Nervous System Flashcards
_____is an extensive, intricate network of neural structures that activates, coordinates, and controls all functions of the body
The nervous system
The nervous system is an extensive, intricate network of neural structures that activates, coordinates, and controls all functions of the body, including:
• Muscle contraction
• Joint movements
• Stimulates glands to secrete
• Regulates the systems of the body (vascular system, digestive system, etc.)
• Allows sensation to be perceived
What are the two main divisions of the nervous system?
• Central nervous system: Brain and spinal cord
• Peripheral nervous system: All of the nervous tissue outside of the brain and spinal cord
The functional cellular component of the nervous system
Neuron
Neurons are composed of what three parts?
• Neural cell body
• Two types of cytoplasmic processes: Axon and Dendrite
___provides metabolic support for the entire neuron
Neural body
___transmits electrical impulses away from the cell body to other neurons or target tissues
Axon
____acts as the primary receiver of signals from other neurons
Dendrite
Long, thin, singular cable-like process
Axon
The axon is encased in
its own membrane and can also be additionally covered by a myelin sheath
What is a Myelin sheath?
• A fatty, insulating layer that wraps around the axons of nerve cells
• Acts like a protective coating
• Allows electrical impulses to travel quickly and efficiently along the nerve fiber
Threadlike process surrounding the cell body
Dendrite
Dendrites usually contains multiple_____
branches
Functions to receive impulses and conduct those impulses towards the cell body
Dendrites
Bundles or tracts of nerve fibers within the nerve
Fascicles
Bundle of neural processes outside the central nervous system and in the peripheral nervous system
Nerves
Nerves allow information to be
carried to and from the brain
Junction between two neurons that allows a signal to pass between them
Synapse
Two main types of synapses:
• Chemical
• Electrical
In order to function, tissues, structures and organs require ____
Innervation
Innervation
a supply of nerves to the body part
An accumulation of neuron cell bodies located in the peripheral nervous system
Ganglion
An appendage to a peripheral nerve where neuronal cell bodies are found outside the
CNS
ganglion
Ganglion are associated with ____nerves
all sensory and autonomic
Preganglionic fibers
the autonomic neuronal fibers that enter a ganglion
Postganglionic fibers
the autonomic neuronal fibers that leave the ganglion after synapsing with preganglionic fibers
Two types of nerves:
• Afferent nerves
• Efferent nerves
Afferent nerves
• Sensory nerves
• Carries information away from the periphery of the body, to the brain or spinal cord
• Touch, taste, pain, proprioception
Efferent nerves
• Motor nerves
• Carries information away from the brain or spinal cord, to the periphery of the body
• Activates muscles
• One motor neuron with its branching processes) may control hundreds of muscle fibers
The body is________, with positively and negatively charged ions floating around
electrically neutral
Some areas of the body have more positive ions, while other areas have more negative ions. Our body has barriers to keep the positive and negative ions separate until we are ready to use them
This barrier is the_____
neural membrane
Fluid outside the neural membrane has a___ charge
positive
Fluid inside the membrane has a____ charge
negative
The difference between the + and - charge is called
resting potential
Nerves work by____
depolarizing at the cell membrane to transmit impulses
Nerves work by depolarizing at the cell membrane to transmit impulses. This nerve impulse is called_____
action potential
Action potential spreads to____
adjacent areas, which sends the impulses
To send impulses across synapses, we need____
neurotransmitters (chemical agents)
Example of neurotransmitters
norepinephrine, acetylcholine, dopamine
The CNS has what two main divisions?
• Brain
• Spinal cord
The CNS is surrounded by
bone (skull or vertebrae), and a layering of membranes
The CNS is surrounded by bone (skull or vertebrae), and a layering of membranes. What is the purpose of this?
to protect the CNS
The membranes of the CNS are called
Meninges
What are the three layers of meninges?
• Dura mater: Also surrounds and supports the venous channels; Carry blood from the brain to the heart - these channels are the dural sinuses
• Arachnoid mater
• Pia mater
Also surrounds and supports the venous channels; Carry blood from the brain to the heart - these channels are the dural sinuses
Dura mater
Four major divisions of the brain:
• Cerebrum
• Cerebellum
• Brain stem
• Diencephalon
• Largest division of the brain
Cerebrum
The cerebrum consists of how many hemispheres?
