The middle cranial fossa is formed by the

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 basilar part of occipital bone, basilar part of the occipital bone. The sphenoid bone is one of the seven bon ...

s, and the

temporal bone The temporal bone is a paired bone situated at the sides and base of the skull, lateral to the temporal lobe of the cerebral cortex. The temporal bones are overlaid by the sides of the head known as the temples where four of the cranial bone ...

s. It lodges the

temporal lobe The temporal lobe is one of the four major lobes of the cerebral cortex in the brain of mammals. The temporal lobe is located beneath the lateral fissure on both cerebral hemispheres of the mammalian brain. The temporal lobe is involved in pr ...

s, and the

pituitary gland The pituitary gland or hypophysis is an endocrine gland in vertebrates. In humans, the pituitary gland is located at the base of the human brain, brain, protruding off the bottom of the hypothalamus. The pituitary gland and the hypothalamus contr ...

. It is deeper than the

anterior cranial fossa The anterior cranial fossa is a depression in the floor of the cranial base which houses the projecting frontal lobes of the brain. It is formed by the orbital plates of the frontal, the cribriform plate of the ethmoid, and the small wings and ...

, is narrow medially and widens laterally to the sides of the

skull The skull, or cranium, is typically a bony enclosure around the brain of a vertebrate. In some fish, and amphibians, the skull is of cartilage. The skull is at the head end of the vertebrate. In the human, the skull comprises two prominent ...

. It is separated from the

posterior cranial fossa The posterior cranial fossa is the part of the cranial cavity located between the foramen magnum, and tentorium cerebelli. It is formed by the sphenoid bones, temporal bones, and occipital bone. It lodges the cerebellum, and parts of the brai ...

by the clivus and the petrous crest. It is bounded in front by the posterior margins of the lesser wings of the

, the anterior clinoid processes, and the ridge forming the anterior margin of the chiasmatic groove; behind, by the superior angles of the petrous portions of the temporal bones and the dorsum sellae; laterally by the temporal squamae, sphenoidal angles of the parietals, and greater wings of the sphenoid. It is traversed by the squamosal, sphenoparietal, sphenosquamosal, and sphenopetrosal sutures.

Anatomy

Features

Middle part

The middle part of the fossa presents, in front, the chiasmatic groove and tuberculum sellae; the chiasmatic groove ends on either side at the

optic foramen The ''optic foramen'' is the opening to the optic canal. The canal is located in the sphenoid bone; it is bounded medially by the body of the sphenoid and laterally by the lesser wing of the sphenoid. The superior surface of the sphenoid bone is ...

, which transmits the

optic nerve In neuroanatomy, the optic nerve, also known as the second cranial nerve, cranial nerve II, or simply CN II, is a paired cranial nerve that transmits visual system, visual information from the retina to the brain. In humans, the optic nerve i ...

and

ophthalmic artery The ophthalmic artery (OA) is an artery of the head. It is the first branch of the internal carotid artery distal to the cavernous sinus. Branches of the ophthalmic artery supply all the structures in the orbit around the eye, as well as some ...

to the orbital cavity. Behind the optic foramen the

anterior clinoid process The anterior clinoid process is a posterior projection of the sphenoid bone at the junction of the medial end of either lesser wing of sphenoid bone with the body of sphenoid bone. The bilateral processes flank the sella turcica anteriorly. The ...

is directed backward and medialward and gives attachment to the cerebellar tentorium . Behind the tuberculum sellae is a deep depression, the sella turcica, containing the fossa hypophyseos, which lodges the

, and presents on its anterior wall the

middle clinoid process The middle clinoid process is a small, bilaterally paired elevation on either side of the tuberculum sellae, at the anterior boundary of the sella turcica. A (larger) anterior clinoid process is situated lateral to each middle clinoid process. ...

es. The sella turcica is bounded posteriorly by a quadrilateral plate of bone, the dorsum sellae, the upper angles of which are surmounted by the posterior clinoid processes: these afford attachment to the cerebellar tentorium, and below each is a notch for the abducent nerve. On either side of the sella turcica is the

carotid groove The carotid groove is an anatomical groove in the sphenoid bone located above the attachment of each great wing of the sphenoid bone. The groove is curved like the italic letter f, and lodges the internal carotid artery The internal carotid ar ...

