229
CHAPTER SEVEN
Skeletal System
At the distal end of the ulna, its knoblike
head
articulates
laterally with a notch of the radius (ulnar notch) and with a
disc of F brocartilage inferiorly (F g. 7.44). This disc, in turn,
joins a wrist bone (triquetrum). A medial
styloid process
at
the distal end of the ulna provides attachments for ligaments
of the wrist.
Hand
The hand is made up of the wrist, palm, and F ngers. The skel-
eton of the wrist consists of eight small
carpal bones
F rmly
bound in two rows of four bones each. The resulting compact
mass is called a
carpus
(kar
pus). The carpus is rounded on
its proximal surface, where it articulates with the radius and
with the F brocartilaginous disc on the ulnar side. The carpus
is concave anteriorly, forming a canal through which tendons
and nerves extend to the palm. Its distal surface articulates
with the metacarpal bones.
Figure 7.45
names the individual
bones of the carpus.
±ive
metacarpal bones,
one in line with each F
nger,
form the framework of the palm or
metacarpus
(met
ah-
kar
pus) of the hand. These bones are cylindrical, with
rounded distal ends that form the knuckles of a clenched
wrenchlike opening, the
trochlear notch
(semilunar notch),
that articulates with the trochlea of the humerus. A pro-
cess lies on either side of this notch. The
olecranon process,
located above the trochlear notch, provides an attachment
for the muscle (triceps brachii) that straightens the upper
limb at the elbow. During this movement, the olecranon pro-
cess of the ulna F ts into the olecranon fossa of the humerus.
Similarly, the
coronoid process,
just below the trochlear
notch, F
ts into the coronoid fossa of the humerus when the
elbow bends.
Lateral
epicondyle
Lateral
epicondyle
Medial
epicondyle
Capitulum
Coronoid
fossa
Trochlea
Deltoid tuberosity
Head
Intertubercular
groove
Lesser tubercle
Greater tubercle
Greater tubercle
Olecranon
fossa
Anatomical
neck
Surgical
neck
(a)
(b)
FIGURE 7.43
Right humerus. (
a
) Anterior surface. (
b
) Posterior surface.
Many a thirtyish parent of a young little leaguer or softball player
becomes tempted to join in. But if he or she has not pitched in many
years, sudden activity may break the forearm. Forearm pain while
pitching is a signal that a fracture could happen. Medical specialists
advise returning to the pitching mound gradually. Start with twenty
pitches, five days a week, for two to three months before regular
games begin. By the season’s start, 120 pitches per daily practice ses-
sion should be painless.
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