Why a description of the foramina is undertaken
Because an ignorance of the foramina of the head would beget no small confusion in describing the veins, nerves, and arteries, and because in describing them (difficult as they are to understand) leading anatomists have made serious errors, I should now consider it worth while to devote this chapter to all the foramina of the head, 1 and to enumerate one by one those that I have identified clearly by careful and painstaking dissection, so that in my account of vessels, nerves, and certain membranes of the head the reader who is attentive and eager to learn will be able to go back and constantly have in readiness whatever foramen is being mentioned. That this may be done more readily, I shall place here four figures to assist the matter at hand, and describe each foramen separately with a letter placed ahead of it so that the language of the figure legend and the chapter text alike may be used at the same time. Then if by chance or design some cavity or process 2 has previously been left out, I shall now describe that also.
FIRST FIGURE OF CHAPTER XII
This figure shows the anterior surface of the skull [cranium] 4 and accordingly displays all the foramina in the eye socket and upper maxilla that appear in this aspect. The canine head placed beneath the human skull has before this been useful for illustrating the bones and sutures of the upper maxilla, as does the figure as a whole.
SECOND FIGURE OF THE TWELFTH CHAPTER
In this figure we have drawn the outside of the base of the skull, where the palate faces out. 6 Here we shall not confine the term skull, calva or calvaria, or bones of the head to the eight bones of the head as they were termed earlier in the sixth and ninth chapters, nor shall we like Aristotle consider it only the portion covered with hair. 7 Rather we shall add the upper maxilla to those eight bones, and shall term “skull” or “head” that which is found everywhere in cemeteries and is depicted as a skull. Our previous distinction between the bones of the head and those of the upper maxilla may readily be understood as having been done for the sake of Galen and in the interest of clearer instruction.
THIRD FIGURE OF THE TWELFTH CHAPTER,
showing the inner base of the skull
FOURTH FIGURE OF THE TWELFTH CHAPTER
The fourth shows the inner surface of the skull’s upper portion [skull cap]; 10 we have resected this from the skull of the third figure with a saw, in the way we normally divide the skull to show the composition of the brain. Let us therefore proceed to the figure legend, adding a numerical subscript to each character showing the figure to which it belongs, noting first that the eighth figure of chapter six, showing the inside of the cuneiform bone [os sphenoidale], the eighth bone of the head, 11 which faces the brain, is no small aid to understanding certain foramina. It will be extremely useful to compare that figure with the inner surface in figure three of this chapter, following the description of the cuneiform bone, the eighth bone of the head.
|A 1 12||Foramen [f. supraorbitale] carved at the middle of the brow, through which a branch [n. supraorbitalis] (N in fig. 2 preceding Ch. 2, Bk. 4, and H in the 4th table of muscles) of the lesser root [n. ophthalmicus] of the third pair [n. trigeminus] of cerebral nerves [nn. craniales] is dispersed from the eye socket [orbita] to the muscular skin of the forehead. 13 This foramen exists on either side, not always completely round, but often just a depression appears, carved out like a semicircle. Sometimes a foramen is seen on one side but only a semicircular depression on the other, as here in the first figure. 14 This foramen belongs to the frontal bone, which is marked with a number of I’s in the first figure of this chapter. It is not necessary for me also to mark a bone here in the text or in the margin when the character marking the foramen readily shows also the bone into which it is carved.|
