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 between the cerebral hemispheres of the human brain, 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-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, 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 and to the frontal 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 (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