Which Of The Following Is Not Part Of The Pelvis

Which of the Following is NOT Part of the Pelvis? A Comprehensive Guide

The pelvis is a complex bony structure crucial for supporting the weight of the upper body, protecting vital organs, and facilitating childbirth. Understanding its components is essential for anyone studying anatomy, physical therapy, or related fields. This article will clarify which structures are, and are not, part of the pelvic girdle.

Meta Description: This article clarifies the components of the human pelvis, distinguishing which bones and structures are included and which are excluded. Learn about the ilium, ischium, pubis, sacrum, coccyx, and more!

The pelvis is commonly understood to include three paired bones: the ilium, the ischium, and the pubis. These bones fuse together during adolescence to form the hip bone (also known as the os coxae). In addition to the hip bones, the sacrum and coccyx also contribute to the overall pelvic structure. These five bones – two hip bones, sacrum, and coccyx – form the bony pelvis.

Bones Included in the Pelvis:

• Ilium: The largest of the three hip bones, forming the upper and lateral portion of the pelvis. It plays a significant role in weight-bearing and muscle attachment.
• Ischium: Located inferior and posterior to the ilium, the ischium forms the lower and back part of the hip bone. It contributes to the weight-bearing surface when seated.
• Pubis: The anterior portion of the hip bone, located inferior to the ilium. The pubic bones of each hip bone meet at the pubic symphysis.
• Sacrum: A triangular bone formed by the fusion of five sacral vertebrae. It articulates with the ilium at the sacroiliac joints, providing stability to the pelvic girdle.
• Coccyx: Commonly known as the tailbone, the coccyx is a small, triangular bone formed by the fusion of three to five coccygeal vertebrae. It has a minimal role in weight-bearing.

Bones and Structures NOT Part of the Pelvis:

Several structures are frequently confused with parts of the pelvis, but are actually distinct anatomical entities. These include:

• Femur: The thigh bone, connecting the hip joint to the knee. While crucial for lower limb movement and interacting with the pelvis, it is not part of the pelvic structure itself.
• Vertebrae (other than sacral and coccygeal): The lumbar vertebrae support the weight of the upper body, but are separate from the pelvic girdle. Similarly, thoracic and cervical vertebrae are part of the spine but outside the pelvic anatomy.
• Rib Cage: Protecting the heart and lungs, the rib cage is a distinct part of the axial skeleton, separate from the pelvis.
• Pelvic Floor Muscles: These are essential for supporting pelvic organs and continence, but they are soft tissues and not bony structures of the pelvis.

Understanding the distinction between structures associated with the pelvis and those that are actually integral to its bony structure is crucial for accurate anatomical comprehension. The pelvis, with its intricate arrangement of bones and ligaments, plays a vital role in locomotion, support, and protection of internal organs. Remembering the core components – ilium, ischium, pubis, sacrum, and coccyx – is key to mastering pelvic anatomy.