|B 1||Foramen [f. infraorbitale] through which a branch [n. infraorbitalis] (O in fig. 2, Ch. 2, Bk. 4 and I in the 4th table of muscles) from the aforementioned lesser root [n. maxillaris] of the third pair of cerebral nerves drops from the eye socket into the cheeks toward the muscles of the upper lip and the alae of the nose. This foramen is carved like an elongated passage in the fourth bone [maxilla] of the upper maxilla, and its path is hollowed deep in the bone in the anterior portion of the maxilla where B is placed in the first figure. 15 Indeed, through the socket of the eye it is covered only by a thin and very scaly bone; we have marked this region L, 16 visible in the eye socket.|
|C 1||A foramen [fossa sacci lacrimalis] larger than the one just mentioned, which extends straight down from the large or inner angle of the orbit into the cavity of the nostrils, equally shared by the the second [os lacrimale] and fourth bones [maxilla] of the maxilla [upper jaw]. This foramen provides a path to a small portion (P in figure 2, Chapter 2, Book 4) [n. nasociliaris] of the lesser root [n. ophthalmicus] of the third pair of cerebral nerves, and is believed to transmit 17 to the nostrils some of the phlegm 18 that flows from the brain to the eye socket. Besides this foramen, another larger one [fossa pterygopalatina] is provided for the flow of phlegm from the eye socket into the nasal cavity, 19 and from here more to the the throat than the nose. Since this lies more deeply hidden and can in no way be displayed in the preceding illustrations, see the fourth figure at the front of Chapter Six, from which we have cut out the jugal bone (to place the hollow of the temple more exactly next to the eyes) and added a F to that illustration so that at least the location of this foramen incised in the cuneiform bone could be shown. The more this is out of sight in skulls, the less surprising that noteworthy as it is, it has escaped the notice of leading anatomists.|
|D 1 , 2||This foramen [fissura orbitalis inferior] 20 is easily the largest of all that are seen in the eye socket, and gives passage to a small branch (Q in fig. 2, Ch. 2, Bk. 4 21 ) of the already oft-mentioned lesser root [n. maxillaris] of the third pair of cerebral nerves cerebral nerve [n. trigeminus], extending from the eye socket into the temporal and masseter muscles. 22 This long, open foramen is not carved only for a small nerve: it also provides strength to the beginning of the temporal muscle. In addition, it furnishes a path for phlegm flowing down to the larger foramen 23 (which we have marked F) extending into the nasal cavity. Indeed, it seems prepared for a certain small nerve (d in fig. 2, Ch. 2, Bk. 4) which we were the first to note runs next to the root of the fifth pair of cerebral nerves [n. facialis and n. vestibulocochlearis]. That little nerve extends through its own foramen a little farther back — to be labeled H [f. zygomatico-orbitale] — into the temporal muscle, the masseter, and the muscle [m. pterygoideus medialis] concealed in the mouth that assists in raising the jaw. This fissure or elongated foramen, labeled D, extends to the cuneiform bone and the fourth bone of the upper maxilla.|
|E 1 , 3||The E placed in the third figure and in both eye sockets of the first figure marks the foramen [canalis opticus] that is highest in the root or vertex of the eye socket and is incised in the cuneiform bone; outside the point where it faces the eye socket it appears quite round, corresponding in size to the optic nerve (N, O in fig. 13, Bk. 7)(for which it is carved out). But inside the skull, where it nears the brain, it has on the outside a slight but sharp angle which is made for a small vein [arteria ophthalmica] that exits here with the optic nerve. The letter g marks this angle [processus clinoideus anterior]. It lies between E and g in the third figure of this chapter.|
|F 3||The junction [chiasma opticum] of the optic nerves (M in fig. 13, Bk. 7) rests in this pocket [sulcus prechiamaticus] carved in the cuneiform bone.|
|G 1 , 3||G is in the left eye socket of figure one, and in the third
figure it occupies the right side of the illustration because in the left side
[fissura orbitalis superior] so
identified is not visible since we have tilted the skull to the side in order
somehow to see this very foramen.