Consists of two cerebral hemispheres
Function of the cerebrum
• Produces muscle coordination
• Maintains normal muscle tone and posture
• Coordinates balance
Second largest division of the brain
Cerebellum
Function of cerebellum
• Coordinates sensory data and motor functions
• Governs aspects of intelligence and reasoning, learning, and memory
What are the divisions of the brain stem?
Divisions include medulla, pons, and midbrain
Function of the medulla
Regulates heartbeat, breathing, vasoconstriction (blood pressure)
Houses reflex centers for vomiting, coughing, sneezing, swallowing, and hiccuping
Houses the cell bodies of the motor neurons for the tongue
The pons houses
the cell bodies for cranial nerves V and VII
The midbrain houses
relay stations for hearing, vision, and motor pathways
What is the function of the midbrain?
Regulates pain and mood
The Diencephalon primarily includes the
thalamus and hypothalamus
The thalamus is the
central relay point for incoming nerve impulses
The hypothalamus regulates____
homeostasis
What is homeostasis?
state of balance among all the body systems needed for the body to survive and function correctly
Runs along the dorsal side of the body; links the brain to the rest of the body
Spinal cord
The spinal cord is encased in
a series of bony vertebrae that comprise the vertebral column
Spinal column consists of what two components of brain substance?
• Gray matter - consists of unmelinized cell bodies and dendrites
• White matter - made up of bundles of myelinated axons
The spinal cord is responsible for______. It is also involved in___
carrying messages to and from the brain; reflexes that do not immediately involve the brain (responses that are automatic responses to stimuli
____is composed of all the nerves and nerve pathways in the body
PNS
PNS is composed of all the nerves and nerve pathways in the body, including:
• Pathways among the CNS
• Receptors
• Muscles
• Glands
PNS is further divided into what two systems?
• Sensory Nervous System or Afferent nervous system
• Motor Nervous System or Efferent nervous system
The Motor Nervous System of the PNS is subdivided into
somatic and autonomic nervous systems
The sensory Nervous System of the PNS processes input from the
environment
What input from the environment does the sensory nervous system of the PNS process?
• Sight
• Smell
• Taste
• Touch
• Hearing
Sensory nerves transmit information to the central nervous system (CNS) through the
peripheral nerves
This nervous system controls unconscious processes in the body
Autonomic nervous system
What are some unconscious processes that the autonomic nervous system controls?
• Breathing
• Digestion
• Heart rate
Contains sensory neurons that monitor the internal environment and make changes to maintain homeostasis
Autonomic nervous system
• The autonomic nervous system has both ____
motor pathways and sensory neurons
The autonomic system has what two divisions?
the sympathetic and parasympathetic nervous systems
Responsible for the “fight or flight” response, which is activated when the body is under stress or in danger
Sympathetic nervous system
Responsible for “rest and digest” mode, which is activated when the body is relaxed and not in danger
Parasympathetic nervous system
The cranial nerves are part of the ____nervous system.
Peripheral
There are ___paired cranial nerves
12
The 12 paired cranial nerves are all connected to the brain at its
base
The cranial nerves pass through the skull by way of___
fissures or foramina
The cranial nerves serve to innervate
structures in the head or neck
the tenth cranial or vagus nerve also descends into the
thorax chest) and abdomen where it innervates internal organs
Cranial nerves are either______
afferent or efferent (some are both)
Cranial nerves are numbered according to their
location in the brain (Anterior to posterior)
The cranial nerves are numbered by
Roman numerals (I to XII)
What is cranial nerve I?
Olfactory nerve
The olfactory nerve is an___ nerve
afferent
This cranial nerve transmits smell
Cranial nerve I or olfactory nerve
“Olfaction”
smell
The olfactory nerve enters the skull through
perforations in the cribriform plate of the ethmoid bone
The olfactory nerve terminates at the
olfactory bulb
What is cranial nerve II?
Optic nerve
The cranial nerve II an efferent or afferent nerve?
