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 25 On the Carpus

[Figures of Chapter XXV]

We shall add an index explaining the six figures above together with their characters 1 on the following page.

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[Table describing the figures of Chapter XXV]
The first two figures apply not only to the present chapter but also to the three following, in which the parts of the hand are also explained. We shall call what Hippocrates named a)kro/xeir 2 the top or end of the “hand,” that is, the part which lies between the forearm and the farthest [distalis] tip of the fingers and which we divide into carpus, metacarpus, and fingers. 3 By “hand,” Hippocrates meant whatever comes between the scapuli and the end of the fingers and is subdivided into arm, forearm, and hand. Thus, the first figure of this chapter shows the inner [palmaris] surface of the bones of the hand. The second includes the outer [dorsalis] surface of the same bones, appropriately drawn. The four subsequent figures are peculiar to this chapter and represent only the eight carpal bones in various aspects. The one identified as third shows the inner [carpale palmare] surface of the eight wrist bones, all together in place. The fourth has the same bones drawn from their outer [carpale dorsale] aspect. The fifth includes the upper part [pars proximalis] of the wrist bones, where they are articulated to the forearm. The sixth displays the lower surface of the wrist bones, to which the first bone of the thumb [os metacarpale I] and the four metacarpal bones [ossa metacarpalia II-V] are attached. The index of characters will be as follows.

1-8[ 1, 2 ] These eight numerals designate the eight bones of the carpus in all six of the present figures, if all were seen on the surface in which the wrist presents itself. Each bone is always identified with its own number, and in this way shows its name. We shall call the first bone [os scaphoideum] that which is marked 1, the second [os lunatum] the one marked 2. Thus 1, 2, 3, 4 mark the upper [proximalis] row of the eight wrist bones, these being the four higher or nearest to the forearm. 5, 6, 7, 8 indicate the lower [distalia] bones, which are conterminous to the metacarpus. 4
I-IV[ 1, 2 ] The four metacarpal bones are marked in the first and second figure; 5 there is no reason not to name them by the number written on them — unless one prefers to name them from the finger they support, and which they precede.
A, B, C 1, 2 Three bones of the thumb [pollex] which we also call internodes. 6
D, E, F 1, 2 Three bones of the index finger [digitus secundus]; the same system applies to the other fingers as well. 7
G 3, 6 Depression [facies articularis, basis metacarpalis I] of the fifth carpal bone [os trapezium], and surface to which the first bone [os metacarpale I] of the thumb is articulated. We measure the length of this depression transversely from a to b in the sixth figure. The internal [medialis] surface is marked c, the external [lateralis] d, which is also visible in the fourth figure.
H 3, 4, 6 Surface [facies articularis] of the sixth carpal bone [os trapezoideum] to which the metacarpal bone supporting the index finger [digitus secundus] is attached; on the fifth bone, h marks the place [facies articularis basis metacarpalis II] which the same metacarpal bone also touches.
K 3, 4, 6 Place [facies] on the seventh wrist bone [os capitatum] to which the metacarpal bone supporting the middle finger [digitus tertius] is attached. In the same figures, k marks the place [facies articularis basis metacarpalis III] where this metacarpal touches the sixth wrist bone.
L 3, 4, 6 Place on the eighth carpal bone [os hamatum] to which the metacarpal bone [os metacarpale IV] leading to the ring finger [digitus quartus] is attached.
M 3, 4, 6 Place on the eighth carpal bone to which the metacarpal bone [os metacarpale V] supporting the little finger [digitus quintus] is articulated.
N 1, 2 Ossicle [os sesamoideum] leaning against the outer side of the articulation of the eighth carpal bone to the metacarpal bone, by which the little finger is supported.
O 1 , 3, 6 Process of the eighth carpal bone [hamulus ossis hamati] protruding into the inner area of the carpus.
P 1 , 3, 6 Process [tuberculum ossis trapezii] of the fifth carpal bone from which originates the transverse ligament [retinaculum flexorum] that makes its insertion into the process of the eighth bone marked O; it is covered by tendons from the forearm 8 that go to the inner area of the hand.
Q 2 Upper epiphysis [basis metacarpalis II] of the metacarpal bone that supports the index finger [digitus secundus]; it is articulated to the carpus [os trapezium] [os trapezoideum].
R 2 Lower epiphysis [caput] of the metacarpal bone leading to the index finger, which forms the head that enters the depression of the first bone [phalanx proximalis] of the index finger. 9
S 1, 2 Interval between the metacarpal bone leading to the index finger and the one that supports the middle finger. The same system of epiphyses and intervals holds for the other metacarpal bones.
T 1, 2 In the first figure the inner of two sesamoid bones placed before the inside of the second thumb joint is marked; in the second figure, the outer.
V, V 1 Two sesamoid ossicles placed in front of the joint of the index finger. 10
X 1 A single sesamoid ossicle, or rather like a mustard seed, placed upon the second joint of the index finger. 11
Y 1 A single sesamoid ossicle, located on the third joint of the thumb. 12 In the remaining fingers the system is the same as with the index finger, though we have not shown the sesamoid ossicle of the second and third joint. 13