It is carved into the cuneiform bone, and in its lower part it is a little less than completely round, while in its upper part it ends in a sharp, long, and narrow angle. This foramen, though it seemed otherwise to Galen, is larger than the the foramen [canalis opticus] of the optic nerve. 24 If it were perfectly round like the optic foramen, it would easily be three or four times larger. Nevertheless, its lower part, which we have said is a little less than completely round, still far surpasses the size of the foramen of the optic nerve. It is hollowed for the sake of the second pair of cerebral nerves [n. oculomotorius] (G in figure 14, Book 7) as they proceed into the eye socket to move the muscles of the eye, 25 and secondly for the lesser root [n. ophthalmicus] of the third pair [n. trigeminus] of cerebral nerves (H [n. trochlearis] in the same figure), which is distributed to the skin of the forehead, to the muscles on the face of the upper maxilla, the nostrils, and the muscles [mm. temporalis, masseter, pterygoideus medialis] that raise the lower maxilla. 26 These roots drop through the lower part of the foramen together with the major branch [arteria carotis interna] (x in the figure for Chapter 14, Book 3 27 ) of the sleep artery, which some allege forms the reticular plexus in man. 28 But in fact a vein [vena ophthalmica superior] (G in the same figure and H in fig. 13, Bk. 7 29 ) is at this point distributed from the eye socket, away from the veins that go to the temporal muscle 30 and through the upper part of the foramen where the foramen [fissura orbitalis superior] is compressed into a long, narrow angle, 31 to the hard membrane [dura mater]; and for its distribution in the base of the skull, it has pockets carved out there corresponding to the swellings of the small veins; these are visible in that part of the skull where z is written in figure 3. This large foramen is by no means carved out only for these nerves, 32 the vein [v. ophthalmica superior], and the large artery [a. ophthalmica] just mentioned: it is also for phlegm that flows into the eye socket from the brain and from hence into the cavity of the nostrils, as dissection brilliantly and delightfully shows, 33 since by no account does this foramen’s great size appear so small as those nerves, the vein, and the artery.
|H 1 , 3||The round foramen [f. rotundum], going farther inside the bone than the two just mentioned, and narrower. 34 This, with others, is carved in the cuneiform bone [os sphenoidale] for the small nerve [n. abducens] (L in fig. 14, Bk. 7) that you will hear originates not far from the principal root of the fifth pair. 35 The one placed beneath G on the right side of the third figure appears a little larger than the one on the left side, because sometimes, besides that nerve, it also transmits the small nerve that is the lesser root of the third pair [n. trochlearis] (H in fig. 14, Bk. 7) which we mentioned a little earlier is brought down through the foramen [fissura orbitalis superior] marked G.|
|I 3||At this location in the eighth bone [lamina cribrosa ossis ethmoidalis] of the head many small foramina [foramina cribrosa] (E in figure 12, Book 7) are seen, made for the entry into the head of odors and inhaled air. As previously stated, these are not straight passages open at both ends but oblique and winding, like the holes in sponges. Among the rest there is one on each side, however, that is straight at both ends and rather large; it is in a manner of speaking the first and nearest the front portion of the frontal bone, transmitting the vein 36 (G in figure 13, Book 7 and H in the figure in Chapter 14, Book 3) that extends to the hard membrane [dura mater] of the brain from the nasal cavity. Yet at the same time the other foramina would even seem straight and open at both ends if only the inner ossicles [labyrinthus ethmoidalis] placed in varying number at the top of the nostrils, noticeably porous and rather membraneous and cartilagineous, were removed.|
|Whether these small foramina were also formed for the purpose of purging the brain of phlegm, we shall explain in the seventh book. But for the present I thought it should be added that phlegm is never filtered out through these except when the brain is full, 37 and that these foramina are blocked and other symptoms of a cold are brought on by the smallest amount of phlegm draining through them. 38 You should also be cautioned that foramina do not appear in this place with equal frequency in all skulls, just as the places [lamina et foramina cribrosa ossis ethmoidalis] (E in fig. 12, Bk. 7) where the olfactory organs [tractus et bulbus olfactorius] (D in the same fig.) are located are not observed in equal size in every case. 39 Moreover, the dog is the least phlegmy animal but is endowed with the most precise sense of smell; as it has the largest places for olfactory organs, so also many wide open foramina are seen in them facing forward and not down as in man.|
