An introduction to nervous system By: shirin Kashfi Helpful Terms CNS Central Nervous System PNS Peripheral Nervous System Ganglion (ganglia) Group of cell bodies found in the PNS Nucleus (nuclei) Group of cell bodies found in the CNS (not the same as a cell nucleus) Nerve Bundle of nerve fibers (axons) found in the PNS tract Bundle of nerve fibers (axons) found in the CNS Primary neurolation • In vertebrates , CNS originates from dorsal ectoderm • CNS forms as a tube during primary neurolation • Part of ectoderm where fusion occurs becomes neural crest which then forms PNS. Neural Groove Neural Tube Brain Spinal Chord • by 4th week: – Forebrain, Midbrain, Hindbrain • Prosencephelon (Forebrain) Telencephalon (cerebrum) Diencephelon (thalamus, hypothalamus) • Mesencephalon (Midbrain) • Rhombencephalon (Hindbrain) Metencephalon (pons, cerebellum) Myelencephalon (medulla) Directional Terms - Brain dorsal superior rostral caudal anterior posterior ventral inferior Directional Terms - Brainstem and Spinal Cord the brain takes a turn at the cephalic flexure rostral dorsal superior posterior ventral caudal anterior inferior Directional Terms - Sections Horizontal cut Has symmetry (mirror images) Long (oval) Directional Terms - Sections Coronal cut Has symmetry (mirror images) round (circle-sort of) Directional Terms - Sections Sagittal cut Does not have symmetry What kind of cut is this? Coronal What kind of cut is this? Horizontal What kind of cut is this? Horizontal Meninge • The meninges are the three membranes that envelop the brain and spinal cord • In mammals, the meninges are the dura mater, the arachnoid mater, and the pia mater • The primary function of the meninges is to protect the central nervous system Dura mater Falx cerebri and cerebellar tentorium • 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 cerebellar tentorium is an extension of the dura mater that separates the cerebellum from the inferior portion of the occipital lobes Arachnoid Arachnoid granules Pia mater .