_D_, Ilium; _Sch._, pubis; _S_, ischium; _a_, anterior border (crest)
of ilium; _b_, internal angle of ilium; _c′_, external angle of
ilium; _d_, great sciatic notch; _e_, external border of ilium; _f_,
iliac surface; _g_, linea arcuata; _h_, rough ligamentous area; _i_,
auricular surface; _k_, ilio-pectineal line; _l_, psoas tubercle;
_m_, transverse branch, and _n_, symphyseal branch of pubis; _o_,
_o′_, symphysis pelvis; _p_, anterior border of pubis (pecten); _q_,
tuberculum pubicum; _r_, ilio-pectineal eminence; _s_, tuber ischii;
_t_, ischial arch; _u_, lesser sciatic notch; _v_, acetabular
branch, and _w_, symphyseal branch of ischium; _x_, obturator
foramen; _y_, articular surface of acetabulum; _z_, fossa acetabuli;
_1_, groove for ilio-lumbar artery; _2_, groove for iliaco-femoral
artery; _3_, subpubic groove; _4_, depression for inner tendon of
origin of rectus femoris; _5_, rough area for attachment of adductor
muscles. (Ellenberger-Baum, Anat. d. Haustiere.)
]
The =internal= or =sacral angle= (Tuber sacrale) curves upward and a
little backward close to the first sacral spine, and forms here the
highest point of the skeleton. It is somewhat thickened and rough.
The =external= or =coxal angle= (Tuber coxæ) forms the basis of the
point of the hip. It is a large quadrangular mass, narrow in its middle,
and enlarged at either end, where it bears a pair of tuberosities. It is
roughened for muscular attachment.
The =posterior= or =acetabular angle= meets the other two bones at the
acetabulum, of which it forms about two-fifths. Its prominent upper
border forms part of the =superior ischiatic spine=, which is roughened
externally, smooth internally. Two depressions above and in front of the
acetabulum give attachment to the tendons of origin of the rectus
femoris muscle. This angle is connected with the ala or wide part of the
bone by a constricted part, often termed the =shaft=. The latter is of
three-sided prismatic form. Its external surface is convex and rough,
and gives attachment to the deep gluteus muscle. Its pelvic surface is
smooth and is grooved for the obturator vessels and nerves. Its ventral
surface is crossed by vascular grooves, below which is a rough area,
bounded internally by the psoas tubercle.