|K 3 , 4||Cavity [sinus frontalis] located between the two scales making up the frontal bone, 40 which many claim is the organ of smell because it contains air, which we have no doubt is marvelously necessary to smell. You will quickly observe how capacious this cavity actually is if you break the frontal bone in the region of the brows: it is very large and encloses a softish body 41 more or less corresponding to marrow, covered by a membrane. But it is all of such a type that you will find nothing resembling it in the entire body except in the numerous caverns and antra [sinus sphenoidales] (C and D in fig. 8, ch. 6) visible in the cuneiform bone. Except where the anterior plate of the frontal bone is eroded by the Gallic disease 42 or punctured by a wound, we see air driven from this cavity [sinus frontalis] with such force in expiration that it will instantly blow out a candle flame. For this cavity not only extends to the area of the brows and certain out-of-the-way foramina [ff. ethmoidalia] in the nasal cavity, but it also runs into that part [pars orbitalis ossis frontalis] of the frontal bone which has been stated makes up the upper region of the eye socket. 43|
|L 3||Foramen [lamina et foramina cribrosa ossis ethmoidalis], or rather fissure, of such a shape as the edge of a fingernail would make in wax; it is made to strengthen the hard membrane [dura mater] of the brain (beneath D in fig. 13, Bk. 7) at this point. No doubt it was necessary, not only here where it is perforated by many foramina but in numerous other places, that the hard membrane be attached to the brain and that it send fibers and vincula through the skull. You will also be able to observe that these fissures assist somewhat in bringing air into the brain if you judge by pushing an animal bristle into the cavity [sinus frontalis] of the frontal bone just mentioned and into the nasal cavity that they come to an end, 44 and if you notice besides that they extend 45 into the caverns [sinus sphenoidale] in the cuneiform bone.|
Channels made to drain phlegm from the brain
[fossa hypophysialis, sella
turcica] cut in the
cuneiform bone containing a small gland
[glandula pituitaria] into which
the phlegm running down from the brain flows, which Galen declared then flows
through the bone forming this pocket into the palate,
claiming that it is perforated with holes like a seive or sponge
and the phlegm strains through it.
Were it not that a certain piety towards Galen restrains me, I
would show that this opinion is no less than totally untrue. This part of the
bone, which is the middle of the cuneiform, is never perforated like a sponge,
much less like a seive, being made there of a solid and continuous scale
containing within many of those large cavities
[sinus sphenoidalis] which we
illustrated in the eighth figure of the sixth Chapter, which can be seen only
if the bone is first broken. Phlegm in no way descends through such foramina
(since there are none) in the cuneiform bone.
Rather, two ducts, carved out as cavities
[sulcus caroticus], run down on
each side from the pocket marked M;
the anterior duct heads to the second foramen [fissura orbitalis superior], marked G, which we described in the root of the eye socket, carrying phlegm to the eye socket and thence through the foramina [fossa sacci lacrimalis] marked C and F. The posterior cavity extends downward to a rough and uneven foramen or rather fissure [foramen lacerum], through which the phlegm flows into the mouth or rather the palate and air also goes to the cranium during respiration.
|N[ 2 , 3 ]||This fissure [foramen lacerum], common to the temporal bone and the occiput, 50 we have marked N on the left side of the second figure and on the right side of the third. These ducts or depressions do not present themselves to view so readily in the third figure (since they do not seem quite hollow);|
|O P[ 3 ]||but we have marked the anterior cavity O and the posterior P in the same figure so that with the help of these letters you may locate the area of these depressions more quickly in actual skulls. To the processes that appear in a circle around the pocket marked M 51 [fossa hypophysialis, sella turcica], the hard membrane [dura mater] of the brain (figure 15, Book 7) is very firmly attached and is as it were supported in that area where it recedes from the base of the skull and has beneath it the greater branches of the sleep arteries [a. carotis interna] and the passages recently mentioned that carry phlegm downward. 52|
|Q 2 , 3||At the side of the uneven, rough fissure or foramen marked N, more toward the anterior, there is cut in the cuneiform bone another foramen [foramen ovale] which is smooth and not exactly round, but resembles a circle slightly squeezed on both sides into an oblong. It was fitting for a foramen with this shape to be introduced because it had to carry two rounded bodies connected to each other by membranes. It provides passage to the thicker and principal root [n. mandibularis] of the third pair of cerebral nerves [n. trigeminus] root together with the fourth pair [nn. palatini, n. maxillaris] (I and K in fig. 14, Bk. 7; M [n. mandibularis] and Z [nn. palatini] in fig. 2, ch. 2, Bk. 4).|
