<prompt> All of the following are true about cavernous sinus thrombosis except?Most commonly spreads through ethmoid sinusLoss of sensation around orbitLoss of jaw jerkInfection can spread to cavernous sinus from danger area of face via inferior ophthalmic vein  <response>: Ans. c. Loss of jaw jerk Ref: Grays anatomy 40e p430; BDC 6e Volume IIIe p193, 194; Snells 9e p544Any spreading infection involving the upper nasal cavities, paranasal sinuses, cheek especially near the medial canthus, upper lip, anterior nares or even an upper incisor or canine tooth, may very rarely lead to septic thrombosis of the cavernous sinuses; infected thrombi pass from the facial vein or pterygoid venous complex into the sinus via either ophthalmic veins or emissary veins that enter the cranial cavity through the foramen ovale. This is a critical medical emergency with a high risk of disseminated cerebritis and cerebral venous thrombosis.Grays anatomy 40e p430Cavernous Sinus ThrombosisUsually results from infection of ethmoid and sphenoid sinusesQRoute of Spread Ethmoid sinus MC via ophthalmic veinsQ Sphenoid sinus by direct spreadQ Frontal sinus via supraorbital and ophthalmic veinsQ Orbit by ophthalmic veinsQ Upper lid via angular vein and ophthalmic veinsQ Ear by petrosal venous sinusesClinical Features:Onset is abrupt with fever, chills and rigorInvolvement of 3rd, 4th, 5th and 6th cranial nerveQChemosis of conjunctivaQProptosis of eye with limited movementsQPupils are dilated and fixedQ due to involvement of sympathetic plexus around carotid artery Decreased visionQ due to optic nerve damageDecreased sensation in distribution of 5th nerve ophthalmic division and engorgement of retinal vesselsQTreatment:Antibiotics in high doses for 4-6 weeks and drainage of involved sinusesQStructures Marked in the DiagramA Oculomotor nerveB Abducens nerveC Ophthalmic nerveD Maxillary nerveThe abducens nerve is the sixth cranial nerve and innervates lateral rectus exclusively. It emerges from the brain stem between the pons and the medulla oblongata and usually runs through the inferior venous compartment of the petroclival venous confluence in a bow-shaped canal, Dorellos canal. It then bends sharply across the upper border of the petrous part of the temporal bone to enter the cavernous sinus, where it lies lateral to the internal carotid artery unlike the oculomotor, trochlear, ophthalmic and maxillary nerves, which merely in vaginale the lateral dural wall of the sinus. The abducens nerve enters the orbit through the superior orbital fissure, within the common tendinous ring, at first below, and then between, the two divisions of the oculomotor nerve and lateral to the nasociliary nerve. It passes forwards to enter the medial ocular surface of lateral rectus. -- Grays Anatomy 40e p430 Cavernous Sinus It is a large venous space situated In middle cranial fossa on either side of body of the sphenoid.Structures in the lateral wall of sinus from above downwardsStructures passing through centre of the sinus content Oculomotor lllrd nerve Trochlear nerve IVth Ophthalmic V1 nerve Maxillary V2 nerve Trigeminal ganglion Abducent VIth nerve Q Internal carotid artery QContents of the Cavernous SinusTributaries of cavernous sinusFrom the orbitFrom the brainFrom the meninges Superior Ophthalmic vein A Branch of the inferior Ophthalmic vein Central vein of retina Superficial middle cerebral vein Inferior cerebral vein Sphenoparietal sinus Frontal trunkof the middle meningeal vein Draining channels of cavernous sinus Into the transverse sinus through superior petrosal sinus Into the internal jugular vein through inferior petrosal sinus Into the pterygoid plexus of veins through emissary veinsQ Into the facial vein through superior ophthalmic veinQ Cranial NerveCharacteristic FeatursOlfactory I Nerve Only Cranial nerve to enter cerebrum directlyQ Only Sensory afferent pathway that reaches cerebral cortex with out synapsing in one of the thalamic nucleiQTrochlear IV Nerve Smallest Cranial nerveQ Most slender cranial nerveQ Only nerve to emerge from dorsal posterior surface of brain stemQ mid brain Passes anteriorly around the brain stem, running the longest intracranial subarachnoid courseQ Nerve crosses the midline within the midbrain, emerges from its dorsal aspect and immediately decussates with the nerve of opposite sideQ Sole supply is superior oblique the only extra ocular muscle that uses pulley trochlea to redirect its line of action Trigeminal V Nerve Largest cranial nerveQ if atypical optic nerve is excluded Large sensory root is composed of central processes of pseudounipolar neuronsQ, whose cell bodies make up the crescent shaped trigeminal semilunar ganglion, which is housed with in a dural recess the trigeminal or Meckels cave lateral to the cavernous. Abducent VI Nerve Longest intradural courseQ with in the cranial cavity from clivus to superior orbital fissure Involved most commonly in raised intracranial tensionQ due to long course of the sharp bend it makes over the petrous temporal bone Only the cranial nerve passing through cavernous sinusQ Facial VII Nerve Longest intraosseous courseQ Most commonly paralyzed of all cranial nerves 