Cranial nerves Flashcards
For corticobulbar tracts, which do not follow the conventional rule of bilateral innervation of nuclei
Crossed for:
-nucleus of CN 12 (hypoglossal)
-nucleus ambiguus of CN 10 - (vagus)
Ipsilateral for
-CN 11 (accessory)
One motor and one sensory will make synapses in the medulla.
One motor and one sensory will travel through the medulla
- Corticobulbar
- Dorsal column-medial meniscus
Through:
- Corticospinal
- Spinothalamic
Describe the different motor and sensory nuclei
Somatic
Visceral
general and special
GSE: skeletal muscle that originate from somites
GVE - preganglionic parasympathetics for cranial, thoracic and abdominal smooth muscle.
SVE - activates STRIATED muscles (not from embryonic somites but from embryonic branchial arches)
ex. muscle of facial expression, jaw muscles, laryngeal/pharyngeal muscles, sternocleidomastoid, trapezius
________________________________________
GSA: sensation from body surface: pain, temp, touch and pressure
GVA: reports physical or chemical features of substances or organ walls
SSA: light and sound
SVA: smell and taste
Hypoglossal nerve
GSE - ipsilateral
Function: movements of
tongue and maintains muscle tone
Innervates: *all muscles of tongue except
palatoglossus (vagus)
Innervated by:
a) corticobulbar for voluntary movements
b) reticular neurons for automatic/reflex movements like during eating
Test: stick out tongue, genioglossus - will deviate to side of lesion
- Lesion the left corticobulbar
- Lesion of left hypoglossal nerve
Presentation of both on protrusion of tongue?
- Tongue deviates to right
- Tongue deviates to left
Tongue deviates to the side where the muscle is weaker.
Spinal Accessory nerve (XI)
SVE! *
Function - moves neck and shoulder, scapula elevation and rotation
__________________________
Innervates: ipsilateral sternomastoid and trapezius
_________________________________
Visceral motor: joins vagus to control larynx
Lesion of Accessory presents as 2.
- Cannot rotate head to healthy side against pressure (right sterno weak, can’t turn to left)
- weakened voice or hoarseness
Vagus nerve (mixed) 5/7
GVE, SVE, GSA, GVA, SVA
Functions:
(SVE): swallowing, vocalization: pharyngeal muscles, laryngeal muscles
***Nucleus Ambiguus - dorsal to inferior olive
(GVE): preganglionic parasympathetics for heart, lungs, GI to splenic flexure
DORSAL MOTOR NUCLEUS OF X
_____________________________________
GSA - touch pain and temp from small part of ear, meninges of posterior fossa, pharynx + larynx
***SPINAL TRIGEMINAL NUCLEUS
_________________________________
SVA - taste from epiglottis and pharynx
**ROSTRAL: taste
GVA-chemoreceptors and baroreceptors of aortic arch, visceral signals from thoracic and abdominal viscera
- *CAUDAL
- **both are NUCLEUS SOLITARIUS
Left lesion of vagus nerve
- Right Uvula deviation: towards healthy side because palate rises
- Right vocal muscles paralysis
- Loss of gag reflex with glossopharyngeal (vagus is efferent control)
- Nasal regurgitation (during swallowing)
- Loss of cough reflex
Glossopharyngeal nerve - also 5/7 exactly like vagus
GVE, SVE, GSA, GVA, SVA
- GVE - preganglionic parasympathetic for parotid gland
* **INFERIOR SALIVATORY NUCLEUS: found in pons not medulla - SVE -stylopharyngeal muscle
**N.ambiguus
______________________________________ - GSA
-posterior one third of tongue
-middle ear/tympanic membrane/eustachian tube
-small region of external ear
-tonsils
-upper pharynx (gag reflex afferent)
unknown?
**SPINAL TRIGEMINAL NUCLEUS
____________________________________
4. SVA: taste from posterior 1/3 of tongue
- GVA: chemoreceptors and baroreceptors of the CAROTID
both are **N.soltarius
N. ambiguus
- Vagus - SVE, swallowing and vocalization
2. Glossopharyngeal - SVE - stylopharyngeal (elevating pharynx)
N. Solitarius - also what does the track do?
- Vagus
- SVA - taste from epiglottis and pharynx
* *ROSTRAL: taste
GVA-chemoreceptors and baroreceptors of aortic arch, visceral signals from thoracic and abdominal viscera
**CAUDAL
____________________________
- Glossopharyngeal
- SVA: taste from posterior 1/3 of tongue
-GVA: chemoreceptors and baroreceptors of the CAROTID
____________________________
-the tract connects to the dorsal nucleus of vagus to get the parasympathetics to influence the heart.
