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]



page 136

Chapter 31 On the Tibia and Fibula

[Figures of Chapter XXXI]





page 137

Index of the figures of the thirty-first chapter and their characters.
The eleven preceding figures have a view to the right lower leg; the first depicts both bones situated in the lower leg in their anterior face: the thicker, inner [medial] bone which we shall call the tibia, and the more slender, which is located more exteriorly [laterally] and will be called by us the fibula rather than the sura. 1 The second figure most suitably delineates the tibia together with the fibula in their posterior aspect. The third shows the anterior surface of the tibia by itself. In the fourth, the posterior surface of the tibia is presented to view. The fifth illustrates the fibula in its anterior surface. The sixth exhibits the fibula drawn from the rear. The seventh portrays the upper [proximal] surface of the tibia, to which the femur is articulated. The eighth contains the two cartilages [meniscus medialis, meniscus lateralis] which extend the cavities [facies articularis superior] in which the heads [condylus medialis, c. lateralis] of the femur are received. The ninth sets forth the lowest [distal] surface of the tibia and fibula in their anterior part so as to expose to view the cavity [facies articularis inferior] provided for the articulation of the talus with the lower leg. The tenth presents the lowest surface of the tibia shown from the posterior, where the talus is received. The eleventh shows the inner side of the fibula’s lower epiphysis, which is articulated to the talus. The index of characters will be as follows.

A, B[ 1, 2, 3 ] By these two characters 2 in the first figure is identified the upper epiphysis of the tibia, while in the third and the second a line [linea epiphysealis] is indicated showing the fusion of the epiphysis with the remaining portion [corpus tibiae] of the bone.
C[ 1 , 5 ] The upper epiphysis of the fibula [caput fibulae] is so marked in the first figure, and in the fifth the fusion of the epiphysis with the rest of the bone [corpus fibulae].
D[ 1, 3 ] In the first figure, the lower epiphysis of the tibia; in the third, the fusion of the epiphysis [linea epiphysialis].
E[ 1 , 5 ] In the first figure, the lower epiphysis of the fibula [malleolus lateralis]; in the fifth, the fusion [linea epiphysialis] of the epiphysis to the bone. Although I have not marked such epiphyses and fusions in all the figures, I believe the epiphyses will be obvious to all. 3
F, G 2, 4 , 7 Depressions [facies articularis superior] in the tibia to which the lower heads of the femur [condylus medialis et lateralis] are articulated.
H, I, K 7 Protuberance of the tibia [eminentia intercondylaris] separating the depressions in which the heads of the femur are received. H [area intercondylaris anterior] marks its anterior end, I [tuberculum intercondylare] 4 the middle, which protrudes more, and K [area intercondylaris posterior] the posterior. These characters are seen in the portions of the protuberance which are depressed. Of these, K and I in the second, third, and fourth figure mark the same thing as in the seventh.
L 8 Cartilage [meniscus lateralis] extending the right 5 depression [facies] of the tibia in which the outer head of the femur [condylus lateralis] is received.
M 8 Cartilage [meniscus medialis] increasing the left or inner depression of the right tibia to which the inner head [condylus medialis] of the femur is articulated.
N 8 At this point the cartilages increasing the depression of the tibia are at their thickest.
O 8 At this point the cartilages just mentioned are at their thinnest, and come to an end before the center of the depressions.
P, P 8 At these points 6 the cartilages end at their tip.
Q 5 Depression [facies articularis capitis fibulae] lightly carved in the surface of the fibula, to which is articulated the tubercle of the tibia marked R.
R 4 Tubercle [facies articularis fibularis] or head of the tibia which is fitted to the fibula.
S 4 , 10 Depression [incisura fibularis] of the tibia, where it receives the lower end of the fibula.
T 5, 6, 11 Inner side of the fibula [facies articularis malleoli lateralis], which is joined to the tibia.
V, X, Y[ 2 ] In the second figure, V [facies articularis fibularis] marks the upper joint of the fibula to the tibia and X the lower. Y marks the interval [interossea cruris] by which these bones separate from each other.
Z 1, 2 In this area the fibula does not run straight, but is angled somewhat inward and is flat on its outer side.
a, b 1, 3 , 7 Anterior surface of the tibia, into which the muscles 7 that extend the tibia are inserted.
c 5, 6 Process [apex capitis fibulae] of the upper epiphysis of the fibula, into which is inserted a tendon of the fourth muscle [m. biceps femoris] that moves the lower leg.
d, e, f, g, h 9 Surface to which the upper part [trochlea tali] and sides [facies malleolaris medialis et lateralis] of the talus are articulated. d, e, and f [facies articularis inferior tibiae] show the upper region of this surface in the ninth and tenth figures. d marks a tubercle in this region; e and f are a part of this region on each side near the side of the tubercle marked d, more deeply depressed than the tubercle itself. g [facies articularis malleoli] marks the inner side of this area, which is formed by the outer side of the process of the lower epiphysis of the tibia, marked F [malleolus medialis] in the first figure. In the ninth and eleventh figures, h [facies articularis malleoli] shows the outer side of this surface which is fitted to the talus, formed by the inner side of the lower epiphysis of the fibula, marked E [malleolus lateralis] in the first figure.
F [ 1 ], i[ 2, 3 , 9, 10 ] In the first figure, F marks the process [malleolus medialis] of the lower epiphysis of the tibia which is the outer 8 malleolus.


