Chapters 7 8 Single

Pons: Ventral Surface „

Pontine protuberance … Pontine

„

sulcus

Cranial nerves … Abducens … Facial … Vesitbulochoclear … Trigeminal … Oculomotor … Trochlear

„

Cerebral peduncle … ‘foot’

of the cortex [cerebrum]

Pons: 2 Divisions „

Basis Pontis … Pontine

nuclei … Corticospinal tract … Corticobulbar tract … Cortcopontocerebellar tract „

Rapid correction of movements

Pons: 2 Divisions „

Tegmentum … …

Reticular formation Specific sensory lemniscal system „ „ „

…

Central tegmental tract „

…

Medial lemniscus Trigeminal Spinothalamic Basal ganglia -> midbrain -> inferior olive

Locus ceruleus „ „

Involved in Parkinson’s, Alzheimer’s, Down’s syndrome Output to: …

Cortex, cerebellum, hippocampus, hypothalamus, and spinal cord

Vestibulocochlear Nerve: Cochlear Division „

Organ of Corti … Auditory

„

organ

Dorsal cochlear nucleus … High-frequency

sound „

Ventral cochlear nucleus … Low-frequency

sound

Vestibulocochlear Nerve: Cochlear Division Dorsal acoustic stria „ Ventral acoustic stria „

… Aka

„

trapezoid body

Intermediate acoustic stria

Vestibulocochlear Nerve: Cochlear Division Lateral lemniscus „ Inferior colliculus „ Medial geniculate nucleus „

… Thalamus

„

Auditory cortex … Heschel’s

gyrus … Temporal lobe

Olivocochlear bundle Origin: periolivary area „ Destination: Organ of Corti „ Feedback to hair cells „ Possible functions „

… Protective

against loud sound … Frequency selectivity … Selective auditory attention „

Example: speech in noisy background

Vestibulocochlear Nerve: vestibular Division „

Semicircular canals … Angular

„

acceleration

Utricle/Saccule … Linear

acceleration … Gravity „

Scarpa’s ganglion … Location

„ „ „

of cell bodies

Vestibular nerve Vestibular nuclei Cerebellum

Input to Vestibular Nuclei Vestibular nerve „ Spinal cord „ Cerebellum „ Vestibular cortex „

Output of the Vestibular Nuclei „

Spinal cord … Lateral „

vestibulospinal tract

Facilitate flexor motor neurons

… Medial

vestibulospinal tract

Facilitate extensor motor neurons „ Dorsal motor nucleus of the vagus „

Motion sickness … Nausea, sweating, vomiting …

Output of the Vestibular Nuclei „

Cerebellum … Via

„

Primary vestibular cortex … Via

„

juxtarestiform body thalamus

Nuclei of extraocular muscles … Medial

longitudinal fasciculus … Project on nuclei of Oculmotor „ Trochlear „ Abducens „

Conjugate Eye Movements ‘yoked together’ „ Nystagmus „

… Involuntary

„

rhythmic oscillations of the eyes

2 pathways … Medial

longitudinal fasciculus … Reticular formation

Medial Longitudinal Fasciculus Syndrome Paralysis of adduction ipsilateral to MLF lesion „ Nystagmus of the other eye „

Facial Nerve (VII) „

Sensory … Ear „

Spinal trigeminal nucleus

… Anterior „

2/3 tongue

Nucleus solitarius

Facial Nerve (VII) „

Motor … Face „

Facial motor nucleus

… Salivary

glands

Submandibular „ Sublingual „ Lacrimal „ Origin „

…

Superior salivatory nucleus

Central Facial Paresis Bilateral innervation to upper facial muscles „ Contralateral to lower facial muscles „ Damage to one hemisphere therefore affects lower facial muscles contralaterally, only. „

Facial Nerve Lesions „

Bell’s Palsy … Facial

„

nerve paralysis

Proximal to ganglion … Eyes

can still tear up

Distal to ganglion „ Motor fibers „

… Facial

only

muscle paralysis

Abducens (VI) „

Motor … Lateral

rectus

muscle „

Modulated by … Corticospinal

tract … Reticular nucleus … Vestibular nuclei

Lesions of Abducens Paralysis of ipsilateral lateral rectus muscle (B) „ Diplopia (A) „

… ‘double

vision’ … When attempting to gaze towards lesioned side

Lateral Gaze Paralysis „

Abducens nucleus sends output to contralateral oculomotor nucleus … Medial

rectus muscle of the other eye

Trigeminal Nerve (V) „

Sensory … Head/Neck … Proprioception … Pain/temperature/touch … Semilunar

„

ganglion

Motor … Mastication

Pons: Clinical Correlates

Caudal Basal Pontine Syndrome Millard-Gubler Syndrome „ Lesion of abducens „ Lesion of facial „ Lesion of corticospinal tract „

Tegmental Pontine Syndrome Abducens „ Facial „ Medial lemniscus „

One-and-a-half Syndrome „

Abducens … “One”

„

Medial longitudinal fasciculus … “Half”