Gag reflex;
- Touch posterior oropharynx
- Glossopharyngeal provides afferent, sensory portion of gag reflex
- Afferents act on nucleus ambiguous motor neurons of Vagus
- Palate elevates symmetrically, pharynx constricts, larynx closes
Wallenberg syndrome
Lateral medullary syndrome - PICA
- ipsilateral face pain and temp loss: trigeminal spinal nucleus
- ipsilateral Horner’s syndrome: lesion of descending hypothalamic fibers (which are always lateral)
- ipsilateral ataxia - lesion of ICP
- taste loss: N. solitarius
- paralysis of larynx, pharynx, palate, dysarthria (slurred speech) - nucleus ambiguus
- loss of gag reflex - N.ambiguus & N- solitarius
- also spinothalamic tract
Medial Medullary syndrome
Anterior spinal artery:
- Ipsilateral flaccid paralysis of tongue with deviation - hypoglossal
- Contralateral decreased position, tactile and vibration sensation: DCML
- Contralateral arm or leg weakness: CST
Facial nerve 5/7 same as all the others
SVE, GVE, GSA, GVA, SVA
- SVE - muscles of facial expression, stapedius, digastric
* **facial nucleus - GVE - parasympathetic preganglionics for lacrimal, sublingual, submandibular (all salivary except parotid)
***SSNucleus (Superior salivary)
____________________________________ - GSA: sensation from small region of outer ear (7,9,10)
**SPINAL TRIGEMINAL NUCLEUS - GVA: mucous membrane of nasopharynx
- SVA - taste from anterior 2/3 of tongue
* *still rostral S. solitary nucleus
Reflexes involving facial nerve
- Corneal reflex
Cornea (trigeminal) - Sucking reflex
Lips (trigeminal) - Blinking to light
Retina (trigeminal) - Blinking to noise
Cochlea (vestibulocochlear - Sound attenuation
Cochlea (vestibulocochlear)
Facial are all the efferents
Bell’s Palsy
- Unilateral facial weakness LMN
- acute (overnight)
- retroauricular pain
- hyperacusis - loss of stapedius
- dry and red eye
- loss of taste
Trigeminal nerve (2/7)
SVE, GSA
- SVE - muscles of mastication and tensor tympani muscle
**MOTOR NUCleus of V
_________________________________ - GSA
touch and pressure: principal sensory nucleus
pain and temp: trigemino-thalamic pathway (trigeminal ganglion > **SPINAL nucleus > VPM)
proprioception:
MESENCEPHALIC nucleus of trigeminal- afferent for jaw jerk reflex, control force of bite
**the only primary sensory neuron in the CNS
________________________________
Ophthalmic division V1:
Cornea, eye, orbit, forehead, Dura
Maxillary division V2: Upper teeth Nasal cavity Maxilla and overlying skin Palate
Mandibular division V3 -buccal region -entire lower jaw -lower teeth anterior 2/3 of tongue, -cornea pain for: -supratentorial dura mater-anterior
Spinal nucleus of V
Collecting ipsilateral impulses of pain and temperature
- Glossopharyngeal: GSA for back of ear, posterior 1/3 of tongue, upper pharynx (gag reflex)
- Vagus: GSA - sensation of pharynx, larynx, external ear, dura of posterior fossa
Uncommon Trigeminal lesion presentation
Pterygoid muscle - draws mandible forward and towards midline, chin deviates in direction of the paralyzed side when jaw opens.
Medial pontine syndrome
- Fibers of abducens (medial strabismus) - odd alignment of eyes
- Contralateral arm/leg weakness (CST) contralateral decreased position, tactile and vibration sense (medial lemniscus)
Lateral pontine syndrome AICA deficit
- Contralateral body pain and temperature loss spinothalamic
- Ipsilateral face pain and temp loss because lesion of SPinal nucleus V
- Ipsilateral horners bc lesion of descending hypothalamic
- Ipsilateral ataxia bc lesion of middle cerebellar peduncles
- Ipsilateral loss of taste (anterior 2/3), lacrimation, salivation, corneal reflex, hyperacusis bc lesion of facial nucleus and axons
Oculomotor nerve (2/7)
- GSE - superior, inferior, medial rectus, inferior oblique, levator palpebrae superioris
- GVE - Edinger Westphal nucleus -for sphincter pupillae, ciliary muscle.
Ventral midbrain syndrome - Weber
- CST
- Contralateral hemiparesis of lower face bc lesion of corticobulbar
3*ipsilateral oculomotor palsy (lateral strabismus, dilated pupil, ptosis
Dorsal midbrain syndrome (Perinauds)
Caused by increased pressure on the dorsal, rostral mid-brain, including posterior commissure.
ex pineal tumor
- Paralysis of upward gaze (pressure on vertical gaze center-dorsal for upward)
- Hydrocephalus (cerebral aqueduct), headaches (intracranial pressure), nystagmus
- Large, irregular pupils (posterior commissure fibers goes to E-W nucleus). Light-near dissociation
possible
-posterior commissure contains the crossing fibers from the pretectal nucleus that coordinates response to light.
(MLF).
- Loss of convergence
Spinal Nucleus V
3 inputs
- Trigeminal - pain, temperature from the head, face, and neck
- Glossopharyngeal - sensation from back of ear, posterior 1/3 tongue, upper pharynx with reflex
- Vagus - sensation from pharynx, larynx, external ear, and dura of posterior fossa.
Jaw jerk reflex
Mesencephalic nucleus of V- receives unconscious proprioception from trigeminal.
There are four nuclei to know for the trigeminal what are they?
- Spinal nucleus of V
- pain and temperature sensation
- crossed projection to VPM - Principal nucleus
- touch and pressure face, mouth, anterior 2/3 of tongue, nasal sinus
- crossed projection to VPM - Mesencephalic nucleus
- proprioception and controls bite strength
- ipsilateral
- *primary neuron in CNS - Motor nucleus of V
- muscles of mastication, tensor tymapni
- ipsilateral, maintains bite strength
Which cranial nerves have a lateral arrangement?
5 & 8
Trigeminal and Vestibulocochlear
What are the 3 nuclei for trigeminal sensation
Spinal nucleus - pain and temperature
Principal sensory nucleus aka main sensory nucleus - touch and pressure
Mesencephalic nucleus of V- unconscious proprioception - afferent loop for jaw jerk
-from teeth, hard palate, muscles of mastication - control force of bite
