Nervous system Flashcards
what is a neuron
- nerve cell composed of a cell body and neural processes
what is a nerve
- bundle of neural processes outside the CNS; a portion of the PNS
what is a synapse
- junction between 2 neurons where neural impulses are transmitted
what is innervation
- supply of nerves to tissues or organs
what is a ganglion
- accumulation of neuron cell bodies outside the CNS
what is an afferent nerve
- ‘sensory nerve’ carries information away from the periphery of the body to the brain or spinal cord
what is an efferent nerve
- ‘motor nerve’ carries info away from brain or spinal cord to the periphery of the body
what are neurotransmitters
- chemical agents discharged from the neuron that transmit signals from a neuron to a target cell across a synapse
CNS contains:
- the brain and spinal cord
PNS contains:
- nerves stretching from the CNS
the PNS can be further broken down into
- afferent and efferent
the efferent system can be further broken down into:
- somatic (voluntary) and autonomic (involuntary)
the automatic nervous system can be further broken down into:
- sympathetic (fight or flight) and parasympathetic (rest)
CNI
- olfactory nerve
- has only a special sensory component
- transmits smell from nasal mucosa to the brain
- special afferent: special sense of smell (olfaction)
- enters the skull via perforations in the cribriform plate
CNII
- optic nerve
- has only a special sensory component
- conveys visual information from the retina to the brain (special afferent)
- enters the skull via the optic canal
what is the optic chiasma
- where the right and left optic nerves join
CNIII
- oculomotor nerve
- somatic motor (efferent)
- eye muscles (to move the eyeball)
- parasympathetic: ciliary ganglion, postganglionic fibers to small muscles inside the eyeball, constricts pupil
- exits skull via superior orbital fissure
CNIV
- trochlear nerve
- somatic motor (efferent)
- somatic motor innervates the superior oblique muscle (one of the eye muscles)
- exits skull via superior orbital fissure
CNV
- the trigeminal nerve
- largest of the cranial nerves
- name derives from the 3 major branches
3 divisions of CNV
1 - ophthalmic nerve (V1): sensory (superior orbital fissure)
2 - maxillary nerve (V2): sensory (foramen rotundum)
3 - mandibular nerve (V3): sensory and motor (foramen ovale)
- ophthalmic and maxillary are purely sensory
- mandibular is sensory and motor
CNVI
- abducens nerve
- somatic motor (efferent), eye muscle (the lateral rectus muscle)
- exits the skull via superior orbital fissure (sphenoid)
CNVII
- facial nerve
- efferent: motor to the muscles of facial expression. parasympathetic innervation of the lacrimal, submandibular and sublingual glands, as well as mucous membranes of nasopharynx, hard and soft palate
- special sensory (special afferent): taste sensation from the anterior 2/3 of tongue; hard and soft palates
- general sensory (general somatic afferent): tiny patch of skin behind ear
- passes through: internal acoustic meatus. exits skull via stylomastoid foramen
CNVIII
- vestibulocochlear nerve
- transmits sound and equilibrium (balance) information from the inner ear to the brain
- enters skull via internal acoustic meatus
CNIX
- glossopharyngeal nerve
- motor: supplies the stylopharyngeus muscle
- parasympathetic innervation: smooth muscle and glands of the pharynx, larynx and viscera of the thorax and abdomen
- general sensory (general somatic afferent): general sensory information from the skin of the external ear, internal surface of the tympanic membrane, upper pharynx and the posterior one-third of the tongue
- special sensory: taste sensation from the posterior third of the tongue
CNX
- vagus nerve
- motor: supplies the voluntary muscles of the pharynx and most of the larynx, as well as the palatoglossus
- parasympathetic innervation: to many organs in the thorax and abdomen including thymus gland, heart and stomach
- visceral sensory (visceral afferent)
- general sensory (afferent): skin around the ear
- special sensory (special afferent): special sense of taste from epiglottis
- passes through jugular foramen
CNXI
- accessory nerve
- has a cranial root and a spinal root, both of which consist of motor fibers
- motor - cranial root: innervates muscles of larynx and pharynx
- motor - spinal root: innervates the trapezius and sternocleidomastoid muscles
- exits skull via jugular foramen
CNXII
- hypoglossal nerve
- somatic motor (efferent)
- innervates all the intrinsic and extrinsic muscles of the tongue
- exits skull via hypoglossal canal
3 main branches of the trigeminal nerve V1: ophthalmic nerve
1 - frontal (roof of orbit): supraorbital and supratrochlear
2 - lacrimal (lateral roof of orbit)
3 - nasociliary (medial orbit): infratrochlear, ciliary, anterior ethmoidal (external and internal nasal), posterior ethmoidal
sensory innervation to trigeminal nerve V2: maxillary nerve
- maxilla (including its gingiva and teeth), overlying skin, maxillary sinuses, nasal cavity, palate, nasopharynx
sensory innervation to trigeminal nerve V3: mandibular nerve
- mandible (including its gingiva and teeth), overlying skin, tongue, floor of mouth, some soft palate
motor innervation to trigeminal nerve V3: mandibular nerve
- mandible: muscles of mastication, tensor veli palatini, anterior digastric and mylohyoid muscles
5 main branches of maxillary nerve (branches into 9 total)
- formed in the pterygopalatine fossa
