Central Nervous System Brain Spinal Cord Development of

Central Nervous System Brain & Spinal Cord

Development of the CNS �Appears as neural tube on dorsal median plane � 4 th week brain formation begins at anterior end of the neural tube �Remaining portion of neural tube becomes spinal cord

4 Major Regions of the Brain �Cerebrum (Cerebral hemispheres) �Cerebellum �Brain Stem �Diencephalon

Cerebrum �Divided into left and right hemispheres (What do you already know about them? ) �Surface is covered in elevated ridges and shallow grooves ◦ Gyri- ridges ◦ Sulci- grooves ◦ Let’s think of a way to remember these! �Fissures are deep grooves that separate large regions of the brain

Cerebrum �Gray matter: ◦ Outermost portion of the cerebral cortex ◦ Neuronal cell bodies are located here �White matter: ◦ Inner tissue of cerebrum ◦ Bundles of fiber tracts (neuronal axons!) �Basal nuclei- small islands of gray matter within inner cerebrum ◦ Regulate voluntary motor activities

The Brain Matters Locate the gray matter, the white matter, and the basal nuclei.

Cerebrum separated into 4 lobes

Each lobe of the cerebrum is unique �Frontal Lobes �Parietal Lobes �Temporal Lobes �Occipital Lobe Do these names sound familiar?

Corpus Callosum �Large fiber tract �Connects and allows communication between left & right hemisphere �“Split-Brain” patients ◦ Severed corpus callosum

Split-Brain Patients Article: http: //www. nature. com/news/the-split-brain-a-tale-of-two-halves 1. 10213

Brain Stem �Parts of the Brain Stem: ◦ Midbrain ◦ Pons ◦ Medulla oblongata �Provides a pathway for ascending & descending tracts from the brain to the spinal cord �Reticular Formation ◦ Gray matter extending along brain stem involved in motor control of organs & consciousness

Brain Stem

Diencephalon �Located on top of the brainstem surrounded by the cerebral hemispheres �Many structures in the diencephalon ◦ ◦ ◦ ◦ Thalamus Hypothalamus Pituitary Pineal Body Choroid Plexus Amygdala Hippocampus

Cerebellum �Located under the occipital lobe of the cerebrum �It has two hemispheres with an outer cortex of gray matter and inner region of white matter

“Let Me Pick Your Brain” Activity �Awesome 3 D Brain Website: �G 2 conline. com �Pages 235 -241 in your book

CNS Protection �Bones of the skull and vertebral column �Connective tissue membranes called Meninges �Aqueous cushion called the cerebrospinal fluid (CSF) �Blood-brain barrier made by the least permeable capillaries in the body keeps the brain in a constant environment ◦ What would happen if the brain were

Meninges of the Brain �Dura Mater ◦ Outermost thick, tough, double layered membrane �Arachnoid Mater ◦ Middle layer with many projections that has CSF flowing through it ◦ Arachnoid villi protrude through dura mater, allowing CSF to drain into superior sagittal sinus to the blood �Pia Mater ◦ Delicate innermost vascular layer that follows every convolution of the brain and spinal cord

Cerebrospinal Fluid �We know where it drains… but where is it made? ◦ Made in the choroid plexuses on roof of ventricles in the brain �The choroid plexuses make about 2030 m. L of CSF per hour �The body has about 150 m. L of CSF at a time �Circulates throughout the CNS ◦ Which cells help circulate CSF?

Blood-Brain Barrier �Brain is the only body organ that cannot handle any environmental fluctuations �Neurons are sequestered from substances in the blood by nearly impermeable capillaries

Spinal Cord �Continuation of the brain stem � 3 layers of Meninges � 31 pairs of spinal nerves �Gray matter is on the inside & contains neuron cell bodies �White matter is on the outside & contains axons