Index of the three figures at hand and their characters (which will follow the order of their presentation in this chapter).

Ilium; Pubis; Hipbone
Its broad part, both superior and posterior, the part [facies sacropelvica, f. auricularis] attached to the sacrum, is called the ilium, while the anterior part of the same bone, by which it is joined (j in the skeletal figures) [symphysis pubica, discus interpubicus] with the bone of the other side in the region of the pubis and has a wide foramen, is called the pubic bone. The area between, positioned at the entrance of the femur, is called the hipbone [os ischii]. In this way the bone of one side [os coxae] is named no differently than if it were constructed of three bones ending at their own border, posterior, anterior, and middle, or ilium, pubis, and hipbone. The entire bone is called the coxa by Celsus, and the i)sxi/on (which is the hipbone) by the author of Introductio seu medicus and often by Hippocrates, ²¹ though both also call the wider, posterior part of this bone the ilium and the anterior the pubis,

The use of the bones attached to the sides of the sacrum
There is a very great affinity with the scapulae in the use of these bones. For as the scapulae are formed particularly to articulate the humerus, these are especially accommodated to articulate the femur (L into Q in the skeletons), so that man may stand erect and sit with their aid. As the scapula is wide and equipped with various processes (to make it fitter for admitting and putting ²³ several muscles), so these bones show nearly every type of construction designed so that almost all the muscles moving the femur can originate from them — in addition to others which originate from these bones and provide movements to the tibia, thorax, and back. ²⁴ What muscles ²⁵ originate from these bones and which ones are implanted in them, the order of narrative describing the parts of the bones will explain. But now, a use of these bones that is by no means the smallest no smallest must not be omitted, how in the common way of bones they are placed beneath the other parts of the body like fulcrums, and hold them in or surround them. These two bones (Q [os ilii] with M [vertebra lumbaris V] in skeletons 1 and 3) together with the sacrum form a kind of basin ²⁶ which neatly supports the intestines and the bladder [vesica urinaria] (these are found in the figures of Book V, especially 22, 24, and 25), and in women it most elegantly contains the uterus and keeps safe the parts that it encloses.

The surface of the ilium attached to the sacrum
First, the area of the ilium attached to the sacrum (A, B, C, D, E, F, G in figure 3) [facies sacropelvica, f. auricularis] is especially varied, as we have said the transverse processes of the sacrum are varied and complex at the point [pars lateralis, facies auricularis] where they are joined to the iliac bones. The convex parts [facies sacropelvica] of the ilium will match individual depressions of those processes, and its depressions will match the convexities of the same processes in such a way that the ilium is joined to the sacrum by the mutual fit of their various parts: not indeed with a connection built for voluntary motion, or with smooth depressions and convexities coated with slippery cartilage, but with a very powerful bond comparable to a type of symphysis or union. ²⁷ This is accomplished by means of cartilaginous ligament, or rather pure cartilage. ²⁸ The shape of the depressions and projections by which the ilium is attached to the sacrum is easily discovered from the description of the sacrum. As it was first stated that the transverse processes of the sacrum are equipped with a long depression, so too the ilium has a long projection (C, C in fig. 3; compare in order with fig. 2, ch. 18) [facies auricularis] that matches the depression; and because the anterior part or brow of the depression of the processes protrudes and extends quite markedly, there are also carved in the ilium, close to the anterior surface of its long ridge, depressions (A, B in fig. 3) which those protruding parts enter. When the lowest part of these depressions (B in fig. 3) is viewed, the ilium becomes sharp like a knife [spina iliaca posterior inferior] so that it makes a single surface with the transverse process [pars lateralis] (the lower L in fig. 2, ch. 18) of the fourth bone of the sacrum. In turn, the long depression of the ilium (D, D in fig. 3) fits and precisely admits the long ridge of the sacrum, which we have said stands out like a spine ²⁹ in the depressions of the processes. The iliac bone (E, F, G in fig. 3) [tuberositas iliaca] does not as perfectly match the two depressions of the processes by the posterior end of the ridge just mentioned, and the ridge protruding transversely between the depressions, ³⁰ since it does not protrude as high as the depressions of the processes are carved deep. Nor does the iliac bone provide a place to receive the ridge between those depressions. In a word, the sacrum is not quite conterminous with the ilium in the area where those two depressions of the processes of the sacrum are seen, but a very large cartilage ³¹ participating in the nature of a ligament ³² comes between these bones and packs the entire space where the bones are separated. The entire surface of the ilium that is attached to the sacrum is rough, uneven, and quite thick, as we know other bones are wide and thick in the areas where they are attached to each other so as to effect a stronger and broader bond.

