 2), which is between the ends of the upper and lower sides of the scapula,
33
is thick and the scapula itself appears compressed at
that point from its wide, thin area and thickened along its latitude. But the
longitude or interval of the neck (from C to D in figures 1 and 2), which I
measure from the upper part of its body to the lower, greatly exceeds its
thickness, which extends from the anterior to the posterior.
The depression made to receive the humerus
The neck continues to be extended considerably outward, and is widened;
being itself oblong, it forms an oblong depression
[cavitas glenoidalis] (A, B in figs.
1 and 2), ending with a circular edge in the lower part but extended more to a
point in the upper part. This happens because of an impression (C in fig. 1)
made here in the inner surface of the neck to make room for the tendon of the
muscle
[m. subscapularis] (G in the 7th
table of muscles, H in the 8th) which rotates the arm inward and anteriorly.
The upper part (A in fig. 1) of the scapular neck and socket extends higher so
that two very strong ligaments of this joint
[ll. glenohumeralia] (e in the 5th
table of muscles and V in the 13th) may better take their origin from this
point, and so that the outer head (m in the 6th table of muscles) of the muscle
[m. biceps brachii, caput longum] that will be
considered the anterior of those that flex the forearm may conveniently take
its origin hence. This scapular cavity is covered with cartilage like the other
joint sockets, and is not carved very deeply. Its length and breadth do not
match the length and breadth of the head of the humerus (A, B, C in figs. 1 and
2, ch. 23) with which it is articulated.
34
Nature devised this feature
in quite a peculiar way in this joint. In other joints, the heads match the
sockets perfectly, unless you wish to make an exception of the joint of the
femur with the tibia
[articulatio genus] (join E, F, I of
fig. 1 ch. 30 with G, F, I of fig. 7 ch. 31 and consult fig. 8 of the same
ch.), where you will understand the sockets of the tibia do not match the heads
[condylus medialis, c. lateralis] of the femur, and that
Nature was making some separate arrangement in that joint as well. We shall
explain in the appropriate place where the knee differs from the system of the
other joints, but now we must explain the shoulder joint.
The cartilage which often augments the socket of the scapula
Since Nature carved out this depression of the scapula rather lightly
for the sake of loose movements and made it not very wide or long (in addition
to special ligaments of this joint,
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Processes of the scapula
There are two processes by which Nature provided for this joint. One of
them is the upper one
[acromion] (K in figs. 1, 2, 3), and
we shall call it the summus humerus; presently it will be explained that it
originates from the spine of the scapula (G, H in fig. 2).
The inner process
The other
[processus coracoideus] (E, F in
figs. 1, 2) is inner and smaller; it takes its beginning from a broad root (F
in figs. 1, 2) on the upper side of the neck of the scapula and from here,
quite wide, it is brought forward opposite the anterior part of the joint more
toward the top. The lower part of this process is quite smooth, and concave
like the ancient Greek letter C
39
,
and for this reason is also called sigmoeidh/j, sigmoid.
40
Others, however, from the
appearance that an anchor presents that has one part fixed in the ground, have
called this process a)gkuroeidh/j.
41
Many, on the other hand, because it is inclined like a
crow’s beak, have called it kwrakoeidh/j, coracoid.
42
Galen’s
translators have subsequently made a mockery of these names — with assistance
from Galen, since he is inconsistent in his nomenclature; for while elsewhere
he almost always calls this process ancyroid, in the thirteenth book of De usu
partium he applied that name to the scapular process which we call the top of
the shoulder.
43
But the names of this
process will necessarily come up later. But now we shall run through what
remains to be told about the interior process
[p. coracoideus]. On its lower
surface it is smooth, but above it is rough and uneven. It looks thicker on the
upper part of its beginning, and bulges in an irregular swelling (F in figs. 1
and 2) against which the clavicle nearly rests and is firmly attached.
44
On its tip (E in figs. 1 and 2), where it puts forth an
epiphysis, it is also rough, so that the inner head of the anterior of the
muscles that flex the forearm
[m. biceps brachii, caput breve] (n in the 6th table of
muscles) may better take its origin from it, and so that the ligament
[l. coraco-acromiale] peculiar to
the shoulder joint may have its beginning here. Between the tip and the
tubercle on which the clavicle is nearly supported
45
(f in fig. 1), this upper surface of the process is also rough
so that the ligament
[l. coraco-acromiale] (c in the 5th
table of muscles) leading from here to the upper process of the scapula may
better be put forth.
