Neuro 3 INCOMPLETE Flashcards
What are the two parts of the midbrain? What position are they in?
Tectum- located dorsal to the cerebral aqueduct
Tegmentum - located ventral to the cerebral aqueduct
What is in the tectum?
Superior colliculi - visual
Inferior colliculi - auditory
What is the function of the superior colliculi?
Regulating eye movements
And reflexes involving visual stimuli
E.g. turning head quickly when something enters field of vision
What is the function of the inferior colliculi?
Involved in sound location
Pitch discrimination
Reflexes associated with auditory stimuli
E.g. turning the head quickly when hearing a loud noise
What is in the tegmentum?
Substantia nigra
Cerebral peduncles (most ventral surface)
Red nuclei
(also periaqueductal grey matter)
Function of the substantia nigra?
Important in motor control by producing dopamine
What are the cerebral peduncles?
On the most ventral surface of the tegmentum
Large white matter bundles that connect the midbrain to the thalami
What is the function of the red nuclei?
Involved in supporting motor control of the limbs
Which prominent nuclei are in the midbrain?
Oculomotor (CN III)
Trochlear (CN IV)
Edinger-Westphal nuclei (pupillary light reflex)
What is on the dorsal surface of the pons?
Middle cerebellar peduncles
- large white matter connections to the cerebellum
What is on the ventral surface?
Basilar artery
Where is the fourth ventricle?
Situated dorsal to the pons, between the two middle cerebellar peduncles
What nuclei does the pons contain?
Trigeminal (CN V)
Abducens (CN VI)
Facial (CN VII)
Vestibulocochlear (CN VIII)
Also pneumotaxic and apneustic centres - involved in regulation of breathing
What structures are associated with the pons?
Basilar artery
Pons
Middle cerebellar peduncle
Fourth ventricle
Nuclei - CN V, CN VI, CN VII, CN VIII
Pneumotaxic and apneustic centres
What does the medulla oblongata connect?
The pons to the spinal cord
What is the name of the groove on the ventral surface of the medulla oblongata?
Anterior median fissure
Separates the two medullary pyramids
What is on the ventral surface of the medulla?
The two medullary pyramids, separated by the anterior median fissure
Medullary olives are immediately lateral to these
What runs inside the medullary pyramids?
Motor tracts
Such as corticospinal tracts
Where are the medullary olives?
On the ventral surface of the medulla, immediately lateral to medullary pyramids
What sensory pathway of nerves runs in the dorsal part of the medulla?
The dorsal column medial lemniscus (DCML) pathway
Runs within two pairs of nerve bundles
What two nerve bundles does the DCML pathway run in?
Fasciculus gracilis
Fasciculus cuneatus
What nuclei does the medulla contain?
Glossopharyngeal (CN IX)
Vagus (CN X)
Accessory (CN XI)
Hypoglossal nerve (CN XII)
Vital centres for regulating respiration, heart rate and blood pressure, initiating vomiting
What is bulbar palsy?
Dysfunction of the cranial nerves that arise from the medulla (9 to 12)
Symptoms include difficulty speaking, swallowing, excessive saliva production, wasting and fasciculations of the tongue, absent gag reflex
Causes include diseases that affect PNS
Why are the cranial nerves named as such?
They originate directly from the brain and not the spinal cord like other nerves
Which is the only cranial nerve that leaves the CNS posteriorly?
The trochlear nerves (CN IV)
For CN I what is the…
Name?
Nerve fibre type?
CNS origin?
Skull base foramen?
- Olfactory nerve
- Sensory nerve
- Cerebrum - olfactory cortex - temporal
- Cribriform plate
What is the function of the olfactory nerve?
What does dysfunction present as?
Smell
Detect odour molecules
Convey information superiorly to the olfactory bulbs
Altered/loss of smell - coffee, chocolate, vanilla, cinnamon
What path does the olfactory nerve take through the brain?
Roof of nasal cavity
Through cribriform plate to olfactory bulbs, either side of the crista galli
Olfactory tracts carry smell info posteriorly under frontal lobes towards olfactory cortices in temporal lobes
For CN II what is the…
Name?
Nerve fibre type?
CNS origin?
Skull base foramen?
- Optic nerve
- Sensory only
- Final destination is visual cortex - occipital lobe
- Optic canal - sphenoid bone
What is the function of the optic nerve? How is it tested for dysfunction?
Provides sense of sight
Altered/ Loss of vision
Visual acuity tested by Snellen chart(letters)
Also visual fields, accoomodation to near and far objects, colour vision, pupillary light reflex test function(Edinger-Westphal nucleus)
What is the path of the optic nerve?
Carries info from retina to the optic chiasm, where fibres cross over
Ends up in visual cortex in the occipital lobe
For CN III what is the…
Name?
Nerve fibre type?
CNS origin?
Skull base foramen?
