Problem 105 - Objective Biology for NEET

Question

The cup-shaped structure of pelvic girdle, the acetabulum in man is formed by (a) Ilium, ischium and pubis (b) Ilium, ischium and cotyloid (c) Ilium and ischium (d) Ilium and cotyloid

Step-by-Step Solution

Answer

The acetabulum in the human pelvic girdle is formed by the ilium, ischium and pubis.

Step 1: Understanding the structure of the pelvic girdle

The pelvic girdle, also known as the hip bone, is made up of three main bones: the ilium, the ischium, and the pubis.

Step 2: Identify the acetabulum formation

The acetabulum is the cup-shaped socket of the hip bone. It is where the femur (thigh bone) inserts into the pelvis. This socket is formed by parts of the ilium, ischium and pubis bones.

Step 3: Determine the correct option

Given the information that the acetabulum is formed by the ilium, ischium, and pubis, the correct answer would be: (a) Ilium, ischium and pubis.

Key Concepts

Acetabulum

The acetabulum is a crucial structure in the anatomy of the pelvic girdle. It can be thought of as a deep, cup-shaped socket that plays an important role in hip stability and movement. The acetabulum is where the femur, or thigh bone, articulates, creating the hip joint. This articulation permits various movements such as walking, running, and jumping.
The acetabulum is not formed by a single bone. Instead, it is the junction of three distinct bones of the pelvis: the ilium, the ischium, and the pubis. These bones come together to form a sturdy structure capable of bearing the weight of the body.
In summary, the acetabulum is a key component of the pelvic girdle, enabling a wide range of movements while providing stability to the hip joint.

Ilium

The ilium is the largest of the three bones that make up the pelvic girdle. It is often identified by its broad, wing-like structure, which gives the pelvis its characteristically wide appearance.
The ilium serves as an important site of attachment for many muscles and ligaments in the body. These connections are essential for functions such as standing, walking, and maintaining balance.

• The uppermost part of the ilium is called the iliac crest, which you can feel at the top of your hip.
• It acts as a support structure for abdominal and back muscles.

This bone not only provides support but also plays a role in forming part of the acetabulum, helping to create the socket for the hip joint.

Ischium

The ischium is one of the three bones that help form the pelvic girdle and contributes to the formation of the acetabulum. It is located below the ilium and at the back of the pelvic area.
A notable feature of the ischium is the ischial tuberosity, known commonly as the "sit bone." This is the part of the pelvis that bears your body's weight when you sit.

• The ischium serves as an anchor point for various muscles, aiding in locomotion and stability.
• It helps distribute body weight during sitting and offers support for activities like walking and running.

Alongside the ilium and pubis, the ischium ensures the pelvic girdle is strong enough to support daily activities.

Pubis

The pubis is one of the trio of bones forming the pelvic girdle, and it plays an integral role in maintaining the structure and function of this body region. Positioned at the front of the pelvic girdle, the pubis contributes to the stability and protection of pelvic organs. It also assists in forming the acetabulum.

• It connects with the other two pelvic bones, the ilium and ischium, at the acetabulum, creating a robust pressure-bearing joint.
• The pubic symphysis, a cartilaginous joint that sits at the front of the pelvis, fuses the two sides of the pubic bones together, providing stability.

The pubis not only works structurally with other pelvic bones but also accommodates the handling of different stresses and movements, sealing its importance in pelvic anatomy.