page 138

In the second, third, ninth, and tenth figures, i marks the same process of the epiphysis.
k 4 , 10 Depression [sulcus malleolaris] of the inner malleolus, from which a cartilaginous ligament 9 is inserted into the talus.
l 1, 3 , 9 10 Rough, irregular depression visible in the anterior surface of the lower epiphysis of the tibia, from which originates a cartilaginous ligament [capsula articularis] to the neck of the talus.
m 2, 4 , 10 At this place depressions [tibia, sulcus malleolaris] are seen which bring down three tendons 11 that are stretched to the lower parts of the foot.
n 2 , 5, 6, 9 In the first figure, E marks the outer malleolus [malleolus lateralis]; it is nothing other than the lower epiphysis of the fibula. But in most of the figures n represents this malleolus.
o, p 1 , 5 This shaded area 12 of the fibula, extending from o to p, is the part of the fibula that presents itself bare and covered by no muscles prior to dissection.
q, q 2 , 6 The tendons of the seventh and eighth muscles [m. fibularis longus, m. fibularis brevis] that move the foot are bent this way; because of them, the fibula is concave here.
r 2 , 6, 11 Depression [fossa malleoli lateralis] of the lower epiphysis of the fibula, from which a ligament [lig. talofibulare posterius] is brought to the talus.
s, s 1 , 5 First line [margo anterior] of the fibula, or first angle thereof.
t, t 1, 2 , 5, 6 Second line [margo interosseus] of the fibula.
u, u 1, 2 , 5, 6 Third [margo lateralis] line of the fibula.
x, x 1 , 5 First side [facies medialis] of the fibula. x and x specifically mark the line on this side that is slightly raised for the muscle [m. extensor hallucis longus] that extends the big toe.
a, a 1 , 5 13 Second side [facies lateralis] of the fibula.
b, b 2 , 6 Third side [facies posterior] of the fibula.
g, g 1, 3 First line [margo anterior] of the tibia.
d, d 1, 2, 3, 4 Second line [margo interosseus] of the tibia.
e, e 1, 2, 3, 4 Third line [margo medialis] of the tibia.
z 1, 3 First side [facies lateralis] of the tibia.
h 1, 3 Second side [facies medialis] of the tibia.
q 2, 4 Third side [facies posterior] of the tibia.
k 2, 4 Rough line [linea musculi solei] in the third side of the tibia, into which the muscle [m. popliteus] hiding in the back of the knee is inserted.

