5. The cavernous sinus Flashcards Preview

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Flashcards in 5. The cavernous sinus Deck (8)
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1
Q

what are the cavernous venous sinuses

A

pair of dural venous sinuses located laterally to body of sphenoid

2
Q

where does the cavernous venous sinus receive blood from

A
  • superior and inferior ophthalmic veins
  • middle superficial cerebral veins
  • sphenoparietal sinus
3
Q

describe the boundaries of the cavernous sinus

A
  • roof: tentorium cerebelli (attached to anterior and middle clinoid processes)
  • floor: greater wing of sphenoid
  • anterior wall: superior orbital fissure (medial end)
  • posterior wall: petrous apex
  • medial wall: body of sphenoid
  • lateral wall: dura mater of middle cranial fossa
4
Q

name 2 structures running in the middle of the sinus

A
  1. internal carotid a.

2. abducens n. (CN VI)

5
Q

name 4 nerves running along the lateral sinus walls

A
  1. occulomotor n. (CN III)
  2. trochlear n. (CN IV)
  3. ophthalmic n. (CN Va)
  4. maxillary n. (CN Vb)
6
Q

how can infection in the danger zone of the face spread to the cavernous sinus

A

via the valveless facial vein which is connected to the cavernous sinus by superior ophthalmic vein - blood can reverse direction and flow into sinus

7
Q

other than infection, how does the facial vein pose a risk to the cavernous sinus

A

blood clot may travel from facial vein, via superior ophthalmic vein, to sinus, causing cavernous sinus thrombosis

8
Q

describe and explain the signs/symptoms of cavernous sinus thrombosis

A
  1. severe pain in eye and ant. forehead
    - sensory info. from ophthalmic n. (CN Va)
  2. complete ophthalmoplegia
    - dysfunction of occulomotor n. (CN III), trochlear n. (CN IV) and abducens n. (CN VI)
  3. dilated unreactive pupils
    - compression of CN III parasympathetic fibres - loss of sphincter pupillae function
  4. ptosis
    - occulomotor n. (CN III) dysfunction (+/- sympathetics)
    - oedema of upper eyelid
  5. exopthalmos & periorbital oedema
    - venous block, e.g. of ophthalmic vv.