Anterior cranial fossa | |
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Superior view of the skull base. Anterior cranial fossa shown in green. 1: Sphenoidal limbus (anterior margin of the chiasmatic groove) Contentslesser wings of the sphenoid | |
Base of skull. Superior view. Boundaries of the cranial fossae drawn as red lines. | |
Details | |
Identifiers | |
Latin | fossa cranii anterior |
MeSH | D035262 |
TA | A02.1.00.048 |
FMA | 9682 |
Anatomical terminology |
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 front part of the body of the sphenoid; it is limited behind by the posterior borders of the small wings of the sphenoid and by the anterior margin of the chiasmatic groove. The lesser wings of the sphenoid separate the anterior and middle fossae.
The frontal lobe is the largest of the four major lobes of the brain in mammals, and is located at the front of each hemisphere. It is separated from the parietal lobe by a groove between tissues called the central sulcus, and from the temporal lobe by a deeper groove called the lateral sulcus. The most anterior rounded part of the frontal lobe is known as the frontal pole, one of the three poles of the cerebrum.
The orbital or horizontal part of the frontal bone consists of two thin triangular plates, the orbital plates, which form the vaults of the orbits, and are separated from one another by a median gap, the ethmoidal notch.
The frontal bone is a bone in the human skull. The bone consists of two portions. These are the vertically oriented squamous part, and the horizontally oriented orbital part, making up the bony part of the forehead, part of the bony orbital cavity holding the eye, and part of the bony part of the nose respectively. The name comes from the Latin word frons.
It is traversed by the frontoethmoidal, sphenoethmoidal, and sphenofrontal sutures.
Its lateral portions roof in the orbital cavities and support the frontal lobes of the cerebrum; they are convex and marked by depressions for the brain convolutions, and grooves for branches of the meningeal vessels.
The cerebrum or telencephalon is a large part of the brain containing the cerebral cortex, as well as several subcortical structures, including the hippocampus, basal ganglia, and olfactory bulb. In the human brain, the cerebrum is the uppermost region of the central nervous system. The prosencephalon or forebrain is the embryonic structure from which the cerebrum develops prenatally. In mammals, the dorsal telencephalon, or pallium, develops into the cerebral cortex, and the ventral telencephalon, or subpallium, becomes the basal ganglia. The cerebrum is also divided into approximately symmetric left and right cerebral hemispheres.
The central portion corresponds with the roof of the nasal cavity, and is markedly depressed on either side of the crista galli.
The nasal cavity is a large, air-filled space above and behind the nose in the middle of the face. The nasal septum divides the cavity into two fossae. Each fossa is the continuation of one of the two nostrils. The nasal cavity is the uppermost part of the respiratory system and provides the nasal passage for inhaled air from the nostrils to the nasopharynx and rest of the respiratory tract.
The crista galli is the upper part of the perpendicular plate of the ethmoid bone, which rises above the cribriform plate. The falx cerebri attaches to the crista galli.
It presents, in and near the median line, from before backward, the commencement of the frontal crest for the attachment of the falx cerebri; the foramen cecum, between the frontal bone and the crista galli of the ethmoid, which usually transmits a small vein from the nasal cavity to the superior sagittal sinus; behind the foramen cecum, the crista galli, the free margin of which affords attachment to the falx cerebri; on either side of the crista galli, the olfactory groove formed by the cribriform plate, which supports the olfactory bulb and presents foramina for the transmission of the olfactory nerves, and in front a slit-like opening for the nasociliary nerve.
The falx cerebri is also known as the cerebral falx, named from its sickle-like form. It is a large, crescent-shaped fold of meningeal layer of dura mater that descends vertically in the longitudinal fissure between the cerebral hemispheres of the human brain. The falx cerebri attaches anteriorly at the crista galli in proximity to the cribriform plate and to the frontal and ethmoid sinuses. Posteriorly, it is connected with the upper surface of the cerebellar tentorium. Its superior margin is attached at midline to the internal surface of skull, as far back as the internal occipital protuberance. The superior sagittal sinus is contained in the superior margin of the falx cerebri and overlies the longitudinal fissure of the brain. The inferior sagittal sinus is contained in the inferior margin of the falx cerebri and arches over the corpus callosum, deep in the longitudinal fissure.
The frontal crest of the frontal bone ends below in a small notch which is converted into a foramen, the foramen cecum, by articulation with the ethmoid.
The superior sagittal sinus, within the human head, is an unpaired area along the attached margin of the falx cerebri. It allows blood to drain from the lateral aspects of anterior cerebral hemispheres to the confluence of sinuses. Cerebrospinal fluid drains through arachnoid granulations into the superior sagittal sinus and is returned to venous circulation.
Lateral to either olfactory groove are the internal openings of the anterior and posterior ethmoidal foramina; the anterior, situated about the middle of the lateral margin of the olfactory groove, transmits the anterior ethmoidal vessels and the nasociliary nerve; the nerve runs in a groove along the lateral edge of the cribriform plate to the slit-like opening above mentioned; the posterior ethmoidal foramen opens at the back part of this margin under cover of the projecting lamina of the sphenoid, and transmits the posterior ethmoidal vessels and nerve.
Lateral to either olfactory groove are the internal openings of the anterior and posterior ethmoidal foramina.
Farther back in the middle line is the ethmoidal spine, bounded behind by a slight elevation separating two shallow longitudinal grooves which support the olfactory lobes.