, which is broad, shallow, and curved somewhat like the italic letter ''f''. It begins behind at the foramen lacerum, and ends on the medial side of the anterior clinoid process, where it is sometimes converted into a foramen (carotico-clinoid) by the union of the anterior with the middle clinoid process; posteriorly, it is bounded laterally by the lingula. This groove lodges the

cavernous sinus The cavernous sinus within the human head is one of the dural venous sinuses creating a cavity called the lateral sellar compartment bordered by the temporal bone of the skull and the sphenoid bone, lateral to the sella turcica. Structure The ...

and the

internal carotid artery The internal carotid artery is an artery in the neck which supplies the anterior cerebral artery, anterior and middle cerebral artery, middle cerebral circulation. In human anatomy, the internal and external carotid artery, external carotid ari ...

, the latter being surrounded by a plexus of sympathetic nerves.

Lateral parts

The lateral parts of the middle fossa are of considerable depth, and support the temporal lobes of the

brain The brain is an organ (biology), organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It consists of nervous tissue and is typically located in the head (cephalization), usually near organs for ...

. They are marked by depressions for the brain convolutions and traversed by furrows for the anterior and posterior branches of the middle meningeal vessels. These furrows begin near the foramen spinosum, and the anterior runs forward and upward to the sphenoidal angle of the parietal, where it is sometimes converted into a bony canal; the posterior runs lateralward and backward across the temporal squama and passes on to the parietal near the middle of its lower border. The following apertures are also to be seen. In front is the superior orbital fissure, bounded above by the small wing, below, by the

great wing The greater wing of the sphenoid bone, or alisphenoid, is a bony process of the sphenoid bone, positioned in the skull behind each eye. There is one on each side, extending from the side of the body of the sphenoid and curving upward, laterally ...

, and medially, by the body of the sphenoid; it is usually completed laterally by the orbital plate of the

frontal bone In the human skull, the frontal bone or sincipital bone is an unpaired bone which consists of two portions.'' Gray's Anatomy'' (1918) These are the vertically oriented squamous part, and the horizontally oriented orbital part, making up the bo ...

. It transmits to the orbital cavity the oculomotor, the trochlear, the

ophthalmic division The ophthalmic nerve (CN V1) is a sensory nerve of the head. It is one of three divisions of the trigeminal nerve (CN V), a cranial nerve. It has three major branches which provide sensory innervation to the eye, and the skin of the upper face an ...

of the trigeminal, and the abducent nerves, some filaments from the

cavernous plexus The cavernous nerve plexus (also called the Walther plexus) is situated below and medial to that part of the internal carotid artery which is placed by the side of the sella turcica in the cavernous sinus, and is formed chiefly by the medial div ...

of the sympathetic, and the orbital branch of the

middle meningeal artery The middle meningeal artery (') is typically the third branch of the maxillary artery#First portion, first portion of the maxillary artery. After branching off the maxillary artery in the infratemporal fossa, it runs through the foramen spinosum t ...

; and from the orbital cavity a recurrent branch from the

lacrimal artery The lacrimal artery is an artery of the Orbit (anatomy), orbit. It is a branch of the ophthalmic artery. It accompanies the lacrimal nerve along the upper border of the lateral rectus muscle, travelling forward to reach the lacrimal gland. It sup ...

to the dura mater, and the ophthalmic veins. Behind the medial end of the superior orbital fissure is the foramen rotundum, for the passage of the

maxillary nerve In neuroanatomy, the maxillary nerve (V) is one of the three branches or divisions of the trigeminal nerve, the fifth (CN V) cranial nerve. It comprises the principal functions of Sense, sensation from the maxilla, nasal cavity, Sinus (anatomy ...

