NBBS - ascending/descending tracts + cranial nerves Flashcards
What makes up the brainstem?
pons, medulla oblongata, midbrain
What connects the brainstem to higher centres?
crus cerebri
What connects the brainstem to the cerebellum?
cerebellar peduncles
What lies between the brainstem and cerebellum?
4th ventricle
Which nerve exits the brainstem dorsally?
trochlear nerve (4th cranial nerve)
Do the pyramids contain ascending or descending fibres?
descending (corticospinal tract)
What side of the brainstem is the pyramidal tract on?
ventral
What side of the brainstem is the gracile and cuneate tracts on?
dorsal (= dorsal column pathways)
Do the gracile and cuneate tracts contain ascending or descending fibres?
ascending
What is the first cranial nerve?
olfactory nerve
What is the path of the olfactory nerve?
- olfactory receptors in nasal epithelium
- synapses in olfactory bulb
- olfactory tract projects to temporal lobe
What is the 2nd cranial nerve?
optic nerve?
What is the path of the optic nerve?
retina -> LGN in thalamus -> visual cortex in occipital lobe
- Nasal side crosses chiasma, temporal side doesnt’ cross
What is the 8th cranial nerve?
vestibulocochlear nerve
What is the path of the vestibulocochlear nerve?
hair in inner ear -> nuclei in floor of 4th ventricle
What does the vestibulocochlear nerve pass through?
internal auditory meatus
What does the olfactory nerve pass through?
cribiform plate of skull
What does the optic nerve pass through?
optic canal of skull
Where does the oculomotor nerve exit the brainstem?
ventral midbrain, between crus cerebri
Where is the abducens nucleus?
In the pons at floor of the 4th ventricle
What is the 3rd cranial nerve?
oculomotor nerve
What is the function of the oculomotor nerve?
eye movement and innervation of levator palpebrae (includes ANS)
- regulates accomodation
Where does the oculomotor nerve originate?
oculomotor and Edinger-Westphal nucleus of midbrain
Where do the oculomotor, trochelar and abducens nerve exit the skull?
superior orbital fissure
What is the 4th cranial nerve?
trochlear nerve
What is the function of the trochlear nerve?
depresses & abducts eye
motor innervation of superior oblique muscle
What is the 6th cranial nerve?
abducens nerve
What is the function of the abducens nerve?
eye abduction and motor innvervation of lacteral rectus muscle
Where does the abducens nerve exit the brain stem?
between the pons and medulla
What happens in trochlear nerve palsy?
misalignment of the eye
What happens in abducens nerve palsy?
eye goes inwards
What happens in oculomotor nerve palsy?
severe movement restriction of eye
What is the 5th cranial nerve?
trigeminal nerve
What are the sensory nuclei of the trigeminal nerve?
mesencephalic - proprioception
principal - light touch and discrimination
spinal - pain, temperature and crude touch
Where is the sensory nuclus of the trigeminal nerve?
stretches from midbrain to medulla
- divided into 3
What provides the main sensory innervation of the face?
trigeminal nerve
Where is the motor nucleus of the trigeminal nerve?
pons at the 4th ventricle
What is the function of the motor component of the trigeminal nerve?
chewing
What are the 3 peripheral branches of the trigeminal nerve?
- opthalamic - upper face, exits superior orbital fissure
- maxillary - middle face, exits foramen rotundum
- mandibular - innervates lower face and jaw, exits foramen ovale
What is the 7th cranial nerve?
facial nerve
What fibres does the facial nerve have?
motor, sensory and parasympathetic
What is the motor component of the facial nerve?
facial expression and inner ear muscle
- facila motor nuclues
What is the sensory component of the facial nerve?
taste and external ear sensation
- nucleus solitarius
What is the parasympathetic component of the facial nerve?
lacrimation and salivation
- superior salivatory nuclues
Where does the facial nerve exit?
stylomastoid foramen
What is the 9th cranial nerve?
glossopharyngeal nerve
What functions does the glossopharyngeal nerve have?
motor - stylopharngues muscle for swallowing
sensory - sensation of pharynx, tongue etc
PNS - regulation of parotid gland
What are the nuclei of the glossopharyngeal nerve?
motor = nucleus ambiguus sensory = spinal nucleus and nucleus solitarius PNS = inferior salivatory nucleus
What is the 10th cranial nerve?
vagus nerve
What are the functions of the vagus nerve?
motor - muscles of respiratory tract
sensory
PNS - viscera
What are the nuclei of the vagus nerve
motor = nucleus ambiguus sensory = spinal nucleus and nucleus solitarius PNS = dorsal nucleus
Where do the 9th and 10th cranial nerves exit?
the jugular foramen
What is the 11th cranial nerve?
accessory nerve
What function is the accessory nerve
motor only - sternocleidomastoid and trapezius muscles, swallowing and gag reflex
What are the 2 origins of the accessory nerve?
C1-6 (back/neck muscles)
nucleus ambiguus in brainstem (muscles of larynx and pharynx
What is the 12th cranial nerve?
hypoglossal nerve
What is the function of the hypoglossal nerve?
motor innervation for tongue muscles (speech)
Where does the hypoglossal nerve exit?
hypoglossal canal
What cranial nerves are affected by compression of cavernous sinus?
3-6
What is trigeminal neuroglia?
- severe pain triggered by trigeminal nerve
- caused by compression, demylination, herpes, tooth/jaw infection, brain stem tumours etc
What is facial nerve palsy?
unilateral paralysis of the face
What is acoustic neuroma?
compression of facial nerve by a tumour in canal
What happens to the cranial nerves in motor neuron disease?
degeneration of nucleus ambiguus and hypoglossal nucleus
What happens in unilateral brain stem lesions?
unilateral or contralateral effects
What happens in bilateral brain stem lesions?
coma or death
