nervous system Flashcards
what does the nervous system do in general (3)
- Perceives information
- Regulates body systems
- Performs tasks without consciousness on our part
body functions that the NS is responsible for (6)
- Muscle contractions
- Facial expressions
- Speech
- Mastication
- Secretion from Glands
- Sensations
what are the two divisions of the nervous system, keep in mind they are CONSTANTLY interacting
- central nervous system
- peripheral nervous system
- define neuron
- define nerve
- define synapse
- define neurotransmitters
- define innervation
- define ganglion
- Neuron: CELLULAR component of the nervous system composed of a cell body and a neural process
- Nerve: a bundle of neural processes
- Synapse: junction between two neurons OR between a neuron and an organ
- Neurotransmitters: chemical agents discharged from the cell to allow impulses to travel/cross the synapse to another cell
- Innervation: a supply of nerves to a body portion; allows transmission of information to and from the brain
- Ganglion: an accumulation of neural cell bodies OUTSIDE of the central nervous system
what are the types of neurons
- motors neurons: Carry signals AWAY from the CNS to muscles/glands (efferent) effects change
- sensory neurons: Carry signals TOWARD the CNS from sensory receptors (afferent). stimulus affects change
- what makes up the CNS
- what makes up the PNS
- brain and spinal cord
- cranial nerves outside of the brain and spinal nerves outside of the spinal cord
what are the divisions of the peripheral nervous system and what do they do
SOMATIC NERVOUS SYSTEM
- afferent/efferent components
- controls actions of skeletal muscles
- conscious control (voluntary)
AUTONOMIC NERVOUS SYSTEM
- without conscious control
- SYMPATHIC system: fight or flight response > causes xerostomia
- PARASYMPATHIC system: rest and digest response > stimulates salivary secretions for digestion
- maintains homeostasis of the body
where are the 12 paired cranial nerves connected?
where do they travel
they can be ___ or _____
- connected to the brain at its base
- pass through foramina
- either efferent or afferent; some have both types
what are the 12 cranial nerves, their types, AND what tissues they innverate
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- olfactory (sensory/afferent); nasal mucosa
- optic (sensory/afferent); retina of the eye
- oculomotor (motor/efferent); eye muscles
- trochlear (motor/efferent); eye muscles
- trigeminal (both); M/E: muscles of mastication and other cranial muscles S/A: face and head skin, teeth, oral cavity, and tongue
- abducens (motor/efferent); eye muscles
- facial (both); M/E: muscles of facial expression, other cranial muscles, lacrimal/submandibular/sublingual glands, minor parasympathetic glands. S/A: skin around the ear and tongue
- auditory (sensory/afferent); inner ear
- glossopharyngeal (both); M/E: stylopharyengeus muscle, and parasympathetic parotid gland. S/A: skin around ear and tongue
- vagus (both); M/E: muscles of the soft palate, pharynx, larynx, thorax, and abdominal organs parasympathetically. S/A: skin around ear and epiglottis
- accessory (motor/efferent); muscles of the neck, soft palate, and pharynx
- hypoglossal (motor/efferent); muscles of the tongue
what is CN 1
where does it exit
olfactory nerve (sensory/afferent)
exits through cribriform plate of ethmoid bone
what is CN 2
where does it exit
optic nerve (sensory/afferent)
optic canal
what are the EFFERENT nerves of the eye; what do they control
where do they ALL exit
- CN III, oculomotor, controls most of the eye muscles
- CN IV, trochlear, superior oblique muscle
- CN VI, abducens, lateral rectus muscle
ALL exit the skull via the superior orbital fissure
what are the divisions of the trigeminal nerve; what are their types; where do they exit the skull
CN V has 3 divisions
- Ophthalmic V1, afferent, superior orbital fissure
- Maxillary V2, afferent, foramen rotundum
- Mandibular V3, both, foramen ovale
what is CN VII
where does it exit
facial nerve (both)
exits skull via stylomastoid foramen
describe the efferent and afferent portions of the facial nerve
MOTOR/EFFERENT
- controls muscles of facial expression
- parasympathetic fibers control the lacrimal/submandibular/sublingual glands
SENSORY/AFFERENT
- skin behind the ear
- taste sensation
- body of tongue
what is CN VIII