The part of the ilium extending behind the transverse processes of the sacrum
This thick part of the ilium stands out and extends to the rear (H, I in figs. 2, 3) [crista iliaca] much more than the breadth of the transverse processes of the sacrum, in the first place because the ilium needed to be extremely broad and spreading like the scapula to allow for the origin of muscles that move the femur as well as many others to be explained later; further, to establish a fit place near the posterior of the sacrum from which the fourth muscle of those that move the thorax in man (D in the 12th table of muscles) [m. iliocostalis thoracis] might originate; together with the eleventh of those that move the back (G in the 13th table of muscles) [m. longissimus thoracis], which takes its origin together with the muscle of the thorax from the inner side of the ilium (whence we have said it is carried backward) and from the posterior surface of the sacrum, in the same way as the thirteenth of the muscles moving the back (T, V in the 14th table of muscles) [m. multifidus] originating from this point in the ilium and the sacrum.

The epiphysis of the ilium: spine, back
The remaining breadth of the ilium, not unlike a flat semicircle, has an epiphysis (L, R, R in fig. 1, H, R, R, P in fig. 2, P, L, H, Q in fig. 3) [crista iliaca] on its upper surface along the entire circumference of the semicircle which the ancients called the spine of the ilium. They named the outermost [lateral] portion of its breadth [ala ossis ilii] the back of the ilium [facies glutealis] because it is wide and more or less convex if compared to the inner [medial] surface [fossa iliaca]. The [anterior] surface of the epiphysis projects outward, and is rightly considered as it were the spine [spina iliaca anterior superior] of that back [ala ossis ilii]. But although the ancients rightly established these names, and Galen noticed that there is also a distinction between them as between the parts of a bone, ³³ nevertheless in his description of muscles that move the tibia and the femur he frequently confused the dorsum [ala ossis ilii, facies glutealis]

Muscles occupying the epiphysis
The bone [ilium] is indented on its inner surface so that this spine will be widened here and better put forth the fleshy part of the transverse abdominal muscle (D in the 6th table of muscles). On its outer side the epiphysis is compressed and widened so that the fleshy part of the obliquely ascending abdominal muscle (P in the 4th table of muscles) [m. obliquus internus abdominis] may best originate from here and the obliquely descending abdominal muscle (Q in the 3rd table of muscles) [m. obliquus externus abdominis] may be inserted here. The entire upper surface of the epiphysis is occupied by these three muscles. As these are wider and more fleshy on the sides of the ilium than next to the backbone or on the anterior surface of the abdomen, so too the part of the epiphysis (from R, through R, to P in fig. 2) which faces the sides of the abdomen and is anterior, together with the surface of the ilium to which the epiphysis is attached, is heavier than the part (from R through H to Q in fig. 2) next to the vertebrae and the backbone. The anterior extremity of the epiphysis (P in figs. 1, 2, 3), or the anterior part of the spine of the ilium [spina iliaca anterior superior], is very thick ³⁵ because in addition to the abdominal muscles attached to it, it provides an origin to two muscles, one of them to be numbered the first of the movers [m. sartorius] of the tibia (S and later s in the 3rd table of muscles), the other the sixth (F, then x in the same table) [m. tensor fasciae latae]. ³⁶

Muscles occupying the inner space of the ilium
From the inner surface of the wide part of the ilium originates first the muscle (C in the 8th table of muscles) [m. quadratus lumborum] that will be the ninth of the movers of the back, which takes a portion of its origin from the smooth but quite broad hollow (next to the left [right] side of K, K in fig. 3) of the ilium, visible near the region of the transverse processes of the fifth lumbar vertebra. But besides this compression of the ilium there is another great hollow [fossa iliaca] in it (within P, L, K, K, M, N, S in fig. 3), not at all rough, occupied by the seventh [m. iliacus] of the muscles that move the femur (L in the 8th table of muscles); we shall explain that this muscle originates from a wide, fleshy, semicircular beginning in this inner breadth of the ilium and then gradually narrows and together with the tendon of the sixth (Q in the same table) [m. psoas major] of the muscles that move the femur and the first nerve (57 in fig. 2, ch. 10, Bk. 4 and z in the 10th table of muscles) [n. femoralis] ³⁷ to the leg is taken through the depression (T in figs. 1, 2, 3) [sulcus supra-acetabularis] carved especially for it in the hipbone. ³⁸

Depression carved in the upper part of the hipbone
In the upper part of the hipbone, near the upper region of the acetabulum (e, f, g in figs. 1 and 2) to which you will hear the head of the femur (A in figs. 1 and 2, ch. 30) is articulated, a wide depression [sulcus supra-acetabularis] is cut corresponding to muscles which descend this way; in a cleaned bone, it is seen to be filled with certain small foramina so it can put forth a ligament [articulatio coxae, capsula articularis] which makes the bone smooth and slippery as if coated with a kind of grease ³⁹ so that the seventh muscle of the femur [m. rectus femoris, caput reflexum] and the tendon of the sixth [m. rectus femoris, caput rectum] may properly bend and twist ⁴⁰ against this depression.

Projections of the depression
At either side of this depression, a single tubercle (the outer one marked S, the inner X in figs. 1, 2, 3) stands out rather prominently, increasing the depression and preventing the muscles descending this way from leaving the depression. But in addition to this use, the tubercle [spina iliaca anterior inferior] at the outer side of the depression ⁴¹ puts forth the ninth (F in the 4th table of muscles) [m. rectus femoris] of the muscles that move the tibia; because of this use it is quite large and uneven, having a small dimple (S is placed on the dimple in the first figure) like a cleft from which that strong muscle originates. The other tubercle [eminentia iliopubica], constituting the inner side of the depression just mentioned, provides considerable strength to the hipbone which needs to be thick and strong not only for the sake of a robust articulation but also because it had to be carved from the deepest socket [acetabulum] in the entire body, to which the femur is articulated.

How the strength of the hipbone is provided for
On account of this use, the iliac bone is made heavy and strong on its inner side toward the upper region of its connection with the sacrum (M, N, O in fig. 3) [linea arcuata] and is extended in a continuous eminence as if to the inner part of a second ⁴² tubercle which not only augments the strength of the hipbone but also provides the starting point for the tenth of the muscles [m. obturator internus] that move the femur (F, G in the 16th table of muscles and r in the 13th), which occupies the inner surface of the pubic bone ⁴³ and rotates the femur outward.

The line on the back of the ilium and the muscles which occupy it ⁴⁴
From the back of the ilium or its wide outer area, which is rougher than the bone’s interior surface, three muscles (the first: P in the 9th table of muscles; second: S in the 10th; third: S in the 11th) [m. gluteus maximus, medius, et minimus] chiefly originate, occupying the entire back of the ilium with their beginnings. The first [m. gluteus maximus] will be counted the first of the muscles that move the femur, filling most of the posterior surface of the iliac dorsum with its origin. Two lines (one is Z, Y [linea glutealis anterior], the other a, b [linea glutealis inferior] in fig. 2) projecting quite obscurely on the back of the ilium indicate how great a portion of this surface it occupies; they run like a semicircle and mark off the back of the iliac bone into three areas. The first, located outside the first line [Y, Z], is occupied by the first of the muscles [m. gluteus maximus] that move the femur. The second, visible between the first line and the second [a, b], puts forth the muscle [m. gluteus medius] which will be counted the second of those that move the femur. The third area, which extends from the second, shorter line to the hip joint, provides the starting place for the third of the muscles [m. gluteus minimus] that move the femur. This is the way the wide part of the bone attached to the sacrum, which is called the iliac bone, is arranged; the middle part, which is called the hipbone [os ischii], has also been explained to a great degree. We have said that the bone in that area is made thicker and stronger so that it may better support the entire body when resting on one leg, and become a fit place for a socket [acetabulum] suitable to articulate the femur to be incised.

The acetabulum provided to articulate the femur
Into this area of the hipbone ⁴⁵ (e, f, g in figs. 1 and 2) is incised the deepest of all depressions of the body into which a bone is articulated, not everywhere smooth and coated with slippery cartilage [cartilago hyalina]. For in its anterior area, a considerable portion (g in figs. 1 and 2) [fossa acetabuli] is cut more deeply than its remaining circumference [fossa lunata]; it is rough and filled with certain small, blind foramina whose purpose is to put forth a ligament (P in fig. 2, ch. 49, Bk. 2) [lig. capitis femoris] which is smoothly rounded and inserted into the middle or vertex [fovea capitis femoris] of the femoral head. The brows ⁴⁶ (i, i, in figs. 1, 2) [limbus acetabuli] of the acetabulum protrude less in the anterior than in the posterior because

The depression by which the thickest nerve in the body is conveyed
In this bone an area (c in figs. 2, 3) [incisura ischiadica major] should be noticed that is seen between the anterior part of the iliac bone which is attached to the sacrum and the posterior region of the hipbone, carved out to provide a path for the nerve (71 in figs. 2, 3, ch. 11 Bk. 4) [n. ischiadicus] which is the fourth of those going to the leg and is the greatest of all the nerves of the body, being composed of several nerves. ⁵²

The acute process of the hipbone
The acute process (d in figs. 2, 3) [spina ischiadica] of the hipbone should also be observed here; it puts forth a ligament (o in the 13th table of muscles) [lig. sacrospinale] that extends to the transverse process (R in figs. 1, 2, ch. 18) [pars lateralis] of the fifth sacral bone, and it provides the origin for the muscle [m. gemellus superior] (x in the 13th table of muscles or b in the 12th, where the tenth muscle is marked a) [m. obturator internus] which we shall either ascribe to the tenth of the muscles that move the femur or number separately the eleventh.

