Peripheral nervous system Flashcards
The Peripheral Nervous System (PNS) consists
of _____
the parts of the nervous system outside of
the brain and spinal cord
The PNS includes
○ Cranial Nerves
○ Spinal Nerve Roots and branches
○ Peripheral Nerves
○ Neuromuscular Junction
CN I
- The Olfactory Nerve carries special viscerosensory information regarding the sense of
smell from the superior aspect of the lateral and septal walls of the nasal cavity. - Olfactory neurons pass through the cribiform plate and then synapse on secondary neurons within the Olfactory Bulb.
Where do olfactory bulb fibers go?
fibers project directly into the ventromedial aspect of the temporal lobe
CN II
The Optic Nerve extends from the retina of each globe and carries special somatosensory information regarding sight, entering through the optic canal.
What happens at the optic chiasm?
Information from both retinas mixes and breaks posteriorly as the Optic Tracts, which extend into the cerebral cortex.
○ Nerves from the medial half of each optic nerve
crosses to the opposite side
CN III
The Oculomotor Nerve originates from the medial midbrain and travels into the orbit through the superior orbital fissure where it performs several functions.
● It provides general somatic motor innervation to
four of the six extraocular muscles, as well as
the levator palpebrae superioris.
Which cranial nerve provides visceromotor parasympathetic innervation with preganglionic fibers that synapse in the Ciliary Ganglion, which project to the ciliary muscle and the pupillary sphincter?
CN III - oculomotor
Lateral retinal tracts recieve input from the _____ visual area
medial
CN IV
- The Trochlear Nerve originates from the lateral midbrain and travels into the orbit
through the superior orbital fissure and carries somatic motor fibers. - provides general somatic motor innervation to
the superior oblique muscle, which depresses
and medial rotates the globe.
____ is a very small nerve in cadaveric specimens and
travels within the anterior portion of the tentorial notch of the tentorium cerebelli before piercing the lateral cavernous sinus towards the eye.
Trochlear nerve
CN V
- The Trigeminal Nerve is the largest of the
cranial nerves and originates from the lateral
aspect of the Pons (mid pontine).
The largest of the cranial nerves
Trigeminal
Which nerve originates Within a dural space on the
petrous part of the temporal bone?
Trigeminal
Within a dural space on the petrous part of the temporal bone is the ______, which is a synapse location for incoming first-order sensory neurons.
Trigeminal Ganglion
Characteristics of Trigeminal - Opthalmic division (V1)
- contains only somatic sensory fibers, passes through cavernous sinus and the superior orbital fissure, and into the orbit.
- Provides sensory innervation to the orbit, the cornea, the nasal cavity, and the skin of
the forehead, parts of the scalp, and the nose (to the tip of the nose).
Characteristics of Trigeminal - Maxillary division (V2)
- passes through the cavernous sinus and foramen
rotundum, contains only somatic sensory fibers, and provides sensory innervation to some of the nasal cavity, the upper oral cavity, and maxillary region of the face through several branches in the mid-face.
Characteristics of Trigeminal - Mandibular division (V3)
- passes through foramen ovale and into the
infratemporal fossa, medial to the ramus of the mandible. - Contains special viscero- motor fibers that provide motor innervation to the muscles of mastication.
- Also contains somatic sensory fibers that provide sensory innervation to the lower oral cavity, ear, and lateral and mandibular part of the face
(“chin strap” distribution).
CN VI
- The Abducens Nerve originates in the Pons and extends from the medial inferior Pons,
basically at the pontine medullary junction (where pons and medulla meet). - It travels into the orbit through the superior
orbital fissure, and provides somatic motor
innervation to the lateral rectus muscle.
very small nerve in cadaveric specimens
and pierces the dura medial to the Trigeminal Nerve, traveling through the cavernous sinus on its way to the superior orbital fissure.
Abducens Nerve
CN VII
- The Facial Nerve originates in the Pons and extends from the mediolateral inferior Pons, basically at the pontine medullary junction, lateral to the Abducens Nerve.
- The Facial Nerve contains somatic
motor, somatosensory, and visceral
neuronal fibers.
Where does CN VII exit the skull?
The nerve leaves the cranium by entering the internal acoustic meatus and into the Facial Canal of
the temporal bone.
Three main branches of the facial nerve that arise within the facial canal
○ Greater Petrosal Nerve
○ Stapedial Nerve
○ Chorda Tympani
What does the greater petrosal nerve do?
Branch of facial nerve
Parasympathetic fibers - travels into the middle cranial fossa and joins with sympathetic fibers and
these then project into the face, innervating the glands of the nasal cavity, palate, and lacrimals.
What does the stapedial nerve do?
travels into the middle ear and provides motor innervation to the Stapedius muscle.
What does chorda tympani do?
travels into and through the middle ear, eventually joining with the lingual nerve branch of CN V3.
○ It provides parasympathetic visceral motor fibers to the submandibular ganglion, stimulating secretion from salivary glands.
○ It also provides special sensory fibers for taste from the anterior part of the tongue.
After giving off these three branches within the Facial Canal, the rest of the Facial Nerve exits the skull base through the _____ foramen and has many branches.
stylomastoid
CN VIII
● The Vestibulocochlear Nerve originates from the lateral Pontine-Medullary junction as
a dual root nerve that has the appearance of a double-barrel shotgun.
● It travels into the internal acoustic meatus alongside the Facial Nerve.
● It contains only special somato- sensory fibers for hearing and balance.
Which nerve travels into the internal acoustic meatus
alongside the Facial Nerve?
Vestibulocochlear nerve