234
UNIT TWO
7.12
LOWER LIMB
The bones of the lower limb form the frameworks of the
thigh, leg, and foot. They include a femur, a tibia, a F
bula,
tarsals, metatarsals, and phalanges
(f
g. 7.50)
.
Femur
The
femur,
or thigh bone, is the longest bone in the body
and extends from the hip to the knee. A large, rounded
head
at its proximal end projects medially into the acetabulum of
the hip bone
(f
g. 7.51)
. On the head, a pit called the
fovea
capitis
marks the attachment of a ligament. Just below the
head are a constriction, or
neck,
and two large processes—
a superior, lateral
greater trochanter
and an inferior, medial
lesser trochanter.
These processes provide attachments for
muscles of the lower limbs and buttocks. On the posterior
surface in the middle third of the shaft is a longitudinal crest
called the
linea aspera.
This rough strip is an attachment for
several muscles.
At the distal end of the femur, two rounded processes,
the
lateral
and
medial condyles,
articulate with the tibia of
the leg. A patella also articulates with the femur on its distal
anterior surface.
On the medial surface at its distal end is a prominent
medial epicondyle,
and on the lateral surface is a
lateral epi-
condyle.
These projections provide attachments for muscles
and ligaments.
and pubis bones. This portion of the pelvis surrounds a short,
canal-like cavity that has an upper inlet and a lower outlet.
An infant passes through this cavity during childbirth.
Differences Between Male and Female
Pelves
Some basic structural differences distinguish the male and
the female pelves, even though it may be difF
cult to F nd all
of the “typical” characteristics in any one individual. These
differences arise from the function of the female pelvis as a
birth canal. Usually, the female iliac bones are more fl
ared
than those of the male, and consequently, the female hips
are usually broader than the male’s. The angle of the female
pubic arch may be greater, there may be more distance
between the ischial spines and the ischial tuberosities, and
the sacral curvature may be shorter and fl
atter. Thus, the
female pelvic cavity is usually wider in all diameters than
that of the male. Also, the bones of the female pelvis are usu-
ally lighter, more delicate, and show less evidence of muscle
attachments (F g. 7.49).
Table 7.10
summarizes some of the
differences between the male and female skeletons.
PRACTICE
33
Locate and name each bone that forms the pelvis.
34
Name the bones that fuse to form a hip bone.
35
Distinguish between the greater pelvis and the lesser pelvis.
36
How are male and female pelves diF
erent?
TABLE
7.10
|
Dif
erences Between the Male and Female Skeletons
Part
Male Dif
erences
Female Dif
erences
Skull
Larger, heavier, more conspicuous muscle attachment
Smaller, more delicate, less evidence of muscle attachment
mastoid process
Larger
Smaller
supraorbital ridge
More prominent
Less prominent
chin
More squared
More pointed
jaw angle
Angle of ramus about 90 degrees
Angle of ramus greater than 125 degrees
forehead
Shorter
Taller
orbit
Superior border thicker, blunt edge
Superior border thinner, sharp edge
palate
U-shaped
V-shaped
Pelvis
Hip bones heavier, thicker, more evidence of muscle
attachment
Hip bones lighter, less evidence of muscle attachment
obturator foramen
More oval
More triangular
acetabulum
Larger
Smaller
pubic arch
Narrow, more V-shaped
Broader, more convex
sacrum
Narrow, sacral promontory projects more forward, sacral
curvature bends less sharply posteriorly
Wide, sacral curvature bends sharply posteriorly
coccyx
Less movable
More movable
cavity
Narrow and long, more funnel-shaped
Wide, distance betweeen ischial spines and ischial tuberosities is greater
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