where does it exit/what does it connect
what does it control
Vestibulocochlear/auditory nerve (sensory/afferent)
exits skull via internal acoustic meatus; connects inner ear to brain
nerves in the cochlea are for hearing, nerves in the semilunar canals are for balance
what is CN IX
where does it exit
Glossopharyngeal nerve (both)
exits skull via jugular foramen
describe the afferent and efferent parts of CN IX
MOTOR/EFFERENT
- pharyngeal muscle
- stylopharyngeal muscle
SENSORY/AFFERENT
- pharynx for taste and sensation at the base of the tongue
- soft palate
- palatine tonsils
- parasympathetic fibers control the parotid glands salivary flow
what is CN X
where does it exit
What does it control
vagus nerve (both)
exits skull via jugular foramen
MOTOR/EFFERENT
- muscles of the soft palate, pharynx, and larynx
- parasympathetic fibers connect to many organs including the thymus, stomach, and heart
SENSORY/AFFERENT
- skin around the ear and taste sensation for epiglottis
what is CN XI
where does it exit the skull
accessory nerve (motor/efferent)
exits skull via jugular foramen
what nerve innervates the cervical muscles
what else does it innervate
the TRAPEZIUS and STERNOCLEIDOMASTOID are innervated by CN XI (accessory nerve)
this nerve also innervates the muscles of the soft palate and pharynx
what CN’s make up the pharyngeal plexus
where do they all exit
what muscles do they play a role in innervating
CN IX, X, and XI (glossopharyngeal, vagus, accessory).
all pass through the jugular foramen
innervate muscles of the: soft palate, major neck muscles, and pharyngeal region
what area is this phrase describing:
Glossopharyngeal fibers join with the pharyngeal branches of the vagus nerve, which joins with the fibers of the accessory
nerve
the pharyngeal plexus
what is CN XII
where does it exit
what does it control
hypoglossal nerve (motor/efferent)
exits skull via hypoglossal canal
EFFERENT
- intrinsic and extrinsic muscles of the tongue
key factors about cranial nerve V (5)
- the trigeminal nerve is the largest CN
- has both afferent and efferent functions
- largest section of the nerve is afferent
- forms trigeminal ganglion located within the skull at the anterior surface of the petrous portion of the temporal bone
- three sensory divisions that arise from ganglion and exit through different foramen
what are the 3 major nerves of the ophthalmic division (smallest division)
ALL SENSORY/AFFERENT
- frontal nerve
- lacrimal nerve
- nasociliary nerve
what are the further branches of the frontal nerve, what do they innervate
SENSORY/AFFERENT
supraorbital nerve: innervates skin of the forehead and the anterior scalp
supratrochlear nerve: skin on the bridge of the nose and medial surfaces of the upper eyelid and forehead
what are the further branches of the lacrimal nerve, what do they innervate
no further branches SENSORY/AFFERENT
lacrimal nerve innervates:
- lateral portion of the eyelid
- conjunctiva
- parasympathetic fibers go to the lacrimal gland and stimulate tears
what are the further branches of the nasociliary nerve, what do they innervate
ALL SENSORY/AFFERENT
infratrochlear nerve: innervates skin on the medial eyelid and side of nose
ciliary nerve: innverates the eyeball
anterior ethmoid nerve: innervates nasal cavity and paranasal sinuses
External nasal nerve: innervates skin on the apex of the nose (branch of the anterior ethmoid nerve)
internal nasal nerve: innervates the anterior nasal septum and wall of the nasal cavity (branch of the anterior ethmoid nerve)
where does trigeminal v2 exit the skull
where does it enter the skull
what functions does it consist of
what general structures does it provide sensation to (6)
- exits skull through foramen rotundum
- enters skull in the pterygopalatine fossa
- afferent branches only
- provides sensation to the maxilla, overlying skin, maxillary sinuses, nasal cavity, palate, and nasopharynx
what are the further branches of trigeminal’s maxillary branch V2
ALL SENSORY/AFFERENT
- zygomatic nerve
- zygomaticofacial
- zygomaticotemporal - infraorbital nerve
- anterior superior alveolar
- middle superior alveolar - posterior superior alveolar nerve
- greater and lesser palatine nerves
- nasopalatine nerve
what are the branches of the zygomatic nerve and what do they innervate
SENSORY/AFFERENT
zygomaticofacial nerve innervates the skin on the cheek