The lower leg: tibia
In the lower leg 14 as in the forearm there are situated two bones (all of fig. 1 and 2 and F and Y to L and W in the skeletons), which Hippocrates always calls “bones of the tibia.” One of these (all of figs. 3, 4) is inner and thicker, which is called by the name of the entire limb knh/mh and tibia.

Fibula and tibia
The other [fibula] (all of figs. 5, 6) is situated exteriorly and is quite thinner then the inner one [tibia], called by the Greeks pero/nh and by the Latins sura and fibula. Out of concern for clarity I shall call the thicker bone tibiae os, distinguishing it from the entire member or tibia because the latter is composed of bones, muscles, veins, arteries, nerves, and the skin surrounding everything. The slenderer bone will conveniently be called the fibula to distinguish it from the calf, sura, which the Greeks called gastroknhmi/a because it is like the belly [m. gastrocnemius] of the lower leg. 15

Epiphyses of the tibia and fibula
An epiphysis attaches to the tibia and fibula above and below; 16 the upper epiphysis of the tibia (the epiphyses of the tibia are A, B in figs. 1 and 3, D in 1 and 3; of the fibula, C in 1 and 5, E in 1 and 5) is quite thick and wide, but thicker in the anterior part, and is seen to run downward (B in figs. 1, 3) in the anterior region of the tibia more than in the posterior.

Area where the femur is articulated to the tibia
Into this epiphysis two oblong depressions [facies articularis superior] (F, G in figs. 2, 4, 7) are carved, separated by a rough, irregular prominence [eminentia intercondylaris] (H, I, K in fig. 7) and coated with slippery cartilage [cartilago articularis]. The lower heads of the femur [condylus medialis, c. lateralis] (E, F in figs. 1, 2, ch. 30) are received by these depressions; the prominence separating them enters the great depression [fossa intercondylaris] (I in fig. 1, ch. 30) that separates the heads of the femur in the posterior 17 surface. From its upper and middle surface, which is rough and depressed and is not lubricated with any cartilage, the prominence [tuberculum intercondylare] (I in figs. 2, 3, 4, 7) sends out a very strong ligament [lig. cruciatum posterius] (X in the figure for ch. 1, Bk. 2) which is inserted in the just mentioned interval or depression between the heads of the femur. 18 The middle area of this prominence is rough and depressed so as better to put forth ligaments [lig. cruciatum anterius, lig. cruciatum posterius] into the femur, bringing them out from its most elevated surface as well as from its posterior region [area intercondylaris posterior] (K in figs. 2, 4, 7). From the anterior region (H in fig. 7) of the prominence [area intercondylaris anterior], which projects very little though it is similarly rough and has a broad depression, no ligament is inserted into the femur; but ligaments are put forth there which bind the cartilages [meniscus lateralis, m. medialis] (all of fig. 8, where the right is marked L and the left M), which I shall presently explain augment the sockets [facies articularis superior] of the tibia, to the anterior surface of this prominence.

Cartilages by which the socket of the tibia is enlarged
Since the two depressions of the tibia that admit the heads of the femur are carved only more or less superficially and do not exactly match the projecting femoral heads with their hollows (even though it seemed otherwise to Galen), 19 Nature augmented the depth of the depressions with a marvellous artifice. In addition to the slippery cartilages [cartilago articularis] covering the depressions of the tibia and the heads of the femur like a coating, she added to each depression a single cartilage [meniscus], unconnected to the femur or the tibia by any means except by ligaments. 20 This cartilage is attached only to ligaments that embrace the knee joint in a circle; it is also connected by a ligament to the anterior and posterior ends of the eminence [emin. intercondylaris] which it has been said separates the depressions [facies articularis superior] of the tibia that receive the heads of the femur. These cartilages [menisci] are softer than altogether simple cartilage and participate, as it were, in the nature of ligament. 21 Where they rest upon the bones, they are quite even, slippery, smooth, and coated with an oily humor [synovia]. They are thick on the circumference of the joint (N in fig. 8), becoming much thinner


