Neuro 8 Flashcards
Fibers from nasal half of retina cross to
contralateral optic tract
Fibers from temporal half of retina enter
ipsilateral optic tract
So each optic tract “sees” the contralateral visual field
Damage anterior to chiasm only affects
ispilateral eye
Damage at chiasm causes
heteronymous deficits
Damage to optic tract causes
homonymous deficits
XII - hypoglossal
Axon: GSE
Origin: Hypoglossal nucleus
Peripheral termination: Tongue muscles
XI - accessory
Axon: SVE
Origin: Accessory nucleus in cervical spinal cord (caudal medulla to ~C5)
Peripheral termination: Sternomastoid, trapezius
IX - a lot - IX: Somatic Afferents
Skin of ear & middle ear
Superior ganglion of IX nerve
Trigeminal spinal nucleus
Hypoglossal Nerve Fibers - neuronal cell bodies in
Neuronal cell bodies in hypoglossal nucleus
Hypoglossal nerve fibers exit
Exits adjacent to pyramid
Hypoglossal nerve (lower motor neuron) lesion:
Deviation toward lesion
Fasciculations
Atrophy
Hypoglossal Corticobulbar Fibers from
motor cortex
Hypoglossal Corticobulbar Fibers decussate
adjacent to hypoglossal nucleus
Corticobulbar (upper motor neuron) lesion
Deviation toward side opposite UMN lesion
No fasciculations
Minimal atrophy
Effect of Accessory Nerve Lesion on the Trapezius Muscle
Scapula and clavicle hang due to weak trapezius
Weak shoulder shrug as levator scapulae must work alone
Muscle atrophy leads to scalloped appearance of neck contour
Each vallate papilla is surrounded by a
- IX afferents
groove filled with taste buds. These taste buds are innervated by IX
Carotid body
- IX: Visceral Afferents
: Blood O2, CO2 & pH
Carotid sinus:
- IX: Visceral Afferents
Changes in blood pressure
Inferior ganglion of glossopharyngeal nerve
Solitary nucleus
Special visceral
(efferents - IX)
Nucleus ambiguus Stylopharyngeus muscle (elevates pharynx in speech & swallowing
General visceral
(efferents - IX)
Inferior salivatory nucleus
Otic ganglion
Parotid salivary gland
Glossopharyngeal Neuralgia
Similar to trigeminal neuralgia
Rare, but distressing
Sudden burst of pain starts in posterior tongue or wall of pharynx, then radiates to ear
Trigger zone on tongue/ pharynx and attacks precipitated by swallowing or talking
Pharmacologic management or tractotomy of spinal trigeminal tract in caudal medulla
X GSA
Origin: Spinal trigeminal nucleus
Superior ganglion of X
Termination: Skin of outer ear
X SVA
Origin: Nucleus of the solitary tract
Inferior ganglion of X
Termination: Taste buds: epiglottis & esophagus
X GVA
Origin: Nucleus of the solitary tract,
Inferior ganglion of X
Termination: Thoracic & abdominal viscera; mucosa of larynx & pharynx; stretch receptors aortic arch; chemoreceptors aortic bodies
X GVE
Origin: Dorsal motor nucleus, nucleus ambiguus
Termination: Thoracic and abdominal viscera: smooth muscle and glands
X SVE
Origin: Nucleus ambiguus
Termination: Larynx & pharynx
IX SSA
Origin: Nucleus of solitary tract
Termination: Taste buds posterior 1/3 tongue
IX GVA
Origin: Nucleus of solitary tract
Termination: Carotid body and sinus
IX GSA
Origin: Spinal trigeminal nucleus
Termination: Mucosa posterior 1/3 tongue, pharynx and middle ear, Skin of outer ear
IX GVE
Origin: Inferior salivatory nucleus
Otic ganglion
Termination: Parotid gland
IX SVE
Origin: Nucleus ambiguus
Termination: Pharynx
X: Somatic Afferents
Skin of ear
Superior ganglion of X
Trigeminal spinal nucleus
X Afferents
Thoracic and abdominal viscera
Aortic arch baroreceptors blood pressure & chemoreceptors (blood O2 & CO2)
Inferior ganglion of vagus nerve
Solitary nucleus of vagus nerve
X Efferents
Nucleus ambiguus (lateral) Nucleus ambiguus (medial) Dorsal motor nucleus of the vagus
Nucleus ambiguus (lateral)
Muscles of speech and swallowing
Nucleus ambiguus (medial)
Heart and lungs
Dorsal motor nucleus of the vagus
All viscera up to transverse colon
Tongue Thrust Reflex
Infants, may persist up to eight years
Can contribute to speech and orthodontic issues
CN V or IX: afferent limb
CN XII: efferent limb
Tongue thrust in response to stimulation of pharynx wall; up to 4 – 6 months of age
67–95% of children 5–8 years old exhibit tongue thrust
Gag Reflex
CN IX – afferent component
CN X – efferent component
Central connections not clear
Touch one side of pharynx; elicit a bilateral response
Central connections may involve the spinal trigeminal tract & nucleus or the solitary tract & nucleus or both as well as the nucleus ambiguus
SVE, special visceral efferent - XI
goes in and then back out again (of skull)**
UMN
LMN
How to tell apart for tongue?
Atrophy – hallmark of LMN. Also, if you injure corticobulbar pathway, you will injure and damage other things.**
Genioglossus
main muscle of tongue protrusion. It throws tongue out in essence**
IX: Visceral Efferents
Postganglionic cell bodies in Otic ganglion**
Tongue thrust in response to stimulation of
pharynx wall; up to 4 – 6 months of age
67–95% of children 5–8 years old exhibit tongue thrust
Central connections may involve the
spinal trigeminal tract & nucleus or the solitary tract & nucleus or both as well as the nucleus ambiguus
Example
79 year male who had a stroke
Hoarse voice - larryngeal muscles talk – innerfvated by 10. Not absent altogether, because it is unilateral. You need bilateral to lose all.
Lost pain sensation, right face. Spinaltrigeminal can account for this.
Lost pain sensation, left body. Ascending sensory system, spinothalamic.
Right side palatal hemiparalysis – 10 as well.
What do you think the gag reflex would show?
No response on right, only left would jump up.
Where is this patient’s lesion?
Most common brain stem stroke can take out trigeminal nerve.
No jaw weakness because while no pain and temp, trigeminal motor nucleus is in pons, and not supplied by PICA. Body is not weak because motor function for body is down pyramids. It is anterior to medial lemniscus, not supplied by PICA.
Tectum
tissue posterior to ventricular cavity. – made up by superior and inferior colliculi.
Homonculus leg hangs over
longitudinal fissure – stroke here would hurt that
Anterior cerebral artery territory
frontal lobe = top of brain
MCA
facial and upper extremity issues/loss if this is destroyed.
