The =ilia= are almost parallel to each other and are also less oblique
with regard to the horizontal plane than in the horse. They are
relatively small. The gluteal line is prominent and is nearly parallel
to the external border; it joins the superior ischiatic spine. A rounded
ridge separates the two parts of the ventral surface. The surface for
articulation with the sacrum is triangular. The internal angle is
truncated, does not extend as high as the vertebral spines, and is
separated from the opposite angle by a wider interval than in the horse.
The external angle is relatively large and prominent; it is not so
oblique as in the horse, and is wide in the middle, smaller at either
end. The shaft is short and compressed from side to side.
The =ischium= is large. Its long axis is directed obliquely upward and
backward, forming an angle of about 45 to 50 degrees with the horizontal
plane. The transverse axis is oblique downward and inward at a similar
angle, so that this part of the pelvic floor is deeply concave from side
to side. The middle of the ventral surface bears a rough ridge or
imprint for muscular attachment. The superior ischiatic spine is high
and thin, and bears a series of almost vertical rough lines externally.
The tuber ischii is large and three-sided, bearing upper, lower, and
external tuberosities. The ischial arch is narrow and deep. The
symphysis bears a ventral ridge, which fades out near the ischial arch.
The acetabular branch of the =pubis= is narrow, and is directed outward
and a little forward. The anterior border is marked by a transverse
groove which ends below the rough ilio-pectineal eminence. The
longitudinal branch is wide and thin.
The =acetabulum= is smaller than in the horse. The rim is rounded and is
usually marked by two notches. One of these is postero-internal and is
narrow and deep; it leads to the deep acetabular fossa and is commonly
almost converted into a foramen by a bar of bone. The other notch is
antero-internal, small, and sometimes replaced by a foramen or absent.
The =obturator foramen= is large and elliptical. Its inner border is
thin and sharp.
[Illustration:
FIG. 101.—SKELETON OF LEFT HIND LIMB OF OX, FROM MIDDLE OF THIGH
DOWNWARD, POSTERIOR VIEW. _21_, Tibia; _24_, tuber calcis; _25_,
large metatarsal bone. (After Ellenberger-Baum, Anat. für Künstler.)
]
The =pelvic inlet= is elliptical and is more oblique than in the horse.
In a cow of medium size the =conjugate diameter= is about nine and a
half inches (ca. 23 to 24 cm.), and the transverse about seven inches
(ca. 18 cm.). The anterior end of the symphysis lies in a transverse
plane through the junction of the third and fourth sacral segments. The
roof is concave in both directions. The =floor= is deeply concave,
particularly in the transverse direction. The =cavity= is narrower and
its =axis= is inclined strongly upward in the posterior part. The
distance between the acetabulum and the external angle of the ilium is
only a little (ca. 3 to 4 cm.) more than the distance between the former
and the tuber ischii.
[Illustration:
FIG. 102.—FRONTAL SECTION OF LEFT FEMUR OF OX, FRONT VIEW.
]
[Illustration: