Inferior gluteal artery Inferior gluteal artery The inferior gluteal artery (sciatic artery), the smaller of the two terminal branches of the anterior trunk of the internal iliac artery, is distributed chiefly to the buttock and back of the thigh. It passes down on the sacral plexus of nerves and the piriformis muscle, behind the internal pudendal artery, to the lower part of the greater sciatic foramen, through which it escapes from the pelvis between the piriformis and coccygeus. It then descends in the interval between the greater trochanter of the femur and tuberosity of the ischium, accompanied by the sciatic and posterior femoral
Mastoid part of the temporal bone the innermost of the mastoid cells by a very thin lamina of bone, and even this may be partly deficient. The "superior border" of the mastoid part is broad and serrated, for articulation with the mastoid angle of the parietal. The "posterior border", also serrated, articulates with the inferior border of the occipital between the lateral angle and jugular process. Anteriorly the mastoid portion is fused with the descending process of the squama above; below it enters into the formation of the ear canal and the tympanic cavity. A section of the mastoid process shows it to be hollowed out