228
UNIT TWO
On the radial shaft just below the head is a process called
the
radial tuberosity.
It is an attachment for a muscle (biceps
brachii) that bends the upper limb at the elbow. At the distal
end of the radius, a lateral
styloid
(sti
loid)
process
provides
attachments for ligaments of the wrist.
Ulna
The
ulna
is longer than the radius and overlaps the end of
the humerus posteriorly. At its proximal end, the ulna has a
Radius
The
radius,
located on the thumb side of the forearm, is some-
what shorter than its companion, the ulna
(fig. 7.44)
. The
radius extends from the elbow to the wrist and crosses over the
ulna when the hand is turned so that the palm faces backward.
A thick, disclike
head
at the upper end of the radius
articulates with the capitulum of the humerus and a notch of
the ulna (radial notch). This arrangement allows the radius
to rotate.
Olecranon
process
Head of radius
Neck of radius
Ulna
Olecranon
fossa
Carpals
Metacarpals
Phalanges
Humerus
Humerus
Ulna
Ulna
Radius
(c)
(d)
(a)
Hand (palm anterior)
(b)
Hand (palm posterior)
FIGURE 7.42
Right upper limb. (
a
) Anterior view with the hand, palm anterior and (
b
) with the hand, palm posterior. (
c
) Posterior view of the right
elbow.
(
d
) Radiograph of the right elbow and forearm, anterior view.
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