The middle cranial fossa, 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 fr ...

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

skull The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, th ...

. It is separated from the posterior fossa by the clivus and the petrous crest. It is bounded in front by the posterior margins of the lesser wings of 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 the occipital bone. The sphenoid bone is one of the seven bones that articulate to form the o ...

, 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 sellæ; laterally by the temporal squamæ, sphenoidal angles of the parietals, and greater wings of the sphenoid. It is traversed by the squamosal, sphenoparietal, sphenosquamosal, and sphenopetrosal sutures. It houses the

temporal lobes 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 pro ...

of the brain and the

pituitary gland In vertebrate anatomy, the pituitary gland, or hypophysis, is an endocrine gland, about the size of a chickpea and weighing, on average, in humans. It is a protrusion off the bottom of the hypothalamus at the base of the brain. The h ...

. 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. Middle cranial fossa surgical anatomy - J M Kartush

Middle part

The middle part of the fossa presents, in front, the chiasmatic groove and

tuberculum sellae The tuberculum sellae (or the tubercle of the sella turcica) is a part of the sphenoid bone that is an elevation behind the chiasmatic groove The superior surface of the body of the sphenoid bone is bounded behind by a ridge, which forms the ante ...

; 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 b ...

, 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 information from the retina to the brain. In humans, the optic nerve is derived fro ...

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 s ...

to the

orbital cavity In anatomy, the orbit is the cavity or socket of the skull in which the eye and its appendages are situated. "Orbit" can refer to the bony socket, or it can also be used to imply the contents. In the adult human, the volume of the orbit is , ...

. Behind the optic foramen the

anterior clinoid process In the sphenoid bone, the posterior border, smooth and rounded, is received into the lateral fissure of the brain; the medial end of this border forms the anterior clinoid process, which gives attachment to the tentorium cerebelli; it is sometimes ...

is directed backward and medialward and gives attachment to the

tentorium cerebelli The cerebellar tentorium or tentorium cerebelli ( Latin for "tent of the cerebellum") is an extension of the dura mater that separates the cerebellum from the inferior portion of the occipital lobes. Structure The cerebellar tentorium is an arc ...

. Behind the tuberculum sellæ is a deep depression, the

sella turcica The sella turcica ( Latin for 'Turkish saddle') is a saddle-shaped depression in the body of the sphenoid bone of the human skull and of the skulls of other hominids including chimpanzees, gorillas and orangutans. It serves as a cephalometr ...

, containing the

fossa hypophyseos The sella turcica ( Latin for 'Turkish saddle') is a saddle-shaped depression in the body of the sphenoid bone of the human skull and of the skulls of other hominids including chimpanzees, gorillas and orangutans. It serves as a cephalometr ...

, which lodges the hypophysis, and presents on its anterior wall the

middle clinoid processes The anterior boundary of the sella turcica is completed by two small eminences, one on either side, called the middle clinoid processes. It is found lateral to the sella turcica The sella turcica ( Latin for 'Turkish saddle') is a saddle-shape ...

. The

is bounded posteriorly by a quadrilateral plate of bone, the

dorsum sellae The dorsum sellae is part of the sphenoid bone in the skull. Together with the basilar part of the occipital bone it forms the clivus. In the sphenoid bone, the anterior boundary of the sella turcica is completed by two small eminences, one o ...

, the upper angles of which are surmounted by the posterior clinoid processes: these afford attachment to the tentorium cerebelli, and below each is a notch for the

abducent nerve The abducens nerve or abducent nerve, also known as the sixth cranial nerve, cranial nerve VI, or simply CN VI, is a cranial nerve in humans and various other animals that controls the movement of the lateral rectus muscle, one of the extraocula ...

. On either side of the sella turcica is the carotid groove, 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 cave ...

and the

internal carotid artery The internal carotid artery (Latin: arteria carotis interna) is an artery in the neck which supplies the anterior circulation of the brain. In human anatomy, the internal and external carotids arise from the common carotid arteries, where these ...

