Brain and Cranial Nerves

Terminology Hemispheres Gyrus (Gyri) Sulcus (Sulci) Longitudinal Fissure Ventricles CSF

Anatomy of the Brain Cerebrum Cerebellum Diencephalon Brain Stem Thalamus Hyothalamus Brain Stem Midbrain Pons Medulla oblongata

Cerebrum Anatomy Functions Frontal lobe Parietal lobe Occipital lobe Precentral gyrus Postcentral gyrus Functions Sensory cortex Motor cortex Emotion Intellectual processes Auditory Visual Speech

Cerebellum Anatomy Functions Hemispheres Compares intended movement with what is actually happening Smooth, coordinated movements Posture/balance

Brain Stem Anatomy Functions Medulla oblongata Pons Midbrain Medulla Relays motor and sensory information Regulates heartbeat, breathing and blood vessel dilation Pons Control breathing

Protective Coverings (Meninges) Dura mater Dense connective tissue Arachnoid Nonvascular connective tissue Pia mater Highly vascular Covers surface of the brain and spinal cord and invaginates along cortical surface to form perivascular spaces

Cerebral Spinal Fluid Formed in the choroid plexus Reabsorbed into saggittal sinus by arachnoid villi Protects brain against concussive trauma removes waste products

Foramen of Monro

Cranial Nerves I: Olfactory II: Optic III: Oculomotor IV: Trochlear V: Trigeminal VI: Abducens VII: Facial VIII:Vestibulocochlear Acoustic IX: Glossopharyngeal X: Vagus XI: Accessory XII: Hypoglossal http://www.gwc.maricopa.edu/class/bio201/cn/cranial.htm

Mnemonic On Old Olympus’ Tower Top A Fin And German Viewed A Hop

MNEMONIC OLFACTORY OPTIC OCULOMOTOR TROCHLEAR TRIGEMINAL ABDUCENS FACIAL VESTIBULOCOCHLEAR GLOSSOPHARYNGEAL VAGUS ACCESSORY HYPOGLOSSAL OH ONCE ONE TAKES THE ANATOMY FINAL VERY GOOD VACATION A-HEAD

CN I: OLFACTORY Cranial nerve I Function: Clinical test for damage: smell Clinical test for damage: determine whether a person can smell something aromatic

CN II: OPTIC Cranial nerve II Function: Clinical test for damage: vision Clinical test for damage: tests peripheral vision and visual acuity Effects of damage: blindness in part or all of the visual field

CNIII: OCULOMOTOR Cranial nerve III Function: eye movements, opening of eyelid, constriction of pupil, focusing, proprioception Clinical tests for injury: differences in pupil size; pupillary response to light; eye tracking Effects of damage dropping eyelid, dilated pupil, double vision

CNIV: TROCHLEAR Cranial nerve IV Function: eye movements and proprioception Clinical test for injury: ability to rotate eye inferolaterally Effects of damage – double vision, patient tilts head toward affected side

CN V: TRIGEMINAL Cranial nerve V Function: sensory nerve of the face Clinical test for injury: corneal reflex; sense of touch, pain, and temperature; clench teeth; move mandible side to side Effects of damage: loss of sensation and impaired chewing Largest of the cranial nerves Blinking in response to light touch to the eyeball

CN VI: ABDUCENS AND CN VII: FACIAL Cranial Nerve VI Function: Eye movements Clinical test: lateral eye movement Effects of damage: inability to rotate eye laterally; at rest – eye rotates medially because of action of antagonistic muscles Cranial Nerve VII Function: facial expression; sense of taste Clinical test: motor functions – close eyes, smile, whistle, frown, raise eyebrows; taste Effects of damage: inability to control facial muscles; distorted sense of taste

CN VIII: VESTIBULOCOCHLEAR Cranial Nerve VIII Function: hearing and equilibrium Clinical tests: test hearing, balance, and ability to walk a straight line Effects of damage: deafness, dizziness, nausea, loss of balance, and nystagmus

CN IX: GLOSSOPHARANGEAL AND CN X: VAGUS Cranial Nerve IX Function: swallowing, salivation, gagging; touch, pressure, taste, and pain sensations from tongue, pharynx, and outer ear Clinical tests: gag reflex, swallowing, and coughing Effects of damage: difficulty swallowing Cranial Nerve X Function: swallowing; taste; speech; respiratory, CV, and GI regulation; sensations of hunger, fullness, and intestinal discomfort Clinical tests: test with cranial nerve IX Effects of damage: hoarseness or loss of voice; impaired swallowing and GI motility Can be fatal if vagus nerve is damaged – 2 routes

CN XI: ACCESSORY AND CN XII: HYPOGLOSSAL Cranial Nerve XI Function: swallowing; head, neck, and shoulder movements Clinical tests: rotate head and shrug shoulders against resistance Effects of damage: impaired movement of head, neck, and shoulders; paralysis of sternocleidomastoid Cranial Nerve XII Function: tongue movements of speech, food manipulation, and swallowing Clinical test: tongue function Effects of damage: difficulty in speech and swallowing; atrophy of tongue; inability to stick out (protrude) tongue Paralysis will cause head to turn toward injured side