zygomaticotemporal nerve innervates the skin on the temporal region
- the zygomatic nerve has parasympathetic fibers that go to the lacrimal gland
what does the infraorbital nerve provide innervation to
describe its pathway
SENSORY/AFFERENT
cutaneous sensation to the upper lip, medial portion of the cheek, lower eyelid, and nose
enters the infraorbital canal through the infraorbital foramen then passes to the pterygopalatine fossa
of the maxillary division, where does the ASA travel and what does it innervate
SENSORY/AFFERENT
- the anterior superior alveolar nerve joins the infraorbital nerve in the infraorbital canal
- it provides sensation to the maxillary anterior teeth and gingival tissues on the facial/labial side. sometimes crosses the midline. Innervates teeth 6-8 on the right and 9-11 on the left
of the maxillary division, where does the MSA travel and what does it innervate
how often is it present, if it’s absent where does innervation come from
- merges with the infraorbital nerve through the lateral wall of the maxillary sinus
- provides sensation to pulps of MAXILLARY PREMOLARS and the MESIAL BUCCAL portion of the FIRST MOLAR as well as surrounding periodontium and overlying gingiva
- only present 30% of the time, if it’s not present then innervation comes from the ASA or PSA
of the maxillary division, where does the PSA originate
where does the internal branches of the PSA enter and what do they innervate
what do the external branches of the PSA provide sensation for
- originates from the maxillary nerve in the pterygopalatine fossa
- internal branches enter the posterior superior alveolar fossa superiorly to the tuberosity > supplies innervation to DISTAL 2/3 OF FIRST MOLAR and SECOND AND THIRD MOLARS (all but MB of first molar); and the mucous membrane of the maxillary sinus
- external branches provide sensation for the facial/buccal gingiva overlying all 3 molars
greater and lesser palatine nerves are _____ while the nasopalatine nerve is ______
- bilateral
- single
both the greater and lesser palatine nerves travel ______ through the ____________ canal to go to the _______ bone
both the greater and lesser palatine nerves travel INFERIORLY through the PTERYGOPALATINE CANAL to go to the PALATINE BONE
where does the greater palatine nerve exit and what does it innervate
where does the lesser palatine nerve exit and what does it innervate
- greater palatine nerve exits through the greater palatine foramen and innervates the gingiva and hard palate of premolars and molars
- Lesser Palatine Nerve exits the
lesser palatine foramen and innervates soft palate and palatine tonsillar tissues
the nasopalatine nerve travels where, innervates what, and communicates with what other nerve
SINGLE NERVE, NOT PAIRED/BILATERAL
maxillary nerve > enters anterior palate via the incisive foramen
innervates the gingiva and hard palate of the canine and incisors (anterior teeth)
Communicates with greater palatine nerve
what is the largest division of the trigeminal nerve
what functions does it have
where does it emerge
what are the two trunks
- Mandibular division / V3
- afferent AND efferent
- emerges from foramen ovale of sphenoid bone
- has an anterior and posterior trunk
the anterior trunk of the mandibular nerve contains what further branches
- long buccal nerve (afferent)
- muscular branches (efferent)
what is the function of the long buccal nerve and what does it innervate
- afferent
- supplies sensation to the cheek and buccal mucosa of the mandibular molars
what is the function of the muscular branches; what does each branch innervate
- all efferent
- Deep temporal nerve: temporalis muscle
- masseteric nerve: masseter muscle
- lateral pterygoid nerve: lateral pterygoid muscles
which nerves are part of the posterior trunk of the mandibular nerve
- auriculotemporal nerve
- lingual nerve
- inferior alveolar nerve
what does the auriculotemporal nerve innervate
where do it’s parasympathetic fibers go
what does it communicate with
- afferent nerve that innervates the external ear and scalp
- parasympathetic fibers go to the parotid gland
- communicates with the facial nerve near the ear
where does the lingual nerve travel
what does it communicate with
what does it innervate
how can it be damaged
where do we anesthetize it
- LINGUAL nerve travels medial to the mandibular molars and lateral to the submandibular gland