page 139

and leaving off (O in fig. 8) before reaching the center of the depressions. Their shape is lunar, as is the inner side of the inner depression and the outside of the outer depression. They are nowhere wider than at the middle of their side, and they are narrowest where they approach the anterior and posterior parts (P, P in fig. 8) of the eminence separating the depressions of the tibia and end in sharp points. The points attached to the anterior end of this eminence are close together and the right cartilage is connected to the left there. 22 The ones that come close to the posterior end of the eminence are farther apart and are not joined together like the anterior points of the cartilages because the extremely thick ligament [lig. cruciatum posterius] from the eminence [tibia, eminentia intercondylaris] that is inserted into the femur [femur, condylus medialis] separates the posterior points of the cartilages. These things being so, it is easily inferred how harmoniously the cavity formed by the depressions of the tibia is enlarged with the aid of these cartilages not only in humans, but also in all the quadrupeds and birds that I have so far seen. Cartilages of this kind are situated in their knee joint; there is every opportunity to inspect the nature of any of them at table if one examines the knee joint closely, and has not supposed, with Aristotle and with Galen in the third Book of De usu partium, 23 that the knee of quadrupeds is situated where the lower part [distalis] of the tibia is attached to the talus.

The connection of the fibula to the tibia
That is how the tibia is articulated to the femur. The fibula, however, does not ascend so high that it touches the femur; but its upper epiphysis has a depression [facies articularis capitis fibulae] (Q in fig. 5) on its inner side that is quite lightly incised and wide, to which the slightly projecting eminence [facies articularis fibularis] (R in fig. 4) of the epiphysis of the tibia is articulated [articulatio tibiofibularis]. This eminence, situated on the outside [lateralis] of the tibia towards the rear, is like the depression of the fibula coated with cartilage [cart. articularis]. At its lower end (X in fig. 2), the fibula is attached to the tibia by a different method of articulation [syndesmosis tibiofibularis] than above (V in fig. 2). The outer side of the tibia forms a long depression [incisura fibularis] (S in figs. 4, 10) in which the protruding inner side (T in figs. 5, 6, 11) of the fibula is inserted; the latter is somewhat rough as is the depression of the tibia, and not at all coated with cartilage. The depression does not 24 receive the fibula with a smooth contact; but where these bones are joined a powerful ligament intercedes, binding them not just on their circumference [lig. tibiofibulare anterius, lig. tibiofibulare posterius] but also where they contact each other [lig. tibiofibulare interosseus].

Where the fibula separates from the tibia
Through the remaining length of the lower leg, the fibula separates considerably from the tibia (Y between V and X in fig. 2) — not, in fact, because it is curved like the radius (from k to k in fig. 1, ch. 24) or is as it were slanted outward from the tibia, but because the tibia is so thick above and below and slender in the rest of its length, that the fibula being attached to those areas of the tibia where it is thick easily separates a good deal from the whole slenderer part of the tibia. But it parts less from the tibia to the same degree that the fibula is not straight, being slightly curved inward toward the tibia a little below the middle of the tibia’s length (Z in figs. 1, 2), becoming flat or concave on its outer side. I shall more opportunely describe the course of the tibia and the fibula and the projecting lines and indentations along their length when I discuss these bones’ upper and lower parts, by which they are attached to others. The upper epiphysis of the tibia is attached to the femur and the fibula in the way I have stated. The anterior 25 surface (A, B in fig. 1, a, b in figs. 1, 3, 7) of the same epiphysis is quite depressed and rough, 26 as is the anterior surface of the tibia closest to the epiphysis, called by many of the Greeks a)ntiknh/mion, 27 which is rough in order to receive the extremely strong tendons of the muscles (5, 6 in the 5th table of muscles, W, g, h, i, etc. in the 8th) 28 that move the tibia; for the sake of these tendons, the upper epiphysis of the fibula protrudes significantly on its outer side and upper portion [apex capitis fibulae] (c in figs. 5, 6) to receive the very robust tendon (Y in the 10th table of muscles, a in the 2nd) of the fourth muscle [m. biceps femoris] that moves the tibia. This part of the fibula puts forth the head of the seventh (x in the 2nd table of muscles, F in the 6th) of the muscles [m. fibularis brevis] that move the foot.

