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]

Chapter 3 Names by which the Parts and Surfaces of Bones are Identified

[Illustrations of Chapter 3]

In the table above, a number of bones are illustrated only to show suitably, at least in a few bones, the parts and areas of bones whose names I shall discuss in this chapter. 1 If in this chapter mention is made of a bone not illustrated here, you should look for it among the illustrations belonging to its own chapter, or in the plates appended to the end of the first Book. However, there is no need in the description of each part and seat to study all the bones that I will bring in as examples, as it shall be quite sufficient to consider the example that is given here in one bone and to remember the name when it occurs elsewhere. 2 The following key will explain the bones illustrated here. 3

A Right femur; we have removed the epiphyses from their seat and removed them a certain distance from the remaining bone.
B Right femur, with epiphyses still attached to their seats.
C Lower maxilla [mandibula], with the lower row of teeth.

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D Here is represented on its outer surface the bone [os coxae] articulated to the right side of the sacrum; following Galen, we have given it no other special name 4 but include it under three names according to its parts, namely the ilium, hip [ischium], and pubis; we shall describe it in the twenty-ninth Chapter. 5 Under the bone just mentioned and the lower maxilla, the bones of the right foot are seen in such a way that the four bones of the tarsus, marked 1 , 2 , 3 , and 4 , 6 with the bone resembling a small boat [os naviculare], marked E , the talus, marked F , and the calx [calcaneus], marked G , are so removed from the five metatarsal bones marked I , II , III , IIII , and V , and from the bones of the digits [phalanges] shown as H and H , that the place can be seen where the bones of the metatarsus are joined to those of the tarsus. By this means the depressions [facies articulares] introduced only into the surface and the slightly protuberant heads are suitably shown.
I The bone of the arm or humerus is beneath the foot, showing its anterior surface.
K Portion of the scapula of the back, drawn to show its spine with the epiphysis of the acromion marked with lines [sulci], and fashioned of various parts. These are the bones represented by the present table; the remaining characters help to show the parts of the bones as follows.
L Four L’s 7 on the femur marked A show the four epiphyses 8 of the femur.
M Four M’s on the other femur mark the four epiphyses of the femur; lines [epiphysial lines] show the edges by which they are separated, so to speak, from the femur.
N N The upper N [tuberculum iliacum], on the bone marked D attached to the side of the sacrum, shows the epiphysis of the iliac bone. The lower N shows the epiphysis [tuber ischiadicum] of the hip bone.
O You see this letter on several metatarsal bones, marked I, III, and V, on the first and second bones of the big toe [phalanx proximalis, phalanx distalis] and the first and second bones of the middle toe [phalanx proximalis, phalanx media], indicating epiphyses [tuberositates] on these bones; this is not to say that they occur only on the bones so marked, but a few characters will show well enough that the same applies to similar bones. 9
P Epiphysis [tuberculum minus] 10 of the humerus.
Q Epiphysis of the spine of the scapula, or acromion. 11
R Lines 12 situated between several portions of the epiphysis of the spine of the scapula.
S On each femur we have written two S’s, marking the processes [trochanter major et minor] of the femur.
T Acute process [coronoideus] of the lower maxilla, also known as the korw/nh. 13
V V Two processes [spina iliaca anterior inferior, spina ischiadica] in the bone attached to either side of the sacrum.
X Process [tuberositas ossis metatarsalis quinti] of the upper epiphysis of the metatarsal bone marked V, leading to the little toe.
Y Y Two processes or tubercles [epicondylus lateralis, e. medialis] of the lower end of the humerus, where it is articulated to the bones of the forearm.
a Placed three times on each of the femurs, showing the three heads [epiphyses] of the femur. In the first femur, marked A, we have placed a on the highest epiphysis [caput femoris]. In the femur marked B, it is outside the epiphysis, lest someone think that the head articulated to the hip is nothing more than an epiphysis. 14
b Right head [processus condylaris] of the lower maxilla [mandibula].
c Head of the talus, entering the depression of the navicular bone.
d Head [trochlea] of the talus, which is also marked F, entering the socket of the tibia. 15
e Appearing several times in the drawing of the foot, e marks the heads of the metatarsal and digital bones.
f Upper head of the humerus, which is articulated to the scapula. 16
g g Two lower heads [capitulum, trochlea] of the humerus, or rather the seats to which the ulna and the radius are articulated.
h h Printed once on each femur, h shows the neck [collum femoris] of the head which is inserted into the hip bone.
i Neck [collum] on the lower maxilla [mandibula].
k Neck [collum] on the talus.
l l Necks of the metatarsal bones, printed only on II and IIII so as not to obscure the others. 17
m Neck [collum chirurgicum] on the humerus.
n Acetabulum in the hip bone, to which the femur is articulated.
o Acetabulum [fossa coronoidea] in the humerus, lying between the two Y’s. 18
p p p Shallow recesses [facies articulares], seen in the bones of the tarsus.
q q Barely swelling tubercles [bases ossis metatarsalis] of the metatarsal bones; we have written q on only two of them because the others would be hidden in the shading, and would also have interfered with the picture. 19
r r Brows [limbus acetabuli] on the hip bone, visible near the upper part of the acetabulum. If it is desired to view these parts or areas of the bones also among the cartilages, the illustrations at the head of Chapter 38 will show all that are visible in the cartilages.

