The sphenoid bone is one of the eight bones that make up the cranium – the superior aspect of the skull the encloses and protects the brain.

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Its name is obtained from the Greek ‘sphenoeides’, to typical wedge-shaped.

In this article, we shall look in ~ the anatomy that the sphenoid bone – its location, structure, and clinical significance.


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Fig 1 – The place of the sphenoid bone (yellow) within the face skeleton.


Anatomical Structure

The sphenoid bone is claimed to be ‘butterfly-shaped‘. It is composed of a body, paired greater wings and lesser wings, and two pterygoid processes.

Body

The body lies at the centre of the sphenoid bone, and is almost fully cubical in shape.

It has the sphenoidal sinuses, which space separated by a septum – an interpretation that the sphenoid body is basically hollow. The body articulates with the ethmoid bone anteriorly, and also it is right here that the sinuses open up right into the sleep cavity.

The superior surface that the sphenoid body contains some important bony landmarks:

Sella turcica – a saddle-shaped depression. It has actually three parts:Tuberculum sellae – creates the anterior wall surface of the sella turcica, and also the posterior aspect of the chiasmatic groove.Hypophyseal fossa – the deepest part of the sella turcica, whereby the pituitary gland is located.Dorsum sellae – forms the posterior wall surface of the sella turcica.Chiasmatic groove – a sulcus created by the optic chiasm (where the optic nerves partly cross).

The sella turcica is surrounding by the anterior and posterior clinoid processes. The anterior clinoid procedures arise indigenous the sphenoidal lesser wings, while the posterior clinoid procedures are the superolateral projections that the dorsum sellae. They serve as attachment points for the tentorium cerebelli, a membranous sheet that divides the brain.


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Fig 2 – Foramina and bony landmarks the the sphenoid wings and also pterygoid process.


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Fig 3 – Bony landmarks of the sphenoid body.


Greater Wing

The greater wing extends from the sphenoid human body in a lateral, superior and posterior direction. The contributes come three parts of the facial skeleton:

Floor that the center cranial fossaLateral wall of the skullPosterolateral wall of the orbit

There room three foramina present in the higher wing – the foramen rotundum, foramen ovale and also foramen spinosum. They command the maxillary nerve, mandibular nerve and also middle meningeal ship respectively.

Lesser Wing

The lesser wing arises from the anterior aspect of the sphenoid human body in a superolateral direction. The separates the anterior cranial fossa native the center cranial fossa.

It likewise forms the lateral border of the optic canal – through i beg your pardon the optic nerve and ophthalmic artery take trip to reach the eye. The medial border that the optic canal is created by the human body of the sphenoid.

There is a ‘slit-like’ gap in between the lesser and also greater wing of the sphenoid – the superior orbital fissure. Countless structures happen through here to with the bony orbit.

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Pterygoid Process

The pterygoid procedure descends inferiorly indigenous the point of junction between the sphenoid body and also the higher wing. It consists of 2 parts:

Medial pterygoid plate – supports the posterior opened of the nasal cavity.Lateral pterygoid plate – site of beginning of the medial and also lateral pterygoid muscles