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 18 On the Sacral Bone and the Coccyx

Description of the canine coccyx

Beneath the sacrum which is composed of three bones in the manner described, three other ossicles 23 (nos. 4, 5, 6 in fig. 4; compare these with the lumbar vertebrae in the skeletal figures) are assembled one after the other, not unlike the lumbar vertebrae in makeup. In no appearance do they differ from those, except that they have wider transverse processes [cornu coccygeum] than the lumbar vertebrae, slanting downward more than upward, and they put forth no spine or a very small one. In the shape of their body they closely correspond to the lumbar vertebrae, unless perhaps someone considering each detail might add that these ossicles are wider in proportion to their mass. In the ascending and descending processes they do not differ in the least. The topmost of these three ossicles has its body attached to the third bone of the sacrum in the same way as the lumbar vertebrae are interconnected, as it receives the descending processes of the sacrum with its ascending processes. It is no doubt these three lower ossicles that Galen calls the coccyx, for between these three ossicles and between their topmost part and the bottom of the sacrum no less cartilage [discus intervertebralis] or rather cartilaginous ligament may be seen than between the lumbar vertebrae, while as we have just now said no cartilage is seen between the three bones of the sacrum, especially in older animals. In dogs and apes the fourth of the muscles [m. piriformis] that move the femur originates from those three bones: that is the muscle that Galen says originates from the coccyx in the third book 24 of De anatomicis administrationibus. In fact, the foramina [ff. sacralia anteriora et posteriora] 25 incised to transmit nerves agree precisely with Galen’s description in De ossibus: three pairs of nerves are attributed by Galen to the sacrum and three to the coccyx. 26 Among the ancient professors of anatomy the customary way of counting nerve pairs was to have a pair of nerves refer always to the vertebra beneath the nerves (these may be found more or less in order in figs. 2 and 3 at the beginning of ch. 11, Bk. 4). Accordingly they would number the first pair of spinal nerves [n. cervicalis I] the one that exits between the occipital bone and the first neck vertebra; the second pair [n. cervicalis II] was the one for which a path is carved between the first and second neck vertebrae. Thus the first pair of nerves of the sacrum [n. sacralis I] is considered the one which comes out between its first bone and the lowest lumbar vertebra, for which foramina are incised in the way already stated they exist in the lumbar vertebrae. The second and third pair do not exit from the sides like the first. Since the sides of the sacrum are blocked by its articulation with the bones of the pelvis, it was impossible for the nerves to come out through the sides here as well. Consequently foramina are carved in the front and back of the sacrum so that by this provision of Nature branches from these pairs [nervi sacrales, rami posteriores et anteriores] may be directed forward and backward as needed, as they are from nearly all the other pairs. Foramina are also cut out for the second pair at the joint of the first bone with the second, and a way is prepared for the third where the second bone of the sacrum joins the third. For the three pairs of nerves sprouting from the coccyx [nervi coccyges], foramina [f. intervertebrale] are carved exactly as they are in the lumbar vertebrae; for since the sides of these bones are not (like those of the sacrum) occupied by a joint [articulationes zygapophysiales], it was more fitting to maintain here the same series of foramina as we have explained exists in the other vertebrae not blocked by a lateral articulation, particularly since the articulation of these ossicles is identical to that by which the lumbar vertebrae are joined together. Thus the first pair [nervus coccygeus, plexus coccygeus] comes forth on either side through a foramen cut between the third bone of the sacrum and the first of the coccyx, the second pair [nervus ano-coccygeus] between the first and second of the coccyx, and the third pair [n. ano-coccygeus] between the second and third. From the lower side of the third bone, what is left of the dorsal medulla [filum terminale] comes forth without a partner and allied with nothing. A path [foramen intervertebrale] is carved for the dorsal medulla in each bone of the sacrum and the coccyx, corresponding to the thickness of the medulla at this point. At the end of the third coccyx bone in dogs and caudate apes, solid and unperforated bones, oblong and somewhat thick above and below but thin in the middle, are connected in a more or less continuous series constituting the tail [vertebrae caudales]. 27 Sometimes, not infrequently, in many species of dogs and apes even more than three coccyx bones are seen, of exactly the same shape as those above, and in them still more nerve pairs come out from their sides. In tailless apes, only cartilage grows upon the lowest bone of the coccyx, though Galen’s opinion is not as readily understood regarding these as regarding dogs. Since this is the case in those animals and because I understand Galen’s description best from them and quite cheerfully give them equal attention when performing demonstrations in the schools and subsequently


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find them altogether different in man, why, I ask, do certain dilettantes and those who swear by Galen’s words, born for no other purpose than to detract and make invidious judgements of others’ labors (since they can do nothing themselves), now rail against me because I so often disagree with the opinions of Galen during dissections? It is as if they had no eyes, and because of some Galenic religion it were not permitted me to present, often to the most learned men of my time, what I find by myself. In the meantime, no spirit good or evil can silence these ranters if they have discovered something they think worthy of the subject of medicine: whether medicine is a craft or a science; whether a discussion of categories is logical or metaphysical in character; about the possibility of understanding; whether knowledge about the soul is the highest form of knowledge, and other foolishness. 28 But in no way do I pay attention to those laughable but arrogant men, as it has been my longstanding habit to ignore them; I expect thanks rather from those who are zealous for truth, for although I repeatedly mention the views of Galen, I myself study the true construction of man, even if perhaps my language digresses too far. Nor do I believe the ghost of Galen (who is seen so often to have lamented in his writings that the study of anatomy would perish utterly with him, as indeed was the case) will be unfriendly to me because I am showing that he taught the fabric of the ape rather than man and on account of the books of other anatomists who preceded him he proceded from the construction of the ape to that of man and confused the two. I do not say this because Galen mixed human bones with simian in his description of the sacrum and coccyx (unless he knowingly counted a smaller number of coccyx bones than often occur in caudate monkeys), but because he counts only five lumbar vertebrae when dogs and caudate monkeys have more; 29 Galen nevertheless describes the vertebrae, sacrum, and coccyx of a monkey. That the ancients conscientiously employed human bones while training their sons in anatomy, 30 is attested by names taken from the parts themselves. I am certain they called a certain bone ko/kkuc from some similarity that it has with a bird also called coccyx by Pliny (and by us cuculus, cuckoo), especially when it has not been completely cleaned of flesh and ligaments. 31 What this resemblance could be, I shall more readily explain after I have appended a brief description of these bones in man.



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 18 On the Sacral Bone and the Coccyx