46
Just as this upper surface of the process is rough so that
it may put forth those ligaments
47
and that muscle’s head,
48
so too the neck of the
scapula shows certain little blind foramina circularly arrayed, from which
hangs the origin of powerful ligaments
[capsula articularis, ll.
gleno-humeralia] belonging to
this joint.
Now it will be timely also to talk about the other process
[acromion] of the scapula. We shall
best discover its nature if we look carefully at the anterior and posterior
surfaces of the scapula.
The anterior surface of the scapula, next to the ribs
The scapula is flat and concave on its anterior surface
[facies costalis] (fig. 1) so as to
fit the convexity of the ribs and while being fixed over them to be moveable as
required, as well as to suit it to the muscle
[m. subscapularis] (G in the 7th
table of muscles, H in the 8th) which fills the entire anterior surface of the
scapula and rotates the humerus inside and forward. This concave surface of the
scapula is indeed smooth, but it is not even in all places; for next to its
lower surface it puts forth certain tubercles (M, M, M in fig. 1) that stand
out slightly as oblique lines
49
which make what amount to depressions, as if the ribs of the
thorax on which this side of the scapula rests had been pressed into the
scapula over time, and the scapula itself had taken on their outline by giving
way. For these depressions and prominences appear more in the old than in
children and youths, in whom everything protrudes and grows out less
conspicuously. The anterior surface of the scapula protrudes somewhat at the
root of the higher angle of the base (F in fig. 1), making a region suitable
for the second of the muscles
[m. trapezius] that lift the scapula
(G, D in the 9th table of muscles) to be firmly inserted.
50
The anterior
surface of the scapula, where it is opposite the base of the acromion (compare
N, O in fig. 1
[fossa subscapularis] to H, G in
fig. 2
[fossa infraspinata]) or the
scapular spine,
51
is more markedly concave than elsewhere, as if when Nature had
fashioned the spine of the scapula she had pulled the hollow
52
part of the scapula toward the posterior and thus increased its hollowness, in
the same way we see it done in vessels of clay and other things that are daily
made of casting material or wax.
53
For when we look at the handle
which is put on the outer surface of a jar, the hollow part of the jar on the
opposite side is observed to be more depressed as if pulled outward from the
jar. This is seen especially
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Posterior surface or dorsum of the scapula
The posterior surface of the scapula (fig. 2), furnished with a
conspicuous, spiny process (G, H, I, K, L
56
in fig. 2), is convex if
casually observed, for Nature would not have been unaware that this shape is
better adapted to enduring injuries without harm. But if we study this
protrusion of the scapula more closely, two concave surfaces will come to our
attention that are perfectly suited to receive muscles. One
[fossa infraspinata] (between G, H,
D, S, T, and Y in fig. 2) lies beneath the spine of the scapula between the
lower surface of the spine and the swelling, thicker part of the lower side of
the scapula. The other
[fossa supraspinata] (between Z, a,
I, G, and especially between b and c in fig. 3) is between the upper surface of
the scapular spine and the upper side of the scapula. A certain muscle
[m. supraspinatus] (k in the 6th
table of muscles, G in the 11th) occupies this surface; we shall declare it the
third
57
of the muscles that rotate the arm. The lower cavity is filled by
a muscle
[m. infraspinatus] (G in the 11th
table of muscles) which will be counted the second of the muscles that rotate
the arm.
58
Although this outer or posterior
surface of the scapula shows these two cavities on account of the spine of the
scapula as well as its sides, nevertheless the whole (since it is seen to swell
out) was called the back or dorsum of the scapula by the ancients, borrowing
from its likeness to the actual human dorsum. Now the process that arises from
this dorsum of the scapula
59
they called the spine for its
resemblance to the posterior processes of the vertebrae, or spines,
60
and since these were quite rightly established as such by the
ancients, I shall not stray so much as a fingernail’s breadth from these names.
I shall call the outer surface of the scapula the dorsum, and the root of the
acromion I shall call the spine of the scapula.
The shoulder top or a)krw/mion, whose careful description must now be
commenced
I use the term summus humerus for what was named the acromion by the
ancients, though it is not so easy to divine what anyone understood by this
word.
