The cotyloid bone, also known as the acetabular bone or os acetabuli, is a skeletal element often considered a fourth pelvic element.
In the realm of anatomy, particularly concerning the pelvic girdle, the term "cotyloid bone" refers to a distinct bone that contributes to the formation of the acetabulum, the socket where the head of the femur (thigh bone) articulates to form the hip joint. The term "cotyloid" itself originates from the Greek word kotyle, meaning "cup-like", aptly describing the shape of the cavity it helps form.
Key Characteristics of the Cotyloid Bone
Based on the provided references, we can highlight several key aspects of the cotyloid bone:
- Location: It is part of the pelvic girdle.
- Classification: It is frequently described as a fourth pelvic element, supplementing the typical ilium, ischium, and pubis.
- Alternative Names: It is also known as the acetabular bone or os acetabuli.
- Contribution to Acetabulum: Its primary role is to contribute to the formation of the cup-like acetabular cavity, essential for the hip joint's stability and movement.
- Variability: Its size and prominence can vary significantly across different species. For instance:
- In Ornithorhynchus (the platypus), the cotyloid or os acetabuli is noted as a larger element of the girdle than is the pubis.
Summary Table: Cotyloid Bone Basics
| Feature | Description |
|---|---|
| Primary Name | Cotyloid Bone |
| Other Names | Acetabular Bone, Os Acetabuli |
| Location | Pelvic Girdle |
| Classification | Often a fourth pelvic element |
| Function | Forms part of the cup-like acetabulum |
| Presence | Occurs very often |
| Example (Size) | Larger than pubis in Ornithorhynchus |
Understanding the cotyloid bone helps in appreciating the intricate structure of the pelvic girdle and its variations across different animal species. Its contribution to the acetabulum underscores its importance in locomotion and weight bearing.
