The falx cerebri (also known as the cerebral falx) is a large, crescent-shaped fold of dura mater that descends vertically into the longitudinal fissure to separate the cerebral hemispheres.Saladin K. "Anatomy & Physiology: The Unity of Form and Function. New York: McGraw Hill, 2014. Print. pp 512, 770-773 It supports the dural sinuses that provide

venous Veins () are blood vessels in the circulatory system of humans and most other animals that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are those of the pulmonary and fetal c ...

and CSF drainage from 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 ...

. It is attached to the crista galli anteriorly, and blends with the

tentorium cerebelli The cerebellar tentorium or tentorium cerebelli (Latin for "tent of the cerebellum") is one of four dural folds that separate the cranial cavity into four (incomplete) compartments. The cerebellar tentorium separates the cerebellum from the cere ...

posteriorly. 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 plant, succulent forage chiefly for feedi ...

-like shape.

Anatomy

The falx cerebri is a strong, crescent-shaped sheet of dura mater lying in the sagittal plane between the two

cerebral hemisphere 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 ...

s. It is one of four dural partitions of the brain along with the falx cerebelli,

, and diaphragma sellae; 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 (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 s ...

and to the frontal and

ethmoid sinus The ethmoid sinuses or ethmoid air cells of the ethmoid bone are one of the four paired paranasal sinuses. Unlike the other three pairs of paranasal sinuses which consist of one or two large cavities, the ethmoidal sinuses entail a number of small ...

es). Posteriorly, it blends into the upper surface of the cerebellar tentorium. 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 (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 ...

lies immediately inferior to the lower (free) margin of falx cerebri.

Dural venous sinuses

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 free margin of the falx cerebri and arches over the

, deep within the longitudinal fissure. The straight sinus 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: ...

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 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 significant surgical landmark for access of the lateral ventricles via the interhemispheric transcallosal approach;

(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 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 cin ...

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 (mTBI/concussion) to severe traumati ...

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

References

External links

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