61
If only because of the divine Hippocrates, this word should not be
neglected, nor should a hasty decision be made regarding it; let us but call
our minds away for now from syrups and juleps,
62
and reckon that the divine oracles of
Hippocrates on fractures, dislocations of the bones, and such afflictions,
63
pertain to us also. It will not therefore
have been out of place to describe the spine of the scapula and the acromion as
seemed best to us, and afterward to add to our account the opinion of
Hippocrates and Galen. A powerful, heavy process (G, H in fig. 2) grows from
nearly the whole width of the dorsum of the scapula: not from the middle of the
longitude of the dorsum (not midway between Z and Y in fig. 2, but more towards
Z), but not far from its upper surface. This process (which is the spine of the
scapula) gradually becomes larger and larger, and finally (H to K in fig. 2)
leaves the dorsum of the scapula near the neck; appearing more or less smoothly
rounded, it is brought slightly forward. It broadens noticeably (K in figs. 1,
2, 3) above the joint of the scapula where it joins the humerus and has a broad
epiphysis which in children is constructed of several ossicles
64
(Q, R in the fig. for ch. 3) joined by
cartilage. The entire anterior, posterior, and lower parts of this process are
smooth and not at all rough, but its upper surface is by no means smooth but
rough, with certain small blind foramina, particularly in the upper surface of
its epiphysis and at a point (I in figs. 2, 3) not far from the base of the
scapula where this process is thicker and often has an additional epiphysis.
Surely, Nature did not devise them in vain:
65
she built
these rough places for the sake of muscles;
66
in them is implanted a
very large muscle
[m. trapezius] (G, D in the 9th
table of muscles) that draws the scapula upward. This process is rougher in the
places I mentioned because the muscle makes a broader and stronger insertion
there. Furthermore, this roughness provides the point of origin
67
for the most
eminent muscle that moves the arm
[m. deltoideus] (D in the 10th table
of muscles), which anatomists have called e)pwmi/j
68
because it
perfectly covers the joint
[articulatio glenohumeralis] of the
humerus with the scapula. In the anterior surface of the process
69
a depression
[facies articularis acromii] (L in
figures 1 and 2) is carved so lightly and superficially that you would scarcely
distinguish whether it is a capitulum or a depression. Into this depression the
slightly projecting tubercle of the clavicle
[extremitas acromialis] (Q in fig.
3, ch. 22) is articulated, and is held in place by the strongest of ligaments.
70
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Cartilage peculiar to the joint of the clavicle with the upper
process of the scapula
Often at this place there intervenes a special cartilage
[articulatio acromioclavicularis, discus
articularis], quite similar
to the one which we stated is observed in joints of the lower with the upper
maxilla.
71
This cartilage is smooth and slippery on both sides where it faces bones; it is
held in place and in contact only with the ligaments surrounding the joint. The
part of the process just mentioned (G, H in fig. 2) which originates from the
dorsum of the scapula and is (so to speak) next to the dorsum, is opportunely
named the spine; it is observed also in dogs (C, D in fig. 4), sheep, and
horses. But the part (from H toward K in fig. 2) which goes away from the
scapula forward to the outside and gradually broadens, can be observed only in
humans, apes, squirrels, and any other animal that has a clavicle, that part we
shall call the summus humerus
[acromion], borrowing this name from
the Greeks, who no doubt named the joint of the humerus with the scapula w=)moj,
and called this part of the process a)krw/mion because it constitutes the upper
surface of the joint and was considered, as it were, that joint’s safest
bulwark. Certainly this is always what one learns from Hippocrates, often in
other places and especially when he says that the humerus (which he himself
calls the braxi/wn) is not dislocated upward
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A third bone enumerated by Galen in the joint of the acromion with
the clavicle
He also adds that some place here a third bone besides this process and
the clavicle, in humans only, and that they call this “acromion” and kataklei/j.
