Question

Write a short note on the hip bone.

Answer 1

Hint: The hip bone refers to the anatomical bone present in the hip and lower waist area in humans and other vertebrates. The bone is highly important as it is an end to the spinal column, has sockets to hold the thigh bone, and has a role in holding the reproductive organs.

Complete answer:
- The hip bone is also known as the pelvic bone, coxal bone, or innominate bone, and is formed of two irregularly shaped left and right hip bones.
- It is composed of three main parts - the ilium, the ischium, and the pubis.
- The bones have three articulations, the sacroiliac joint which is articulated with the sacrum, the pubic symphysis where the left and right hip bones articulate, and the hip joint which is the articulation with the head of the femur.
- The ilium, pubis, and ischium form a cup-shaped socket known as the acetabulum where the head of the femur articulates to form the hip joint.
- The ilium is the largest part of the hip bone. The upper part of the ilium, the wing, has two surfaces, the concave inner surface, that produces the iliac fossa (site of origin of the iliacus muscle), and the convex outer surface, and provides attachments to gluteal muscles.
- The ischium is at the posteroinferior part of the hip bone. It has two main parts, the body, and the ramus. It is a binding site for the sacrospinous and sacrotuberous ligament.
- The pubis or the pubic bone is the anterior most portion of the hip bone. It is composed of a body and two rami.
- The hip bones join at the pubic symphysis.

Additional Information:
- The hip bones form a part of the pelvic girdle which attaches the axial skeleton to the lower limbs.
- The three main bones are separated by the triradiate cartilage before puberty. They fuse and ossify after puberty, around the age of 25.
- The acetabulum has the following parts present on it - the lunate surface, acetabular fossa, acetabular notch, and iliopubic eminence.

Note:
- The two rami in the pubis are the superior pubic and inferior pubic ramus.
- The obturator foramen is an opening formed from the joining of the three hip bones. The obturator artery, vein, and nerve pass out of the pelvis through this to reach the lower limbs.