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The carpus is constructed of eight bones differing from each other in shape 14
The Greeks call the part of the hand (V to Z in the skeletal figures, nos. 1-8 in all the figures of this chapter) that is articulated to the forearm karpo/j; we call it brachiale in imitation of Celsus. 15 It is constructed of eight bones separated in a double row. In people of mature years, these bones are hard and small, not porous inside, and filled with a slight amount of marrow like the epiphyses, not altogether lacking in marrow. 16 This is particularly so in the larger of these bones, as they are all of different size, shape, and location, nor is there one in the lot which at all resembles another: each one has some feature by which it can readily be distinguished from the others. But varied though they be, they are so harmoniously fitted to each other and attain such a unity of composition, that their number is not very easy to discover. For unless you cut away the very strong cartilaginous ligaments [articulationes carpi] (D in the 8th table of muscles, l in the 12th) with which they are covered, as well as the membranes, and carefully scrape them off, they will all appear to be a single one, 17 or like Celsus you will believe they consist of an uncertain number. 18

Where the carpus is covered with ligaments, and where by cartilage
They are all(compare figs. 1 and 2, then the 3rd to the 4th) bound together (but not, as some think, fused) by these sinewy and cartilaginous bonds, forming two complete surfaces: convex on the outside [carpale dorsale] as much as is useful to the hand, and hollow on the inside [carpale palmare], as concave as is convenient to this part of the hand. 19 Only these surfaces are bound by ligaments; 20 above (fig. 5), where the bones [ossa carpi proximalis] are joined to the forearm [radius et ulna], they are smooth and coated with cartilage, just as they are below (fig. 6) [ossa carpi distalis], where they are joined to the metacarpal bones [ll. carpometacarpalia dorsalia et palmaria] and the first bone of the thumb [artic. carpometacarpalis pollicis]. Indeed, where the bones touch each other they are not everywhere rough and uneven or covered with ligaments, but smoothly fitted depressions are carved in all of them, lined with smooth, slippery cartilage, and they receive the tubercles or heads of the other bones, which are likewise smooth and covered with cartilage. 21 Ligaments [ll. intercarpalia dorsalia, palmaria, interossea] or membranes come between none of the carpal bones except in the spaces [interossea] between the bones of the lower row [ossa carpi distalis], where a small amount of cartilaginous ligament, scarcely worth noticing, intervenes as if at a point, and where the lower bones are not so closely packed together as the upper.

Why there are two rows of carpal bones
Nature constructed this justly, fashioning two rows of wrist bones particularly because the upper row [ossa carpi proximalis] (1-4 in nearly all the figs.) needed to be joined to the forearm in quite a different way than the lower row [ossa carpi distalis] (5-8 in all figs.) needed to be joined to the metacarpus and the first bone of the thumb. The carpus is articulated to these as separate and distinct bones while it articulates with the forearm as to a single bone, so that the bones of the upper row are rightly articulated with each other more closely and intimately than the bones of the lower row, and without the intervention of any body. 22 Anatomists believe this is the chief reason for the large number of wrist bones, adding as a secondary reason that it is difficult to hurt; they believe the wrist is made more resistant to injury because it is composed of many bones that break the force of objects that strike it by giving way, as we observe that a spear or arrow has more trouble penetrating loose targets than those that are taut. 23 At the same time, we notice that this strength and abundance of bones was constructed by Nature not least for a countless variety of motions of the hand. I shall now endeavor to explain what depressions and outgrowths the wrist bones have. 24

