The falx cerebri (also known as the cerebral falx) is a large, crescent-shaped fold of
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. ...
that descends vertically into the
longitudinal fissure
The longitudinal fissure (or cerebral fissure, great longitudinal fissure, median longitudinal fissure, interhemispheric fissure) is the deep groove that separates the two cerebral hemispheres of the vertebrate brain. Lying within it is a continu ...
between the
cerebral hemispheres
The vertebrate cerebrum (brain) is formed by two cerebral hemispheres that are separated by a groove, the longitudinal fissure. The brain can thus be described as being divided into left and right cerebral hemispheres. Each of these hemispheres ...
of the
human brain
The human brain is the central organ of the human nervous system, and with the spinal cord makes up the central nervous system. The brain consists of the cerebrum, the brainstem and the cerebellum. It controls most of the activities of the ...
,
[Saladin K. "Anatomy & Physiology: The Unity of Form and Function. New York: McGraw Hill, 2014. Print. pp 512, 770-773] separating the two hemispheres and supporting dural sinuses that provide venous and
CSF drainage to the brain.
The falx cerebri is often subject to age-related calcification, and a site of falcine meningiomas.
The falx cerebri is named for its
sickle
A sickle, bagging hook, reaping-hook or grasshook is a single-handed agricultural tool designed with variously curved blades and typically used for harvesting, or reaping, grain crops or cutting succulent forage chiefly for feeding livestock, ei ...
-like form.
Anatomy
The falx cerebri is a strong, crescent-shaped sheet lying in the sagittal plane.
It is a
dural
Dural is a suburb of Sydney, in the state of New South Wales, Australia 36 kilometres north-west of the Sydney central business district in the local government areas of Hornsby Shire and The Hills Shire. Dural is part of the Hills District ...
formation (one of four dural partitions of the brain along with the
falx cerebelli
The falx cerebelli is a small sickle-shaped fold of dura mater projecting forwards into the posterior cerebellar notch as well as projecting into the vallecula of the cerebellum between the two cerebellar hemispheres.
The name comes from two ...
,
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 arche ...
, and
diaphragma sellae
The diaphragma sellae or sellar diaphragm is a flat piece of dura mater with a circular hole allowing the vertical passage of the pituitary stalk. It retains the pituitary gland beneath it in the fossa hypophyseos as it almost completely roofs th ...
); it is formed through invagination of the dura mater into the longitudinal fissure between the cerebral hemispheres.
Anteriorly, the falx cerebri is narrower, thinner, and may have a number of perforations. It is broader posteriorly.
Attachments
The falx cerebri attaches anteriorly at the
crista galli
The crista galli (Latin: "crest of the rooster") is the upper part of the perpendicular plate of the ethmoid bone of the skull. It rises above the cribriform plate. The falx cerebri (a fold of the dura mater surrounding the brain) attaches to th ...
(proximally to the
cribriform plate
In mammalian anatomy, the cribriform plate (Latin for lit. ''sieve-shaped''), horizontal lamina or lamina cribrosa is part of the ethmoid bone. It is received into the ethmoidal notch of the frontal bone and roofs in the nasal cavities. It supp ...
and to the
frontal
Front may refer to:
Arts, entertainment, and media Films
* ''The Front'' (1943 film), a 1943 Soviet drama film
* ''The Front'', 1976 film
Music
* The Front (band), an American rock band signed to Columbia Records and active in the 1980s and e ...
and
ethmoid sinus
The ethmoid sinuses or ethmoid air cells of the ethmoid bone are one of the four paired paranasal sinuses. The cells are variable in both size and number in the lateral mass of each of the ethmoid bones and cannot be palpated during an extraoral e ...
es).
Posteriorly, it blends into the upper surface of the
cerebellar tentorium
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 arche ...
.
Its convex superior margin is attached to the internal surface of the skull on either side of the midline. This attachment runs as far back as the
internal occipital protuberance
Along the internal surface of the occipital bone, at the point of intersection of the four divisions of the cruciform eminence, is the internal occipital protuberance. Running transversely on either side is a groove for the transverse sinus
The ...
(the latter representing its posterior-most point of attachment
); the superior sagittal sinus runs in the cranial groove between the falx cerebri's two attachments.
The (concave) inferior margin of the falx cerebri is free.
Vascular supply
The falx cerebri receives its blood supply primarily from two vessels; the anterior portion receives blood supply from the anterior meningeal artery (a.k.a. anterior falx artery, or anterior falcine artery) (a branch of the anterior ethmoidal artery), and the posterior portion from the posterior meningeal artery (a branch of the ascending pharyngeal artery).
Lymphatic drainage of the falx cerebri occurs mostly via meningeal lymphatic vessels that run parallel to the dural sinuses and that eventually exit the cranial vault through the jugular foramen to empty into deep cervical lymph nodes. A minority of lymph from the falx cerebri is drained anteriorly through the cribiform plate into the lymphatics of the nasal mucosa.
Innervation
The falx cerebri receives innervaton from all three branches of the trigeminal nerve. It receives symphatetic innervation predominantly from the superior cervical ganglia. It may receive additional innervation from dorsal rami of CN 1 and CN 2, the hypoglossal nerve, and recurrent branches of the vagus nerve.