. Behind and lateral to the foramen rotundum is the foramen ovale, which transmits the

mandibular nerve In neuroanatomy, the mandibular nerve (V) is the largest of the three divisions of the trigeminal nerve, the fifth Cranial nerves, cranial nerve (CN V). Unlike the other divisions of the trigeminal nerve (ophthalmic nerve, maxillary nerve) which ...

, the

accessory meningeal artery Accessory may refer to: * Accessory (legal term), a person who assists a criminal In anatomy * Accessory bone * Accessory breast * Accessory kidney * Accessory muscle * Accessory nucleus, in anatomy, a cranial nerve nucleus * Accessory nerve * ...

, and the lesser superficial petrosal nerve. Medial to the foramen ovale is the foramen Vesalii, which varies in size in different individuals, and is often absent; when present, it opens below at the lateral side of the

scaphoid fossa In the pterygoid processes of the sphenoid, above the pterygoid fossa is a small, oval, shallow depression, the scaphoid fossa, which gives origin to the tensor veli palatini The tensor veli palatini muscle (tensor palati or tensor muscle of t ...

, and transmits a small vein. Lateral to the foramen ovale is the foramen spinosum, for the passage of the middle meningeal vessels, and a recurrent branch from the mandibular nerve. Medial to the foramen ovale is the foramen lacerum; in the fresh state the lower part of this aperture is filled up by a layer of

fibrocartilage Fibrocartilage consists of a mixture of white fibrous tissue and cartilaginous tissue in various proportions. It owes its inflexibility and toughness to the former of these constituents, and its elasticity to the latter. It is the only type of ...

, while its upper and inner parts transmit the

surrounded by a plexus of sympathetic nerves. The nerve of the pterygoid canal and a meningeal branch from the ascending pharyngeal artery pierce the layer of fibrocartilage. On the anterior surface of the petrous portion of the temporal bone are seen the eminence caused by the projection of the superior semicircular canal; in front of and a little lateral to this a depression corresponding to the roof of the

tympanic cavity The tympanic cavity is a small cavity surrounding the bones of the middle ear. Within it sit the ossicles, three small bones that transmit vibrations used in the detection of sound. Structure On its lateral surface, it abuts the external audit ...

; the groove leading to the hiatus of the

facial canal The facial canal (also known as the Fallopian canal) is a Z-shaped canal in the temporal bone of the skull. It extends between the internal acoustic meatus and stylomastoid foramen. It transmits the facial nerve (CN VII) (after which it is nam ...

, for the transmission of the greater superficial petrosal nerve and the petrosal branch of the

; beneath it, the smaller groove, for the passage of the lesser superficial petrosal nerve; and, near the apex of the bone, the depression for the semilunar ganglion and the orifice of the carotid canal.

Clinical significance

A middle fossa craniotomy is one means to surgically remove acoustic neuromas (

vestibular schwannoma A vestibular schwannoma (VS), also called acoustic neuroma, is a benign tumor that develops on the vestibulocochlear nerve that passes from the inner ear to the brain. The tumor originates when Schwann cells that form the insulating myelin sheath ...

) growing within the internal auditory canal of the temporal bone.

References

Additional images

File:Middle cranial fossa - animation.gif, Animation File:Cranial endobasis of a 19-20 weeks foetus 2.JPG, Middle cranial fossa at human foetus File:Schädelbasis1.jpg,

Base of skull The base of skull, also known as the cranial base or the cranial floor, is the most Anatomical terms of location#Superior and inferior, inferior area of the human skull, skull. It is composed of the endocranium and the lower parts of the Calvaria ...

File:Base of skull 22.jpg, Middle cranial fossa File:Base of skull 23.jpg, Middle cranial fossa File:Slide28hhhh.JPG, Middle cranial fossa

External links

* {{Authority control Skull