- communicates with submandibular ganglion
- provides sensation/innervates the floor of the mouth and lingual gingiva of mandibular teeth
- can be damaged during dental procedures due to its close proximity to the molars
- can be anesthetized along with the inferior alveolar injection
INFERIOR ALVEOLAR NERVE
- where is the inferior alveolar nerve in comparison to the lingual nerve; where does it travel
- what does it innervate
- The inferior alveolar nerve is an afferent nerve that sits posterior to and parallels the lingual nerve on the medial side of the mandible. It enters the mandibular foramen and travels through the mandibular canal
- innervates/provides sensation to the mandibular teeth and the periodontium
which nerve is associated with a bifid-nerve or extra mandibular foramen
the inferior alveolar nerve :
In some anatomical variations, the inferior alveolar nerve may split into two branches before entering the mandibular foramen, creating a bifid appearance.
And, an extra mandibular foramen may be present, which can affect the course of the nerve as it innervates the lower teeth
what further branches does in inferior alveolar nerve split into
- mylohyoid nerve (both)
- mental nerve (afferent)
- incisive nerve (afferent)
where does the mental nerve exit
what does it innverate
the mental nerve (afferent) exits the mental foramen
provides sensation to the chin, lower lip, and labial mucosa of MANDIBULAR ANTERIOR TEETH
what does the incisive nerve innervate
the incisive nerve (afferent) is a continuation of the IA nerve and provides sensation to MANDIBULAR ANTERIOR TEETH AND PREMOLARS
is the mylohyoid nerve afferent or efferent
where does the mylohyoid nerve branch off
where does it travel
what does it innervate/supply
- both
- the mylohyoid nerve branches off of the inferior alveolar nerve just prior to the mandibular foramen
- it travels inferiorly and anteriorly in the mylohyoid groove of the mandible
- It supplies innervation for the mylohyoid muscle and the anterior belly of the digastric (EFFERENT). It sometimes supplies sensation to the mandibular first molar (AFFERENT)
what are the branches of the facial nerve (
NERVES INSIDE SKULL
- stapedius nerve
- greater petrosal
- chorda tympani
NERVES OUTSIDE OF SKULL
- posterior auricular
- stylohyoid
- posterior digastric
MUSCLES OF FACIAL EXPRESSION
- temporal branch
- zygomatic branch
- buccal branch
- marginal mandibular branch
- cervical branch
what are the functions of the facial nerve (CN VII)
where does it enter the skull
what branch does it FIRST give off
- afferent AND efferent
- enters the brain from the internal acoustic meatus within the petrous portion of the temporal bone, then travels through the facial canal
- small efferent branches that innervate the stapedius muscle (stapedius branches)
what are the 2 larger branches of the facial nerve
- greater petrosal nerve
- chorda tympani nerve
the greater petrosal nerve branches off of the facial nerve just before it exits the skull
describe the efferent AND afferent aspects of the greater petrosal nerve
EFFERENT
- efferent and parasympathetic fibers go to the pterygopalatine ganglion then join the maxillary nerve (v2) and go to the lacrimal gland, nasal cavity, and minor salivary glands of the hard and soft palate
AFFERENT
- nerve fibers for taste in the palate
where does the chorda tympani nerve exit the skull
what does it communicate with
describe the efferent AND afferent aspects of the chorda tympani nerve
- exits skull via petrotympanic fissure and travels with the lingual nerve to the floor of the mouth
- communicates with submandibular ganglion
- EFFERENT
- provides efferent parasympathetic fibers for the submandibular/sublingual salivary glands
AFFERENT
- provides afferent fibers for taste sensation to the body of the tongue
once the facial nerve exits the _________ it gives off 3 EFFERENT nerves, what are they and what do they supply
once the facial nerve exits the STYLOMASTOID FORAMEN it gives off 3 (EFFERENT) nerves:
- Posterior auricular nerve: innervates occipital belly of epicranial
- stylohyoid nerve: innverates the stylohyoid muscle
- posterior digastric nerve: innervates the posterior belly of the digastric muscle
after dividing into the posterior auricular, stylohyoid, and posterior digastric nerves, where does the nerve go?
