Brainstem part II: The Pons Flashcards
what does the Pons contain?
- Cranial nerve nuclei for V, VI, VII, and VIII.
- The ‘base’ of the pons.
- The ‘tegmentum’ of the pons.
- Ascending and descending tracts (lemnisci, etc).
- Pontine nuclei.
- MLF, reticular formation
Why is the Pons is more complicated than midbrain?
- More cranial nerves
- Cerebellar connections (peduncles) very important here.
- Cortical inputs to cerebellum pass through the pons.
what do we find in the Rostral pons?
- Mesencephalic nucleus is part of CN V
- Medial longitudinal fasciculus connects CN’s III, IV, VI and VIII
- Superior cerebellar peduncle connects midbrain with cerebellum
What is this part of the pons?
the rostral pons
identify the parts of the rostral pons
what part of the pons is this?
rostral pons
identify the rostral pons parts
What are the pontine nuclei and tranverse pontine fibers?
What is another name for this?
what is it for?
- Cortical axons going to the cerebellum first synapse ipsilaterally on pontine nuclei.
- Axons of pontine nuclei cross to the other side; they are then called the tranverse pontine fibers
- Tranverse pontine fibers enter the cerebellum via the middle cerebellar peduncle
Corticopontocerebellar pathway: is the means
by which the cortex sends its ‘blueprint’ for movement to the cerebellum.
what level of the pons is this?
Mid Pons
identify the parts of the mid pons
what part of the pons is this?
mid pons
identify the parts of the mid pons
what landmarks can tell us we are at the level of the caudal pons?
Note position of CN VI and VII.
what level of the pons is this?
caudal pons
identify the parts of the pons
identify the parts of the caudal pons
The facial colliculus is formed by what?
the motor axons of CN VII; they ‘wrap’ around the nuclei of CN VI before exiting the pons. This creates a ‘bulge’ in the wall of the 4th ventricle
How is the medial lemniscus located in the pons compared to the midbrain?
more medially located
name the vascular supply to the pons
what syndrome will we have if area A is damaged?
what syndrome will we have if area B is damaged?
A: Medial Inferior Pontine Syndrome
B: Lateral Inferior Pontine Syndrome
What is another name for Foville Syndrome?
Why does it happen?
Medial Inferior Pontine Syndrome
Results from occlusion of branches of the basilar artery.
what symptoms will we see in Foville’s?
mention why we see such symptoms?
Symptoms:
- Ipsilateral medial deviation of eye: Due to damage to lateral rectus muscle (CN VI).
- Contralateral weakness of lower face: Damage to corticobulbar tracts.
- Contralaleral hemiparesis of trunk and limbs: Damage to corticospinal tracts.
- Bilateral limb and gait ataxia: Damage to pontine nuclei on one side, pontine fibers on the other side.
- Contralateral loss of discriminative touch, propriception, and vibration sense: Damage to dorsal column system.
- May include VII if lesion is big enough.
why does Lateral Inferior Pontine Syndrome happen?
What is another name for this syndrome?
Results from occlusion of the AICA
AICA syndrome
What symptoms do we see in AICA syndrome?
why do these happen?
Symptoms:
- Ipsilateral facial nerve paralysis. - Damage to Facial Nerve (VII)
- Loss of taste from anterior 2/3 of tongue. -Damage to Facial Nerve (VII)
- Loss of corneal and stapedial reflexes. - Damage to Facial Nerve (VII)
- Unilateral central nerve deafness. - Damage to Cochlear Nerve (VIII)
- Nystagmus, nausea, vomiting, and vertigo. - Damage to Vestibular Nerve (VIII)
- Ipsilateral loss of pain and temp (face). - Damage to Spinal Trigeminal Nerve and Tract
- Ipsilateral limb and gait ataxia. - Damage to Cerebellar Peduncles
- Contralateral loss of pain and temp (body). - Damage to Spinothalamic Tracts
- Ipsilateral Horner’s syndrome. - Damage to Descending Sympathetic Tract