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In the thirteenth book of De usu partium
Galen counts this third bone in humans and denies that simians have it;
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likewise in his
books De anatomicis administrationibus and in his commentary on Hippocrates’ De
articulis. For he writes that besides this upper process of the scapula and the
clavicle there is a third cartilaginous bone which is placed in the joint of
the clavicle with that process of the scapula, and from it originate membranes
and ligaments by means of which this joint is more strongly held together. In
the fifth book of De anatomicis administrationibus Galen says that such a bone
is called a)krw/mion by Hippocrates, and he himself calls it by that name in the
same place, just as he testified in his book De ossibus that certain people
place a third bone here and it is called by them a)krw/mion. But at the same
time, he sometimes in his books De usu partium, De anatomicis
administrationibus, and in almost all his commentaries on Hippocrates, he
called this process of the scapula a)krw/mion, or at least the joint of this
process of the scapula with the clavicle. I therefore wonder greatly at the
inconsistency of Galen here and will wonder much more until I discover this
third cartilaginous bone in man. For by no means do I believe that Galen
considered the above mentioned special cartilage of this joint to be a bone,
since cartilages of this sort generally resemble true cartilage less than the
do ligament and are not by any means osseous, and furthermore since it is found
in the ape as much as in man. Even if it were to be considered a bone, apart
from the fact that Galen would have mentioned it differently and would have
written that it occurs in the joint instead of being laid upon it, he would
still not escape censure for not having established the peculiar bone
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in the joint
of the clavicle with the pectoral bone
[sternum] (the larger part of the
4th fig. in ch. 22) and again in the joints of the lower maxilla with the upper
(marginal fig. in ch. 10),
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and in the knee
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(fig. 8, ch. 31). Cartilages of that type
[cartilago fibrosa] are in fact
easier to find there than here in the acromion, but they seem to have been
unknown to Galen and overlooked by him. It would therefore be much better now
not to call this peculiar cartilage a bone (even if it were osseous), than
tacitly to imply that so many bones escaped Galen’s notice.
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I have so far never been able to find a third bone here, for
all my diligent dissection with Hippocrates in mind.
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I think
it is clear enough that Galen never saw it either, and should I dare venture so
far in impiety toward him, I would affirm that he invented a bone of this sort
from its similarity to bones which resemble a sesame seed
[ossa sesamoidea] (V, V in fig. 1
ch. 25, y, w in fig. 2, ch. 33), which
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you will learn are put
in front of joints and junctures of other bones in the same way Galen gave out
that a cartilaginous bone is situated here. I will gladly therefore admit that
I have found this third bone no more in man than in ape, nor has anyone been
present when I was dissecting where one was observed by even a single person,
though I always adminish all present to watch closely for it.
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And accordingly if someone shows me this bone or anything
like it in addition to the process of the scapula and the clavicle (Q and l in
the skeletons), I assure him I will more quickly demonstrate something else of
that kind in the joint
[articulatio glenohumeralis] of the
humerus with the scapula that is far worthier of close consideration and
intensive study. For this reason only, I now knowingly pass it by.
The only animals in which the upper process of the scapula
exists
At the same time I wish all to know that I have never encountered any
animal possessing this process of the upper scapula except man, ape, squirrel,
and, if I remember rightly, the dormouse. I therefore have no doubt that
whoever first wrote that only man possesses an acromion understood that man
alone had this process; when he saw no upper process of the scapula (but only
the spine) in dogs,
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sheep, goats, rabbits (which indeed have only the inner process of
the scapula) and other quadrupeds that are served as food, he did not bother
with apes, as Galen did. We may therefore call this upper process of the
scapula summus humerus or “the upper process” until a more correct view comes
to light.
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The use of the acromion
We shall explain better for what use the acromion is given to humans and
other animals possessing clavicles when we have begun our account of the
clavicles. For besides the fact that this process prevents an upward
dislocation of the shoulder, it is an extremely safe bulwark for the shoulder
joint, and serves perfectly for the origin and insertion of muscles
[mm. deltoideus et trapezius]; it is
most of all helpful, when the clavicle is attached, in holding the shoulder
joint as far as possible from the sides and ribs of the thorax, and keeping it
in a place which it most requires for those quite various and different motions
that it performs.
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These matters will be resumed at greater length in the descriptions of the
clavicles, for it will soon be time to put a limit on our discussion of the
scapulae, especially as nothing else remains to be explained except perhaps
something quite small. Such a thing could be that the base of the scapula,
where it is equipped with epiphyses, is quite spongy and porous. Several
foramina
[canalis nutriens] extend into the
spine of the scapula, carrying veins to it (since it is thick) to supply it
with nutriment. One (c in fig. 3) is often seen in the broad part
[fossa supraspinata] that is formed
by the upper side of the scapula and its spine, and another on the inner
surface of the scapula where it is more deeply hollowed.
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Book One -- The things that sustain and support the entire body, and what braces and attaches them all. [the bones and the ligaments that interconnect them] |
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