Bauhaus-Universität Weimar

Titel:
The Cyclopaedia of Anatomy and Physiology, vol. 2: Dia-Ins
Person:
Todd, Robert Bentley
PURL:
https://digitalesammlungen.uni-weimar.de/viewer/image/lit25760/513/
BONES OF THE HAND. 505 
HAIR. See Tegumentary System. 
HAND, BONES OF THE, (Human Ana¬ 
tomy.) The hand tnanus; Fr. la main; 
Germ, die Hand,) is the inferior segment of 
the upper extremity. Its presence is charac¬ 
teristic of man and the Quadrumana. 
Although formed on the same general type, 
the hand will be found to exhibit many points 
of difference from the foot—characters strongly 
indicative of the diversity of use for which it 
is designed. In examining the skeleton of the 
hand, we observe subdivisions analogous to 
those which exist in the foot—the carpus cor¬ 
responding to the tarsus, the metacarpus to the 
metatarsus, and the phalanges of the fingers in 
every way analogous to those of the toes. 
Independently of the lightness and mobility 
which are such prominent features in the me¬ 
chanism of the hand, when contrasted with 
that of the foot, the divergence of the first or 
radial finger (the thumb) from the line of 
direction of the other four, is peculiarly cha¬ 
racteristic of the hand. Whilst the four fingers, 
properly so called, are parallel to the middle 
line of the hand, the thumb, when extended, 
forms with it an angle of rather more than 45°. To 
this position of the thumb is due in the greatest 
part the facility of opposing it to one of the 
fingers, a movement so necessary in the pre¬ 
hension of minute objects.* 
The general form of the hand is oval, the 
obtuse extremity corresponding to the tips of 
the fingers, the unequal lengths of which oc¬ 
casion the curvature in this situation. On its 
posterior surface or dorsum, the hand is convex ; 
on its anterior surface or palm, it is concave : 
both these surfaces correspond to, and in the 
recent state are supported by, the bones of the 
carpus and metacarpus. 
I. Carpus (Germ, die Handwurzel). The 
carpus bears a much less proportion in size to 
the whole hand than the tarsus does to the foot; 
it forms scarcely more than one-fourth of the 
hand. Its outline is oval, the long axis being 
transverse : if examined in a hand to which 
the ligaments are attached, the carpus will be 
found to form the posterior and osseous portion 
of an osseo-ligamentous ring, which gives pas¬ 
sage to the tendons of the fingers. It is con¬ 
sequently hollowed from side to side, and is 
bounded on each side by a bony ridge, which 
gives attachment to the ligament (annular 
ligament) which forms the anterior part of the 
ring ; on the radial side the ridge is formed by 
a process of the os trapezium and of the sca¬ 
phoid; on the ulnar, where there is a more 
prominent ridge, by a process of the unciform 
bone, and by the os pisiforme. 
Seven bones, arranged in two rows, form 
the carpus. The superior row consists of the 
os naviculare, os lunare, and os cunéiforme, 
to which last is articulated a bone, constantly 
reckoned as a carpal bone, but which, I con¬ 
ceive, may be more correctly regarded as a 
sesamoid bone, the os pisiforme. The second 
* See the prefatory observations to the article 
Foot. 
or inferior row is formed by the os trapezium, 
os trapezoides, os magnum, and os une forme. 
1. Os naviculare (os scaphoideum ; Fr. le 
scaphoide; Germ, das Kahnbein). The na¬ 
vicular or scaphoid is the largest of the upper 
row, and likewise the most external. Its su¬ 
perior surface is convex, oval, with long axis 
transverse, articular, and is adapted to the 
outer part of the carpal articular extremity of 
the radius. The hollowed surface, to which it 
owes its name (boat-like), is directed down¬ 
wards and inwards ; this is likewise articular and 
receives the head of the os magnum : con¬ 
tinuous with and to the inner side of this 
hollow surface, there is a plane one of a semi¬ 
lunar form, with which the os lunare is articu¬ 
lated. The scaphoid bone articulates with the 
trapezium and trapezoides, by a convex surface 
directed downwards and outwards. Externally 
this bone terminates in a pointed extremity 
which receives the external lateral ligament of 
the wrist-joint and the annular ligament (tuber- 
culum ossisnavicularis, s,.eminentia carpiradialis 
superior). The anterior and posterior surfaces 
of the bone are rough, and give attachment to 
the anterior and posterior radio-carpal ligaments. 
2. Os lunare, (os semilunare v. lunatum; 
Fr. le semilunaire ; Germ, das Mondbein), 
situated between the scaphoid and the cunei¬ 
form bones, it presents four articular surfaces ; 
an upper one, convex and somewhat triangular 
in its outline, articulated with the radius; an 
inferior one, very much hollowed from before 
backwards (to the crescentic form of which the 
bone owes its name), articulated with the os 
magnum ; an external surface, plane and 
square, adapted to the cuneiform bone ; and, 
lastly, an internal surface, by which it articu¬ 
lates with the scaphoid. 
3. Os cunéiforme (os triquetrum s. pyra¬ 
midale; Fr. le pyramidale; Germ, das dreiseitige 
Bein). This bone terminates the superior 
carpal row on the ulnar side ; its upper surface 
is partly smooth, encrusted with cartilage in 
the recent state, where it is in contact with the 
triangular ligament of the wrist-joint, and 
partly rough where it gives attachment to liga¬ 
ments. Externally it articulates with the cunei¬ 
form bone, and inferiorly with the unciform 
by a large and concave suaface. The inner 
half of its anterior surface articulates with the 
pisiform bone, and the radial half of the same 
surface is rough for ligamentous insertion. 
The three bones just described, constituting 
the superior row of the carpus when united, 
present on their superior aspect a convex arti¬ 
cular surface which forms the carpal portion 
of the radio-carpal joint, the scaphoid and 
lunar being articulated with the radius, while 
the cuneiform glides upon the triangular carti¬ 
lage of the wrist. 
4. Os pisiforme (from pisum, a pea; Fr. 
le pisiforme; Germ, das Erbsenbein). This 
little bone projects at the anterior part of the 
ulnar extremity of the superior carpal row; 
it forms what some anatomists designate 
eminentia carpi ulnaris superior, being part of 
the bony ridge already referred to on the ulnar- 
side of the carpus. The prominence produced
        

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