Chapters 5 6 Single

Clarifications from last lecture Parasympathetic Rest and digest

Sympathetic Fight or flight

Steven Hawking does have ALS. He’s had it most of his adult life.

Medulla – Ventral Surface Anterior median sulcus Continues from spinal cord

Pyramids – corticospinal tract Pyramidal decussation Anterior lateral sulcus Inferior Olive

Medulla – Ventral Surface Cranial Nerves (9-12) Glossopharyngeal (IX) Vagus (X) Accessory (XI) Hypoglossal (XII)

Medulla - Dorsal Surface Posteromedian sulcus Posterolateral sulcus Clava Gracile tract protuberance

Cuneate tubercle Cuneate tract protuberance

Fourth Ventricle Contains CSF Choroid Plexus Makes CSF

Space between Medulla/Pons and Cerebellum/medullary velums Velum – “veil” Thin membrane

Internal Structure 3 levels Motor (pyramidal) decussation Sensory (lemniscal) decussation Inferior olive

Motor Decussation Level Pyramidal decussation Corticospinal Lower extremities Lateral Decussate last

Upper extremities Medial Decussate first

Corticobulbar Cortex to cranial nerve nuclei

Pyramidal Decussation Bilateral upper extremity paralysis Rostral lesion

Hemiplegia cruciata ‘crossed’ Opposite arm/leg Caudal lesion

Motor Decussation Level Dorsal column nuclei Cuneate C1 to T7

Gracile Below T7

Spinal trigeminal nucleus Trigeminal nerve Pain, temperature, light touch Ipsilateral face

Sensory Decussation Level Medial lemniscus DC-ML Kinesthesia Discriminative touch Contralateral

Accessory cuneate nucleus Not part of DC-ML Spinocerebellar system Fibers from above C8 Projects to cerebellum Hypertension activates Bradycardyia Hypotension

Inferior Olive Level Inferior olivary nuclear complex Principal olive Dorsal accessory olive Medial accessory olive

Inputs to Inferior Olive ‘Relay station’ inputs from Cortex Basal ganglia Spinal cord Midbrain Medulla Cerebellum

Output to cerebellum Olivocerebellar tract

Inferior Olive Level Restiform body Inferior cerebellar peduncle Foot

2 other cerebellar peduncles Middle Pons

Superior Midbrain

Tracts within Restiform Body Olivocerebellar tract Largest Inferior olive and cerebellum

Dorsal spinocerebellar tract Spinal cord to cerebellum

Reticulocerebellar tract Reticular formation to cerebellum

Medulla: Cranial Nerve Nuclei Cranial Nerves 8-12 Vestibulochoclear (VIII) Glossopharyngeal (IX) Vagus (X) Accessory (XI) Hypoglossal (XII)

Hypoglossal (XII) Hypoglossal nucleus Motor Tongue Nerve Travels between olive and pyramid

Hypoglossal Lesions (and Surrounding Structures) Nerve Nerve and medial lemniscus (DC-ML) Nerve and pyramid

Accessory Nerve: Roots Spinal Spinal cord Ventral horn C1-C6 Nucleus ambiguus

Cranial Medulla Accessory nucleus

Accessory Nerve: Output Larynx Recurrent laryngeal nerve Galen and the silent pig

Some neck muscles Lesions Winged scapula Sagging shoulder Weak turning head to opposite side

Vagus Nerve Dorsal motor nucleus Vestibular input Motion sickness Nausea, vomiting, heart rate

Glossopharyngeal Nerve Motor Nucleus ambiguus Pharynx Swallowing Speech

Inferior salivatory nucleus Dry mouth Fear/anxiety

Salivation Food odor

Glossopharyngeal Nerve Sensory Posterior 1/3 of tongue Carotid sinus nerve Chemoreceptor/bar oreptor Increase pressure activates it It causes vagus nerve to slow heart rate

Nucleus Solitarius 2 zones Taste Facial nerve Anterior 2/3 of tongue

Glossopharyngeal nerve Posterior 1/3 of tongue

Vagus nerve Epiglotts

Output to posterior thalamus Then primary gustatory cortex

Nucleus Solitarius 2 zones Cardio-respiratory (also visceral) Input Glosspharyngeal Vagus

Output Nucleus ambiguus Dorsal motor nucleus of Vagus Medullary reticular formation Parabrachial pontine nucleus Visceral to amygdala & hypothalamus

Medulla and Respiratory Function Nucleus solitarius Inspiration

Nucleus ambigguus Inspiration Expiration

Sleep apnea Stop breathing when sleeping Lesions of nucleus ambiguus & reticular formation

Sneezing Nasal mucosa Trigeminal nerve

Sneezing center Medulla

2 phases Nasal – nasal secretion Respiratory – muscular output Close eyes, deep breath, close pharynx, forceful expiration, explosive air release through mouth and nose You can’t sneeze with your eyes open ☺

Vomiting Instinctive defensive reaction Triggers Motion Adverse drug reactions Trauma Toxin ingestion

Chemoreceptor trigger zone in floor of fourth ventricle [devoid of blood-brain barrier] Taste receptors Vestibular Autonomic input from intestines

Medulla: Clinical Correlates

Medial Medullary Syndrome Occlusion of anterior spinal artery or vertebral artery

Lateral Medullary Syndrome Occlusion of vertebral artery or posterior inferior cerebellar artery Horner’s Miosis – small pupil Droopy eyelid – ptosis Lack of facial sweat anhidrosis

Lateral Medullary Syndrome: Sensory Patterns

#1 – 26% #2 – 24% #3 – 18%

#4 – 20% #5 – 8% #6 – 4%