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Difficult as the description of things is made by the multitude and varied usage of terms by other writers and often by the same writer, still no collection of language is as complicated and contradictory as the names by which the parts and areas of the bones are designated and must continually be used in the description of bones. In order now to put off until the next chapter various terms by which the bones of a joint are designated as a series of connectors, a number of terms just now come to mind: kw=lon, e)pi/fusij, a)po/fusij, korw/nh, korwni/j, kefalh/, kefa/laion, a)/rqron, ko/nduloj, tra/xhloj, au)xh/n, kotu/lh, kotulhdw/n, o)cu/bafon, glh/nh, i/)tuoj, o)fruoj, a)/mbonoj, xei/lh, baqmi/doj, and very many other words of this kind, which are words of the Greeks. 20 As for the Latins, though they had only a few separate names, nevertheless, through the prodigality of translators, so many myriads of names are everywhere under foot that now as each separate Greek name comes up for use, it must be added what the ancients, who taught boys at home a system of careful dissection, understood these words to mean. Finally, it must be decided what terminology we too are to use throughout our text.

Kw=lon: limb, member 21
Kw=lon, a word which translators of Greek authors often use, is sometimes translated limb, sometimes member; it was applied by the Greeks to only four members: the arm, the forearm, the thigh, and the lower leg. Galen seems to have understood no other part by that word. Since I rarely or never use this word, I do not think it worth dwelling on at greater length.

E)pi/fusij: epiphysis 22
E)pi/fusij, which Latin writers translate appendage, insertion, attachment, accretion, growth, and undoubtedly countless other ways, I shall always Latinize as appendix. An epiphysis is a bone grown onto another bone; it has its own border and is not a true part of the bone to which it is attached. It is possible to learn the nature of such an epiphysis whenever part of a calf, kid, lamb or any young animal is put on the dinner table. When a femur, humerus, tibia, radius, ulna, or similar bone has been cleaned of other matter and handled a little roughly, we see as it were another bone fall from it. That is called the epiphysis, and we see it only in younger animals. With age, the epiphyses grow so tenaciously to their bones that they cannot be torn away. 23 They barely show the line where they are joined, and they seem to be an actual part of their bones, while in recently born animals one sees a large amount of cartilage 24 between the epiphysis and the bone to which it is attached, which binds epiphysis to bone like glue. This juncture is not accomplished along a smooth or even surface; rather, the bone to which the epiphysis is joined abounds in cavities and rough spots [centers of ossification], to which the cavities and tubercules of the epiphysis are the more strongly fitted by mutual accommodation. This connection is also unique in that no bone is softer than in precisely this area; the bone is seen to be harder and more solid outside of the connection itself. For in that place bone is always full of pores inside, like pumice or sponge [cancellous bone]; and though the bone often has a single large, hollow cavity along most of its length filled only with marrow and is extremely hard and strong along the length of this cavity, nonetheless the cavity stops before the bone is joined to the epiphysis, and the bone becomes softer and full of pores, like the epiphysis itself. 25

