CRANIAL NERVES PT1 Flashcards
Parasympathetic nucleus
Edinger-Westphal Nucleus
Form a V shape as they curve over the dorsal aspect of the oculomotor nuclei and fuse anteriorly in the midline
Edinger-Westphal Nucleus
Edinger-Westphal Nucleus:
Fibers from pupils run in superficial and medial portion of ________________
oculomotor nerve
Axons accompany the other oculomotor fibers to orbit
Synapse with ciliary ganglioEdinger-Westphal Nucleus
Edinger-Westphal Nucleus
Short ciliary nerves
Constrictor pupillae and ciliary muscles
Edinger-Westphal Nucleus
Receives ______________ for accommodation reflex, and __________________ for the direct and consensual light reflexes
corticonuclear fibers, fibers from pretectal nucleus
Oculomotor Nerve Course:
Lie in lateral wall of cavernous sinus
Emerge on the anterior surface of the midbrain
Enter the orbits through superior orbital fissure
Continues to middle cranial fossa
Divides to superior and inferior ramus
Pass forward between PCA and SCA
1.) Emerge on the anterior surface of the midbrain
2.) Pass forward between PCA and SCA
3.) Continues to middle cranial fossa
4.) Lie in lateral wall of cavernous sinus
5.) Divides to superior and inferior ramus
6.) Enter the orbits through superior orbital fissure
Oculomotor nerve supplies the Extraocular Muscles:
Levator palpebrae superioris
Superior rectus
Medial rectus
Inferior rectus
Inferior oblique
Intrinsic Ocular Muscle - Parasympathetic (ciliary ganglion, short ciliary nerve) supplies:
Constrictor pupillae
Ciliary muscle
Purely Motor
GSE
Assist in turning eye ball downward and medially (intorsion and depression) = superior oblique muscle
TROCHLEAR NERVE (CN IV)
Situated in anterior part of gray matter that surrounds the cerebral aqueduct or also called
periaqueductal gray matte
Situated in anterior part of gray matter that surrounds the cerebral aqueduct
Trochlear Nerve Nucleus
Only cranial nerve that exits POSTERIORLY
Acts through the trochlea in the orbit to rotate the top of the eye medially and move it downwards
TROCHLEAR NERVE (CN IV)
Nerve fibers pass posteriorly around the central gray matter to the posterior surface of midbrain
Trochlear Nerve Nucleus
Superior orbital fissure
Most slender cranial nerve
TROCHLEAR NERVE (CN IV)
Receives corticonuclear fibers from both central hemispheres
Receive tectobulbar fibers connecting it to visual cortex
Trochlear Nerve Nucleus
Lies inferior to the oculomotor nucleus at the level of the inferior colliculus
Trochlear Nerve Nucleus
Receives fibers from MLF connecting it with CN III, VI, and VIII nuclei
Trochlear Nerve Nucleus
Arrange the trochlear Nerve Course
Pass forward through middle cranial fossa in lateral wall of the cavernous sinus
Emerges at the posterior surface of midbrain
Immediately decussates at the level of the anterior medullary vellum
Superior oblique
Enters orbit through superior orbital fissure
Turns eye downward and laterally
1.) Emerges at the posterior surface of midbrain
2.) Immediately decussates at the level of the anterior medullary vellum
3.) Pass forward through middle cranial fossa in lateral wall of the cavernous sinus
4.) Enters orbit through superior orbital fissure
5.) Superior oblique
6.) Turns eye downward and laterally
Purely motor
GSE
Turns eyeballs laterally (abduction)
ABDUCENS NERVE (CN VI)
supplies Lateral rectus for abduction of the eyes
Exits through Superior orbital fissure
ABDUCENS NERVE (CN VI)
Abducens Nerve Nucleus receives afferent _________________ from both hemispheres
corticonuclear fibers
Abducens Nerve Nucleus receives ___________ from superior colliculus
tectobulbar fibers
Beneath the floor of the upper part of the 4th ventricle
Receives fibers from MLF
Abducens Nerve Nucleus
Close to the midline and under the facial colliculus
Abducens Nerve Nucleus
Arrange abducens Nerve Course:
Ascend between pons and clivus
Passes anteriorly through pons and emerge in groove between lower border of pons and medulla
Passes forward through cavernous sinus, lying below and lateral to internal carotid artery
Exit the dura to enter Dorello’s canal, running between the dura and skull, under the petroclinoid ligament
Enter the orbit through superior orbital fissure
Lateral rectus (LR6)
1.) Passes anteriorly through pons and emerge in groove between lower border of pons and medulla
2.) Ascend between pons and clivus
3.) Exit the dura to enter Dorello’s canal, running between the dura and skull, under the petroclinoid ligament
4.) Passes forward through cavernous sinus, lying below and lateral to internal carotid artery
5.) Enter the orbit through superior orbital fissure
6.) Lateral rectus (LR6)
Largest cranial nerve
Trigeminal Nerve (Cranial Nerve V)
3 divisions of trigeminal nerve:
Ophthalmic division (V1)
Maxillary division (V2)
