Neuro - Anat & Phys (Cranial nerves applications) Flashcards
Pg. 474-475 in First Aid 2014 Sections include: -Cavernous sinus -Common cranial nerve lesions -Auditory physiology -Hearing loss -Facial lesions -Mastication muscles
What is the Cavernous sinus, and where is it located?
A collection of venous sinuses on either side of the pituitary
From where does blood flow to the cavernous sinus, and to where does it from from there?
Blood from eye and superficial cortex –> Cavernous sinus –> Internal jugular vein
Which nerves pass through the cavernous sinus, and on their way to which structure? What vessel joins them?
CN III, IV, V1, V2, and VI (i.e., the nerves that control extraocular muscles plus V1 and V2) and postganglionic sympathetic fibers en route to the orbit all pass through the cavernous sinus; Carvenous portion of internal carotid artery is also here.
What are 3 causes of Cavernous sinus syndrome?
Cavernous sinus syndrome (e.g., due to mass effect, fistula, thrombosis)
What is the presentation of Cavernous sinus syndrome?
Cavernous sinus syndrome (e.g., due to mass effect, fistula, thrombosis) - ophthalmoplegia and decreased corneal and maxillary sensation with normal visual activity
Which CN is commonly affected by Cavernous sinus syndrome?
CN VI commonly affected
Draw the Cavernous sinus and its related structures, labeling the following: (1) Anterior cerebral artery (2) Anterior clinoid process (3) Arachnoid (4) Abducens (VI) nerve (5) Dura (6) Hypophysis (7) Internal carotid artery (8) Optic chiasm (9) Oculomotor (III) nerve (10) Ophthalmic (V1) nerve (11) Maxillary (V2) nerve (12) Pia (13) Sphenoid sinus (14) Subarachnoid space (15) Trochlear (IV) nerve.
See p. 474 in First Aid 2014 for visual
What sign/symptom occurs with a CN V motor lesion, and why?
Jaw deviates TOWARD side of lesion due to unopposed force from the opposite pterygoid muscle
What sign/symptom occurs with a CN X lesion, and why?
Uvula deviates AWAY from side of lesion. Weak side collapses and uvula points away
What signs/symptoms occur with a CN XI lesion, and why?
Weakness turning head to contralateral side of lesion (SCM). Shoulder droop on side of lesion (trapezius). The left SCM contracts to help turn the head to the right.
What sign/symptom occurs with a CN XII lesion, and why? What kind of motor neuron lesion is this?
Tongue deviates TOWARD side of lesion (Think: “lick your wounds”) due to weakened tongue muscles on the affected side; CN XII lesion (LMN)
What are the 3 major parts of the ear?
(1) Outer ear (2) Middle ear (3) Inner ear
What 3 structures are associated with the Outer ear?
Visible portion of ear (pinna), includes auditory canal and eardrum
What is the function of the Outer ear, and how does it work?
Transfers sound waves via vibration of eardrum
What is the Middle ear, and what does it contain?
Air-filled space with three bones called the ossicles (malleus, incus, stapes)