The sphenoid bone is among the eight bones that make up the cranium – the superior element of the skull the encloses and protects the brain.
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Its name is obtained from the Greek ‘sphenoeides’, to median wedge-shaped.
In this article, us shall look at the anatomy the the sphenoid bone – its location, structure, and clinical significance.
Fig 1 – The place of the sphenoid bone (yellow) in ~ the facial skeleton.
The sphenoid bone is stated to be ‘butterfly-shaped‘. It consists of a body, paired greater wings and lesser wings, and also two pterygoid processes.
The body lies at the centre of the sphenoid bone, and is almost totally cubical in shape.
It has the sphenoidal sinuses, which space separated by a septum – definition that the sphenoid human body is essentially hollow. The body articulates with the ethmoid bone anteriorly, and also it is right here that the sinuses open up into the sleep cavity.
The premium surface that the sphenoid body has some important bony landmarks:Sella turcica – a saddle-shaped depression. It has three parts:Tuberculum sellae – forms the anterior wall of the sella turcica, and also the posterior facet of the chiasmatic groove.Hypophyseal fossa – the deepest part of the sella turcica, wherein the pituitary gland is located.Dorsum sellae – creates the posterior wall surface of the sella turcica.Chiasmatic groove – a sulcus created by the optic chiasm (where the optic nerves partially cross).
The sella turcica is surrounded by the anterior and posterior clinoid processes. The anterior clinoid processes arise indigenous the sphenoidal lesser wings, if the posterior clinoid procedures are the superolateral projections that the dorsum sellae. They serve as attachment points because that the tentorium cerebelli, a membranous sheet that divides the brain.
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Fig 2 – Foramina and also bony landmarks of the sphenoid wings and also pterygoid process.
Fig 3 – Bony landmarks that the sphenoid body.
The greater wing extends native the sphenoid human body in a lateral, superior and posterior direction. It contributes come three components of the face skeleton:Floor that the center cranial fossaLateral wall surface of the skullPosterolateral wall surface of the orbit
There are three foramina present in the better wing – the foramen rotundum, foramen ovale and also foramen spinosum. They conduct the maxillary nerve, mandibular nerve and also middle meningeal ship respectively.
The lesser wing occurs from the anterior aspect of the sphenoid body in a superolateral direction. It separates the anterior cranial fossa indigenous the middle cranial fossa.
It also forms the lateral border of the optic canal – through i beg your pardon the optic nerve and also ophthalmic artery take trip to with the eye. The medial border that the optic canal is formed by the human body of the sphenoid.
There is a ‘slit-like’ gap between the lesser and also greater wings of the sphenoid – the superior orbital fissure. Numerous structures happen through here to with the bony orbit.
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The pterygoid procedure descends inferiorly native the allude of junction in between the sphenoid body and the greater wing. It consists of 2 parts:Medial pterygoid plate – support the posterior opening of the sleep cavity.Lateral pterygoid plate – website of origin of the medial and lateral pterygoid muscles