What part of the body is coxal? An Expert Guide to Your Hip Bone

September 21, 2025 •

2 min read

The human skeletal system is a complex marvel, and one of its most vital components, the coxal bone, is often misunderstood. It is actually the medical term for your hip bone, a large, irregularly shaped bone that forms the pelvic girdle. Understanding what part of the body is coxal is key to appreciating its function in mobility and support.

Quick Summary

The coxal bone, also known as the hip bone or os coxae, is a large, irregularly shaped bone located on each side of the pelvis, formed by the fusion of the ilium, ischium, and pubis during adolescence.

Key Points

The Hip Bone: The coxal bone is the large, irregularly shaped bone on either side of the pelvis, also known as the hip bone.
Three Parts: Each coxal bone is a complete fusion of three distinct bones: the ilium (upper part), ischium (lower-back part), and pubis (lower-front part).
Body Support: These bones are crucial for bearing the weight of your upper body, especially when sitting, where the ischial tuberosities take the load.
Hip Joint Socket: The three parts meet at the acetabulum, a deep socket that forms the ball-and-socket hip joint with the femur.
Pelvic Girdle: The two coxal bones, joined together, form the pelvic girdle, the bony framework connecting the lower limbs to the spine.
Protective Role: The coxal bones contribute to the bony pelvis, which protects and houses vital pelvic and abdominal organs.

Understanding the Coxal Bone

The coxal bone, or hip bone (os coxae), is a large, irregularly shaped bone situated on each side of the pelvis. It is not a single bone from birth but forms from the fusion of three distinct bones during adolescence: the ilium, the ischium, and the pubis. This fusion is centered around the acetabulum, a key anatomical feature.

The Three Fused Components

Ilium: The largest and most superior part, forming the upper, fan-like portion of the hip bone. Its upper border is the iliac crest, and it includes the iliac fossa.
Ischium: Located inferiorly and posteriorly, this is the strongest part. It features the ischial tuberosity, which bears weight when sitting.
Pubis: The most anterior and inferior part, it curves inward to meet the opposite pubis at the pubic symphysis. It contributes to the acetabulum and the obturator foramen.

These three bones meet and fuse at the acetabulum, a deep socket that articulates with the femur to form the hip joint.

Pelvic Girdle vs. Bony Pelvis

The pelvic girdle consists of the two coxal bones. The bony pelvis is a more comprehensive structure, including the two coxal bones, the sacrum, and the coccyx.

Pelvic Structure Comparison


Feature	Pelvic Girdle	Bony Pelvis
Components	Two coxal bones	Two coxal bones, sacrum, coccyx
Shape	Framework	Ring-like structure
Function	Connects lower limbs to axial skeleton	Support, protection of organs

Vital Roles of the Coxal Bone

The coxal bone is essential for numerous functions:

Support: Bears upper body weight, crucial for standing and sitting.
Locomotion: Facilitates leg movement through the hip joint.
Protection: Helps shield pelvic organs within the bony pelvis.
Muscle Attachment: Provides points for muscles of the abdomen, back, and lower limbs, supporting posture and balance.

Maintaining Hip Health

Maintaining the health of your coxal bones is important for overall mobility. Strategies include:

Good Posture: Reduces pressure on weight-bearing areas like the ischial tuberosities.
Ergonomic Support: Using appropriate cushions can alleviate pain, especially coccyx pain.
Exercise: Strengthening pelvic floor muscles and stretching hip flexors can improve support and flexibility.

For more detailed anatomical information, consult resources like the National Library of Medicine.

NIH StatPearls: Anatomy, Bony Pelvis and Lower Limb: Pelvis Bones

Conclusion

The coxal bone, or hip bone, is a fundamental component of the human skeleton, formed by the fusion of the ilium, ischium, and pubis. It provides critical support, enables movement, and protects vital organs. Understanding the structure and function of the coxal bone highlights its significance in daily life and the importance of maintaining its health.

Frequently Asked Questions

The coxal bone refers to a single hip bone. The pelvic girdle, however, is the complete structure formed by both the left and right coxal bones joined together at the front and connected to the sacrum at the back.

In children, the ilium, ischium, and pubis are three separate bones connected by cartilage. They fuse completely during adolescence to form a single, composite coxal bone in adults.

The coxal bone has several key functions: it bears the weight of the upper body, provides attachment points for numerous muscles, protects the pelvic organs, and enables locomotion by forming the hip joint.

The acetabulum is the deep, cup-shaped socket on the outer surface of the coxal bone where the ilium, ischium, and pubis converge. It is the socket for the head of the femur, forming the ball-and-socket hip joint.

The ischial tuberosity is a large, bony protuberance on the ischium, the posterior-inferior part of the coxal bone. These are commonly known as the 'sitting bones' because they bear the body's weight when seated.

Yes, coxal bone pain is possible and can be caused by various issues, including trauma, arthritis, poor posture, or conditions like coccydynia (tailbone pain). Pain management and physical therapy are common treatments.

While the basic structure is the same, there are notable differences due to sexual dimorphism. Female pelvic girdles tend to be wider and broader, with a larger pubic arch, to accommodate childbirth, whereas male pelves are generally narrower.

Many muscles attach to the coxal bone, including major groups like the gluteals, hamstrings, adductors, and abdominal muscles. These attachments are essential for movement and stability.