|R 2 , 3||Again at the outer side of the foramen marked Q, there is seen in the cuneiform bone another foramen [f. spinosum], much smaller and perfectly round, through which a portion [vena meningea media] of the interior jugular vein (F in the fig. in ch. 14, Bk. 3) moves away from the sleep artery and goes up into the skull. Sometimes a small foramen [f. venosum] 53 is observed near the inner side of the foramen [f. ovale] that carries the two pairs of nerves [n. trigeminus] just mentioned, made for a small branch [v. emissaria] of the same vein. But it is rarely seen in one side of the skull, and much more rarely still on both sides.|
|S[ 2 , 3 ]||Nevertheless, we have included the foramen here also, on the left side (because among the other skulls there was one with this foramen, that seemed a better specimen than all the others) 54 ; we have labeled it S [f. venosum] in the second and third figures.|
|T T[ 3 , 4 ]||From this foramen, depressions 55 that correspond to the arch of the divided vein [vv. meningeae mediae] ascend 56 through the interior of the skull, hollowed out so that the bone of the skull will not press and constrict the depressions (D, D in fig. 1, Bk. 7) as they run like veins in the hard cerebral membrane. We have labeled these depressions in the skull T, T several times in the third and fourth figures. 57|
|V 2||This foramen [tuba auditoria, pars ossea], visible on the outside 58 of the base of the skull, cannot readily be seen. From here it is extended obliquely to the outside into the cavity carved in the temporal bone for the organ of hearing (the main portion of the fig. in ch. 8), and ends. I shall therefore put in a drawing a little later with several foramina of the organ of hearing 59 . The foramen is made to extend a passage for a small branch (b in fig. 2, ch. 2, Bk. 4) of the fifth pair [n. facialis] of cerebral nerves that runs out from the cavity of the organ of hearing by this route to the muscles that raise the lower maxilla. In addition, a branch of the inner jugular (n in the fig. for ch. 14, Bk. 3) goes to the organ of hearing through this foramen, and air as well is carried through it into the chamber [cavitas tympanica] of the temporal bone belonging to the organ of hearing. You will easily perceive this if you take air into your mouth and try as it were to expel it through your ears: you will hear the sound of winds in your ears, or a sound not unlike that of whirlpools.|
|X 2 , 3||A conspicuous foramen
[canalis caroticus], hollowed
out for the greater branch of the sleep artery
[a. carotis interna] (L in the
fig. for ch. 14, Bk. 3) as it enters the skull; it does not pierce the skull at
a right angle, but is carved in an elongated course from the rear obliquely
inward toward the front of the temporal bone. The part of the bone
[os temporale, apex partis
penetrated by this foramen, where it faces downward toward the throat
and is labeled œ in the second figure, looks rough and uneven like pumice. X
[canalis caroticus], placed in
the second and third figures, shows the course of this foramen, as does the
illustration which we have added at this point,
where X and Y do not have the same location relative to each other as they to in the larger figures. 60 Nature fashioned 61 this duct [canalis caroticus] running obliquely over a long course in the bone for the longer and more oblique progress of the sleep artery, no doubt so that the vital spirit would be more perfectly prepared for the brain by this roundabout route of the duct. For this reason I am especially suprised at Galen, who missed this large foramen (among many others) as not worth considering in passing, 62 and who left it written in his book about the dissection of an ape’s veins and arteries 63 that the sleep arteries enter the skull through the foramen marked Q [f. ovale in this chapter], used by the third and fourth pairs of cerebral nerves. 64 And just as in that book he inspected neither dogs not apes concerning this foramen and passed falsehoods on to posterity, so also it is no surprise that in his imagination he made up the amazing reticular plexus in humans also, and passed on to memory a series of cerebral vessels that is not everywhere factual. 65
|Y 3||From the region of the end of the foramen just mentioned, marked X [canalis caroticus], which faces the cavity of the skull, another foramen 66 [f. lacerum] is begun, extending straight forward into the nasal cavity like an elongated passage, 67 providing a route for a branch 68 (s, t in the fig. for ch. 14, Bk. 3) of the artery which extends as far as the nostrils from the larger part of the sleep artery [a. carotis interna] where it enters the skull, there giving out a noticeable pulse along with other arterial twigs reaching that way. You will find that this foramen is peculiar to the cuneiform bone.|
|a 2 , 3||Path of the fifth pair of cerebral nerves
[n. facialis et n.
vestibulocochlearis] (a in fig. 2, ch. 2, Bk. 4), or auditory passage
[meatus acusticus externus
osseus], whose beginning in the inner space of the skull is marked a in
the third figure.