Behind this is the anterior margin of the chiasmatic groove, running laterally on either side to the upper margin of the optic foramen.
The anterior cranial fossa contains the following parts of the brain:
There are several openings connecting the anterior cranial fossa with other parts of the skull, and these are the following:
The paired anterior ethmoidal foramen connects the anterior cranial fossa with each orbit and transmits the anterior ethmoidal artery, nerve and vein.
The cribriform foramina are the openings in the cribriform plate of the ethmoid bone, which connect the anterior cranial fossa with the nasal cavity and transmit the olfactory nerves. [2]
Articles related to anatomy include:
The ethmoid bone is an unpaired bone in the skull that separates the nasal cavity from the brain. It is located at the roof of the nose, between the two orbits. The cubical bone is lightweight due to a spongy construction. The ethmoid bone is one of the bones that make up the orbit of the eye.
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 temporal bone and the basilar part of the occipital bone. The sphenoid bone is one of the seven bones that articulate to form the orbit. Its shape somewhat resembles that of a butterfly or bat with its wings extended.
In anatomy, the orbit is the cavity or socket of the skull in which the eye and its appendages are situated. Anatomical term created by Gerard of Cremona. "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 30 millilitres, of which the eye occupies 6.5 ml. The orbital contents comprise the eye, the orbital and retrobulbar fascia, extraocular muscles, cranial nerves II, III, IV, V, and VI, blood vessels, fat, the lacrimal gland with its sac and nasolacrimal duct, the eyelids, medial and lateral palpebral ligaments, check ligaments, the suspensory ligament, septum, ciliary ganglion and short ciliary nerves.
In human anatomy, the cribriform plate of the ethmoid bone is received into the ethmoidal notch of the frontal bone and roofs in the nasal cavities.
The ophthalmic nerve is the first branch of the trigeminal nerve. The ophthalmic nerve is a sensory nerve mostly carrying general somatic afferent fibers that transmit sensory information to the CNS from structures of the eyeball, the skin of the upper face and anterior scalp, the lining of the upper part of the nasal cavity and air cells, and the meninges of the anterior cranial fossa. Some of ophthalmic nerve branches also convey parasympathetic fibers.
The nasociliary nerve is a branch of the ophthalmic nerve (CN V1; one of three branches of the trigeminal nerve a.k.a. CN V). It is intermediate in size between the two other main branches of the ophthalmic nerve, the frontal nerve and the lacrimal nerve, and is more deeply placed.
The greater wing of the sphenoid bone, or alisphenoid, is a bony process of the sphenoid bone; there is one on each side, extending from the side of the body of the sphenoid and curving upward, laterally, and backward.
The ethmoidal labyrinth or lateral mass of the ethmoid bone consists of a number of thin-walled cellular cavities, the ethmoid air cells, arranged in three groups, anterior, middle, and posterior, and interposed between two vertical plates of bone; the lateral plate forms part of the orbit, the medial plate forms part of the nasal cavity. In the disarticulated bone many of these cells are opened into, but when the bones are articulated, they are closed in at every part, except where they open into the nasal cavity.
The anterior ethmoidal artery, also anterior ethmoid artery is an artery of the head.
The anterior ethmoidal foramen is a small opening in the ethmoid bone in the skull.
The anterior ethmoidal nerve is a nerve which provides sensory branches to the nasal cavity. The nerve is the continuation of the nasociliary nerve after it enters the anterior ethmoidal foramen into the anterior ethmoidal air cells. The nasociliary nerve arises from the Ophthalmic division of the Trigeminal nerve within the orbit. The anterior ethmoidal nerve arises only after the nasociliary has given off its four branches - 1) Ramus communicans to ciliary ganglion, 2) Long ciliary nerves, 3) infratrochlear nerve, 4) Posterior ethmoidal nerve.
The petrous part of the temporal bone is pyramid-shaped and is wedged in at the base of the skull between the sphenoid and occipital bones. Directed medially, forward, and a little upward, it presents a base, an apex, three surfaces, and three angles, and houses in its interior, the components of the inner ear. The petrous portion is among the most basal elements of the skull and forms part of the endocranium. Petrous comes from the Latin word petrosus, meaning "stone-like, hard". It is one of the densest bones in the body.
The middle cranial fossa, deeper than the anterior cranial fossa, is narrow medially and widens laterally to the sides of the skull. It is separated from the posterior fossa by the clivus and the petrous crest.
The body of the sphenoid bone, more or less cubical in shape, is hollowed out in its interior to form two large cavities, the sphenoidal sinuses, which are separated from each other by a septum.
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 skull roof.
The following outline is provided as an overview of and topical guide to human anatomy:
The olfactory foramina, also known as the cribriform foramina, is the grouping of holes located on the cribriform plate. The cribriform plate forms the roof of the nasal cavity, and the olfactory foramina are in the two depressions lateral to the median blade of the cribriform plate called the crista galli. There is a pair of olfactory bulbs of the brain that rest in these two depressions. These holes that make up the olfactory foramina allow passage for about 20 bundles of nerve fibers that make up the olfactory nerve, also known as Cranial Nerve I (CNI), from the nasal cavity to meet with the olfactory bulbs. Therefore, the olfactory foramina are necessary for the human sense of smell. These foramina vary in size and number with age.
This article incorporates text in the public domain from page 190 of the 20th edition of Gray's Anatomy (1918)
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