Names of the carpal bones
Four bones are located in the upper [proximalis] part of the carpus, in the row that faces the forearm. To these we shall assign appropriate names according to the order in which they are arranged, always naming the first [os scaphoideum] (1 in the first five figs.) the bone that constitutes the inner [lateral] side of the upper row, and the second [os lunatum] (2 in the same figs.) the one that follows this and is more distant from the inside; third [os triquetrum] (3 in the same figs.), the one that is closest to the second toward the outside [medial]; fourth [os pisiforme] (4 in the same figs.) the one that occupies the outermost side. 25 Similarly, we shall name the four bones of the lower [distalis] row (5-8 in all figs.) the fifth, sixth, seventh, and eighth, and in this fashion we shall approach the account of the individual bones. The first, second, and third are very strongly and closely joined together and linked in a single row as if they were a single bone, forming the upper area of the carpus in such a way that they are smoothly articulated into the depression [facies articularis carpalis] of the radius and ulna as if they were the head of a single long, wide bone. The first [os scaphoideum] and the second [os lunatum] are placed in a depression (x, y in figs. 1 and 8, ch. 24) carved in the epiphysis of the radius; the third [os triquetrum] leans against the cartilage [discus articularis] (T in figs. 1-3, 8, ch. 24) which we have written begins at the radius and chiefly separates the ulna from the carpus. But the outer side of the third bone also comes into contact with the sharp process [p. styloideus] (R in figs. 1, 2, 5, 10, ch. 24) of the epiphysis of the ulna when we incline the hand to the outside. 26 At the same time, this third bone does not have a depression visually distinguishable in man that is made especially for the sharp process and lined with cartilage, since the process itself protrudes only along the side of the depression where the carpus is contained, acting in the same way as the brows of the other depressions, including the apex (a in figs. 1, 2, 7, ch. 24) of the epiphysis of the radius in this area. 27 This is readily decided even by touch, if when the hand is bent to the inside, one tries to insert the tip of the thumb of the other hand between the carpus and the ulna. Therefore the first three carpal bones are so joined together on their upper [proximalis] surface and so protrude that they make up as it were a single head of the wrist, smooth and covered with cartilage, by which it is articulated to the forearm and is moved in many vigorous motions as if formed of a single large bone. 28

Peculiarities claimed by the fourth bone
The fourth carpal bone [os pisiforme] (there is no need to identify the bones marginally hereafter, as the numbers are obvious in nearly all the figures of this chapter) does not touch the ulna, but on its upper surface it admits the portion of the ligament of this joint [l. ulnocarpale palmare]

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which originates from the sharp process [p. styloideus] of the epiphysis of the ulna. The tendon [m. flexor carpi ulnaris, tendo] (d in the 4th table of muscles) of the muscle which is reckoned the lower of those flexing the wrist is attached to the upper surface of the fourth bone. From its lower surface the muscle [m. abductor digiti minimi] (r in the 3rd table of muscles) originates by which the little finger is abducted from the others. Also, the muscle [m. flexor digiti minimi brevis] which is the outer of two that flex the first bone of the little finger takes a portion of its origin from this point.

To what bone it is attached
Thus this fourth bone [os pisiforme] is articulated with another neither on its lower nor its upper surface, nor even on its outer side, but only on its inner side, by a very low capitulum, to the outer side of the third bone [os triquetrum] (but more near the palm of the hand), in the way that we have said bones are placed together by a)rqrwdi/a. 29 This fourth carpal bone therefore has the peculiarity that it is joined to only one wrist bone, that it is the smallest of all the bones of the carpus, and is less concave and convex than the rest. It is more or less spherical but a little longer than it is thick, because it puts forth muscles below 30 while above it receives the insertion of a very strong tendon [m. flexor carpi ulnaris, tendo], as we have said, and for that reason it needed to protrude above and below more than to the sides. Hence the ancient professors of anatomy called it (I conjecture) rectum, the upright bone, 31 being in a quandary which row to assign it to.

To what row it should be assigned
We assign it to the upper row because it is articulated to the third bone of this row, and this is in fact the row in which it stands. Anatomists name it the cartilaginous bone, 32 the same name Marinus 33 gave to the bone [patella] (figs. 1, 2, ch. 32, C in the skeletons) in front of the knee joint which we call the mola 34 or patella. It is not (I believe) because they thought this bone to be soft and cartilaginous, since it is easily the hardest and most solid of all the bones of the carpus, but because when cooked its outside appears covered with cartilage on account of the origins of muscles and ends of tendons which after boiling resemble slightly soft cartilage. Galen appears to have counted this the eighth carpal bone, 35 attributing this property to it, that it is a bulwark for a certain nerve [ramus palmaris nervi ulnaris] (46 in fig. 2, ch. 11, bk. 4) that is bent from the inner part of the hand to the outer around this carpal bone. 36 I am not unaware of this nerve, but in humans it does not bend upon this ossicle. This is the nerve [n. ulnaris] from the fifth of the nerves 37 going to the arm that you will be told in the fourth book extends posteriorly from the inner side of the forearm a little after the midpoint, putting forth two twigs [n. digitalis palmaris proprius, n. digitalis palmaris communis] to the little finger, the same number 38 to the ring finger, and one [r. communicans cum nervo ulnari] to the middle. This nerve does not touch the fourth carpal bone, much less is it bent around it from the inside of the hand to the outside. 39 Except for the fourth carpal bone, there is not a single one that is not attached and contiguous to several bones. 40