The letter a in the second figure marks its exterior portion [meatus acusticus externus], which begins from the ear, more or less resembles the auricle, and appears rough. 69 Although this passage is rather large and hollow, it is found to be so twisted, winding, and richly variable that it very rarely accepts the insertion of a bristle. That one does not pass through is less because of the twists and turns of the passage than it is because near the ear [cavitas tympanica] and later where it turns toward the brain it ends up narrower than in the middle (i in the figure for chapter 8, book 1) where it appears quite large and wide. 70 But Aristotle is not at all to be heeded when he claims that no passage
|runs from the ear to the brain. “But a passage does run to the roof of the mouth,” 71 he says, “and a vein runs to it from the brain.” 72 The auditory meatus [m. acusticus internus] extends to the skull cavity and also admits a vein (n in the fig. for ch. 14, Bk. 3): 73 it does not bring it down 74 from the brain, but it takes the vein to the organ of hearing from the inner jugular as it enters the skull, 75 and as we earlier stated it provides a path to the small branch [n. vestibulocochlearis] of the fifth pair of cerebral nerves. Furthermore, if you introduce a bristle into the auditory passage from the outside and push it in at a slightly forward angle, you will see it borne much more easily into the foramen marked V [tuba auditoria, pars ossea] than into the space of the skull.|
|b 2||Foramen [f. stylomastoideum] beginning from the middle of the space belonging to the organ of hearing and extending backward from there. Because of bends and labyrinths, and because it does not reach the inner part of the skull, it will not let a bristle pass through. It is provided for a small branch [n. facialis] (c in fig. 2, ch. 2, Bk. 4) of a nerve of the fifth pair; since Nature wished it to harden, she very cleverly brought this branch through a winding foramen of the hardest and driest bone [os temporale, pars petrosa]. It is called by all professors of dissection tuflo/n, the blind [caecum] or one-eyed foramen, not because the passage is not real or penetrable, but because it does not admit a bristle or lead wire 76 into the space belonging to the organ of hearing. This foramen is located above the root of the mammillary process [p. mastoideus] in wolves and dogs, where it is much larger and more spacious than in humans. Some, perhaps, call the foramen [tuba auditoria, pars ossea] extending forward out of the auditory meatus [auris media], marked V, “blind.” However that may be, they know nothing about this foramen V or the one marked b. But so far I have found in no author even a single foramen described as fits the subject, though the exploration of foramina is most rewarding and they are evidence of Nature’s supreme diligence. 77|
|c 2 , 3||Foramen
[f. jugulare] common to the
occipital and temporal bones, carved out for the sixth pair
of cerebral nerves (N in fig. 9, Bk. 7), the
greater branch of the inner jugular vein (C and then I in the fig. for ch. 14,
and the lesser branch of the sleep
[a. carotis interna].
Because the organs passing through here are very large, it is large in accordance with the shape of the bodies passing through. For it is not perfectly circular but more or less doubled and turned in upon itself; one part (which is inner) is made for the nerve 80 exiting the skull in a more or less forward direction; the other (which is outer) serves the [internal jugular] vein and the [internal carotid] artery entering the skull in a posterior direction.
