CN III Flashcards
Function of CN V
- General sensation
- General propriocepation from extraocular muscles, TMJ, muscles of mastication etc
- Skeletal motor to muscles of mastication and some others
- CARRIES parasympathetic “hitch hikers” of other cranial neres and sympathetic fibers from the internal carotid plexus in its own branches.
What are the parasympathetic fibers that CN V carries
- OCULOMOTOR: parasympathetic fibers leave CILIARY GANGLION via opthalamic division (V1) to terminate in SPHINCTER PUPILLAE and CILIARY MUSCLES
- FACIAL: Parasympathetic fibers leave the PTERYGOPALATINE GANGLION via the maxillary division (V2) to terminate int he LACRIMAL, NASAL and PALATINE GLANDS
- FACIAL: Parasympathetic fibers leave SUBMANDIBULAR GANGLION via the mandibular divison (V3) to terminate in the PAROTID GLAND
- GLOSSOPHARYNGEAL: parasympathetic fibers leave OTIC GANGLION via mandibular division (V3) to terminate in PAROTID GLAND
Describe the sympathetic “hitch hikers” that the trigeminal nerve carries
- Sympathetic hitch hikers from the internal carotid plexus are carried by OPTHALAMIC DIVISION (V1) to the dilator pupillae muscle
What are the divisons of the Trigeminal nerve and are they motor or sensory
- Opthalamic = sensory
- Maxillary = sensory
- Mandibular = sensory and motor
What neruons are found in Trigeminal ganglion (Gasserian ganglion)
- Is a sensory ganglion
- contains PSEUDOUNIPOLAR NEURONS
- no synapses
Define Mesencephalic nucleus of the trigeminal
- Sensory nuclei
- located in midbrain
- Function = general proprioception from muscles innervated by trigeminal nerve and periodental ligament (PDL)
- -> muscles of mastication and PDL contain nerve receptors that convey info to the brain about position of the jaw
Define Principal (main, Chief) sensory nucleus of tigeminal
- Sensory nuclei
- Location = midpons
- Function = discriminatory (fine, detailed) touch and pressure sensation from orofacial structures, GP from extraocular muscles and TMJ
–> sensory input is relayed to principal nucleus by central processes of sensory neurons located in V ganglion
define the spinal nucleus of the trigeminal
- Sensory nuclei
- Located = pons, medulla, extends to spinal cord levels C1-C2(3)
–> sits on top of substantia gelatinosa of the spinal cord
- FUNCTION = nociceptive and thermal sensation and some tactile sense from orofacial structures (resembles substantia gelatinosa structuraly and functionaly)
** ONLY cranial nerve that has PAIN NUCLEUS**
Define Motor nucleus of trigeminal
- Motor nucleus
- Location = midpons
- Function = contains cell bodies of motor neurons whose axons gather to from motor root of trigeminal nerve
–> innervate muscles of mastication and a few others
define the spinal tract of trigeminal
- Origin = Pons, near sensory root of V
- Course = descends in pons, through medulla to C1 or C2
- Termination = spinal nucleus of trigeminal (pons, medulla, C1-C2)
- Function = Pain, temperature, some tactile sense
**merges with lissauers tract at upper cervical levels**
Define ventral trigeminal lemniscus (ventral trigeminothalamic tract)
- origin = spinal nucleus of V
- Course = ascends to the thalamus
- Termination = VPM nucleus of thalamus
- Function = pain, temeprature, tactile sensation
** similar to spinothalamic tract of anteriolateral system **
Define dorsal trigeminal lemniscus (dorsal trigemnothalamic tract)
- Origin = main sensory nucleus of V
- Course = ascends to the thalamus
- Termiantion = VPM nucleus of thalamus
- Function = discriminative (fine, detailed) touch, proprioception
** similar to medial lemniscus **
Define tigeminoreticular fibers
- Origin = main sensory nucleus/spinal nucleus of V
- Course = project to nearby brainstem reticular formation, BILATERALLY
- Termination = reticular formation
- Function = Arousal, produced by stroking or slapping the face, or “smelling salts” (containing ammonia)
** similar to/counterpatrs of spinoreticular tract **
Describe the pathways of the trigeminal nerve: Discriminatory touch and pressure sensation of orofacial region
- 1st order neuron cell bodies found in TRIGEMINAL GANGLION –> terminate in MAIN SENSORY NUCLEUS OF V
- 2nd order neurons are located in MAIN SENSORY NUCLEUS and their axons join the DORSAL TRIGEMINAL LEMNISCUS to ascend to the VPM nucleus of thalamus
- 3rd order neurons in VPM project to the POSTCENTRAL GYRUS (representing orofacial region)
describe the pathway of the rigeminal nerve: pain and temperature sensation
- 1st order neruon: cell bodies found in trigeminal ganglion and DESCEND in the spinal tract of V to terminate in SPINAL NUCLEUS OF V
- 2nd order neurons located in SPINAL NUCLEUS OF V join VENRAL TRIGEMINAL LEMNISCUS to ASCEND TO VPM
- 3rd order neurons in VPM project to POSTCENTRAL GYRUS as well as ANTERIOR CINGULATE and ANTERIOR INSULAR CORTICES (emotional component of pain)
Describe the pathway of the trigeminal nerve: Motor pathway
- Lower motor neuron cell bodies found in MOTOR NUCLEUS of V
- Axons exit brianstem at MIDPONTINE LEVEL as motor root of V
- Axons join the MANDIBULAR DIVISION of the trigeminal to districute to ALL MUSCLES INNERVATED by trigeminal
What will damage to opthalmic division result in?
- Reduce sensation over V1 zone
- Inhibit corneal blink reflex
damage to the maxillary division will result in?
- reduce or inhibit sensation over the V2 zone
damage to the mandibular division will result in?
- reduce or inhibit sensation over V3 zone
- may cause paralysis of muscles of mastication resulting in jaw or DEVIATE TO THE SIDE OF THE LESION