Afferent
The optic nerve or cranial nerve II enters skull through
optic canal of the sphenoid bone
In the skull, both right and left optic nerves join at the___
optic chasm
Fibers of the optic nerve___ before continuing into the brain
cross
What is cranial nerve III?
Oculomotor Nerve
The Oculomotor Nerve is an efferent or afferent nerve?
Efferent nerve
The oculomotor nerve is responsible for
eye movement and pupillary constriction
The oculomotor nerve or cranial nerve III is located in the
lateral wall of the cavernous sinus
The oculomotor nerve or cranial nerve III exits the skull through the
superior orbital fissure of the sphenoid bone
What is Cranial Nerve IV?
Trochlear Nerve
What type of nerve is the trochlear nerve?
Efferent nerve
The trochlear nerve is responsible for
eye movement and proprioception
What is Proprioception?
the body’s ability to sense movement, action, and location
The trochlear nerve is located
in the lateral wall of the cavernous sinus
The trochlear nerve exits the skull through the
superior orbital fissure of the sphenoid bone
What is cranial nerve V?
Trigeminal nerve
Is the trigeminal nerve an afferent or efferent nerve?
Both
Efferent fibers of the trigeminal nerve controls
the muscles of mastication and some cranial muscles
The Afferent fibers of the trigeminal nerve innervates
the teeth, tongue, oral cavity, and skin of
the face and head
Largest cranial nerve
Cranial nerve V or trigeminal nerve
The trigeminal nerve has what two roots?
Sensory and motor roots
The sensory root of the trigeminal nerve has what three divisions?
• Ophthalmic nerve (first division)
• Maxillary nerve (second division)
• Mandibular nerve (third division)
The Ophthalmic nerve (first division, V1) of the trigeminal nerve passes through the
superior orbital fissure
The Ophthalmic nerve (first division, V1) of the trigeminal nerve carries sensory fibers to:
• the eyeball, conjunctiva, lacrimal glands
• skin of the forehead, eyelid, and nose, and part of the nasal mucosa
The Maxillary nerve second division, V2) of the trigeminal nerve Passes through the
foramen rotundum
The Maxillary nerve second division, V2) of the trigeminal nerve carries sensory fibers to:
the middle third of the face
The Mandibular nerve (third division, V3) of the trigeminal nerve passes through the
foramen ovale
The motor root of trigeminal nerve travels with____
Mandibular nerve (third division, V3) of the sensory root of the trigeminal nerve
The Mandibular nerve (third division, V3) of the trigeminal nerve Provides sensory information from the
lower face, including the jaw, tongue, mouth floor, and cutaneous tissues between the lower lip and base of the mandible
The motor root of the trigeminal nerve supplies motor innervation to the
muscles of mastication and other muscles in the floor of the mouth
What is cranial nerve VI?
Abducens Nerve
The abducens nerve is a afferent or efferent nerve?
Efferent nerve
The abducens nerve or cranial nerve VI is responsible for
Eye movement
The abducens nerve or cranial nerve VI controls one muscle of the eye called the
Lateral rectus muscle
The abducens nerve or cranial nerve VI exits the skull through the
superior orbital fissure of the sphenoid bone
What is cranial nerve VII?
Facial nerve
Is the facial nerve an efferent or afferent nerve?
Both
The Efferent fibers of the facial nerve or cranial nerve VII controls the
muscles of facial expression and posterior supra hyoid muscles
The efferent portion of the facial nerve or cranial nerve VII also provides parasympathetic innervation to the
lacrimal gland, submandibular salivary gland, and sublingual salivary gland
The afferent portion of the facial nerve or cranial nerve VII serves
a tiny patch of skin behind the ear, and taste sensation with the taste buds of certain lingual papillae from the anterior two-thirds of the tongue
The facial nerve efferent fibers of the cranial nerve VII leaves the cranial cavity by passing through the _____and exits the skull through the____
internal acoustic meatus; stylomastoid foramen
The facial nerve Branches into what three segments?
• Facial nerve (Main trunk)
• Chorda tympani
• Greater petrosal nerve
What is Cranial Nerve VIlI?
