Brainstem I and II Flashcards
What divides the rhomboid fossa into two symmetrical halves?
Median sulcus
What divides each side of the midline of the rhomboid fossa?
Sulcus limitans
What is the main eyelid elevator and what innervates it?
Levator palpebrae superioris, innervated by CN 3
What problems would you have with a hypothetical facial nerve lesion? (4 big groups)
- Loss of facial expression muscles
- Digastric stylohyoid and stapedius muscles (hyperacusis)
- Taste on anterior 2/3 of tongue
- loss of parasympathetic to salivary glands (except parotid) and lacrimal and nasal glands
What carries taste from posterior 1/3 of tongue?
CN 9
Name 4 big functions of glossopharyngeal nerve?
- Taste from posterior 1/3 of tongue
- Sensory inputs from external ear, tympanic membrane and wall of upper pharynx
- Visceral afferents from aortic arch and carotid sinus
- Parasympathetic input to parotid gland and motor innervation of stylopharyngeus
Where are the neurons for parasympathetic outflow through CN 3?
In the Edinger-Westphal nucleus.
How does visual information reach the Edinger-Westphal nucleus?
- Visual input goes to superior colliculus, to pretectal nuclei.
- Pretectal nucleus project to EW nucleus
- Pretectal axons cross to contralateral side in posterior commissure (this ensures the direct and consensual response)
Where do the parasympth neurons in the Edinger-Westphal nucleus synapse?
In the ciliary ganglion, where the postganglionic neurons synapse to the sphincter pupillae
What two muscles contribute to eyelid retraction?
Levator palpebrae superioris (innervated by CN 3)
Superior tarsal muscle (sympathetic fiber innervation)
What happens to the eye when the superior oblique muscle is contracted?
Depression and intorsion of the eye
Lesion of what CN is likely to cause diplopia? What will the patient do to compensate?
Lesion of CN 4, due to the inability of the eye to intort or depress. The affected eye drifts upward. The patient tilts head forward to comp for the upward drift, and also tilts to the unaffected side to compensate for the inability to intort.
What muscle does the left CN 4 innervate?
The RIGHT (contralateral) superior oblique
What is the mesencephalic nucleus of CN 5?
Has unipolar cell bodies with peripheral sensory fibers, so it is comparable to a sensory ganglion. Receives proprioception from the jaw to control mastication
What deficit results with a CN 6 lesion?
Inability to abduct the affected eye
Where do auditory afferents from CN 8 terminate?
In the dorsal and ventral cochlear nuclei
Where do the parasympathetic fibers destined for the parotid gland from the CN 9 originate from?
From inferior salivatory nucleus
CN 9 carries both afferents and efferents. What 2 locations do the afferents go, and what 2 locations do the efferents go?
NTS and trigeminal project (which only carries limited portion of outer ear) are the afferents. The efferents (parotid gland and the stylopharyngeus) originate from the inferior salivatory and the nucleus ambiguus, respectively.
What 2 zones are in the reticular formation?
Medial zone: mix of larg and small neurons, source of most long ascending and descending within reticular formation.
Lateral zone: cranial nerve reflexes and visceral functions.
Also at the midline are the raphe nuclei
What supplies the caudal medulla?
Anterior and posterior spinal arteries, vertebral artery
What supplies the rostral medulla?
Vertebral arteries, PICA.
What supplies the pons?
Basilar artery, AICA, and superior cerebellar artery
What supplies the midbrain?
Primarily the posterior cerebral artery
What are the symptoms in Wallenberg syndrome?
- Contralateral loss of pain and temp in body
- Ipsilateral loss of pain and temp in face
- Vertigo and nystagmus
- Ipsilateral cerebellar signs
- Difficulty in swallowing and gag reflex diminished
- Horner’s syndrome common
What are the 3 key features of Horner’s syndrome?
Ptosis, miosis, anhydrosis
What are the signs and symptoms of medial medullary syndrome (Dejerine)
- Damage to corticospinal tract
- Damage to medial lemniscal pathway
- Damage to hypoglossal
Occlusion of what artery causes lateral pontine syndrome and what are the signs?
AICA
- Vestibular problems
- Ipsilateral deafness
- Ipsilateral paralysis of face
- Ipsilateral loss of lacrimation and reduced salivation
- Ipsilateral loss of taste from anterior 2/3s
- Ipsilateral loss of pain and temp on face
- Contralateral loss of pain and temp on body
- Horner’s syndrome
What is Bell’s Palsy?
Damage to cranial nerve VII (7) likely due to viral infection such as herpes
What are the symptoms of Bell’s Palsy?
- Facial paralysis (central facial palsy)
- Inability to close the eyes
- Decrease in lacrimation and salivation
- Loss of taste from anterior 2/3s of tongue
What is different about the facial muscle innervation of 7 for the upper and lower face?
Upper face receives bilateral innervation, lower face receives only contralateral innervation
What symptoms are present in oculomotor palsy?
- Down and out position of the eye
- Ptosis
- Mydriasis (dilation due to loss of parasympathetic input to sphincter pupillae) (e.g. blown pupil)
Aneurysm in what artery commonly causes oculomotor palsy?
PComm
