Brain and Cranial Nerves

The brain has four major regions…

the cerebrum, diencephalon, brainstem, and cerebellum

Cerebral lobes

Frontal, parietal, occipital, and temporal

Gyri

The brain folds

Sulci

The depressions between gyri

Gray matter

Houses motor neuron and interneuron cell bodies. Includes dendrites and unmyelinated axons. Found in the cerebral cortex and nuclei in the cerebrum

White matter

Myelinated axons

Cranial meninges

3 connective tissue layers that cover the brain

Pia mater

Deepest layer, highly vascular

Arachnoid mater

Middle layer, fibrous web

Dura mater

Superficial layer, dense fibrous

Subarachnoid space and subdural space

Contains important structures

Brain ventricles

4 continuous cavities that also connect to the central canal of the spinal cord. Contains cerebrospinal fluid

Cerebrospinal fluid

The “blood of the brain”. Allows for buoyancy, protection, and environmental stability. Formed from the choroid plexus in the ventricles. Flows and removed at subarachnoid space

Blood-brain barrier

Keep neurons in the brain from being exposed to substances in the blood. Made from glial cells and blood capillary cells

Cerebrum

Location of conscious thought and intellectual functions. Separates right and left cerebral hemispheres by a deep longitudinal fissure

Corpus callosum

Connects right and left cerebral hemispheres. Made of myelinated axon tracts

Diencephalon

Connects cerebrum to the brainstem and encloses third ventricle

Epithalamus

Posterior aspect of diencephalon. Contains pineal gland

Pineal gland

Secretes melatonin and helps with circadian rhythm

Thalamus

Pair of grey matter masses, made of mainly nuceli

Hypothalamus

Anteroinferior portion of diencephalon. Has more grey matter nuclei, is in charge of important systems. Pituitary gland extends inferiorly, in charge of certain hormones

Brain stem

Connects to the spinal chord. Contains autonomic centers and reflect centers required for survival. Houses nuclei of many of the cranial nerves

Brain stem sections

Midbrain, pons, medulla oblongata

Cerebellum

Second largest part of the brain, has right and left hemispheres. Responsible for muscle coordination, fine-tuning and “muscle memory”

Arbor vitae

Tree like structure found in cerebellum. White matter tracts

Cerebellar penduncles

Connects cerebellum to brain stem

Limbic system

Contains cerebral and diencephalic structures responsible for emotions

Cranial nerves

Nerves of the peripheral nervous system that originate from the brain. Made of 12 pairs left and right

Spinal cord and spinal nerves

The pathway for sensory and motor impulses. Responsible for reflexes

Gross anatomy of spinal cord

Cervical, thoracic, lumbar, sacral and coccygeal parts. Starts after medulla oblongata, through foramen magnum, and down through the vertebral canal of vertebrae. Stops at L1 vertebra

Cauda equina

The nerve roots that extend inferiorly from the spinal cord down the vertebral canal