210 SPECIAL ANATOMY OF THE SKELETON 



portion of the internal surface which enters into the formation of the true pelvis, 

 and which gives origin to part of the Obturator internus muscle. Behind the 

 iliac fossa is a rough surface divided into two portions, an anterior and a posterior. 

 The anterior (Jades auricularis), so called from its resemblance in shape to the 

 ear, is coated with cartilage in the recent state, and articulates with a surface 

 of similar shape on the side of the sacrum. The posterior portion (tuberositas 

 iliaca) is rough, for the attachment of the posterior sacroiliac ligaments and for 

 a part of the origin of the Erector and Multifidus spinae. 



The crest of the ilium (crista iliaca) is convex in its general outline and sinuously 

 curved, being concave inward in front, concave outward behind. It is longer in 

 the female than in the male, very thick behind, and thinner at the centre than at 

 the extremities. It terminates at either end in a prominent eminence, the anterior 

 superior and posterior superior spinous process (spina iliaca anterior superior ct 

 spina iliaca posterior superior). The surface of the crest is broad, and divided 

 into an external lip (labium externum), an internal lip (Labium internum), and an 

 intermediate space (linea intermedia}. About two inches behind the anterior 

 superior spinous process there is a prominent tubercle on the outer lip. To the 

 external lip is attached the Tensor fasciae femoris, Obliquus externus abdominis, 

 and Latissimus dorsi, and along its whole length, the fascia lata; to the space 

 between the lips, the Internal oblique; to the internal lip, the Trans versa! is, 

 Quadratus lumborum, and Erector spinae, the Iliacus, and the iliac fascia. 



The anterior border of the ilium is concave. It presents two projections, sepa- 

 rated by a notch. Of these, the uppermost, situated at the junction of the crest 

 and anterior border, is called the anterior superior spinous process of the ilium, 

 the outer border of which gives attachment to the fascia lata and the origin of 

 the Tensor fasciae femoris; its inner border, to the Iliacus; while its extremity 

 affords attachment to Poupart's ligament and the origin of the Sartorius. Beneath 

 this eminence is a notch which gives origin to the Sartorius muscle, and across 

 which passes the external cutaneous nerve. Below the notch is the anterior 

 inferior spinous process, which terminates in the upper lip of the acetabulum; 

 it gives origin to the straight tendon of the Rectus femoris muscle and the ilio- 

 femoral ligament. On the inner side of the anterior inferior spinous process is 

 a broad, shallow groove, over which passes the Iliopsoas muscle. This groove 

 is bounded internally by an eminence, the iliopectineal eminence (eminentia 

 iliopectinea), which marks the point of union of the ilium and os pubis. 



The posterior border of the ilium, shorter than the anterior, also presents two 

 projections separated by a notch, the posterior superior spinous process (spina 

 iliaca posterior superior) and the posterior inferior spinous process (spina iliaca 

 'posterior inferior}. The former corresponds with that portion of the inner 

 surface of the ilium which serves for the attachment of the oblique portion of the 

 sacroiliac ligaments and the Multifidus spinae muscle; the latter, to the auricular 

 portion which articulates with the sacrum. Below the posterior inferior spinous 

 process the posterior border forms the upper part of a deep notch, the great 

 sacrosciatic notch (incisura ischiadica major). 



The Ischium (os ischii) forms the lower and back part of the os innominatum. 

 It is divisible into a thick and solid portion the body; a large, rough eminence, 

 on which the trunk rests in sitting the tuberosity; and a thin part which passes 

 forward and slightly upward the ramus. 



The body (corpus ossis ischii), somewhat triangular in form, presents three 

 surfaces, externaf, internal, and posterior; and three borders, external, internal, 

 and posterior. The external surface corresponds to that portion of the acetabulum 

 formed by the ischium; it is smooth and concave, and forms a little more than 

 two-fifths of the acetabular cavity; its outer margin is bounded by a prominent 

 rim or lip, the external border, to which the cotyloid fibrocartilage is attached. 



