Brain & Cranial Nerves

Major Regions Brain stem Cerebrum Diencephalon Mesencephalon Pons Largest region of the brain Divided into the cerebral hemispheres Fold – “gyrus” Groove – “sulcus” Diencephalon Thalamus Hyptothalamus Mesencephalon Pons Medulla Oblangata Most inferior Connects brain to spinal cord Cerebellum Brain stem

Cranial Meninges and Ventricles of the Brain Dura mater* Arachnoid mater – forms smooth covering of the brain Pia mater – contains the blood vessels that supply the brain

Dura Mater – Brain Endosteal layer – “outer” layer Meningeal layer – “inner” layer Stabilizing extensions Falx cerebri Tentorium cerebri Falx cerebelli Dural sinuses – drain the blood from cranial veins into jugular veins Superior / Inferior sagittal sinuses Transverse sinus

Ventricles 4 chambers  ventricles Each ventricle has a choroid plexus where CSF is produced 2 “lateral” ventricles Divided by Septum pellucidum 3rd ventricle In the diencephalon 4th ventricle Between brain stem and cerebellum

Regions of the Brain Cerebrum Diencephalon Mesencephalon Pons Medulla Oblangata Cerebellum

CEREBRUM Conscious thought, memory processing/storage, reasoning Central Sulcus Conscious thought, memory processing/storage, reasoning Regional specializations: Central sulcus – separates the motor region from sensory region Pre-central gyrus – contains the primary motor cotex Post-central gyrus – contains primary sensory cortex (touch is perceived) Association areas – interprets and integrates information Premotor Cortex – somatic motor association area

Corpus Callosum Connects the cerebral hemispheres Relevance in epileptic episodes? Corpus calloscotomy – split brain? https://www.youtube.com/watch?v=wfYbgdo8e-8&t=29s

Fornix / Anterior Commissure Fornix is the inferior portion of the corpus callosum that connects the structures of the limbic system – “emotional” brain Fornix Anterior Commissure

Basal Nuclei Involved in automating voluntary muscle contractions

DIENCEPHALON Thalamus – sense of awareness Picks up on sensory impulses (except smell and proprioception) Relays sensory information to proper sensory cortex Hypothalamus – links nervous system to endocrine system Regulates hunger, thirst, fatigue, circadian rhythms, body temperature Mamillary bodies – control eating reflexes Infundibulum attaches the pituitary gland to hypothalamus Pituitary gland – major endocrine gland responsible for growth and development

MESENCEPHALON (MIDBRAIN) Superior colliculi Visual reflec Keep an object centered on the retina by moving eyeballs and head Inferior colliculi Auditory reflex Moves the head to follow sound

PONS Directs sensory information to the thalamus and cerebellum

MEDULLA OBLONGATA Autonomic center for visceral functions Sensory information enters brain via ascending tracks, and motor information enters spinal cord via descending tracts Nuclei in this region regulate cardiovascular, respiratory, and digestive activities

CEREBELLUM Covered by the cerebral cortex Hemispheres are divided by vermis Anterior and posterior lobes (smaller) are separated by primary fissure Coordination of somatic motor functions Stores muscle patterns (i.e. playing piano, playing tennis)

Primary Fissure

Higlly branched white matter is called arbor vitae Cerebellar nuclei function in the regulation of involuntary skeletal muscle contraction Purkinjie (large neurons) cells branch extensively and synapse with thousands of neurons!

CRANIAL NERVES Olfactory nerve (I)  receptors in the nose Optic nerve (II)  transmit signals from retina Oculomotor nerve (III)  enables movement of the eye and eyelid Trochlear nerve (IV)  innervates trochlea of the eye Trigeminal nerve (V)**  muscles of mastication / largest nerve Abducens nerve (VI)  controls lateral recturs muscles of eye Facial nerve (VII)  muscles of facial expression / taste sensation from 2/3 front of tongue Vestibulocochlear nerve (VIII)  conducts information about hearing and balance Glossopharyngeal nerve (IX)  receives sensory information from tongue Vagus nerve (X)  parasympathetic control of heart, lungs, and digestive organs Accessory nerve (XI)  supplies sternocleidomastoid and trapezius muscles Hypoglossal nerve (XII)  innervates extrinsic and intrinsic muscles of tongue (except palatoglossus)