How many bones are conterminous to the first wrist bone
The first bone [os scaphoideum], besides being articulated to the radius, is also articulated to the second carpal bone [os lunatum], entering a depression there with a quite large tuberculum. Then with a much larger convexity coming out of its lower [distalis] surface it enters a common depression made by the fifth wrist bone [os trapezium] together with the sixth [os trapezoideum]. But as a precaution lest this bone enter the depressions of other bones everywhere, and itself like a tyrant receive none, Nature carved out in it a conspicuous depression so that together with the second carpal bone (with which this depression is common) it might admit the great, rotund head of the seventh bone [os capitatum], easily the largest of them all. Thus the first bone is joined to the radius, the second carpal bone, the fifth, the sixth, and the seventh.

How many bones are conterminous to the second
The second bone [os lunatum] (which is as much smaller than the first as it is itself larger than the third) 41 is connected to the first and the seventh bones as we have just said, and to the third [os triquetrum] it is attached by a broad connection via arthrodia 42 [ll. intercarpalia interossea]; thus the second 43 bone is joined to the radius and three carpal bones, to wit the first, seventh, and third, and it also not much removed from the eighth [os hamatum].

How many bones are conterminous to the third
The third bone [os triquetrum] enters a depression [facies] of the eighth bone [os hamatum] with a moderately protuberant but wide tubercle [hamulus ossis hamati]; from this it is readily established that this bone is conterminous with the ulna — still more to the peculiar cartilage [discus articularis] (T in figs. 1 and 2, ch. 24) of this joint — and to the second, fourth [os pisiforme], and eighth carpal bones.

How many bones are conterminous to the fifth
The fifth wrist bone [os trapezium], which we counted the first of the lower row, receives the capitulum of the first wrist bone in a depression carved in its upper surface, and being hollowed also on its outer side, it receives the head of the sixth bone. Thus the fifth bone is connected to two carpal bones, the first and the sixth. 44 In addition, it separately supports the first bone of the thumb [os metacarpale I] (A in figs. 1 and 2) as well.

Connection of the first bone of the thumb and the metacarpal bones to the carpus
On its lower surface, it [os trapezium] has a wide, elongated (a, b in fig. 6) depression [facies articularis basis metacarpalis I] (G in figs. 3, 6) and on its inner [medialis] (c in fig. 6) and outer [lateralis] (d in fig. 6) sides it is carved out more than in the sides and the middle; to this is connected the capitulum [basis metacarpalis] of the first internode of the thumb by means of the type of joint [articulatio carpometacarpalis pollicis] which produces a motion clear to all, quite different from the mutual connections of the carpal bones, whose motion is so inconspicuous that it can scarcely be distinguished. This is the type of articulation 45 [articulationes carpometacarpales] by which the four metacarpal bones are attached to the four carpal bones of the lower row. The first metacarpal bone [os metacarpale II], placed before the index finger [digitus secundus], is for the most part articulated to the sixth carpal bone (H in figs. 3, 4, 6), also touching a portion (h in figs. 3, 4, 6) of the fifth bone. For where the fifth bone is attached to the sixth, a common depression is carved in either bone, to which part of the head of the first metacarpal bone [basis metacarpalis II] is articulated so that the fifth carpal bone, besides touching the first and sixth, also touches the first bone of the thumb along with the first metacarpal. The second metacarpal bone [metacarpalis III], supporting the middle finger [digitus tertius], is articulated by a depressed but slanting

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head to the very lightly and obliquely carved depression (K in figs. 3, 4, 6) of the seventh carpal bone [os capitulum], slightly touching the sixth carpal bone [os trapezoideum] (k in the same figs.) with its sharper part and its inner side. The two remaining metacarpal bones [ossa metacarpi IV, V] , the ones that support the ring finger [digitus quartus] and the little finger [digitus quintus], are attached only to the eighth carpal bone [os hamatum] by smooth depressions (L and M in figs. 3, 4, 6) carved only in the surface.