- enters skull through foramen rotundum
1 - zygomatic nerve (enters skull via inferior orbital fissure): branches into zygomaticofacial (skin of cheek) and zygomaticotemporal (skin of temporal region) nerves
2 - infraorbital nerve (enters skull via infraorbital canal): branches into anterior superior (mx anterior teeth and associated tissues) and middle superior alveolar nerves (mx premolars and mandibular root of 6’s and associated tissues)
3 - posterior superior alveolar nerve (PSA): enters via foramina in mx tuberosity (mx molars and associated tissues and maxillary sinuses)
4 - greater and lesser palatine nerves (enter via greater and lesser palatine foramina): greater = posterior hard palate and lingual gingiva, lesser = soft palate and palatine tonsils
5 - nasopalatine nerve (enters via incisice foramen): anterior hard palate and lingual gingiva and nasal septum
5 main branches of mandibular nerve (branches into 8 total)
- starts branching in infratemporal fossa
- enters skull via foramen ovale
1 - buccal nerve (long) (on surface of buccinator, deep to masseter): long buccal (skin of cheek, buccal gingiva of mandibular posterior teeth)
2 - muscular branches (motor) (to muscles of mastication and TVP): muscular branches (medial pterygoid/tensor veli palatini, lateral pterygoid, masseter, temporalis)
3 - auriculotemporal nerve (deep to lateral pterygoid) (external ear and scalp, posterior to parotid gland)
4 - lingual nerve (passes under duct of submandibular salivary gland): anterior 2/3 tongue, lingual gingiva, floor of mouth
5 - inferior alveolar nerve (IAN) (travls through mandibular canal): includes mylohyoid nerve (mylohyoid and anterior belly of digastric * motor), mental nerve (chin, lower lip, labial mucosa of mandibular anteriors and premolars), and incisive nerve (mandibular premolars and anterior teeth and associated tissues)
efferent, special sensory and general sensory of the facial nerve (CN VII)
- efferent: motor to the muscles of mastication; parasympathetic innervation of the lacrimal, submandibular and sublingual glands, as well as mucous membranes of nasopharynx, hard and soft palate (more secretions)
- special sensory (special afferent): taste sensation from the anterior 2/3 of tongue; hard and soft palates
- general sensory (general afferent): tiny patch of skin behind the ear
- passes through: internal acoustic meatus, exits skull via: stylomastoid foramen
the facial nerve branches to which muscles
- hyoid muscles: stylohyoid muscle and posterior belly of digastric
- posterior auricular (occipital belly of epicranial)
- muscles of facial expression: 5 branches (temporal, zygomatic, buccal, mandibular and cervical)
what are ganglions
- cluster of cell bodies and is associated with parasympathetic nerve fibers
- parasympathetic: rest and digest: stimulations of glands (e.g. stimulation of salivary glands to help with digestion)
- otic ganglion
- submandibular ganglion
- pterygopalatine ganglion
what is the otic ganglion
- associated with parotid gland
what is the submandibular ganglion
- associated with submandibular and sublingual glands
what is the pterygopalatine ganglion
- associated lacrimal gland
2 main types of anesthesia/nerve blocks
- local infiltration
- nerve block
local infiltration
- type of injection where a small area (one or 2 teeth) is anesthetized by placing the anesthetic close to terminal nerve endings
- local infiltration works best in the maxilla
nerve block
- type of injection where a large area is anesthetized by placing the anesthetic near large nerve trunks
- nerve blocks are usually used in the mandible
maxillary nerve blocks
- ASA, MSA, PSA blocks
- infraorbital blocks
- nasopalatine block
- greater palatine block
ASA blocks
- anterior superior alveolar
- pulpal and vestibular gingiva of 1 to 3
- landmark: 2 (at depth of vestibule, angled towards apex of canine)
- for maxillary canine, centrals and laterals
MSA blocks
- middle superior alveolar
- pulpal and vestibular gingiva of 4, 5 and MB 6
- landmark: 5 (at depth of vestibule, anterior to zygomatic process of maxilla)
PSA block
- posterior superior alveolar
- pulpal and vestibular gingiva of 6 (except MB) to 8
- landmark: 7 (at depth of vestibule, posterior to zygomatic process of maxilla)
IO block
- infraorbital
- blocks ASA and MSA together
- also can freeze lower eyelid, side of nose and upper lip
- ***must massage IO foramen for 2 minutes after injection
- landmark: 4 (at depth of vestibule, lined up with infraorbital foramen)
NP block
- nasopalatine block
- lingual gingiva and palate from 3 to 3
- landmark: incisive foramen, behind central incisors
GP block
- greater palatine block
- lingual gingiva and palate for posteriors
- landmark: GP foramen (near 7, toward midline)
mandibular nerve blocks
- inferior alveolar nerve block
- lingual nerve block
- long buccal block
- mental/incisive block
IA and Li blocks
- interior alveolar and lingual blocks
- IA: pulpal of entire quad, vestibular gingiva 1-5
- Li: lingual gingiva, floor of mouth and tongue of entire quadrant
- landmark: height of coronoid notch, in pterygomandibular fold
deposition side for LB block
- long buccal block
- buccal gingiva of mandibular molars
- landmark: D and B to last mandibular molar
penetration site for mental/incisive block
- vestibular gingiva 1-5
- incisive block includes pulpal 1-5 ** must massage mental foramen for 2 minutes after injection
- landmark: mental foramen, between 4 and 5