The depressions and eminences of the tibia, by which it is articulated to the talus
The lower epiphyses of the tibia and fibula together form the socket (d, e, f, g, h in fig. 9) and the area [trochlea tali, facies superior] [facies malleolaris medialis et lateralis] to which the talus (all of figs. 3-6, ch. 33) is articulated as if by mutual entry. If you pay careful attention to the depressions and eminences of the tibia and fibula, you will rightly assign the connection of the talus with the tibia to the type of ginglymus. 29 We shall provide an account of the talus in its own place; now we must consider the depression [facies articularis inferior, facies articularis malleoli] on the surface of the tibia’s lower epiphysis, which is rather wide and more or less a double depression (e, f in figs. 9, 10) because in the middle it is divided by a wide but rather prominent eminence (d in figs. 9, 10) and is distinctly hollowed more deeply at the sides of the eminence. At the inner [medialis] side of this depression the lower epiphysis of the tibia is brought down in a large, strong process [malleolus medialis] (F in fig. 1, i in figs. 2, 3, 9, 10) which is hollow [facies articularis malleoli] on its outer [lateralis] side (g in fig. 9) where it faces the cavity [articulatio talocruralis] and like the cavity is smooth and coated with cartilage [c. articularis]. On its inner side facing the other leg, it is convex; and since it is unfleshed (k in the 2nd table of muscles) and covered with no muscle parts, it is readily perceived in us by touch: it is the inner malleolus [tibia, malleolus medialis].

The inner malleolus
This process has a depression 30 [sulcus malleolaris] (k in figs. 4 and 10) in its lowest part towards the posterior, whence it puts forth a ligament 31 (f in the figure for ch. 1, Bk. 2) attaching the cartilaginous bone 32 of the tibia to the talus. In order to produce such a ligament, the anterior surface (l in figs. 1, 3, 9 33 ) of the lower epiphysis of the tibia, in its lowest part, also produces transversely a long, rough, uneven depression from which it puts forth a ligament [capsula articularis] that binds the neck of the talus [collum tali] (N in fig. 3, ch. 33) to the tibia. The posterior surface of this epiphysis is indented (m in figs. 2, 4, 10 and 1, 2, 3 in the 15th table of muscles) where it first puts forth the inner malleolus, and shows depressions which are covered by transverse ligaments [retinaculum musculorum flexorum] and allow the tendons of the muscles going this way to the foot to be carried safely without wandering from their depressions. These muscles are three in number (the first [m. tibialis posterior] is marked D, E in the 15th table, the second O [m. flexor hallucis longus], the third P [m. flexor digitorum longus]): the fifth of the muscles


page 140

that move the foot, and two that serve the flexion of the foot.

Articulation of the fibula with the talus
The outer side of the lower epiphysis of the tibia puts forth no process corresponding to the inner malleolus. But the epiphysis (E in fig. 1, n in figs. 2, 5, 6, 9) of the fibula that is attached to the outside of the tibia thickens considerably here and is carried farther downward than the interior malleolus. This is the reason why the talus is dislocated less often to the outside of the foot than to the inside. The fibula here descends as much lower than the tibia as the tibia extends above the fibula on top toward the femur; in this way the fibula is not in the least exceeded in length by the tibia. This lower epiphysis of the fibula makes up the outer side [facies articularis malleoli] (h in figs. 9, 11) of the hollow that receives the talus. But the epiphysis is coated with cartilage and so protrudes on its inner [medialis] side that one could justly say it is more truly received by the talus [talus, facies malleolaris lateralis] (H in fig. 6, ch. 33) than it receives it, even though it closely covers the outer side of the talus and in this manner encloses the talus together with the inner malleolus, so that in undamaged persons the talus can never be touched.