The epiphyses are not covers of the cavities containing marrow
This happens in such a way that Galen reported the epiphyses to be covers of the cavities containing marrow, 26 as if the pores of the epiphyses contained no marrow, 27 and as if there were no epiphysis on a great number of bones lacking cavities containing marrow unmixed with bony fibers. But in fact, in the broad bones [ossa ilii] that are attached to the sides of the sacrum, such a cavity is nowhere present; nevertheless, an epiphysis [tuberculum iliacum] (N, N in figure D) grows on the entire spine of the ilium, just as it does on the entire lower area [tuber ischiadicum] of the hip bone. Moreover, the scapulae are almost nowhere medullary (see X, Y, E, and K in Ch. 21, figs. 1 and 2) but have four epiphyses: two at its base, one at the point of the scapula’s inner process [p. coracoideus], and a fourth [acromion], which is unusually constructed, near the shoulder top. 28 Finally, the back vertebrae lack this kind of cavity, but have epiphyses [facies intervertebrales] above and below (A, B, etc. in figure 1 and 2, Chapter 17); in fact not only do the vertebrae [bodies] have epiphyses [processes], but the epiphyses are connected to the tips of the transverse processes and spines of the thoracic and lumbar vertebrae. The vertebral epiphysis is also joined to the base [collum costae] of the ribs, even though the bone of the ribs has no large cavity containing marrow.

Large bones are not the only ones with epiphyses
The vertebrae and the teeth of children, which also have epiphyses, not only show that bones without these cavities have epiphyses, but they also argue that Nature gave epiphyses not just to large bones, notwithstanding that the leading anatomists 29 declared the opposite, ascribing epiphyses only to the large bones. 30 Of the bones having such cavities, 31 the femur has four epiphyses (marked L in figure A, M in figure B): one at the head [caput femoris], where it is joined to the hip bone; one at its lower part [condylus medialis, condylus lateralis], where it is joined to the tibia; and two others at its two processes [trochanter major et minor], which we usually call the rotators.

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Epiphyses are attached to the tibia and the fibula at the knee and the foot. The radius also has them at the carpus and the humerus. The humerus has an epiphysis only above, where it faces the scapula; likewise the ulna, only at the carpus. 32 And these are large bones, on which Nature has bestowed large cavities [cavitas medullaris]. Small bones, which we have explained are also given this kind of cavity contrary to the view of Galen, 33 by no means lack an epiphysis: the metacarpal and metatarsal bones (O, O in the illustration of the foot) each put out a very obvious epiphysis [caput], where they enter the indentation [basis] at the joint [articulatio metatarsophalangeale] of the first bones of the digits. Also at the top, where these bones face the carpus and tarsus, they often do have an epiphysis, but it is always more tightly fused to the bone than at the lower end. Likewise, all the digital bones above and below are generally equipped with epiphyses [basis et caput], if you except the last [phalanx distalis] which have epiphyses only at the upper end. All of these are quite visible in young children. But in those who have already reached their full growth, the fusion of epiphyses is hard to see, while in the old it is entirely hidden and unseen. 34

A)po/fusij: process
A)po/fusij, which translators render process, projection, explantation, addition, and I know not what other words, will be called by us process. It is no different from the bone of which it is a part, coming out from the bone like a tubercule or gibbosity, just as roots and branches are observed to jut out and proceed from the trunk of a tree. There are a great many such processes 35 on the bones. There is no vertebra of the back which does not have many; we shall show later that some vertebrae of the neck (indicated by the numbers in figure 8, Chapter 15) [vertebra cervicalis III] have more than eleven, the thoracic vertebrae seven, the lumbar nine. The lower maxilla has two on each side (T to i in figure C) 36 ; so does the humerus (Y, Y in figure I) [epicondylus lateralis, e. medialis]. All bones of the body put forth processes whenever they swell at some point beyond a simple level surface.