Vestibulocochlear Nerve
The Vestibulocochlear Nerve or cranial nerve VIII is an afferent or efferent nerve?
Afferent
The vestibulocochlear nerve conveys signals from the
inner ear to the brain
The vestibulocochlear nerve functions in ___
Hearing and balance
Where is the Inner ear located?
in the temporal bone
Cranial nerve VIII or the vestibulocochlear nerve enters the cranial cavity through the
internal acoustic meatus
What is Cranial Nerve IX?
Glossopharyngeal Nerve
Is the glossopharyngeal nerve an afferent or efferent nerve?
Both
The efferent portion of cranial nerve IX or the glossopharyngeal nerve controls the
pharyngeal muscle and the stylopharyngeus muscle
The efferent portion of cranial nerve IX or the glossopharyngeal nerve controls the pharyngeal muscle and the stylopharyngeus muscle. It also provides parasympathetic innervation to the______
parotid salivary gland
The Afferent portion of the glossopharyngeal nerve innervates the____ and allows for____
oropharynx; taste and general sensation from the base of the tongue
_____is the afferent limb of the gag reflex
CN IX
Responsible for carrying sensory information about blood pressure to the brain along with the vagus nerve (X)
Afferent portion of the glossopharyngeal nerve or cranial nerve IX
Cranial nerve IX or the glossopharyngeal nerve passes through the skull at the
jugular foramen
CN IX has several branches, including:
• Tympanic branch
• Stylopharyngeal branch
• Tonsillar branch
• Lingual branch
• Carotid branch
• Pharyngeal branch
The Tympanic branch of CN IX supplies the
middle ear
The Tympanic branch of CN IX leaves the skull through the
foramen ovale of the sphenoid bone as the lesser petrosal nerve
Stylopharyngeal branch of the CN IX control the
stylopharyngeus muscle, which aids in swallowing and speaking
Tonsillar branch of the CN IX forms the
tonsillar plexus, which innervates the palatine tonsils
The Lingual branch of CN IX provides
general and taste sensation to the posterior third of the tongue
The Lingual branch of CN IX provides
general and taste sensation to the posterior third of the tongue
The Carotid branch of the CN IX innervates the
carotid artery
The Pharyngeal branch of CN IX combines with the vagus nerve (X) to form the
pharyngeal plexus, which innervates the mucosa of the oropharynx
What is cranial nerve X?
The vagus nerve
Is the vagus nerve or cranial nerve X an Efferent or afferent nerve?
Both
The large efferent component of the vagus nerve or cranial nerve X controls the
Muscles of the soft palate, pharynx, and larynx
The large efferent component of the vagus nerve or the cranial nerve X controls the muscles of the soft palate, pharynx, and larynx. It also provides parasympathetic innervation to
many organs in the thorax and abdomen (including the thymus gland, heart, and stomach)
The Afferent portion of the vagus nerve innervates
a small amount of skin around the ear, and provides taste sensation for the epiglottis
The three cranial nerves that carry taste information are
VII (facial), IX (glossopharyngeal), and X (vagus)
• Responsible for carrying sensory information about blood pressure to the brain along with the glossopharyngeal nerve (X)
Vagus nerve or cranial nerve X
Cranial nerve X or the vagus nerve passes through the skull at the
jugular foramen
What is cranial nerve XI?
The accessory nerve
Is the cranial nerve XI an efferent or afferent nerve?
Efferent nerve
Innervates the trapezius and sternocleidomastoid muscles
Cranial nerve XI
The accessory nerve or cranial nerve XI assists the vagus nerve (X) in
innervating the muscles of the soft palate and pharynx
The accessory nerve or cranial nerve XI assists the vagus nerve (X) exits the skull through the____
jugular foramen
What is Cranial Nerve XII?
Hypoglossal Nerve
is Cranial Nerve XII or the hypoglossal nerve an afferent or efferent nerve?
• Efferent nerve
The Cranial Nerve XII or the hypoglossal nerve innervates the
intrinsic and extrinsic muscles of the tongue
The Cranial Nerve XII or the hypoglossal nerve exits the skull through the
hypoglossal canal in the occipital bone