The talus is not exposed to touch before dissection
The epiphysis of the tibia (compare the figures showing the complete structure of bones with the tables showing muscles in the foot) covers the upper surface of the talus [trochlea tali] and its inner side [facies malleolaris medialis] as well, while the fibula occupies the outer side [facies malleolaris lateralis] of the talus with its epiphysis. The anterior surface of the talus [collum tali], exposed to view in a bare structure of bones, is veiled by tendons 34 running to the toes over the top of the foot. So too its posterior surface, no less visible in bare skeletons, is covered by tendons [Tendo calcaneus] inserted in the heel and by some 35 passing this way to the bottom of the foot.

The outer malleolus
This lowest part of the fibula [fibula, malleolus lateralis], attached to the talus, is convex on its outer side and covered by absolutely no part of a muscle (e in the 1st table of muscles, C in the 2nd, and ϕ 36 in the skeletons); it constitutes the outer malleolus, which Galen attests is, like the inner malleolus, wrongly called the talus by certain persons. 37 This error has run down all the way to us. Not to mention others, our own Erasmus of Rotterdam in his Colloquy De talorum lusu 38 agrees with Pliny 39 that the malleoli in humans are called tali: which so pleased many translators of Galen that they have constantly translated sfura/, i.e. the malleoli, as tali. The outer side of the outer malleolus is convex and unfleshed, like the inner side of the inner malleolus [malleolus medialis]. 40 The posterior surface of the outer malleolus [malleolus lateralis] shows a large depression (q in figs. 2, 6) which is covered by a transverse ligament [retinaculum mm. fibularium superius] (the ligament is S in the 2nd table of muscles; the muscles are x [m. fibularis longus] and y [m. fibularis brevis]) and brings down the tendons of the sixth and seventh of the muscles that move the foot, containing them lest they move out of place. The inner side of the same malleolus shows on its lowest surface towards the posterior a deep, rough depression [fossa malleoli lateralis] (r in figs. 2, 6, 11) from which it puts forth a cartilaginous ligament 41 (g in the figure for ch. 1, Bk. 2) that quite firmly connects the fibula here to the talus.

The unfleshed part of the fibula
Of the entire extent of the fibula, no part is naked and unfleshed except the outer side of its lowest part (o, p in figs. 1, 5), which is also unfleshed for some distance above the lower epiphysis. The rest of it is covered with muscles so embracing the fibula that it seems everywhere to be giving way to some and to be squeezed by others. 42

The fibula is a triangle along its length
If you examine the fibula, you will see that along its longitudinal course it is a triangle, especially close to the middle of its length. In the middle of its anterior surface 43 there appears a sharp and conspicuously protuberant line [margo anterior] (s, s in figs. 1, 5), constituting the first angle of the fibula. On its posterior surface [facies posterior] it is depressed and flat, and on each side at the sides of its posterior surface it displays a single line (the second line [margo interosseus] is marked t, t in figs. 1, 2, 5, 6; the third [margo lateralis] is u, u) which protrudes rather prominently and forms another angle of the fibula. The line that occupies the inner side of the posterior surface of the fibula can be called the second angle of the fibula, and the one that holds the outside if this surface the third. In these three lines or angles are contained the three sides of the fibula (the first [facies medialis] is x in figs. 1, 5; the second [facies lateralis] a in 1, 5; the third [facies posterior] b in 2, 6). One is situated between the first and second angles, providing, in combination with the outer side [facies lateralis] (z in fig. 1) of the tibia, a fit seat for those muscles which are borne from the anterior surface of the tibia to the top of the foot. Those are the sixth [m. tibialis anterior] (Y in the 3rd table of muscles) of the muscles moving the foot, the muscle [m. extensor digitorum longus] extending the four toes (Y in the 4th table on muscles), the ninth [m. fibularis tertius] (W in the 4th table) of those that move the foot, and the one [m. extensor hallucis longus] that extends the big toe (F in the 5th table). The fibula puts forth a separate line [facies medialis] (x, x in figs. 1, 5) that protrudes slightly in this first side from which a beginning is provided for that muscle. The second side is bordered by the first and third line; wide and quite concave, it provides a place for the seventh [m. fibularis longus] (F in the 6th table of muscles) and eighth [m. fibularis brevis] (Y in the 6th table of muscles) muscles moving the foot. For the sake of the eighth muscle, this side is quite rough so that it may have its entire beginning from here in a fine way. The first line or angle of the fibula [margo anterior] is produced by the muscles 44 that occupy the first side [facies medialis] of the fibula and those [m. fibularis longus, m. fibularis brevis] that are extended along the second side [facies lateralis]. The third side [facies posterior], bordered by the second and third lines, 45 is compressed by the muscles occupying the posterior surface of the tibia, and especially by the muscle [m. flexor hallucis longus] (L in the 14th table of muscles) that flexes the second bone of the big toe and is fleshy at its origin from this side of the fibula. Since these things are so, the third line is pushed outward by the muscles occupying the second and third side, while the second line is produced by the muscles which compress the third and first sides of the fibula. 46 But this second line separately puts forth a ligament [membrana interossea cruris] (a in the figure for ch. 1, Bk. 2) binding the fibula to the tibia along the entire area where these bones separate; it is inserted into the second line [margo interosseus] (d, d in figs. 1, 2) of the tibia.