Varieties of processes and epiphyses
There are several varieties of processes, as there are of epiphyses. Certain processes have an epiphysis attached: the femoral processes called rotators [trochanter minor et major] (S in figures A and B) and the spine of the scapula (which is a process of the scapula) have epiphises; so also the interior process [p. coracoideus] of the scapula, which looks like an anchor. 37 There are no epiphyses on the other processes: they very rarely occur in the processes of the lower maxilla, the calcaneus, 38 the talus, and the other spongy bones, except as the processes of those bones too are spongy. To the processes of the humerus [epicondylus medialis, e. lateralis] that are near the joint of the forearm no epiphyses are attached; likewise the processes of the ulna [processus coronoideus, olecranon] which articulate with the humerus. 39 On the other hand, epiphyses usually provide themselves with processes. The epiphysis of the ulna (R in figures 1 and 2, Chapter 24) [processus styloideus] has a process which experts at dissection have compared to a pillar or a pen with which we write; there is a process, which we call the inner malleolus, on the epiphysis of the lower bone of the tibia [malleolus medialis] (i in figure 3, Chapter 31). Furthermore, the upper epiphysis of the metatarsal bone that supports the little toe puts out a process [tuberositas ossis metatarsalis quinti] (X in the foot illustration), into which it will be shown is inserted the eighth of the muscles [m. peroneus brevis] that move the foot. The epiphysis of the humerus [condylus humeri], 40 and likewise the lowest epiphysis of the femur, are divided into two processes [condylus medialis et lateralis] so prominent that you hear it said they should be called separate heads. And so the parts that we are about to explain as head, neck, cavity, tubercule, and brow are comparable to epiphyses and processes. However, the name of process is better applied only to those which are not articulated to another bone. We therefore do not call the heads of the femur and the humerus processes, nor the acute processes of the lower maxilla or the tubercules of the humerus, which jut out near the sides of the elbow joint. Further, we think it will be more convenient to call processes that have epiphyses simply processes, not epiphyses. We shall call the rotators 41 of the femur [trochanter major et minor] and the processes of the scapula and vertebrae processes, even if they have epiphyses, following the practice of other anatomists (who often confuse e)pi/fusij with a)po/fusij). 42 We will never make reference to the process of an epiphysis simply as a process without adding the name of the epiphysis; we shall say, for example, that the inner malleolus [malleolus medialis] is a process “of the lower tibia,” an epiphysis. But all of this is incidental to an understanding of the names and will be presented in descriptions of the bones, just as also the function of the processes as well will come out more clearly with reference to individual bones.

The function of processes
Processes contribute particularly to the good articulation and joining of bones, and also to the origin or insertion of many parts. For if bones did not swell out somewhere and were not drawn upward like hills and hollowed out again like valleys, very little could begin from them or be inserted into them. As it is, processes stand out from them like a mountain, from which more things spring forth than from level ground, and other things are then (so to speak) planted into it and built out over it. Indeed, processes serve in place of a rampart, as those of the scapulae and vertebrae will testify.

The korw/nh or korwni/j is called by some translators cornix, crow. 43 The ancient Greeks meant by this word the acute process in bones which they compared to the horn of a bow and the notch where the bowstring lies. One of this kind is on either side of the lower maxilla [processus coronoideus] (T in figure C and A, B in the 6th table of muscles); the tendon of the temporal muscle is inserted into it. Another is seen in the temporal bone [processus mastoideus] (k in figures 4 and 5, Chapter 6); people compare it to the nipples on breasts. There is another [processus styloideus] (i in the same figures) on the same bone that is compared to the spur of a cock or a writing stylus.

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Galen seems to have used this word not only for acute processes suited for the origin and insertion of muscles, but also for a number of heads of bones which enter depressions in other bones for the sake of articulation. More than once he applied this name to the small heads of the occipital bone [condylus occipitalis] (figures 5 and 6, Chapter 11 [sic: 7]) which are articulated to the ends of the first cervical vertebra, though in fact, particularly in humans, they by no means deserve to be called a sharp process. 44

Kefalh/, kefa/laion: the head; prominences and depressions of the head.
Kefalh/ and kefa/laion are explained by Latin writers as the head. They apply this term to the swelling portion of a bone entering the hollow of another bone for articulation and voluntary motion. We also call the head prominent or low when judging it by its cervix: the head of the femur is called prominent where it is fitted into the hollow [acetabulum] of the hip because a long distance extends from its neck to its tip. Likewise we consider the head of the humerus where it is joined to the scapula [cavitas genoidalis] a prominent head because in its most projecting part it extends far beyond the cervix or neck. The heads 45 of the metatarsal bones (q, q in illustration of the foot), which are attached to the bones of the tarsus, are so depressed and flat that you could scarcely say whether they enter the cavities of the tarsal bones or receive tubercules of them. It is also impossible to distinguish heads from depressions in the connection of the three bones [ossa cuneiformes] of the tarsus with the bone resembling a small boat [os naviculare] (compare s, t, and u in figure 13, Chapter 33 with n, m, and l in figure 10). We will later point out that capitula (d in fig. 9, ch. 13; X, Y in the figs. for ch. 16) of this kind occur in most of the vertebrae. For the present it suffices to add that the Greeks, in their ardent enthusiasm for the works of Nature, gave the name “prominent heads” to points which display an obvious swelling, and which stand out in a circular shape or swell in their middle rather than their sides. Low parts (depressa) is what they called parts having so obscure a swelling or lump that it is unclear whether they should be called a head or a hollow. Experts at dissection seem to have called these last heads kondu/loi, 46 “condyles,” and the former simply kefa/laia, “heads.” We shall presently add some remarks about the condylus (since this name is so variously employed by many writers).

