Bones of Pelvis
The pelvis refers to a bone structure that looks like a ring and is located at the lower end of the trunk. It is crucial for your moment as well as support. Connecting the spine to the lower limbs, it is home to several vital organs. Whether you are learning about anatomy, orthopaedics, or medical studies related to trauma, childbirth, and surgery, understanding the bones of the pelvis is essential. Let’s take a look at its types, structure, and function.
1.0Types of Pelvic Bone
Your genetics and environmental factors play a crucial role in influencing the pelvic bone’s shape and structure. Based on the shape of the human’s pelvic inlet (the entry point of the birth canal and upper opening of the pelvic cavity), pelvic bones are categorised into four distinct types:
The Four Main Types of Pelvic Bones
Greater and Lesser Pelvis
The pelvis is divided into two main parts based on the location of the pelvic inlet:
- Greater (False) Pelvis: Located above the pelvic inlet, this region supports abdominal organs. It is bordered laterally by the iliac bones and remains open anteriorly between the front edges of the ilia. Posteriorly, there is a space between the base of the sacrum and the ilia.
- Lesser (True) Pelvis: Found below the pelvic inlet, it houses reproductive organs, the bladder, and part of the colon. Its borders are formed by the superior rami of the pubis and the pubic symphysis in the front, and the sacrum and coccyx in the back.
2.0Pelvic Hip Bones
The hip bone, also called the innominate bone of the pelvis, is an irregular, bilateral structure that makes up the majority of the pelvic girdle. Each hip bone is typically formed by the fusion of three bones:
During childhood, these bones remain separate, connected by cartilage. As a person reaches puberty, the ilium, ischium, and pubis fuse at a central depression called the acetabulum, a cup-shaped socket that forms the hip joint by articulating with the femoral head.
These innominate bones of pelvis join at the front via the pubic symphysis and laterally at the acetabulum, creating a strong, weight-bearing ring essential for standing, walking, and supporting internal organs.
3.0Function of the Pelvis Bone in the Human Body
The pelvis serves several vital roles in the human body, contributing to support, movement, and protection. Key functions include:
- Weight Transmission: The main function of pelvis bone is to transfer weight from the upper body to the lower limbs, especially during activities like walking, standing, and running.
- Muscle and Ligament Attachment: It provides strong attachment points for numerous muscles and ligaments involved in locomotion, posture, and core stability.
- Organ Protection: The pelvis shields essential internal organs, including those in the abdominal and pelvic cavities, such as the bladder, reproductive organs, and parts of the intestines.
4.0Male and Female Pelvic Bones
The pelvis is one of the most distinctive skeletal features used to differentiate between males and females.
Female pelvic bones are generally wider, larger, and more circular to accommodate childbirth. The pelvic inlet is broader and more rounded, allowing space for fetal passage. In contrast, male pelvises are taller and narrower, with iliac crests that are positioned higher, giving the false pelvis a more vertical appearance.
The sacrum in males is longer, narrower, and straighter with a pronounced sacral promontory, while in females, it is shorter, wider, and more curved to increase the size of the birth canal.
Another key difference lies in the pubic arch:
- In females, the angle between the inferior pubic rami is obtuse (90–100 degrees), forming a wider pubic arch.
- In males, this angle is acute (around 70 degrees), referred to as the subpubic angle.
These anatomical differences reflect evolutionary adaptations: the female pelvis is optimised for childbirth, while the male pelvis offers structural advantages for bipedal locomotion and greater weight support.
5.0Pelvis Bone: Medical Interventions
Several surgical procedures may be required to treat injuries, deformities, or diseases affecting the pelvic bones. The operation of pelvis bone is often essential for restoring mobility, relieving pain, or addressing life-threatening conditions such as fractures or tumours.
Common pelvic bone surgeries include:
- Pelvic Fracture Fixation: This surgery stabilises broken pelvic bones using metal plates, screws, or rods to ensure proper healing and alignment after trauma.
- Pelvic Osteotomy: Often performed in children with developmental hip dysplasia, this procedure involves reshaping or repositioning the pelvic bones to improve joint function and structure.
- Total Hip Replacement: In this procedure, the damaged acetabulum (part of the pelvis) and the femoral head are replaced with artificial prosthetic components, typically to treat severe arthritis or injury.
- Tumour Resection: This involves the surgical removal of cancerous tissue from the pelvic bones and may be accompanied by reconstruction, depending on the extent of the resection.
These procedures are critical in restoring normal pelvic function and improving the quality of life for patients suffering from serious pelvic conditions.