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 19 On the Bones of the Thorax

Key to the seven figures of the nineteenth chapter 1

Since the following figure legend will refer to all seven of the figures that precede it, we shall as usual add a note for the several numbers 2 so you may understand more easily to which of the figures the letters refer.

1, 2, 3, 4, 5, etc.[ 1 , 2 ] In the first and second figure, the twelve ribs [costae] of the thorax are indicated by this number. Of these, the seven upper ribs are articulated to the pectoral bone [sternum], but not the five lower. The numbering of the thoracic vertebrae is evident from the marked ribs even without the help of markings, if you observe that one rib on each side is articulated with a single vertebra.


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A, A 1 , 3 Whatever part of the ribs runs from the vertebrae to this point [corpus costae] is entirely osseous; here the ribs begin reverting 3 into cartilage [cartilago costalis]. The legend for the remaining markings will be placed below the figures.

FIRST FIGURE OF THE NINETEENTH CHAPTER,


where the complete structure of thoracic bones [ossa thoracis] is drawn in its anterior aspect, including the twelve thoracic vertebrae and the twelve ribs on each side, together with the pectoral bone [sternum] formed from several bones.

SECOND FIGURE OF THE PRESENT CHAPTER,


showing the posterior aspect of the complete structure of thoracic bones. It will be helpful also to examine in passing the three figures by which the entire structure of bones is illustrated in three aspects at the end of this Book. 4



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THE THIRD FIGURE


includes three vertebrae from the middle of the thoracic vertebrae seen from the right side, together with a middle rib of the same side. By means of this figure the articulation of the ribs to the vertebrae is shown as well as the course of the ribs.

IN THE FOURTH


is illustrated the posterior portion of a rib nearest the vertebrae to bring into clear view the swellings 5 [caput, crista, tuberculum] by which the nine upper ribs are articulated to the vertebrae. We have also broken a part of this rib to show the bony substance [substantia spongiosa, s. compacta, s. corticalis] of the ribs, labeled F.

THE FIFTH FIGURE


displays a portion of the the twelfth rib in the posterior aspect, where it is articulated 6 to the twelfth thoracic vertebra. We have broken this one also, where you see the F, to show the bony substance of the rib.

THE SIXTH FIGURE,


showing the anterior part of the pectoral bone free of rib cartilages [cartilago costalis].

THE SEVENTH FIGURE,


illustrating the posterior aspect of the pectoral bone free of rib cartilages.

B B 1 , 3 Returning to the figure index, B, B marks the beginning of the cartilaginous substance [cartilago costalis] of the ribs. The line [articulatio costochondralis] between A and B marks its union with bony tissue [os costale].
C 1 Union of cartilage of the first rib with the pectoral bone [articulatio sternocostalis I].
D 1 Articulation of cartilage of the second rib [art. sternochondralis II] with the pectoral bone, from which the type of joint of the five subsequent ribs may readily be inferred.
E 3 Cartilaginous tubercle 7 by which the second rib and the five that follow are articulated to the pectoral bone.
F F 1 End of cartilage of the false ribs [costae spuriae VIII-XII], which is seen to be pointed.
G 1 Area where cartilage of the eleventh rib is often separated from that of the tenth.
H 1 Point where cartilage of the twelfth rib is always separated from that of the eleventh.
I I 1 In these places the cartilages of the ribs protrude unevenly, often filling the space between.
K K 1 , 4 In this region an elongated depression [sulcus costae] is carved in the inner surface of the middle ribs, to be occupied by a vein, an artery, and a nerve [vasa et nervi intercostales].
L 4 Tubercle or capitulum [facies articularis capitis costae] by which the ribs are articulated to the vertebral bodies.
M 4 Tubercle [facies articularis tuberculi costae] by which the ribs are articulated to the tips [facies articularis processus transversi] of the transverse processes. These are more or less common to the nine upper ribs. 8
N 5 A type of tubercle [caput costae] by which the eleventh and twelfth ribs are articulated to the vertebrae.
O 4 , 5 Tubercle [t. costae] located in the posterior portion of the ribs next to the tip of the transverse process, into which is inserted the eleventh of the muscles [m. erector spinae, m. longissimus thoracis] that move the spine. 9


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Q 4 Interval [collum costae] between L and M, made rough for the purpose of producing a ligament [l. costotransversarium].
R 4 This area [angulus costae] too is roughened for muscles 10 which we shall enumerate in this chapter.
S, T, V 3 Three joined vertebrae, 11 or the bodies [corpora] of these vertebrae. We have noted other parts or processes of the vertebrae in the appropriate places.
X 3 Depression [foveae costales superior et inferior corporis vertebrae] common to two vertebral bodies, to which the head of a rib is articulated. 12
a 3 Joint of the rib to the vertebral body [art. costovertebralis].
b 3 Depression carved in the transverse process of the vertebra [facies articularis processus transversi], to which the rib is also articulated.
c 3 Joint [art. costotransversaria] of the rib to the transverse process.
d, e 3 In the topmost vertebra marked S, the depression is also marked, d [fovea costalis superior], like the one marked X between the middle and lowest vertebra. Also, e marks the depression in which you see b written in the lowest vertebra. 13
f 3 Region [angulus costae] of the rib most extended posteriorly, from which you may conveniently gauge the course of the ribs as follows: 14 from a and c to f, the rib runs obliquely downward from the vertebra to the posterior; but from A and B to E, the rib is bent back upward to the front in a curve.
g, h, i, k 1 The pectoral bone [sternum] is marked with these letters in the first figure. The first pectoral bone [manubrium sterni] is marked g to h; the second [corpus sterni], h to i, the third i to k; k also marks the pointed cartilage [proc. xiphoideus] of the pectoral bone. We shall now approach the pectoral bone more exactly in the sixth and seventh figure.
l 6 In the anterior surface of the first bone, a part protruding like a triangle, which could be circumscribed by t, q, and r.
m, n 6 Depressed area on each side of the protruding part. 15
o 7 Posterior area of the first bone which is seen to be rather concave.
p 6 , 7 Part [incisura cartilaginis costalis I] of the first bone to which the cartilage of the first rib is attached.
q, r 6 Depression [incisura clavicularis] of the first bone to which the capitula [extremitas sternalis claviculae] of the clavicles are articulated; 16 r also marks the right depression in the seventh figure.
s 6 , 7 Area [incisura jugularis] between the two depressions incised for the clavicles, carved out like a moon. 17
t 6 , 7 Here the first bone is joined to the second [angulus sterni]. 18
u 6 , 7 Common depression [incisura cartilaginis costalis II] of the first and second bone to which the cartilage of the second rib is attached.
x, y, z, a, b 6 , 7 Depressions 19 of the second bone to which cartilages of the third, fourth, fifth, sixth, and seventh ribs are articulated.
g, d, e 6 , 7 At these locations, distinctions of the second bone sometimes appear in children as if it had been formed of several bones fusing together to make a union. 20
z 6 , 7 This [processus xiphoideus] is counted the third pectoral bone; it ends in a cartilage not unlike a sword’s point, marked h. Foramina, in which the inner surface of the pectoral bone abounds, readily show themselves, though they are not marked by letters. 21



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 19 On the Bones of the Thorax