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 33 On the Bones of the Foot

THE CALCANEUS

The side facing the ground

The heelbone 54 (D in figs. 1-2 and all of figs. 7-9; a in skeletons 2, 3), which is easily the largest of all the bones of the foot and is made of the same substance as the talus, is smoothly rounded 55 in the part on which we step [tuber calcanei] (X, Y, Z in fig 2), but it is also somewhat wide for the sake of a safe design. But at the same time, it is rough and irregular thereabouts on account of certain muscles. 56 First, it projects transversely downward near the back on its lower [plantar] surface and puts forth a rough process (Y, Z in fig. 2, Y in the 8th, Z in the 9th) 57 from whose anterior surface begins a muscle [m. flexor digitorum brevis] (Q in the 14th table of muscles) which flexes the second bone of the four digits [phalanges mediae] of the foot. A muscular substance [m. quadratus plantae] (l, m in the 14th table of muscles, N in the 15th) also originates from here, which produces four sections of muscle by which we adduct the four digits toward the big toe. In order to put forth these muscles, this lower [plantar] surface of the calcaneus is wide and irregular, and the process [tuber calcanei] projects and comes closer to the ground than the remaining body of the calcaneus so that the heads of the muscles will not be compressed in treading the ground.

The upper surface of the calcaneus, brought backward beyond the straight line of the tibia

The upper [dorsal] surface of the calcaneus, which runs from the posterior part of the talus [proc. posterior tali] to the back of the heelbone itself (a to b in fig. 7), presents the appearance of a smooth body, showing nothing special except a slight roughness into which ligaments of the tibia and the talus are inserted. 58 It is free from the origin or insertion of muscles, and from articulation. This posterior surface of the heelbone goes somewhat beyond the axis of the tibia, being extended posteriorly so that the tibia may be advantageously supported on the foot like a perpendicular line on another line drawn horizontally beneath it, and so the strongest tendon of the entire body [tendo calcaneus] (l in the 13th table of muscles, or the tendon combined from n, o, q in the 14th table) may be inserted in the posterior part (c in figs. 2, 8, 9) of the calcaneus. To this low and quite rough part 59 of the calcaneus the tendon is inserted that is combined from the first, second, and fourth


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muscles that move the foot. 60 In quadrupeds such as dogs, sheep, and horses, this posterior part of the heelbone also claims an oblong depression where the tendon is safely conveyed which in those animals, unlike humans, produces a broad tendon growing up from the skin of the sole.

The inner side of the calcaneus

Of the sides of the calcaneus, which are wide and flat, the inner [medial] one (d, e in figs. 2, 8; e marks the depressed surface) is smooth and visibly depressed to make it a fit place for the tendons of muscles 61 going this way to the bottom of the foot which are quite securely bent back upon this inner side of the heelbone. In addition to the principal vein, artery [a. & v. tibialis posterior] (d in the last figure of Bk. 3), and nerve [n. tibialis] (w in the last figure of Bk. 4) to the bottom of the foot, the tendon of the fifth muscle moving the foot (k in the 14th table of muscles) and the tendons (e,h in the 14th table) of two muscles [m. flexor digitorum longus, tendo] [m. flexor hallucis longus, tendo] that flex the last joints of the digits of the foot are led down by this route. These tendons are turned chiefly on the posterior surface of the process of the calcaneus where Nature has carved a depression [calcaneus, facies articularis talaris media] (R in figs. 7, 8, 9) 62 receiving the head of the talus, forming the anterior joint of the talus with the heelbone. This process [sustenaculum tali] projecting into the inner side of the foot makes the inner [medial] side of the calcaneus quite concave 63 in the same way that the protruding inner side [tuber calcanei, proc. medialis tuberis calcanei] (Y in figs. 2, 8) of the posterior part of the heelbone also substantially augments this hollow. It also projects significantly so that the muscle [m. abductor hallucis] (xr in the 6th table of muscles) by which the big toe is abducted inward away from the other toes may originate from here.

The outer side

The outer [lateral] side (f, g in figs. 1, 7, 9) of the calcaneus is not concave, but rough, irregular, and unfleshed with the exception of its lower surface [tuber calcanei, proc. lateralis tuberis calcanei] (Z in figs 2, 9) which puts forth a small muscle [m. abductor digiti minimi] (P in the 2nd table of muscles, u in the 14th) that abducts the little toe from the others toward the outside. The anterior portion (g in figs. 1, 7, 9) 64 of this side is in some of its area smooth and very slightly concave on its surface, making room for tendons of the seventh and eighth muscles [m. fibularis longus, m. fibularis brevis] (F and Y in the 6th table of muscles) that move the foot, which are bent back upon the posterior surface of the outer malleolus [malleolus lateralis] (w in the 6th table) and run along this region of the calcaneus.

The anterior part of the calcaneus

Of the anterior parts of the heelbone, that one [facies articularis talaris anterior] (h in fig. 7) which is on the side of the big toe and goes out like a process into the inner side of the bone, is articulated to the talus in the manner previously stated and is contiguous to no other bone. But the anterior part [facies articularis cuboidea] (i in figs. 7, 9) of the calcaneus corresponding in its placement to the little toe is smooth on its anterior face, coated with slippery cartilage, and projects in a low, wide head which is articulated with a concavity [facies articularis calcanea] (x in fig. 13) of the bone resembling a cube [os cuboideum] which is likewise covered with slippery cartilage and is only superficially incised. This joint is made by the type of attachment which we have said is called a)rqrwdi/a by the Greeks. 65



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 33 On the Bones of the Foot