Anatomical relations
The falx cerebri is situated in the longitudinal fissure, in between the cerebral hemispheres.
The
corpus callosum
The corpus callosum (Latin for "tough body"), also callosal commissure, is a wide, thick nerve tract, consisting of a flat bundle of commissural fibers, beneath the cerebral cortex in the brain. The corpus callosum is only found in placental mam ...
lies immediately inferior to the lower (free) margin of falx cerebri.
Dural venous sinuses
The
superior sagittal sinus
The superior sagittal sinus (also known as the superior longitudinal 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 hemispher ...
is contained in the superior margin of the falx cerebri and overlies the longitudinal fissure of the brain.
The
inferior sagittal sinus
The inferior sagittal sinus (also known as inferior longitudinal sinus), within the human head, is an area beneath the brain which allows blood to drain outwards posteriorly from the center of the head. It drains (from the center of the brain) to ...
is contained in the inferior
free
margin of the falx cerebri and arches over the
corpus callosum
The corpus callosum (Latin for "tough body"), also callosal commissure, is a wide, thick nerve tract, consisting of a flat bundle of commissural fibers, beneath the cerebral cortex in the brain. The corpus callosum is only found in placental mam ...
, deep within the longitudinal fissure.
The
straight sinus
The straight sinus, also known as tentorial sinus or the , is an area within the skull beneath the brain. It receives blood from the inferior sagittal sinus and the great cerebral vein, and drains into the confluence of sinuses.
Structure
The s ...
courses along the juncture of the falx cerebri and cerebellar tentorium.
Anatomical variation
Total or partial
agenesis In medicine, agenesis () refers to the failure of an organ to develop during embryonic growth and development due to the absence of primordial tissue. Many forms of agenesis are referred to by individual names, depending on the organ affected:
* A ...
of the falx cerebri may occur, and may result in adherence of the cerebral hemispheres across the midline. Agenesis is usually associated with other developmental complications; falx cerebri agenesis in absence of other neural symptoms is exceedingly rare.
Microanatomy
The falx cerebri contains blood vessels, and nerves.
Clinical significance
Calcification
Calcification of the falx cerebri is more prevalent in older patients, often without a determinable cause, and without pathogenic symptoms.
Meningioma
Falcine meningioma is a
meningioma
Meningioma, also known as meningeal tumor, is typically a slow-growing tumor that forms from the meninges, the membranous layers surrounding the brain and spinal cord. Symptoms depend on the location and occur as a result of the tumor pressing o ...
arising from the falx cerebri and completely concealed by the overlying cortex. Falcine meningioma tends to grow predominantly into one cerebral hemisphere but is often bilateral, and in some patients the tumor grows into the inferior edge of the sagittal sinus. However, although much information is available regarding meningiomas, little is known about falcine meningiomas.
[Chung SB, Kim CY, Park CK, Kim DG, Jung HW (2007). "Falx Meningiomas: Surgical Results and Lessons Learned from 68 Cases." ''J Korean Neurosurg Soc.'' 42 (4): 276-280. ]
Surgical landmark
The falx cerebri is a significal surgical landmark for access of the lateral ventricles via the interhemispheric transcallosal approach;
agenesis In medicine, agenesis () refers to the failure of an organ to develop during embryonic growth and development due to the absence of primordial tissue. Many forms of agenesis are referred to by individual names, depending on the organ affected:
* A ...
(complete or partial) of the falx cerebri results in the adherence of the cerebral hemispheres, blocking midline transcallosal surgical access to the ventricles.
Subfalcine brain herniation
Subfalcine
herniation
A hernia is the abnormal exit of tissue or an organ, such as the bowel, through the wall of the cavity in which it normally resides. Various types of hernias can occur, most commonly involving the abdomen, and specifically the groin. Groin herni ...
of the
cingulate gyrus
The cingulate cortex is a part of the brain situated in the medial aspect of the cerebral cortex. The cingulate cortex includes the entire cingulate gyrus, which lies immediately above the corpus callosum, and the continuation of this in the ci ...
may occur following
traumatic brain injury
A traumatic brain injury (TBI), also known as an intracranial injury, is an injury to the brain caused by an external force. TBI can be classified based on severity (ranging from mild traumatic brain injury TBI/concussionto severe traumatic b ...
.
Additional images
File:Sobo 1909 589.png , Falx cerebri in relation to the skull.
File:Gray135.png, Frontal bone. Inner surface.
File:Gray568.png, Sagittal section of the skull, showing the sinuses of the dura.
File:Human brain dura mater (reflections) description.JPG, Human brain dura mater (reflections)
File:Falx cerebri.jpg, Falx cerebri
See also
*
Falx (disambiguation) Falx may refer to:
*Falciform ligament, a ligament of the liver
*Falx, a sickle, scythe or sickle-like weapon used by Dacians
*Falx cerebelli and falx cerebri, two parts of the dura mater of the brain
*Foramen ovale (heart), a fetal cardiac shunt, ...
, other parts of the anatomy with names including "falx"
References
External links
*
*
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Meninges