The floor of the cranial cavity is divided into three distinct depressions. Lock are well-known as the anterior cranial fossa, middle cranial fossa and posterior cranial fossa. Every fossa accommodates a different component of the brain.
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The center cranial fossa is located, as its surname suggests, centrally in the cranial floor. It is claimed to it is in “butterfly shaped”, v a middle component accommodating the pituitary gland and two lateral parts accommodating the temporal lobes the the brain
In this article, us shall look at the borders, contents and clinical correlations that the center cranial fossa.
The middle cranial fossa consists of 3 bones – the sphenoid bone and the two temporal bones.
Its boundaries are as follows:Anteriorly and also medially it is bounded by the limbus the the sphenoid bone. The limbus is a bony ridge that creates the anterior border of the chiasmatic sulcus (a groove running between the right and left optic canals).Posteriorly and medially it is bounded by the dorsum sellae the the sphenoid bone. This is a large superior projection of bone that arises from the sphenoidal body.The floor is developed by the body and greater soup of the sphenoid, and also the squamous and petrous parts of the temporal bone.
Fig 1.0 – The skeletal of the cranial floor. The middle cranial fossa has been highlighted.
The center cranial fossa is composed of a main portion, which consists of the pituitary gland, and also two lateral portions, i beg your pardon accommodate the temporal lobes that the brain.
Both parts of the fossa are marked by many bony landmarks, which will be discussed below.
The main part of the center cranial fossa is formed by the body of the sphenoid bone. It contains the sella turcica (latin because that Turkish saddle), i m sorry is a saddle-shaped bony prestige (see Fig 1.2). That acts come hold and also support the pituitary gland, and also consists of three parts:The tuberculum sellae (horn that the saddle) is a upright elevation of bone. It creates the anterior wall of the sella turcica, and the posterior element of the chiasmatic sulcus (a groove running between the right and also left optic canals).The hypophysial fossa or pituitary fossa (seat of the saddle) sits in the middle of the sella turcica. The is a depression in the body of the sphenoid, i m sorry holds the pituitary gland.The dorsum sellae (back that the saddle) creates the posterior wall surface of the sella turcica. It is a huge square of bone, pointing upwards and also forwards. It separates the center cranial fossa from the posterior cranial fossa.
The sella turcica is surrounding by the anterior and posterior clinoid processes. The anterior clinoid procedures arise native 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.
Fig 1.1 – Bony landmarks of the main part of the center cranial fossa.
Fig 1.2 – Sagittal ar of the skull, mirroring the saddle-like sella turcica.
The depressed lateral parts of the center cranial fossa are formed by the greater wings the the sphenoid bone, and the squamous and also petrous parts of the temporal bones. They assistance the temporal lobes that the brain. That is the website of numerous foramina – small holes by which vessels and also nerves enter and leave the cranial cavity.
There are numerous foramina the transmit vessels and also nerves into and also out the the middle cranial fossa. This foramina will certainly be discussed in relation to the bones castle are located in.
Foramina of the Sphenoid Bone
The optic canals are positioned anteriorly in the center cranial fossa. Lock transmit the optic nerves (CN II) and ophthalmic arteries right into the orbital cavities. The optic canals are linked by the chiasmatic sulcus, a depressed groove to run transversely between the two.
Immediately lateral come the main part the the middle cranial fossa are four foramina:The foramen spinosum additionally opens into the infratemporal fossa. The transmits the middle meningeal artery, middle meningeal vein and a meningeal branch the CN V3.
Fig 1.3 – The foramina the the middle cranial fossa.
Foramina of the Temporal Bone
The temporal bone is marked by three major foramina:Hiatus that the higher petrosal nerve – transmits the higher petrosal nerve (a branch the the facial nerve), and the petrosal branch of the middle meningeal artery.
At the junction of the sphenoid, temporal and also occipital skeletal is the foramen lacerum. In life, this foramen is filled v cartilage, i beg your pardon is pierced only by tiny blood vessels.
Clinical Relevance: Pituitary Surgery
The pituitary gland lies in the sella turcica of the sphenoid bone, in ~ the center cranial fossa. In situations of a pituitary tumour, it may need come be removed surgically.
Surgery to remove pituitary tumours is typically by a endoscopic transsphenoidal approach. An endoscope is inserted through the nostrils, or an ext rarely with an incision into either the upper lip or sleep septum. The is then progressed through the sleep cavity. The sphenoid sinus is opened and also the endoscope passes with to the pituitary gland wherein it lies on the sella turcica. The tumour have the right to then be removed in sections.
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Complications that pituitary surgery incorporate CSF rhinorrhoea, meningitis, diabetes insipidus, haemorrhage and visual disturbances.