The depression against which the tenth of the muscles that move the femur turns
We must not pass over (here see r, s, t, u, x, y, z in the 13th table of muscles) ⁵³ the depression [incisura ischiadica minor] carved out from the posterior and inner ⁵⁴ region of the hipbone beneath the process just mentioned, against which by the admirable cleverness of Nature the tenth of the muscles [m. obturator internus] that move the femur is bent back as if on the wheel of a pulley.

Epiphysis of the hipbone
The epiphysis of the hipbone (l marks the posterior area in fig. 2, q the anterior) [tuber ischiadicum] will not be hastily investigated on its entire lower surface, attached to the point on which we rest when we sit. This epiphysis, to which the bone fuses, preserves its breadth. Both for the sake of strength and for the origin of muscles it is seen to be remarkably thick and quite wide. From this epiphysis, at a minimum, four large muscles originate, each of whose heads claims a depression and place of its own (in fig. 2, the first is m, the second o, the third n, the fourth from p to q) on the epiphysis, easily visible in a cleaned bone. ⁵⁵ The first (F in the 10th table of muscles) [m. semitendinosus] will be the third of the muscles that move the tibia, taking its origin from the higher ⁵⁶ part of this epiphysis. The second (Y in the same table, and m and later ϖ in the 11th table) [m. biceps femoris, caput longum] will be held to be the fourth of the muscles that move the tibia; the beginning of this muscle is less wide than that of the first, and it begins more towards the anterior, next to the outermost side of the first muscle. The third muscle (Y in the 11th table of muscles) [m. semimembranosus] I shall consider the fifth of those that move the tibia. The fourth (W in the 11th table, C in the 12th) [m. adductor magnus] is the largest part of the muscle that Galen counts as the fifth of the muscles that move the tibia, ⁵⁷ but which I shall say constitutes the fifth of those that move the femur. This occupies the largest area of the epiphysis with its origin, and is easily the largest of all the muscles in the body. This is how the middle part ⁵⁸ of the bone we are describing, which we call the hipbone, is arranged.

An account of the pubic bone
The anterior, which is called the pubic bone, is quite slender, and the right bone is attached to the left by means of cartilage (j in the skeletons) [discus interpubicus] as if by symphysis [symphysis pubica]. The more advanced in age a person is, the less this union is filled with cartilage and the less cartilage it shows. This is common to both men and women.

The difference between the attachment of bones to the sacrum in men and women
It should by no means be thought on account of vulgar opinion ⁵⁹ that the pubic bones are continuous in men but attached with cartilage in women so they may be loosened and detached from each other in time of childbirth. When women give birth (as with quadrupeds) these bones are not detached from each other; but they do have this special feature in the union of these bones, that their bones are not attached along such a long line as men’s. Moreover, the lower parts of the hipbones [os ischii], both left and right, are farther apart from each other in women than in men. When the lowest parts of the pubic bones [ramus inferior ossis pubis] are pulled apart beneath their meeting place, they are separated and stand apart ⁶⁰ much more in women than in men. Thus in the bones of women there is an empty area between the coccyx and the inner regions of the lowest hipbones much larger than occurs in men. This difference is so marked as clearly to show by itself that the bones of the pubis are not opened up in childbirth — it is attested by touch during parturition, though it is not easily felt. Animals with tails also demonstrate clearly how much the coccyx (G, H, I, K in figs. 1 and 3, ch. 18 and N in skeletons 1 and 2) aids in expanding this wide area still more when giving birth; but it is also possible to observe this in women whose coccyx is so extended outward like a tail that among all the nations I have seen chairs are fitted to them because of this bone by having a round hole cut in them. For this reason, most women give birth better when resting on their knees and bending forward somewhat, as it is more difficult for them in an erect or backwardly reclined position. ⁶¹ This is the provision Nature has made for women in expelling the fetus. In order that

