PNS 5 Flashcards
Where does CN VII, the Facial Nerve, arise from?
The BRAINSTEM at the Inferior Pontine Sulcus, in line with the Postolivary Sulcus of the Medulla.
What are the 4 functional components (Nerve fiber types) that CN VII carries?
- SVE
- GVE
- SVA
- GSA
What CN lies next to CN VIII in the Cerebellopontine Angle (the angle between the lateral pons and the inferior aspect of the cerebellum)?
CN VII
CN VII consists of 2 Primary Roots. What are they and what Fiber Type(s) does each carry?
- The Larger division, or MOTOR ROOT, carries
- Branchial Motor Fibers (SVE). - The Smaller division, or NERVUS INTERMEDIUS, carries
- Preganglionic Parasympathetics (GVE)
- Special Sensory Fibers (SVA - Taste)
- General Sensory Fibers (GSA)
CN VII fibers either arise from (Efferents) or project to (Afferents) a number of PONTINE Nuclei. Give the Nuclei associated w/ each of the following fibers
- Branchial Efferent (SVE) fibers
- GVE fibers
- SVA (taste) fibers
- GSA
- Facial (MOTOR) Nucleus
- SALIVATORY Nucleus
- Nucleus of the SOLITARY TRACT
- Spinal Nucleus of CN V
From what Ganglion do the Afferents (SVA & GVA) of CN VII arise from primary cell bodies in? Note: Ganglion is found w/in the temporal bone
GENICULATE GANGLION
Through what hole does CN VII enter the temporal bone through? What other CNs pass through this opening?
INTERNAL ACOUSTIC MEATUS
-Along w/ the COCHLEAR & VESTIBULAR Nerves of CN VIII
The Geniculate Ganglion, which gives rise to the afferent facial nerves, is located in what Canal?
It is located at a bend (hence geniculate) in the FACIAL CANAL.
CN VII branches extensively in what Canal that is located in the petrous portion of the temporal bone?
The FACIAL CANAL
What are the 3 motor branches of CN VII to leave while in the Facial Canal? List in order of departure
- GREATER PETROSAL Nerve
- Nerve to STAPEDIUS
- CHORDA TYMPANI
The Greater Petrosal nerve leaves the facial canal at the level of the Geniculum through what opening? The greater petrosal nerve then enters the middle cranial fossa and eventually exits the skull through what opening?
- The Greater Petrosal Nerve leaves the facial canal through the HIATUS OF THE GREATER PETROSAL NERVE into the Middle cranial fossa.
- The Greater Petrosal Nerve Leaves the skull through the FORAMEN LACERUM.
After exiting the skull the Greater Petrosal Nerve passes through the Pterygoid Canal to reach what Ganglion?
The PTERYGOPALATINE GANGLION
The STAPEDIAL Nerve is second to branch from CN VII. What muscle is it responsible for innervating?
The STAPEDIUS MUSCLE in the Middle Ear Cavity.
Chorda Tympani is the last branch to leave CN VII w/in the facial nerve. It courses along the lateral wall of the Tympanic cavity until leaving the cranium how? This complex course leaves Chorda Tympani vulnerable to what?
Chorda Tympani exits the cranium through the ITER CHORDAE ANTERIUS at the Medial End of the PETROTYMPANIC FISSURE.
-Chorda Tympani is vulnerable to Middle Ear Infections and the swelling that results
After exiting the Iter Chordae Anterius from the petrotympanic fissure where does Chorda Tympani end up?
INFRATEMPORAL FOSSA
Through what opening does the Trunk of the FACIAL NERVE exit the skull?
STYLOMASTOID FORAMEN
Fibers in the trunk of the facial nerve are primarily concerned with innervating what group of muscles?
MUSCLES OF FACIAL EXPRESSION
Note: Also Stylohyoid and Posterior Digastric Muscles
Give a short description of the 5 distinct segments of CN VII w/in the Facial Canal
- LABYRINTHE
- EXTERNAL GENU
- TYMPANIC
- MASTOID
- TRUNK
- Labyrinth: Enters facial canal and passes above the labyrinth housing the Vestibular System
- Ext. Genu: Includes the Geniculate Ganglion
- Tympanic: Travels posteriorly & laterally along the medial wall of the middle ear cavity
- Mastoid: Gives rise to the nerve to stapedius and Chorda Tympani
- Trunk: Exits the facial canal
SVE fibers (Branchial Motor) of CN VII innervate second arch derivatives, which can be summarized into what 3 categories?
- Muscles of facial expression
- Stylohyoid & Posterior Digastric Muscles
- Stapedius Muscle
Most SVE fibers in the TRUNK of CN VII ramify within what plexus? What is the exception?
PAROTID PLEXUS
-The POSTERIOR AURICULAR Nerve brings some SVE fibers to more Posterior muscles of facial expression