|d 2 , 3||Foramen [canalis hypoglossi] in the occipital bone incised for a nerve [n. hypoglossus] (O in fig. 9, Bk. 7 and n in fig. 2, ch. 2, Bk. 4) of the seventh pair of cerebral nerves; it is round, but has a long and slanting course. It is carried downward 81 from a posterior and inner point in the skull so that the nerve of the seventh pair would pass through this foramen and be joined to the sixth pair more quickly, and so that at the same time both would stick together and descend safely. 82|
|e 2 , 3||A single foramen [f. magnum], easily the largest of them all, is introduced into the occipital bone for the sake of the dorsal medulla [m. spinalis] (H in fig. 9, Bk. 7) that takes its origin from the brain.|
|f 2||A not especially large foramen [canalis condylaris], which begins from the outer part of the skull out of the posterior part of the head’s occipital bone (l in fig. 5, ch. 6) which is articulated to the first cervical vertebra, and goes by a long course through the bone into the inside of the skull, ending in the higher part of the foramen marked d [canalis hypoglossi] belonging to the seventh pair [n. hypoglossus] of cerebral nerves. This is hollowed out for the vein [vv. columnae vertebralis] and artery [a. vertebralis] (D and K of the fig. for ch. 14, Bk. 3) climbing upward through the transverse processes of the neck vertebrae. In certain skulls, you will find this foramen is missing on one side, and sometimes even on both; in such cases its function is performed by the foramen of the seventh pair of cerebral nerves, marked d, which then does not appear exactly round but oblong, suitable for transmitting the nerve together with the vein and the artery. 83|
|g 2 , 3||This foramen [f. mastoideum] is carved out in the temporal bone near the posterior region of the mammillary process [pars petrosa, processus mastoideus], by the side of the lambdoid suture (C in figs. 3, 4, 5, ch. 6); entering the skull transversely, it furnishes a path to a branch 84 (E in the fig. for ch. 14, Bk. 3) of the outer jugular vein that goes into the skull at this point. I have occasionally noticed that this foramen is missing, sometimes on one side, sometimes on both.|
Skull cavities accommodating vessels of the hard membrane
[sinus durae matris]
In the third figure (see also M, N, O, P in the fig. for ch. 14, Bk. 3; P, Q, R, S in fig. 7, Bk. 7, S, T in fig. 9, C in fig. 1, and B in fig. 2), close attention must be paid to the cavity inside the skull 85 where the cerebrum is contained, into which come the three foramina labeled c, f, and g, made to carry veins and arteries. From the foramen [f. jugulare] of the sixth pair of cerebral nerves [n. glossopharyngeus, n. vagus, n. accessorius], marked c, and the inner part of the foramen marked f, a cavity [sulcus sinus transversi et sulcus sinus sigmoidei] begins in the right and left sides of the skull, which we have marked h, h, h on the left [right] side and on the right [left] with three i’s. These sinuses [ss. durae matris] climb obliquely to the rear like the quarter part of a circle until the right joins the left, where we have placed a k [sulcus sinus sagittalis superioris]. The location of this meeting is seen in the middle of the occipital bone, which is midway between the highest point [lambda] of the lambdoid suture (D in fig. 3, ch. 6) and the posterior area of the foramen [f. magnum] that carries the dorsal medulla, marked e, and is marked k at the point [protuberantia occipitalis interna] where, in our account of that bone, we stated it is thickest and most dense. From this junction [sulcus sagittalis superioris] of two depressions [sulcus sinus transversi], another is carried straight up beneath the highest part of the lambdoid suture and under the entire sagittal suture [sulcus sinus sagittalis superioris]
|ll[ 4 ], m[ 3 ]||The fourth figure has this depression [sulcus sinus sagittalis superioris] marked l a number of times, while the third marks it with the letter m on the frontal bone. These depressions are carved out for the hard cerebral membrane, whose vessels [sinus durae matris] recede into them 87 to avoid being crushed by the bones of the skull, as you will hear when I explain in the third book the array of cerebral vessels, which is no less elegant than difficult to follow, 88 and little attended to by other professors of anatomy.|
|n, o 2||Note the palate in the second 89 figure, where the large nasal foramina [choanae], divided by a septum [vomer] labeled x and extending from the nostrils into the space [meatus nasopharyngeus] of the throat, are marked n and o. Although these have many functions for man, they are believed especially suited for normal inhalation and for the voice.|
|p 2||This foramen [f. incisivum] near the back of the incisor teeth runs from the palate into the nasal cavity and is common to the fourth bones [maxillae] of the upper maxilla. It is single in humans, double in horses and dogs. It is made for the connection and meeting of the tunic [t. mucosa] covering the palate (beneath Z in fig. 2 preceding ch. 2, Bk. 4) with that which covers the nasal cavity (lower P in the same fig.). 90 A very small part of that tunic runs through it, together with a small vein and a small artery [v. palatina externa, a. palatina major].|
