Term
| what is the major sensory nerve for the face region? |
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Definition
| the trigeminal nerve (nasopharyngeal region from neck up) which responds to pain/temperature, proprioception, discriminative touch, simple touch and vibration |
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Term
| what characterizes the sensory cranial nerve nuclei associated w/the trigeminal nerve? |
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Definition
| it runs the entire length of the brainstem from the midbrain down to the medullary region |
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Term
| what characterizes the motor nucleus is associated w/the trigeminal nerve? which branch is it associated with? what characterizes the pathway? |
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Definition
| this is small and is housed in the pons region (just medial to sensory nucleus) -> controls muscles of mastication (masseter, temporalis, medial/lateral pterygoids, +tensores tympani, tensores veli palatini, mylohyoid and the anterior belly of the digastrics). there is bilateral innervation from the cortex (unilateral UMN lesion: not a big deal) to the trigeminal motor nucleus, which then sends efferent signals along V3/mandibular afferent branch. |
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Term
| what is the V1 branch of CN5? what are the branches which come off of V1? |
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Definition
| opthalmic, which gives off the lacrimal, nasociliary, and frontal branches. |
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Term
| what is the V2 branch of CN5? what are the branches which come off of V2? |
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Definition
| maxillary, which gives off the zygomatic, infraorbital, superior alveolar, pterygopalatine, and meningeal branches. |
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Term
| what is the V3 branch of CN5? what are the branches which come off of V3? |
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Definition
| mandibular, which gives off the buccal, lingual, inferior alveolar, auriculotemporal, and meningeal branches. |
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Term
| where do all the CN5 modalities exit? |
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Definition
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Term
| what are the different orifices which CN5 uses to exit the skull? |
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Definition
| V1: superior orbital fissure. V2: foramen rotundum. V3: foramen ovale (very close to middle meningeal artery). |
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Term
| what vascular bodies are located very close to the trigeminal ganglion? what is this area called? |
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Definition
| the internal carotid artery and basilar artery - problematic if either has an aneurysm. this area is called meckel's cave and is located right on top of the petrous temporal bone. |
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Term
| what is the somatotrophic organization of sensory afferents projecting to the trigeminal nucleus? |
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Definition
| general sensory information (simple touch/pain) is projected to the *spinal nucleus which runs down below the pons into the medulla. tactile/discriminatory touch information is projected directly on the same level as the pons to the *chief/main/superior trigeminal nucleus. vibration/proprioception is projected up towards the midbran in the *mesencephalic nucleus. |
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Term
| what characterizes CN5: general sensory information (pain/temp) projection to the cortex? |
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Definition
| trigeminal ganglion -> tract of spinal trigeminal nucleus (medulla) -> *decussates and travels superiorly as the spinal lemniscus -> ventral posterior thalamic nucleus -> face region of the sensory cortex |
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Term
| what characterizes CN5: discriminative touch (tactile) projection to the cortex? |
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Definition
| trigeminal ganglion -> chief/main/superior trigeminal nucleus (pons) -> *decussates and travels superiorly as the spinal lemniscus -> ventral posterior thalamic nucleus -> face region of the sensory cortex |
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Term
| what is the sensory/motor trigeminal reflex? |
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Definition
| tactile information goes to the sensory trigeminal nucleus (**mainly pons region**) which then signals the motor nucleus to send efferent signals to the muscles of mastication = chewing. |
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Term
| how is CN5: motor function tested? |
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Definition
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Term
| how is CN5: sensory function tested? |
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Definition
| corneal reflex (V1) and then various sensory tests on V2-3 areas of distribution. |
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Term
| other than the corneal reflex (CN5->CN7), what other reflexes cause the eye to shut? |
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Definition
| bright light CN2->CN7 and loud sounds CN8-> CN7 |
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Term
| what characterizes trigeminal neuralgia/tic douloureux? |
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Definition
| this condition involves excruciating/lancinating pain which occurs in the mandibular/maxillary divisions of CN5 and lasts for a few sec-min. the pain occurs spontaneously or may be elicited by eating, walking, talking, shaving, brushing teeth, or touching a trigger zone. it is thought to be due to local irritation of the sensory fibers in CN5 (MS, tumor compression, viral - deterioration causes abnormal signals to be sent to the brain). this occurs more commonly in women over 50. |
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