Parasympathetic Nerves - 21 Flashcards
What Four of the twelve pairs of cranial nerves carry parasympathetic information?
Oculomotor (III)
Facial (VII)
Glossopharyngeal (IX)
Vagus(X)
Oculomotor Nerve (III)
The oculomotor nerve carries two modalities:
•General somatic motor (GSM) and general visceral motor
GSM:
•Cell bodies of these motor neurons are located in the oculomotor nuclear complex.
•Pathway:
•From: •Oculomotor complex
•Through: •Superior orbital fissure
•To: •4 of 6 extrinsic muscles of the eye •Levatorpalpebrae superioris
GVM: •Preganglionics: •From: •Edinger-Westphal nucleus •Through: •Superior orbital fissure •To: •Ciliary ganglion •Post ganglionics: •To: •Constrictor pupillae •Ciliary muscles
Trigeminal Nerve (V)
The trigeminal nerve is named for its three major branches, which are sometimes referred to as separate nerves or divisions:
•Ophthalmic (V1)
•Maxillary (V2)
•Mandibular (V3)
The trigeminal nerve is not a parasympathetic nerve, but branches of the facial nerve piggy-back on some of the branches of the trigeminal nerve, and so it is considered here.
The trigeminal nerve is the major sensory nerve to the face (GSS).
It also supplies motor innervation to muscles of mastication (SVM): •Muscles derived from first pharyngeal arch (mandibular arch).
The trigeminal nerve is the largest of the twelve cranial nerves.
Ophthalmic (V1):
- This division enters orbit along with oculomotor, trochlear, and abducens nerves.
- General sensory nerve to the orbit and its contents
- Also conveys sensation to nose, skin above the eye, including upper eyelid, but not the lower eyelid
- Sensory fibers reach eyeball either through the short or the long ciliary nerves.
- Long ciliary nerves also convey sympathetic fibers to the dilator muscle of the pupil.
- Branches include frontal, lacrimal, and nasociliary
Maxillary (V2):
- Provides sensation to the maxillary region
- Branches include infraorbital, anterior superior alveolar, zygomatic, palatine, nasal, and posterior superior alveolar.
Mandibular (V3):
- Provides sensation to the mandibular region
- Branches include motor branches to the four muscles of mastication, auriculotemporal(sensory to scalp behind jaws), inferior alveolar, lingual, and buccal.
Trigeminal Nerve V GSS modality:
- Cell bodies of sensory neurons are located in the trigeminal (semilunar) ganglion.
- These neurons carry sensory information from:
- Face and anterior scalp. •Conjunctiva and eyeball.
- Paranasal sinuses.
- Nasal and oral cavities.
- Anterior 2/3 of tongue.
- External surface of ear drum.
- Dura of middle and anterior cranial fossae.
Trigeminal Nerve (V) SVM modality:
Cell bodies of these motor neurons are located in the masticator nucleus. These motor neurons supply: •Muscles of mastication •Tensor veli palatini. •Tensor tympani. •Mylohyoid. •Anterior belly of digastric
Facial Nerve (VII)
The facial nerve is the primary motor nerve to muscles of facial expression.
•The facial nerve supplies muscles of facial expression derived from the second pharyngeal arch (hyoid arch) (SVM).
•The facial nerve also carries general sensory fibers (GSS) as well as special visceral sensory fibers (SVS).
•The facial nerve carries general visceral motor (GVM) fibers as part of the parasympathetic system.
Motor branches of the facial nerve include: •Temporal •Zygomatic •Buccal •Mandibular •Cervical
SVM, GSS, SVS, GVM
Facial Nerve (VII) SVM
Cell bodies of these motor neurons are found in the motor nucleus of CN VII.
Nerve fibers exit through the stylomastoid foramen.
Supply mimetic muscles: •Temporal •Zygomatic •Buccal •Mandibular •Cervical
Also supply: •Stapedius •Stylohyoideus •Posterior digastric
Facial Nerve (VII) GSS
Cell bodies of these sensory neurons are located in the geniculate ganglion.
Supply: •Part of external ear
Facial Nerve (VII) SVS:
Cell bodies of these sensory neurons are located in the geniculate ganglion.
Carry taste sensation from anterior two-thirds of tongue and hard and soft palates.
Cell bodies of primary sensory neurons are located in geniculate ganglion.
Secondary neurons originate from solitary nucleus.
Tertiary neurons end in thalamus.
Facial Nerve (VII) GVM:
Cell bodies of preganglionic neurons are located in: •Superior salivatory nucleus and lacrimal nucleus
Cell bodies of postganglionic neurons are found in: •Submandibular (sublingual) and pterygopalatine ganglia.
Supplies: •Lacrimal gland •Submandibular and sublingual glands •Mucous glands (oral and nasal)
Peculiar branches of the facial nerve split off from inside the petrous part of the temporal bone before the nerve leaves the stylomastoid foramen and carry the parasympathetic part of the facial nerve.
Greater petrosal nerve: •Merges with deep petrosal nerve carrying sympathetic fibers from around the internal carotid. •The two petrosal nerves join to form the nerve of the pterygoid canal.
Chorda tympani: •Branches from facial nerve inside the petrous portion of the temporal bone. •Emerges into the rear of the middle-ear cavity and runs along the inner surface of the eardrum. •Joins lingual nerve of V3.
Glossopharyngeal Nerve (IX)
Modalities of CN IX include SVM, GVM, GVS, GSS, and SVS.
SVM: •Cell bodies of these motor neurons are found in the nucleus ambiguous. •These motor neurons supply the stylopharyngeus muscle (third arch).
GVM: •Cell bodies of preganglionic neurons are in the inferior salivatorynucleus. •Cell bodies of the postganglionic neurons are found in the otic ganglion. •Supply the parotid gland
GVS: •Cell bodies these sensory neurons are found in the inferior ganglion. •These neurons carry sensation from the carotid body and carotid sinus.
GSS: •Cell bodies these sensory neurons are found in the superior or inferior ganglion. •These neurons carry sensation from the: •Posterior one-third of the tongue •External ear •Middle ear cavity
SVS: •Cell bodies of these sensory neurons are found in the inferior ganglion. •These neurons carry taste sensation from the posterior third of the tongue.
