Sphenoid bone

Sphenoid bone

The sphenoid bone is an unpaired bone of the neurocranium. It is situated in the middle of the skull towards the front, in front of the temporal bone and basilar part of the occipital bone. The sphenoid bone is one of the seven bones that articulate to form the orbit. Its shape somewhat resembles that of a butterfly or bat with its wings extended.

Structure

The sphenoid bone consists of a central part, the body, and six distinct processes with two greater wings, two lesser wings, and two pterygoid processes; the latter are observed in the facial skeleton.

Body

The body, more or less cubical in shape, is hollowed into two cavities, the sphenoidal sinuses, which are separated by a septum.

Greater wings

The greater wings of the sphenoid are two strong processes of bone, which arise from the sides of the body, and are curved upward, laterally, and backward.

Lesser wings

The lesser wings of the sphenoid are two thin triangular plates, which arise from the upper and anterior parts of the body, and, projecting lateralward, end in sharp points.

Pterygoid processes

The pterygoid processes, one on either side, descend perpendicularly from the regions where the body and the greater wings unite.

Development

The sphenoid bone ossifies from six centers which first appear about the eighth week of fetal life.

Clinical significance

Due to its location, fractures of the sphenoid bone are often associated with serious injuries. In addition, it may be affected by various diseases, such as sphenoid wing meningioma, a type of brain tumor.

See also

• Sphenoidal sinuses
• Sphenoid wing meningioma
• Skull

External links

• Sphenoid bone at Encyclopædia Britannica

Sphenoid bone Resources
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