|q 2||At the end of the palate near the sixth bone [os palatinum, lamina horizontalis] of the upper maxilla, two foramina are seen on each side, one in front of the other, and larger. The first or anterior, marked l [foramen palatinum majus], is of a noteworthy size, proceeding up from the palate in a posterior direction to the vertex [fissura orbitalis superior] or root of the eye socket. It ends at the foramen [fissura orbitalis inferior] which we explained is one of those that drain phlegm into the nostrils and which we previously described under the letter F. The posterior foramen [ff. palatina minora] is labeled k, and it is quite small and ascending upward; sometimes it terminates in the same foramen as the anterior one marked l, but sometimes it has a terminus of its own in the suture [s. sphenomaxillaris] common to the cuneiform bone and the fourth bone of the upper maxilla.|
Small foramina scattered throughout the skull cavity
Besides the foramina already mentioned, if you take a skull in your hands you will notice a large number of others (but small) carved out to carry veins and attach membranes. A number of this type are seen hard by the greater or inner angle of the eye socket next to the suture [s. frontolacrimalis, s. frontoethmoidalis] common to the second [os lacrimale] and third [os ethmoidale] bones of the upper maxilla and the frontal bone. These run into the cavity [sinus frontalis] between the plates of the frontal bone previously marked K. Their [foramina ethmoidalia] location is shown in the first figure of this chapter by T and V, letters by which we identified the above mentioned suture in its own place, and the bones mentioned are labeled there I, D, and Q. 91 Small foramina of this kind occur also in the frontal bone [foramen supraorbitale] near the eyebrows; likewise also in both bones of the nose, 92 which we counted the fifth [os nasale] of the upper maxilla. In addition, in the first bone [os zygomaticum] of the maxilla, which forms the outer angle of the eye socket, one or two foramina of this kind 93 are found. The sides [ala major] of the cuneiform bone [os sphenoidale], which with other bones [os temporale, pars squamosa] form the hollow of the temples, also possess such a foramen. In addition to these, beside the sagittal suture in the bones [os parietale] of the vertex, and particularly near the lambdoid suture, such foramina appear, whose locations are marked by a number of ∫’s [foramen parietale] hidden in the shading of the fourth figure. But besides those mentioned, one of a noteworthy size is on the inside of the frontal bone, where this bone is joined to the anterior part of the eighth bone [os ethmoidale] of the head, and the anterior part [lamina perpendicularis] of the septum of the sinuses of the olfactory organs is seen; this foramen [f. caecum] is visible between m and h of the third figure. It extends into the cavity [sinus frontalis] of the frontal bone, marked K at the top. Also, in the fourth bone of the upper maxilla, next to the large or inner angle of the eye socket, another foramen of this class presents itself. On the outer base of the cuneiform bone where it is joined to the nasal septum [vomer], five are often seen; and three, marked m, n, and c, stand behind, one on each side and the third between them: 94 these, extending forward like tiny passages, end in the nasal cavity; but the end of the middle foramen, marked n, rarely admits a bristle. Two others, which we have labeled ϖ and w [canalis palatovaginalis], begin more to the front and climb forward in a straight path, ending at the vertex and root of the eye socket. The ends of these foramina cannot readily be illustrated; therefore I urge you the more earnestly to learn them from human skulls rather than from bare pictures of bones: make conjectures about the location of each foramen from the letters on the page and consider at length whether some noteworthy foramen has escaped my attention. There remain still in the third and fourth figures some Greek capital letters which we used previously to label sutures of the skull; only W remains to be explained, by which certain cavities [foveolae granulares] in the vertex are marked: you will hear that the hard membrane [dura mater] of the brain (K in fig. 1, Bk. 7 95 ) is attached to these. 96 The arrangement of these cavities is not always the same; sometimes none are seen, sometimes a few, sometimes many and variable. These should especially be noted by those (if any are present) who are too quick to scorch this part of the vertex or too brashly and confidently drill holes in the fractures of the bones. 97 At this point I would also mention two hollows [sinus sphenoidales] in the cuneiform bone, placed like caves in its middle, had I not already described them