Mandibular division (V3)
Cornea, skin of forehead, scalp, eyelids, and nose; mucous membrane of paranasal sinuses and nasal cavity
exits Superior orbital fissure
GSA function of Ophthalmic division (V1)
exit of Maxillary division (V2)
Foramen rotundum
Skin of face over maxilla; teeth of upper jaw; mucous membrane of nose, maxillary sinus and palate
GSA function of Maxillary division (V2)
exit of Ophthalmic division (V1)
Superior orbital fissure
exit of Mandibular division (V3)
Foramen ovale
skin of cheek, skin over mandible and side of head, teeth of lower jaw and TMJ; mucous membrane of mouth and anterior part of tongue
Anterior ⅔ taste of tongue
SVE function of Mandibular division (V3)
muscles of mastication; mylohyoid, anterior belly of digastric muscle, tensor veli palatini and tensor tympani
Ears have CN 7, 9, 10
GSE function of Mandibular division (V3)
4 nuclei of trigeminal nerve :
Main sensory nucleus
Spinal nucleus
Mesencephalic nucleus
Motor nucleus
Trigeminal nuclei receive GSA inputs from CN V, VII, IX and X
Touch, pain, temperature, position and vibration sense for face, sinuses and meninges
Trigeminal Nuclear Complex
From CN V - sensation for face, mouth, anterior 2/3 of tongue, nasal sinuses and supratentorial dura
Smaller inputs from CN VII, IX and X – sensation for part of external ear
Trigeminal Nuclear Complex
CN IX sensation to middle ear, posterior 2/3 of tongue and pharynx
CN X – infratentorial dura and some pharyngeal sensation
Trigeminal Nuclear Complex
Chief or Principal Sensory Nucleus
Lies in posterior part of pons, lateral to motor nucleus
Main Sensory Nucleus
Continuous below with spinal nucleus
Above with mesencephalic
Main Sensory Nucleus
Fine touch, dental pressure through trigeminal lemniscus to VPM
Trigeminal nucleus crosses to opposite side of the brainstem to ascend with the medial lemniscus towards the thalamus to VPM. Tertiary neurons travel to face area of primary somatosensory cortex
Main Sensory Nucleus
dorsal trigeminothalamic tract – does not decussate and travel to ipsilateral VPM conveying touch and pressure sensation from oral cavity including teeth
Smaller pathway – for main sensory nucleus of trigeminal nerve
Continuous superiorly with main sensory nucleus in pons
Spinal Nucleus
Composed of a column of unipolar cells in the lateral part of the periaqueductal gray matter
Mesencephalic Nucleus
Extends inferiorly as far as the main sensory nucleus
Mesencephalic Nucleus
Extends inferiorly through the whole length of the medulla and into upper part of the spinal cord as far as C2 segment
Spinal Nucleus
Proprioception from muscles of mastication, tongue and possibly from EOMs
Mesencephalic Nucleus
Crude touch, pain and temperature through trigeminothalamic tract to VPM
Fibers enter lateral pons with trigeminal nerve and descend in spinal trigeminal tract to synapse with spinal nucleus
Spinal Nucleus
Located in upper to mid pons near the level of trigeminal nerve exit from brainstem
Situated in the pons medial to the main sensory nucleus
Motor Nucleus
Secondary neurons from spinal nucleus cross to ascend as trigeminothalamic tract (ventral trigeminothalamic tract)
Spinal Nucleus
Synapse with VPM and tertiary neuronal fibers travel in internal capsule to reach primary somatosensory cortex
Spinal Nucleus
uns inferomedial to trigeminal ganglion along the floor of Meckel’s cave then joins V3 to exit via foramen ovale
Motor Root of motor nucleus of trigeminal nerve
Supplies muscles of mastication and smaller muscles (tensor tympani, tensor veli palatini, mylohyoid and anterior belly of digastric)
Motor Nucleus
Rests on upper surface of petrous part of the temporal bone in middle cranial fossa
Pass forward out of the posterior cranial fossa
Leaves anterior aspect of pons as small motor and large sensory root
Large sensory root expands to form trigeminal ganglion
Ophthalmic, maxillary and mandibular nerves arise from anterior border of the ganglion
V1 – sensory – superior orbital fissure
V2 – sensory – foramen rotundum
V3 – motor and sensory – foramen ovale
1.) Leaves anterior aspect of pons as small motor and large sensory root
2.) Pass forward out of the posterior cranial fossa
3.) Rests on upper surface of petrous part of the temporal bone in middle cranial fossa
4.) Large sensory root expands to form trigeminal ganglion
5.) Ophthalmic, maxillary and mandibular nerves arise from anterior border of the ganglion
6.) V1 – sensory – superior orbital fissure
V2 – sensory – foramen rotundum
V3 – motor and sensory – foramen ovale
Semilunar or gasserian ganglion
Trigeminal Ganglion
Sensory ganglion of trigeminal nerve
Trigeminal Ganglion
Lies in Meckel’s cave - small fossa just posterior and inferolateral to cavernous sinus
Trigeminal Ganglion