, the latter being surrounded by a plexus of

sympathetic nerves The sympathetic nervous system (SNS) is one of the three divisions of the autonomic nervous system, the others being the parasympathetic nervous system and the enteric nervous system. The enteric nervous system is sometimes considered part of the ...

Lateral parts

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

of the

brain A brain is an organ (biology), organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It is located in the head, usually close to the sensory organs for senses such as Visual perception, vision. I ...

. 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 The squamous part of temporal bone, or temporal squama, forms the front and upper part of the temporal bone, and is scale-like, thin, and translucent. Surfaces Its outer surface is smooth and convex; it affords attachment to the temporal muscle ...

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 The superior orbital fissure is a foramen or cleft of the skull between the lesser and greater wings of the sphenoid bone. It gives passage to multiple structures, including the oculomotor nerve, trochlear nerve, ophthalmic nerve, abducens ne ...

, bounded above by the small wing, below, by the great wing, and medially, by the body of the sphenoid; it is usually completed laterally by the orbital plate of the

frontal bone The frontal bone is a bone in the human skull. The bone consists of two portions.'' Gray's Anatomy'' (1918) These are the vertically oriented squamous part, and the horizontally oriented orbital part, making up the bony part of the forehead, ...

. It transmits to the

the oculomotor, the trochlear, the

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

of the trigeminal, and the

abducent nerves The abducens nerve or abducent nerve, also known as the sixth cranial nerve, cranial nerve VI, or simply CN VI, is a cranial nerve in humans and various other animals that controls the movement of the lateral rectus muscle, one of the extraocula ...

, some filaments from the cavernous plexus of the sympathetic, and the orbital branch of the middle meningeal artery; and from the orbital cavity a recurrent branch from the

lacrimal artery The lacrimal artery is an artery of the 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 supplies the lacri ...

to the

dura mater In neuroanatomy, dura mater is a thick membrane made of dense irregular connective tissue that surrounds the brain and spinal cord. It is the outermost of the three layers of membrane called the meninges that protect the central nervous system. ...

, and the

ophthalmic veins Ophthalmic veins are veins which drain the eye. More specifically, they can refer to: * Superior ophthalmic vein * Inferior ophthalmic vein The inferior ophthalmic vein is a vein of the orbit that - together with the superior ophthalmic vein - ...

. Behind the medial end of the

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 sensation from the maxilla, nasal cavity, sinuses, the pala ...

. 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 nerve (CN V). Unlike the other divisions of the trigeminal nerve ( ophthalmic nerve, maxillary nerve) which contain only ...

, the accessory meningeal artery, and the

lesser superficial petrosal nerve The lesser petrosal nerve (also known as the small superficial petrosal nerve) is the general visceral efferent (GVE) component of the glossopharyngeal nerve (CN IX), carrying parasympathetic preganglionic fibers from the tympanic plexus to the ...

. Medial to the foramen ovale is the

foramen Vesalii In the base of the skull, in the great wings of the sphenoid bone, medial to the foramen ovale, a small aperture, the sphenoidal emissary foramen, may occasionally be seen (it is often absent) opposite the root of the pterygoid process. When prese ...

, which varies in size in different individuals, and is often absent; when present, it opens below at the lateral side of the scaphoid fossa, 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 The ascending pharyngeal artery is an artery in the neck that supplies the pharynx, developing from the proximal part of the embryonic second aortic arch. It is the smallest branch of the external carotid and is a long, slender vessel, deeply se ...

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 auditor ...

; the groove leading to the hiatus of the facial canal, for the transmission of the greater superficial petrosal nerve and the petrosal branch of the middle meningeal artery; beneath it, the smaller groove, for the passage of the

; and, near the apex of the bone, the depression for the semilunar ganglion and the orifice of the carotid canal.

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 inferior area of the skull. It is composed of the endocranium and the lower parts of the calvaria. Structure Structures found at the base of the skull are for ...

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

Middle part

Lateral parts

See also

References

Additional images

External links