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 hemisphere ...

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 ...

,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 plant, succulent forage chiefly for feed ...

-like form.

Anatomy

The falx cerebri is a strong, crescent-shaped sheet lying in the sagittal plane. It is a dural formation (one of four dural partitions of the brain along with the falx cerebelli,

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 ...

, 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 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 ea ...

and ethmoid sinuses). 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 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 m ...

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: *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 ...

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;

(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 hernia ...

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 ...

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 br ...

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

* * {{Authority control Meninges