- Oculomotor nerve
- Motor and parasympathetic
- Midbrain
- Superior orbital fissure - sphenoid bone
What is the function of the oculomotor nerve?
What does dysfunction look like and how is it tested for?
Motor supply to extra-ocular muscles (LPS, SR, IR, MR, IO), Accommodation, Parasympathetics to the ciliary and constrictor pupillae muscles
Eye rests in ‘down and out’ position, ptosis, mydriasis
Clinician asks patient to follow their finger, watches to see how well patient can follow (H), can also test the pupillary light reflex
For CN IV what is the…
Name?
Nerve fibre type?
CNS origin?
Skull base foramen?
- Trochlear nerve
- Motor only
- Midbrain
- Superior orbital fissure
Why is the Edinger-Westphal nucleus important?
Involved in the pupillary light reflex - where optic and oculomotor nerve communicate
What is the function of the trochlear nerve What does dysfunction look like and how is it tested for?
Eye movement - superior oblique muscle only
Eye is unable to look down when adducted
Ask patient to follow clinicians finger movements and observe to see if the eye is following (H)
For CN V what is the…
Name?
Nerve fibre type?
CNS origin?
Skull base foramen?
- Trigeminal nerve
- Both motor and sensory - some branches only sensory
- Pons origin
- V1 - superior orbital fissure
V2 - foramen rotundum
V3 - foramen ovale
What are the 3 branches of the trigeminal nerve?
V1 - ophthalmic branch
V2 - maxillary branch
V3 - mandibular branch
For CN V1 what is the…
Name?
Nerve fibre type?
CNS origin?
Skull base foramen?
- Ophthalmic branch
- Sensory only
- Pons
- Superior orbital fissure
What is the function of the ophthalmic branch of the trigeminal branch?
How is dysfunction of the nerve tested?
Sensation to the upper 1/3 of the face
Test by seeing if the patient can detect brush of cotton wool over forehead on both sides, seeing if they can tell the difference between crude and sharp touch, test corneal reflex - do they blink when the cornea is touched?
What nerves are involved in the corneal reflex?
Afferent nerve - ophthalmic nerve (V1)
Synapse at the pons
Efferent nerve - facial nerve (VII) causes blinking
For CN V2 what is the…
Name?
Nerve fibre type?
CNS origin?
Skull base foramen?
- Maxillary branch of the trigeminal
- Sensory only
- Pons origin
- Foramen rotundum - sphenoid bone
What is the function of the maxillary branch of the trigeminal nerve?
What does dysfunction of V2 look like? How is it tested for?
Sensation to the middle third of the face, including most of internal nasal cavity, upper teeth and palate
Altered/absent sensation in dysfunction
Sensation is tested by brush of cotton wool against cheek on both sides, test if patient can differentiate between crude and sharp touch
For CN V3 what is the…
Name?
Nerve fibre type?
CNS origin?
Skull base foramen?
- Mandibular branch of trigeminal nerve
- Both sensory and motor
- Pons
- Foramen ovale - sphenoid bone
What is the function of the maxillary branch of the trigeminal nerve?
What does dysfunction of V3 look like?
Sensation to lower third of face
Motor to the muscles of mastication (temporalis, masseter, medial and lateral pterygoid), tensor tympani and some suprahyoid strap muscles
Dysfunction - altered/absent sensation, weakness in mastication
For CN VI what is the…
Name?
Nerve fibre type?
CNS origin?
Skull base foramen?
- Abducens nerve
- Motor only
- Pons
- Superior orbital fissure - sphenoid bone
What is the function of the abducens nerve?
What does dysfunction look like? How is it tested?
Eye movement - lateral rectus only
Dysfunction - unable to abduct the eye
Tested by seeing if the patient’s eyes can follow the clinician’s finger correctly or not (H)
For CN VII what is the…
Name?
Nerve fibre type?
CNS origin?
Skull base foramen?
- Facial nerve
- Both motor and sensory (and parasympathetic)
- Pons
- Internal auditory meatus, then stylomastoid foramen (temporal bone)
What is the function of the facial nerve?
What does dysfunction look like?
Motor to muscles of facial expression, stapedius muscle
Sensation to the ear canal, secretomotor function (parasympathetics) to sublingual and submandibular salivary glands and lacrimal gland
Taste to anterior 2/3 of the tongue
Dysfunction - weakness/paralysis of facial muscles, reduced salivation
How is dysfunction of the facial nerve tested for?
Only function that is routinely tested is motor function.
Ask patient to perform series of facial movements e.g. raising eyebrows, closing eyes tightly, blowing cheeks out, showing all their teeth
Clinician checks for asymmetry
How is dysfunction of V3 tested for?
Tested for sensation by brushing cotton along jaw on both sides, can they tell the difference between crude and sharp pain.