it enters the parotid gland and divides into 5 major branches supplying the muscles of facial expression
temporal, zygomatic, buccal, marginal mandibular, and cervical
does the facial nerve innervate the parotid gland?
NO! it only passes through it
what do the branches for muscles of facial expression supply
temporal: anterior ear, frontal belly of the epicranial, superior part of orbicularis oculi, and corrugator supercilli
zygomatic: inferior part of orbicularis oculi, zygomaticus major and minor
buccal: muscles of the upper lip, the nose, buccinator muscle, risorius, and orbicularis oris
marginal mandiublar: muscles of the lower lip and mentalis muscle
cervical: platysma
From the brain, the facial nerve enters the skull via the __________________ and gives off two branches, the __________________ and the __________
The trunk of facial nerve exits skull through the ______________ of the temporal bone & gives off ______ nerves, the _________________, __________, and the ______________.
It continues forward passing THROUGH the ___________ gland and supplies the muscles of ___________ .
From the brain, the facial nerve enters the skull via the INTERNAL ACOUSTIC MEATUS and gives off two branches, the CHORDA TYMPANIC NERVE and the GREATER PETROSAL NERVE.
The trunk of the facial nerve exits the skull through the STYLOMASTOID FORAMEN of the temporal bone & gives off EFFERENT nerves, the POSTERIOR AURICULAR NERVE, STYLOHYOID NERVE, AND THE POSTERIOR DIGASTRIC NERVE.
It continues forward passing THROUGH the PAROTID gland and supplies the muscles of FACIAL EXPRESSION
what is facial paralysis and what are the causes (5)
- the loss of function to muscles of facial expression
- Secondary to brain injury usually by way of a stroke
- Direct injury (superficial location) or pathology to nerve
- Can be bilateral or unilateral
- Local anesthesia-usually due to local anesthesia deposited in the parotid is usually only transient
what is bells palsy
what theory is associated with it
- unilateral facial paralysis with no know cause, all or some of the branches may be involved, it can be a recurrent chronic problem
- nerve inflammation of possible viral origin-treat with antivirals and or anti-inflammatories.
parotid cancer, facial surgery, or facial laceration can cause what?
injury to the facial nerve resulting in unilateral facial paralysis
what is trigeminal neuralgia, what does it affect?
what are the symptoms? (2)
treatments (3)
- Idiopathic (no know cause)
- Affects afferent nerves of maxillary or mandibular divisions of the trigeminal nerve
- doesn’t affect ophthalmic division (possibly due to blood vascular pressure on the sensory
root of V2 or V3).
Symptoms:
- Excruciating pain when facial trigger zones are touched causing brief spasms.
- Trigger Zones vary but can include around eyes and ala of nose -the right side more often
Treatment:
- cutting the nerve
- alcohol injection into nerve
- anticonvulsants and antidepressants