A)/rqron: joint
A)/rqron, which we call joint, is what the Greeks first called a joining of bones made for movement. Hippocrates often, particularly in his books De fracturis and De articulis, and Galen also in his Commentaries on those books, called the joint the round part of a bone, also named the head, inserted into the hollow or cavity [fossa] [incisura] of the adjacent bone.

Vertebrum, vertebra, spo/nduloj
Latin authors seem to have called this kind of head vertebrum or vertebra; 47 this is the name they use when the head of the femur enters the cavity [fossa acetabuli] of the hip. Though some have been willing to give this name to the entire joint of the hipbone with the femur, it would have been better to use this term only for the bones of the dorsal vertebra; so for us vertebra means what spo/nduloj meant to the Greeks: any bone of the back, which is also called verticulum by many, probably from the shape of the pivot or whorl (verticula) with which women weight their spindles.

Types of head
The heads which swell out in the manner just described are of a simple or single type in certain bones, as in the femur where it is articulated with the hip and in the metatarsal and metacarpal bones, where they meet the first digital bones. Others are of a double or twin variety, divided by a gap, as on the femur [fossa intercondylaris] where it meets the tibia and in the first and second digital bones at the lower end 48 where they enter the cavity of the next bone. Other heads appear round, like the upper head of the femur; others are drawn out farther from the right side to the left and thus become rather broad, like the heads [processus condylaris, caput mandibulae] of the lower maxilla. Still others are stretched from front to back, like the heads [condyli occipitales] of the occipital bone that enter the depressions [massa lateralis atlantis, facies articularis superior] of the first vertebra. But although the shapes and varities of such heads are as worth knowing by a physician worthy of the name as one’s own fingernails, if only for the sake of dislocations, at this point I did not think them worth subdividing at greater length because I will try to describe them individually in the greatest detail when I describe each bone. 49 The heads of bones are more than once called e)pifu/seij by Galen, perhaps because many of them are made up of an epiphysis, as is the head of the femur, the upper head of the humerus, and the heads of the metatarsal and metacarpal bones where they are held in by the first digital bones. But many heads of bones are not made of an epiphysis: the talus is completely lacking in epiphysis, and likewise the humerus [condylus humeri] where it is joined to the forearm. 50 Also, the lower maxilla puts out heads [processus condylaris] but not epiphyses. Hence the words of Galen are not altogether authoritative where he taught that the heads of the kw/la or limbs are called e)pifu/seij and kondu/loi. 51

Ko/nduloj or Condyle
Latin writers translate ko/nduloj now joint, now node, now hump, now head, now capitulum, now digital bones, because they recognize that it is quite variously understood by the Greeks. In the treatise of Galen just mentioned, the heads of the limbs are seen to be called by that name. In De anatomicis administrationibus he so names the two lower heads of the femur [condylus medialis, c. lateralis] and the lower tubercules or heads of the humerus [condylus humeri], exactly as if twin heads of bones were called by that name. Hippocrates introduces the same usage into his book De articulis 52 where he says that a dislocated shoulder can be restored by the ko/nduloi, that is by the joints of the fingers. It is reasonable that the bones of the fingers should have been so named by some because they have twin heads (G and H in figure 2, Chapter 27), like the lower end of the femur. 53 This is particularly true of the first bones of the four digits [phalanx proximalis], which in the treatment of a dislocation are chiefly what moves the humerus outward and then up. 54 In addition, Galen in the first

