Ischium Ischium The ischium () forms the lower and back part of the hip bone ("os coxae"). Situated below the ilium and behind the pubis, it is one of these three bones whose fusion creates the hip. The superior portion of this bone forms approximately one third of the acetabulum. The ischium is made up of three parts–the body, the superior ramus and the inferior ramus. The body contains a prominent spine, which serves as the origin for the superior gemellus muscle. The indentation inferior to the spine is the lesser sciatic notch. Continuing down the posterior side, the ischial tuberosity
Squamous part of temporal bone from the external acoustic meatus; it is divided into two parts by a narrow slit, the petrotympanic fissure (Glaserian fissure). The anterior part, formed by the squamous part, is smooth, covered in the fresh state with cartilage, and articulates with the condyle of the mandible. Behind this part of the fossa is a small conical eminence; this is the representative of a prominent tubercle which, in some mammals, descends behind the condyle of the mandible, and prevents its backward displacement. The posterior part of the mandibular fossa, formed by the tympanic part of the bone, is non-articular, and sometimes lodges