Motor function tested by palpating jaw muscles as they clench their teeth or asking patient to forcibly open jaw against resistance
Describe the pathway of the facial nerve out of the brain
Origin - pons
- First - internal auditory meatus with CN VIII
- Shortly after - gives off branch to supply lacrimal gland
- In middle ear cavity - gives off branch to stapedius muscle - also gives ‘chorda tympani’ branch for taste in tongue (2/3) and parasympathetic to submandibular and sublingual glands
- Then - leaves temporal bone of the skull by stylomastoid foramen
- After exiting - gives branch for sensory info from the ear and motor supply to some of scalp
- Main body of CN VII then enters parotid gland and splits into 5 branches to supply facial muscels - DOESNT INNERVATE THIS GLAND
What are the 5 branches of the facial nerve that supply facial muscles?
Temporal
Zygomatic
Buccal
Marginal mandibular
Cervical
For CN VIII what is the…
Name?
Nerve fibre type?
CNS origin?
Skull base foramen?
- Vestibulocochlear
- Sensory only
- Pons
- Internal auditory meatus
What is the function of the vestibulocochlear nerve?
What does dysfunction look like? How is it tested?
Provides sense of balance and hearing
Dysfunction - vertigo or tinnitus or deafness
Simplest test - block one ear and whisper word/number into other ear and ask patient to repeat it
Other tests with specialist equipment available
For CN IX what is the…
Name?
Nerve fibre type?
CNS origin?
Skull base foramen?
- Glossopharyngeal nerve
- Both motor, sensory and parasympathetic
- Medulla
- Jugular foramen - temporal/occipital bone
What is the function of the glossopharyngeal nerve?
Motor - stylopharyngeus muscle - assists swallowing
Sensation - pharynx, middle and auditory tube, and posterior 1/3 of the tongue (also taste), carotid baroreceptors and chemoreceptors
Secretomotor (parasymp) - parotid salivary gland
What does dysfunction of the glossopharyngeal nerve look like? How is it tested for?
Loss of gag reflex, reduced salivation
Test by assessing gag reflex, tongue depressor pressed against oropharynx - normal finding is patient gagging
For CN X what is the…
Name?
Nerve fibre type?
CNS origin?
Skull base foramen?
- Vagus nerve
- Both motor, sensory, parasympathetic
- Medulla
- Jugular foramen - temporal/occipital bone
What is the function of the vagus nerve?
Motor - muscles of soft palate, pharyngeal muscles, internal laryngeal muscles, palatine folds
Sensation - external ear and ear canal, taste from epiglottis
Parasympathetics - to thoracic and abdominal organs
What does dysfunction of the vagus look like? How is it tested for?
Loss of gag reflex, absent rise of soft palate, weak or absent cough/swallow, loss of parasympathetics to thoracic/abdominal organs
Test gag reflex
Ask patient to open mouth and say AAA - check elevation of soft palate
Which nerves partake in the gag reflex?
Afferent nerve - glossopharyngeal nerve
Communicate in the medulla
Efferent nerve - vagus
For CN XI what is the…
Name?
Nerve fibre type?
CNS origin?
Skull base foramen?
- Accessory
- Motor only
- Spinal cord C1-C5 - passes into medulla
- IN - foramen magnum - occipital bone
- OUT - jugular foramen - temporal/occipital bone
What is the function of the accessory nerve?
Motor to the trapezius and sternocleidomastoid muscles
Dysfunction - weakness to shrugging shoulders and turning head
Test by asking patient to do these alone, then against resistance
What is the pathway of the accessory nerve?
Originates spinal cord level C1 - C5
Join to form spinal accessory nerve
Enter skull by foramen magnum
Leave via jugular foramen
For CN XII what is the…
Name?
Nerve fibre type?
CNS origin?
Skull base foramen?
- Hypoglossal nerve
- Motor only
- Medulla
- Hypoglossal canal - occipital bone
What is the function of the hypoglossal nerve?
What does dysfunction look like? How is it tested for?
Motor to intrinsic and extrinsic muscles of the tongue (except palatoglossus which is vagus)
Dysfunction - weakness or paralysis of the tongue - tongue deviates to affected side
Test by asking patient to protrude their tongue - deviation implies damage
Where do the cranial nerves originate from?
Which cranial nerve originate from the pons?
Which cranial nerves originate from the medulla?
Which cranial nerve exits the brainstem posteriorly?
4 - abducens
Which cranial nerves originate in the midbrain?
3 and 4
Which cranial nerves don’t originate in the brainstem?
1 and 2
They originate from
Which cranial nerves run through the wall of the carotid sinus? Which is the only one that isn’t in the lateral wall? Which vessel also runs through this sinus?
3, 4, 5)1, 5)2, 6
Abducens is the only one not in the lateral wall
Internal carotid runs through
Which cranial nerves are purely motor?