How many bones are conterminous to the sixth
The sixth carpal bone [os trapezoideum] is attached to two metacarpal bones, viz. that which precedes the index finger and — inconspicuously — the one that is placed beneath the middle finger. It is attached to three carpal bones: it receives the first bone in its own depression, and with its own protrusion 46 it enters the depression of the fifth bone; then it is articulated to the seventh by the most slightly protruding capitulum, or rather by a level surface, and it is the smallest bone of the lower row as the seventh is the largest. The fifth and the eighth are of a middling sort, though the eighth is a little larger than the fifth.

Bones conterminous to the seventh
The seventh bone [os capitatum] enters the common depression of the first and second with its round or more protuberant head, and in this way is connected to those two bones. On its inner side it is articulated to the sixth bone, and on its outer to the eighth by a rather wide articulation which has a low head and a depression barely carved in the surface. A piece of cartilaginous ligament [l. intercarpale interosseum] comes between a part of this articulation; though this strongly attaches the seventh bone to the eighth, the seventh is of all the carpal bones the most often displaced towards the interior, first because being larger, it does not tolerate impacts as easily as its neighbors, and then again because the ligament on its inner surface securing this bone to its neighbors is not as thick as in the remaining area of the carpus. 47 This is chiefly because Nature wished to fill the passage with tendons of the mass and thickness of ligaments (Q in the 5th table of muscles, C in the 6th), 48 which extend this way in great numbers from the inner area of the forearm to move the fingers. However this may be, the seventh bone is connected to four carpal bones: the first, second, sixth, eighth, and to the metacarpal bone supporting the middle finger.

Bones conterminous to the eighth
The eighth bone [os hamatum] enters the seventh and the third more or less like a wedge, and is attached to those two: to the seventh, in the manner we have just explained, while it admits the third into a depression carved out in itself. Besides these two carpal bones, it is attached also to the metacarpal bones that lie below the ring finger and the little finger. So this bone too is conterminous with four bones.

The ossicle located at the joint of the fourth metacarpal bone with the carpus
To these bones there is sometimes added a tiny ossicle [os sesamoideum] (N in figs. 1, 2), one of those which resembles a sesame seed (V, V, X in fig. 1) and is called shsamoeidh= by the Greeks. 49 At the external side [lateralis] of the joint of the metacarpal bone that supports the little finger with the eighth carpal bone, 50 there is a bone of this kind, as if meant to fill up an area which is left more or less vacant here because this metacarpal bone is unable to press completely upon the eighth carpal bone with its upper part and moves away slightly to the outside. This ossicle, when it is present, is seen separately to reinforce the joint and give some underpinning to the metacarpal bone that supports the little finger. In such a case as this the eighth carpal bone is also contiguous to this ossicle 51 as well as the bones I have just mentioned.

The process of the eighth bone
Indeed, the eighth bone has this too as its special property that on its inner surface where it more or less faces the hollow of the palm it puts forth a noteworthy process [hamulus ossis hamati] (O in figs 1, 3, 6) that inclines from the outside [lateralis] towards the inside [medialis] and is carved out like the letter C on its inner side. This is to make a suitable place where the tendons of the muscles [mm. flexor digitorum superficialis et profundus, tendines] (proceding from the forearm) that flex the fingers may conveniently be carried and enclosed.

The process of the fifth bone
To make this location more suitable for such a mass of tendons, the fifth carpal bone [os trapezium] also puts forth a process [tuberculum ossis trapezii] (P in figs. 1, 3, 6) on its inner surface inclining toward the outer side and similarly carved on its outer side for the very same purpose as the process of the eighth bone, to furnish a path for those tendons [m. flexor carpi radialis, tendo] as well as to provide an origin for an extremely powerful ligament [retinaculum flexorum] (q in the 4th table of muscles) from the tips of those processes. This ligament surrounds the tendons transversely, enclosing and embracing them lest they stray and rise out of their seat (fig. inserted in ch. 1, Bk. 2). This spot, hollowed out for the tendons, 52 is quite smooth, as we have stated the other depressions are as well which transmit tendons as in rings. 53 The remaining part of the carpal bones outside this cavity, and the seats to which the bones are articulated, is uneven and more or less rough to put forth stronger ligaments and receive more securely those 54 by which it has earlier been explained the bones are bound and attached to each other.

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]