Squamosal bone

Squamosal bone is a bone found in the skull of most reptiles, birds, and mammals. It is named for its somewhat flattened or squamous shape. The squamosal bone forms part of the temporal bone in mammals.

Etymology

The term "squamosal" is derived from the Latin word "squama", meaning "scale", due to the bone's flat, scale-like appearance.

Anatomy

The squamosal bone is located at the side of the skull, forming a part of the cranium. It is situated near the temporal bone, and in mammals, it is often fused with the temporal bone to form a single structure. The squamosal bone is typically flat and somewhat rectangular in shape, and it plays a crucial role in forming the temporal fossa and the zygomatic arch.

Evolution

In early tetrapods, the squamosal bone was a separate element that, along with the quadratojugal, made contact with the quadrate bone to form the upper part of the jaw joint. In mammals, the squamosal has become part of the temporal bone, and the quadrate has become the incus, one of the ossicles of the middle ear.

Clinical significance

While the squamosal bone is generally robust and not prone to injury, fractures can occur as a result of severe trauma to the skull. Such fractures may lead to complications including intracranial hemorrhage, cerebrospinal fluid leak, and cranial nerve injury.

See also

• Cranial bones
• Temporal bone
• Zygomatic arch

References

Squamosal bone Resources
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