Nerves Flashcards
nervous system
Nervous system is an extensive, intricate network of neural structures that activates, coordinates, and controls all functions of the body.
function of nervous system
carry messages or impulses based on electrical action potentials
nerve
a bundle of neural processes outside the central nervous system and in the peripheral nervous system.
synapse
the junction between two neurons or between a neuron and an effector organ, where neural impulses are transmitted.
innervation
A supply of nerves to a specific body part that allows for information to be carried back & forth from body part to brain.
ganglion
An accumulation of neuron cell bodies outside the central nervous system
nodes of ranvier
Gap in the myelin sheath, allowing for faster conduction of impulses
how do impulses travel
Impulse travels along myelinated axons via saltatory conduction
how much of a nerve has to be covered with local anesthetic
8-10mm
central nervous system
Consists of brain & spinal cord
Surrounded by bone
peripheral nervous system
Consists of all the nervous tissue outside of these organs
Somatic – operates with conscious control
Autonomic – operates without conscious control
Sympathetic – “fight or flight”
Parasymphetic – “rest or digest”
afferent
sensory
Carries information from the periphery of body TO the brain
Taste, pain, proprioceptionProprioception: info about movement, equilibrium & positioning of the body
efferent
motor
Carries information AWAY (exiting) the brain to periphery of body
Gives orders to muscles to activate them
2 Divisions:
Somatic & Autonomic
somatic nervous system
Includes all nerves controlling the muscular system & external sensory receptors
Operates with conscious control
Autonomic Nervous System
“Caretaker of the body”
Operates without conscious control (it just does it)
Has 2 divisions:
Sympathetic
Parasympathetic
Sympathetic
Fight or flight
Response leads to hyposalivation = dry mouth
Parasympathetic
Rest or Digest
Response leads to stimulation of salivary glands
Saliva flow aids in digestion
Peripheral nervous system two types of nerves
sensory, efferent
afferent
Carries information from the periphery of body TO the brain
Taste, pain, proprioceptionProprioception: info about movement, equilibrium & positioning of the body
efferent
Carries information AWAY (exiting) the brain to periphery of body
Gives orders to muscles to activate them
2 Divisions:
Somatic & Autonomic
Somatic nervous system
Includes all nerves controlling the muscular system & external sensory receptors
Operates with conscious control
Autonomic Nervous System
“Caretaker of the body”
Operates without conscious control (it just does it)
Has 2 divisions:
Sympathetic
Parasympathetic
cranial nerves
Emerge from the inferior surface of the brain
All pass through the foramina of the skull & innervate structures in the head, neck, & facial region
Cranial Nerve I – Olfactory
Afferent (sensory)
Transmits smells from the nasal mucosa to the brain
Enters skull through cribriform plate in the ethmoid bone
Cranial Nerve II – Optic
Afferent (sensory)
Transmits sight from the retina to the brain
Enters skull through the optic canal of the sphenoid bone
Cranial Nerve III – Oculomotor
Efferent (motor)
Moves the eyeball & constricts pupil
Runs in the lateral wall of cavernous sinus
Exits skull through the superior orbital fissure of sphenoid bone
Cranial Nerve IV – Trochlear
Efferent for one eye muscle, proprioception
Runs in the lateral wall of cavernous sinus
Exits skull through the superior orbital fissure of sphenoid bone
Cranial Nerve V – Trigeminal
Sensory & Motor
Efferent to muscles of mastication & some cranial muscles
Afferent to teeth, tongue, oral cavity, skin of face & head
Three branches
Cranial Nerve V – Trigeminal origin and branches
Within the skull (temporal bone) this nerve has a bulge called the Trigeminal Ganglion
Anterior to the ganglion, the nerve divides into 3 branches
V1 Ophthalmic Sensory
V2 Maxillary Sensory
V3 Mandibular Sensory & Motor
Cranial Nerve VI – Abducens
Efferent for one eye muscle
Runs near the internal carotid artery, often affected by infections of the sinus
Exits skull through the superior orbital fissure of sphenoid bone
Cranial Nerve VII – Facial
Afferent (Sensory) & Efferent (Motor)
Afferent (sensory) to skin behind ear, taste sensation & body of tongue
Efferent to muscles of facial expression, lacrimal gland, submandibular & sublingual salivary glands