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book of De motu musculorum 55 calls the low capitulum of a bone a ko/nduloj when he compares a kefalh/ or head to a kotu/lh, acetabulum or deep recess; ko/nduloj, by comparison, is a low, very slightly protruding or flat capitulum, and glh/nh 56 is what we call a recess, so lightly carved in the bone that you can scarcely distinguish whether it is a recess or a capitulum. This is the way the name ko/nduloj was no doubt established by the first professors of dissection; but I shall in the meantime take the simple precaution of seeing to it that this word does not create any obscurity in my discourse, since it is no less easy to call the inner or outer head of the femur next to the knee “an imperceptably and slightly protruding capitulum” than to bring ambiguous language such as “condyle” or “node” or the like into my text. Likewise in the description of each bone we will consistently establish that name for ourselves. In our subsequent account of the muscles, veins, arteries, and other parts of the body, we shall never depart from it. 57

Tra/xhloj, a)uxh/n: neck, cervix
Latin writers call tra/xhloj and au)xh/n the neck and cervix, meaning by these words the part of the bone which corresponds to our neck. The neck or cervix is a thin process of a bone whose end thickens into a head. Such necks are nowhere seen quite as well as they are in the femur (h, h, in figures A and B) [collum femoris] next to the very elevated head that is articulated into the hip. In the lower maxilla such a conspicuous neck presents itself (i in figure C) [collum mandibulare] that we know anatomists often use the term “head of the neck of the lower maxilla.” In the talus also a cervix appears (k in the foot) [collum tali], visible before its rounded head which is articulated into the navicular bone. In addition to these the metatarsal and metacarpal bones show necks (l, l in the foot) where they are articulated with the digits. In other bones they are not as clearly seen. Sometimes, not only are thinner parts of bones that swell out into heads called necks, but we also use the term for thin processes that become thicker and form a depression into which another bone articulates. If this is seen anywhere, it is certainly clearest in the scapula, whose narrower part [collum scapulae](C, D in figure 1 and 2, Chapter 21), located before the cavity [cavitas glenoidalis] to which the humerus is articulated, has also gotten the name neck from professors of anatomy. 58

Kotu/lh, o)cu/bafon: acetabulum, socket, etc.
Kotu/lh, kotulhdw/n, and o)cu/bafon are terms which in their description of bones the Latin authors translate acetabulum, acceptabulum, commonly pyxis, and sometimes buccella (we are applying here no standard of measurement). 59 By these names they identify the cavities which descend deeper and are hollowed out further to receive the heads of bones. Sockets or acetabula of this sort are seen in the hip bone [os coxae], where the head of the femur is admitted [fossa acetabuli] (n in figure D); also in the navicular bone [facies articularis] (k in figure 11, Chapter 33), where the head of the talus enters. Nowhere in the body are there cavities [facies articulares] deeper than these into which the heads of bones are fitted. But I believe the first professors of dissection applied this name not only to obviously deep cavities, but also every cavity receiving the head of a bone, provided somebody affirmed at first glance that there was such a cavity.

Glh/nh or glenoid depression
The form of depression that is only lightly and superficially hollowed out is called glh/nh, I conjecture, from the eye socket. 60 It takes such a form that you would not know whether it admits one bone or enters another, no differently than if two flat, planed roof timbers were placed against each other. The glh/nh would resemble a flattened head which I think was originally called a ko/ndulon. Depressions such as this occur on the tarsal bones where they meet the metatarsals [facies articularis metatarsalis] (p, p, p in the foot illustration). Likewise, the places on the navicular bone where it receives the bones of the tarsus are of this type, and several of the carpal bones (M, L, and K in figure 6, Chapter 25) to which the metacarpals are articulated. Those scarcely hollowed depressions occur 61 also in the first vertebra [atlas] of the neck, where it admits the low capitula of the second [axis]. I do not say these things because I wish to prevent certain cavities (which though they clearly present the shape of a depression are still not very deeply impressed) from being called glh/nai also. I would not want to enter into a dispute whether the depressions [facies articularis superior] of the tibia in which the lower heads [condylus medialis, c. lateralis] of the femur fit deserve the name kotu/lh or glh/nh. Still, if we conscientiously separate the types of articulation, we will most justifiably call a visible depression kotu/lh, and glh/nh a depression so unclear that we are unsure whether it should truly be counted as such.

The function of depressions and heads
We shall explain why depressions are carved now lightly, now deeply by the Maker of things 62 in the next chapter, which will explain the different ways in which bones are jointed — since it is for the sake of joints that both depressions and heads are fashioned. Here, however, it will suffice to state only the names, and if in the meantime anyone wishes, it will be permitted to add here, incidentally, the types of cavity.

