474-475: Neuro Anatomy/Physio Flashcards
What is the cavernous sinus?
a collection of venous sinuses on either side of the pituitary
What drains into the cavernous sinus?
blood from the eye and superficial cortex
Where does the cavernous sinus drain to?
internal jugular vein
Which cranial nerves pass through the cavernous sinus?
III, IV, V1, V2, and VI
Which sympathetic nerves pass through the cavernous sinus?
postganglionic sympathetic fibers en route to the orbit
Which artery passes through the cavernous sinus?
the cavernous portion of the internal carotid artery
What deficits characterize the cavernous sinus syndrome? What is not affected?
ophthalmoplegia and decreased corneal and maxillary sensation; normal visual acuity
What are three causes of cavernous sinus syndrome?
mass effect, fistula, thrombosis
What artery lies between the optic chiasm inferiorly and the base of the brain superiorly?
ACA
A patient presents with a jaw deviated toward the right on physical examination. You suspect a CN lesion. Which CN? What side is the lesion on?
Motor component of CN V on the right; jaw deviates toward side of lesion due to unopposed force from the opposite pterygoid muscle
On CN exam you note the uvula deviates toward the right. Which CN is affected on which side?
CN X on the left; uvula deviates away from weakened left side
On CN exam you note weakness when the patient turns her head to the left. Which CN is affected on which side? Which muscle?
CN XI on the right is affected –> SCM
In a patient with weakness in turning her head to the right, what do you expect on examination of her shoulder elevation? Which nerve and muscle is affected in the shoulder?
CN XI lesion on the left –> left trapezius weakness –> drooping shoulder
On CN exam your patient’s tongue deviates to the right. Which CN is affected on which side?
CN XII on the right (“lick your wounds”)
What are the components of the outer ear?
Pinna, auditory canal, eardrum
What is the middle ear? What is it’s main function?
An air-filled space with the ossicles (malleus, incus, stapes); amplifies sound
What is the name of the structure in the cochlea that vibrates with sound waves? Describe its structural variation as it coils through the cochlea.
basilar membrane; thin and rigid at base of cochlea –> wide and flexible at apex near helicotrema
What part of the basilar membrane vibrates in response to low frequency sound waves?
the apex
What part of the basilar membrane vibrates in response to high frequency sound waves?
the base
What are the Rinne and Weber test results in conductive hearing loss?
Rinne: bone > air (abnormal)
Weber: localizes to affected ear
What are the Rinne and Weber test results in sensorineural hearing loss?
Rinne: air > bone (nml)
Weber: localizes to unaffected ear
Why should you wear ear protection at a loud concert? What will be damaged, and what function will be lost first?
damage to stereocilliated cells in the organ of Corti –> loss of high-frequency hearing first
What is the risk of a sudden extremely loud noise to your inner ear structures?
hearing loss due to tympanic membrane rupture
A patient presents with paralysis of the face below the forehead on the right side. Where is the lesion?
UMN on the left (i.e. corticobulbar tract; or cortical lesion)
A patient presents with paralysis of the left side of the upper and lower face. Where is the lesion?
LMN on the left (i.e. facial nerve proper)
What are the components of the facial nucleus? Does complete destruction of the facial nucleus present like a UMN or LMN lesion, or components of both?
Upper division - receives input from both sides of cortex
Lower division receives input from contralateral cortex only
Presents as a LMN lesion
What is the name given to idiopathic lesions of the facial nerve? What is the prognosis?
Bell’s palsy; gradual recovery in most cases
What are 6 causes of facial nerve palsy?
- Lyme dz
- herpes simplex
- herpes zoster
- sarcoidosis
- tumors
- diabetes
What is the treatment for facial nerve palsy?
Corticosteroids
What 3 mm. close the jaw?
Masseter
teMporalis
Medial pterygoid
(M’s Munch)
Which single muscle is responsible for jaw opening?
Lateral pteryoid (“Lateral Lowers”)
What is the innervation to the muscles of mastication?
trigeminal nerve (V3)