Why the pubic bone is pierced by a very large foramen; its depressions and convexities
Why the pubic bone is perforated by the largest foramen (r in figs. 1, 2, 3) [f. obturatum] of all the bones of the body (which also, because of its size it is called quroeide/j from its resemblance to a door) ⁶³ is understood by those who have learned in dissecting exactly what muscles originate from the hipbone and the pubis, for they say that the pubic bone needed to be a wide area fit for the origins of muscles. Lest an animal be needlessly weighed down but rather be light, it has the foramen which we mentioned. No one should think that the seminal vessels (e and from i to u in fig. 20, Bk. 5; or from g to z in fig. 22) [ductus deferens] or the largest veins (j in the figure for ch. 6, Bk. 3) [v. iliaca communis] and arteries (f in the figure for ch. 12, Bk. 3) [a. iliaca communis], or even the nerves (71 in fig. 2 ch. 11 Bk. 4) [plexus sacralis] descend this way, as anyone untrained in anatomy believes who looks at the bare structure of bones. For those organs have another route: the largest vein to the leg [v. femoralis], and the artery [a. femoralis], together with the second nerve (60 in the same figure) [n. femoralis] to the leg make their own depression (V in figs 1, 2, 3) [ramus superior ossis pubis], worked into the upper surface of the pubic bone away from the vicinity of the upper area of the foramen (r in figs. 1, 2, 3) [f. obturatum] just mentioned. Furthermore, you will hear that a course has been provided for the seminal vessels even higher than where the pubic bone projects in the abdomen. The great foramen of the pubis is filled with a strong membrane (O, O in fig. 2, ch. 49, Bk. 2) [membrana obturatoria] which separates the muscle (F, G in the 16th table of muscles) [m. obturator internus] next to the inner surface of the foramen from the one (Y in the 8th table of muscles) [m. obturator externus] ⁶⁴ which occupies the outside surface of the foramen. Nothing else transits this foramen [f. obturatum] except a vein (ei in ch. 6, Bk. 3) [v. obturatoria], an artery (j in the figure for ch. 12, Bk. 3) [a. obturatoria], and the nerve (66 in figure 2, ch. 11, Bk. 4) [n. obturatorius] ⁶⁵ whose series of branches ⁶⁶ is not carried as far as the knee. These vessels are not borne through the middle of the foramen; rather, a depression (s in figs. 1, 2, 3) [sulcus obturatorius] is carved in the upper surface of the foramen, provided to bring them down. That the upper part (to the right side of u in fig. 2) of the pubic bones where they are joined together [corpus ossis pubis, facies symphysialis] is rough happens because Nature saw fit to have the straight muscles of the abdomen (D in the 5th table of muscles) [rectus abdominis] originate from here. The anterior surface of these bones is also rough there so that the sinewy head of the second (D in the 16th table of muscles) [m. gracilis] of the muscles that move the tibia might duly begin from here. Also, on the anterior surface of the pubis from the inner side of the acetabulum of the hip to the joining of the pubic bones (from h to u in fig. 2) a projection and kind of prominence [crista obturatoria] is seen, from which the eighth (a in the 7th table of muscles) [m. adductor longus] of the muscles that move the femur takes its origin. Just as this anterior area of the pubic bone protrudes, so also the posterior shows a sharp line (O in fig. 3) [pecten ossis pubis] from which the tenth (G in the 16th table of muscles) [m. obturator internus] of the muscles that move the femur takes a portion of its origin. To all of these is added the thick part (t in figs. 1, 2, 3) [ramus inferior ossis pubis] of the pubic bone next to the lowest area of the connection of the pubic bones and the inner side of the great foramen where the pubic bone is more or less rounded and heavy ⁶⁷ so as to increase the strength of the bone and also so that in addition to certain muscles of the penis (L, K in the same figures) [mm. ischiocavernosi], one of the bodies (A, B in figs. 1 and 2, ch. 49, Bk. 2) [corpora cavernosa penis] that make up the penis may originate here.

The bones attached to the sides of the sacrum are made up of three bones in small children
This is how the bones are which are attached to the sacrum. In those of advanced age they appear to be only two, each having two epiphyses ⁶⁸ (as has been related). But in young children, each of the two is made up of three bones which are distinguished by three lines filled with cartilage. ⁶⁹ These lines, joined together at the center of the acetabulum of the hipbone, extend from here; one runs to the upper part of the acetabulum, the second to the outer side of the acetabulum; the third is carried to the inner side and proceeds through the pubic bone where we said it is somewhat smoothly rounded and produces one of the bodies of the penis. ⁷⁰ But since these are no less plain to see in lambs and kids than in humans, anyone can see them even while eating. ⁷¹