CN Shortened Version Flashcards
Pathway of the trochlear nerve
The only cranial nerve that emerges dorsally from the brain. Therefore, it has a very long pathway.
Enters the cavernous sinus, and then travels through the SOF (above the common tendinous ring) to innervate the superior oblique muscle.
It is the thinnest nerve that supplies the eye and also has the longest route. Due to this, it is easily damaged and can result in a trochlear nerve palsy.
Oculomotor nerve pathway
Travels through the cavernous sinus and enters the SOF and common tendinous ring. Two branches emerge, the superior and inferior division. The superior division innervates the levator and superior rectus. The inferior division innervates the inferior oblique, medial rectus, and and inferior rectus and ciliary ganglion.
Olfactory nerve pathway
It’s sensory fibers extend through the ethmoid bones cribriform plate. It does not join the brainstem and is the shortest cranial nerve within the head.
Optic nerve pathway
Retinal ganglion merge to form the optic nerve. The optic nerve exits the orbit through the optic canal and then termites at the lateral geniculate system.
Where is the optic chasm
in the middle cranial fossa.
Superior to the cavernous sinus, pituitary glad and internal carotid.
V1 division of the trigeminal components
Ophthalmic nerve. Sensory. GSA. Travels through the SOF.
Nasociliary
- Anterior and posterior ethmoidal cells
- Infratrochlear nerve
- Long ciliary nerve
- Passes through ciliary ganglion (no synapse, since this is a sensory nerve and the ciliary ganglion is strictly autonomic)
Frontal
- Supraorbital nerve
- Supratrochlear nerve
Lacrimal
V2 division of the trigeminal components
Maxillary. Sensory. GSA.
Enters the cavernous sinus via the foramen rotundum, which is within the pterygoindpalatine fissure.
Travels through inferior orbital fissure and branches to form zygomatic nerve and infratrochlear nerve.
V3 division of the trigeminal components
Mandibular. Motor AND sensory. SVE and GSA.
This is the only division of the trigeminal that does not travel through the cavernous sinus. Instead, it enters the skull by foramen ovale.
Branches include:
Masseteric- to masseter (motor)
Medial and lateral pterygoid- lesser muscles of mastication (motor)
Auriculotemporal (sensory)
linguial (sensory)
Inferior alveolar- lower teeth. Through the mental foramen. (Motor and sensory)
What enters the skull through the rotundum
V2- maxillary division
What enters the skull through the ovale
V3- Mandibular division
What parts of CN V innervate the.. Facial skin? Nasal/pharyngeal? Anterior 2/3 of tongue? Muscles of mastication?
Face- CN V 1, 2, 3. Sensory.
Nasal/Pharyngeal- CN V1, V2. Sensory.
Anterior 2/3 of tongue- CN V3. Sensory.
Muscles of mastication- CN V3. Motor.
CN VI pathway
Abducens. Motor. GSE.
Travels over the sharp petrous ridges and through the cavernous sinus. Then it travels through the superior orbital fissure and innervates the lateral rectus.
Any swelling or damage to the nerve can cause abducens palsy. Pt will not be able to adbuct eye and present as an isotope. Head tilt whichever side nerve damage is on.
How to clinically assess the three divisions of the trigeminal?
Touch forehead to stimulate V1.
Touch cheek to stimulate V2.
Touch chin to stimulate V3.
Facial nerve pathway
Exits brains stem and runs into the posterior medial wall near petrous ridges. To avoid going over, it travels through the internal acoustic meatus. Travels in the facial canal before reaching the geniculate ganglion. (home of the cell bodies of the sensory neurons that contribute to the facial nerves. Motor nerves pass through without synapse)
Which two cranial nerves enter through the internal acoustic meatus
Facial and vestibulocochlear
What does the large motor root of the facial nerve innervate? (SVE)
Branches to muscles such as the stapedius, posterior belly digastric, stylohyoid, and the many muscles of facial expression. (To Zanzibar By Motor Car)
- Temporal (superior)
- Zygomatic
- Buccal
- Mandibular
- Cervical (inferior)
What does the small sensory root/intermediate root of the facial nerve innervate?
-Contains sensory (GSA, SVA) and parasympathetic (GVE) fibers.
Parasympathetic innervates:
Salivary nucleus.
Grater petrosal nerve (lacrimal gland and nasal/maxillary mucosal glands)
Chorda tympani is innervated by both. Taste fibers in the anterior 2/3 of tongue is SVA (sensory) and the parasympathetic portion sends signals to the salivary glands.
How does the facial nerve innervate the tongue?
Innervated by the sensory root (which also contains parasympathetic fibers).
Chorda tympani is SVA(taste senses) and GVE (Sends signals to salivary glands)
3 temporal bone branches of the facial nerve
Greater petrosal nerve (GVE/parasympathetic)
-Innervates lacrimal gland and the glands of the nasal cavity and maxillary sinus mucosa.
Stapedial nerve (SVE)
Chroda tympani (GVE and SVE)
Chorda tympani unites with which a sensory nerve from which branch?
Unites with the lingual nerve from V3. (Sensory, mandibular)
Posterior and anterior tongue. Which nerves innervate/are responsible for taste and touch?
Posterior tongue- 9. Taste and touch.
Anterior tongue- 7 (taste) and V3 (touch)
CN IX pathway
Exits posterior cranial fossa via jugular foramen.
Intracranial (superior ganglion-sensory)
Extracranial (Inferior ganglion- sensory, and otic ganglion- parasympathetic or GVE)
Upper and lower branches of glossopharyngeal
Upper (serial)
- Tympanic
- Tympanic plexus
- Lesser petrosal
- Otic ganglia
Lower branches
- Pharyngeal branch (motor for swallowing)
- Stylopharyngeus (motor for swallowing)
- Carotid sinus
- Tonsilar branches
- Lingulal branches
Vagus nerve pathway
Passes through jugular foramen. Descends in neck within the carotid sheath within the internal carotid.
Which 3 cranial nerves pass through the jugular foramen
9, 10, and 11
All the divisions of the vagus nerve
SVE
- Soft palate
- Larynx/pharynx
- Tongue muscle- palatoglossus
SVA
GSA
- Larynx
- Laryngopharynx
GVE
- pharynx and larynx
- Thorax and abdomen
GVA
Two lower branches of the vagus nerve
*** Primarily considered the parasympathetic nerve of the thorax and abdomen.
Thoracic
Abdominal- many innervated by the enteric system.
CN XI- two roots and their pathway/innervation
Accessory nerve. Cranial root is SVE and spinal root is GSE
The spinal root (larger, SVE)
- Travels up to pass through foramen magnum and runs along cranial root and exits through the jugular foramen. In and right back out.
- Targets sternocleidomastoid and trapezius
Cranial root (smaller, GSE)
- Exits jugular foramen
- Travels with CN X
- Innervates the pharyngeal region and larynx muscles.
CN XII
Hypoglossal nerve. Motor. GSE only.
Leaves the cranial cavity through the hypoglossal canal and enters the roof of the tongue above the hyoid.
- Supplies muscles that comprise the tongue, except the palatoglosus.
- GENIOGLOSSUS (allows you to stick your tongue out)
- Hyoglossus and styloglossus