Types of cavity
Besides the fact that some are cut in deeply and others only on the surface, some are round and spherical, like the cavity of the hip bone that receives the head of the femur, and the cavities of the finger bones into which the postbrachial bones are articulated. Others are oblong, like the cavity [facies articularis carpalis] of the radius (x, z, y in figure 8, Chapter 24) that receives the carpus, and the cavities [facies articulares superiores] of the first vertebra that take the capitula [condyli occipitales] of the occipital bone; in this category are also placed the cavities [fossae mandibulares] of the upper maxilla that admit the lower maxilla [mandibula]. Others are twin, like the cavities [condylus medialis, c. lateralis] of the tibia into which are placed the lower heads [condylus medialis, c. lateralis] of the femur; most cavities of the digital bones (K in figure 2, Chapter 27) are also considered twins. 63 Others resemble pulleys [trochleae] or small sheaves, like the depression [fossae olecrani, coronoidea, radialis] of the humerus that admits the ulna (K, L, M in figures 1 and 2, Chapter 23). Others resemble the letter C, like the cavity of the ulna (E, C, D in figure 1, Chapter 24) [incisura trochlearis, olecranon, processus coronoideus] which the humerus enters.

I)/tuej, o)fruej, a)/mbonej, xei/lh: brows, lips
As the cavities and heads are constituted

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for the sake of the joints, so also are the i/)tuej, o)fruej, a)/mbonej, and xei/lh, which in the Latin writers are called brows and lips. These are processes projecting towards the round space of the cavities like lips, increasing their depth. Although these are conspicuous in almost all joints and articulations of bones, they most clearly display their nature in the deepest cavities. So in the socket [fossa acetabuli] of the hip bone to which the femur is articulated the highest and most projecting brows [limbus acetabuli] are seen, making the cavity more hollow and more effectively preventing dislocation of the femur. Brows primarily contribute to preventing dislocation.

Baqmi/dej: hollows
Baqmi/dej are 64 cavities that like a base or brace prevent a bone from being moved at all beyond what is useful to the creature. In the anterior part [fossa coronoidea] of the humerus (N in figure 1, Chapter 23) and in the posterior [fossa olecrani] (O in figure 2, Chapter 23) a cavity is carved, each receiving a process of the ulna (C and D in figure 1, Chapter 24) [processus coronoideus, olecranon]. The anterior cavity [fossa coronoidea] admits the forward process of the ulna when the forearm in fully flexed; the posterior cavity [fossa olecrani] admits the posterior process of the ulna in extensions of the forearm. Since the posterior cavity does not admit passage into the anterior, they prevent the ulna from being moved at all beyond what is useful. If they were interconnected and did not obstruct the processes, we could extend our forearm as readily into an acute angle as we now bend it. And so the first professors of dissection justifiably termed these cavities baqmi/dej, though Hippocrates used the term not only for this kind of cavity but also for others into which protuberances that enter the bones become embedded. 65 He called the C-shaped cavity [incisura trochlearis] which the furrow of the humerus enters a baqmi/j, as others term the joint [articulatio cubiti] of the rest of the elbow. Those cavities that I first described in the humerus claim solely for themselves a feature they have almost alone of all the cavities that receive the processes of another bone in the movement of joints: they are covered with almost no cartilage.

Depressions not made for joints
The same applies to most of the other cavities of bones not made for joints but carved only for the stronger insertion of muscles and ligaments in a better seat, and sometimes also to provide origins for the same. Such a depression is observed on the inner side [fossa trochanterica] of the large outer process of the femur (R in figure 1, Chapter 30), and in the talus and calcaneus between the two joints by which these bones are joined together (T, T in figure 4 [collum tali], and V, V [sulcus calcanei] in figures 7 and 8, Chapter 33). But all of this (as well as the depressions [canales] in which tendons 66 are carried and prevented from leaving their seat (g, d, i, and z in figure 2, chapter 24) such as occur 67 on the external seat of the radius next to the carpus) will be more obvious in the separate descriptions of the bones; and if I omit here any name which will be needed in the description of bones, I shall cover it in subsequent chapters. However useful, I fear that such prolixity before the account of each bone may deter someone eager to move along from his interest in anatomy, and that he may seek out another compendium at no small expense. Yet no less for the reading of Galen’s books than for the description of bones that follows, this first taste of names has been worth the trouble.

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]