The shape of the tibia along its length
The tibia, like the fibula, is in some degree triangular in the middle of its length. 47 Its first line [margo anterior] (g, g in figs 1, 3) is situated on the anterior surface of the bone and stands out prominently, for which it is also called the “spine” by professors of anatomy. This extends so sharply that when children are fighting with their feet we see them aim nowhere more often at each other


page 141

than at the anterior surface of the tibia, where the line is closest beneath the skin and cuts it like a knife whenever the skin is battered by a blow to the tibia. The second [margo interosseus] (d, d in figs 1, 2, 3, 4) and third [margo medialis] (e, e in the same figures) lines of the tibia make up the sides 48 of the posterior surface [facies posterior] (q in figs. 2, 4); the third, not sharply formed but quite obtuse and almost rounded, is the inner side of this surface. The second line is a little sharper, and forms the outer side of the posterior surface of the tibia. This is the one to which it was recently said the ligament [membrana interossea cruris] connecting the fibula to the tibia is inserted. The three sides of the tibia are made by these three lines: the first [facies lateralis] (z in figs. 1, 3), bordered by the first and second lines, is depressed and flat, hollowed because of the same muscles [m. tibialis anterior] to which it has been said the first side [facies medialis] of the fibula (x in figs. 1, 5) gives way. The second side [facies medialis] of the tibia (h in figs. 1, 3, x, y in the first table of muscles, q, k in the 2nd), bordered by the first and third lines, is distinctly convex and convered by no muscle at all. It is called kre/a by the Greeks, and more often a)ntiknh/mion. 49 The third side [facies posterior] (q in figs. 2, 4) of the tibia, circumscribed by the second and third lines, is not very much depressed, and is occupied by muscles that claim their place in the posterior surface of the tibia, especially by the one [m. flexor digitorum longus] (C in the 14th table of muscles) which will be called the flexor of the third bone of the four toes, and the one [m. tibialis posterior] (D, E in the 15th table of muscles) which we shall establish as the fifth of the movers of the foot. In addition, this third side shows a rough line [linea musculi solei] (k in figs. 2, 4) in its upper part, extending obliquely, in which a muscle [m. popliteus] (G in the 14th table of muscles) is inserted which we shall call the one hidden in the back of the knee [popliteal fossa]. Such lines and sides of the fibula and tibia easily show how suited these bones are to supporting and producing 50 muscles, while the joints show how ingeniously Nature has constructed these bones for undertaking the motions that we make with our legs, 51 enlarging them near the joints in the way we have stated. No one can contemplate them without the greatest admiration of our Creator, or readily inferring how He would have vitiated their entire structure had He fashioned a construction altered from any of those which we have just now described. 52


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]