Anatomy Nervous System for Leatra
Astrocytes
-star shaped, processes cling to neurons and capillaries ▪ Provide structural support - anchor neurons to surrounding tissues and capillaries ▪ Maintain blood brain barrier-feet wrap around capillaries and controls uptake of selected materials from the blood ▪ Adjusts interstitial environment - recaptures released neurotransmitters and leaked ions ▪ Guides neuron development-directs growth of neurons and synapse formation
Cranial nerve 06 (VI)
Abducens
Superior and inferior ganglia
Contains cell bodies of sensory fibers of the vagus nerve associated with the external ear, taste buds, proprioceptors in muscles of the throat and neck
Sternocleidomastoid muscles
Draws head toward shoulder of the same side, flexes cervical part of the vertebral column; assists in elevating the thorax
Which three cranial nerves transmit impulses from taste receptors to the brain stem as you chew your food?
Facial (VII) - anterior taste buds; glossopharyngeal (IX) - posterior taste buds; vagus (X)
Which cranial nerves stimulate the production of saliva from salivary glands as you anticipate your meal?
Facial (VII), glossopharyngeal (IX)
Read the description of the accessory nerves. What is the origin of these nerves?
First five segments of the cervical portion of the spinal cord
How many branches are produced by the motor portion?
Five branches
Cranial nerve 09 (IX)
Glossopharyngeal
Which cranial nerves regulate muscles of the tongue, mouth, and throat to facilitate swallowing?
Glossopharyngeal (IX), vagus (X), hypoglossal (XII)
Read back through each description of the vagus nerve and make a list of all the organs and tissues innervated by the nerve:
Larynx, pharynx, lungs, heart, liver, and abdomen; soft palate for swallowing, external ear, taste buds, epiglottis, proprioceptors in muscles of the throat and neck; the heart, muscles of breathing, sweat glands, digestive organs; trachea
Identify the geniculate ganglion and describe its significance:
Located anterolaterally to the pons, prior to the branching of the 5 segments of the facial nerve; it serves the junction of the facial sensory fibers with the chorda tympani and greater superficial petrosal nerves
What is the function of chemoreceptors in the carotid body?
Monitor changes in blood chemistry
What is the function of baroreceptors in the carotid sinus?
Monitor changes in blood pressure
What is the function of the proprioceptors of swallowing muscles?
Monitor position of the tongue in the mouth
Cranial nerve 03 (III)
Oculomotor
Which nerve is responsible for accommodation of the lens and constriction of the pupil to enable close vision of this delicious meal?
Oculomotor (III)
Which nerves are responsible for motor control of the extraocular muscles as you glance back and forth at the food on your plate?
Oculomotor (III), trochlear (IV), abducens (VI)
Which five cranial nerves are designated as purely motor?
Oculomotor (III), trochlear (IV), abducens (VI), spinal (accessory) (XI), hypoglossal (XII)
Which nerve is responsible for your sense of smell as the delicious aromas rise from the plate?
Olfactory (I)
Which three cranial nerves are designated as purely sensory?
Olfactory (I), optic (II), vestibulocochlear (VIII)
Where is the limbic system found?
On the inner border of the cerebrum (between the hemispheres), above the diencephalon
Cranial nerve 02 (II)
Optic
Which nerve is solely responsible for the sense of sight as you see your waiter carrying your food to the table?
Optic (II)
Describe how the peripheral nervous system (PNS) is further divided in terms of function.
The PNS is divided into the somatic nervous system (SNS), which controls voluntary movement, and the autonomic nervous system (ANS), which controls involuntary, visceral functions. The ANS is further divided into sympathetic and parasympathetic divisions. The sympathetic division raises heart rate and other body functions in response to an emergency. The parasympathetic division is responsible for rest functions such as digestion.
From which branch of the aorta does the right common carotid artery arise?
The brachiocephalic trunk
What is the lowest of the chain ganglia?
The ganglion impar
Which lobe is located posterior to this sulcus?
The occipital lobe
Which division is responsible for rest functions such as digestion?
The parasympathetic division
Which sulcus defines the posterior border of the parietal lobe?
The parieto-occipital sulcus
Which two structures are shared by the brainstem and the hindbrain?
The pons and medulla oblongata
Identify these motor branches and describe the regions they innervate for the Zygomatic branch of the facial nerve:
Travels from the back of the jaw across the cheek, to the muscles and skin above the mouth and lateral to the nose
Identify these motor branches and describe the regions they innervate for the Buccal branch of the facial nerve:
Travels from the back of the jaw along the lower part of the cheek to the muscles and skin lateral to the mouth and nose
Identify these motor branches and describe the regions they innervate for the Cervical branch of the facial nerve:
Travels from the back of the jaw, down the lateral side of the neck
Cranial nerve 05 (V)
Trigeminal
Cranial nerve 04 (IV)
Trochlear
Somatic efferent fibers
control voluntary skeletal muscle contraction
Cell bodies of the sensory fibers are found in which two ganglia?
Superior and inferior ganglia
What are the two main parts of the nervous system and where are they found?
The central nervous system (CNS) is found in the skull and vertebral column. The peripheral nervous system (PNS) is found outside the skull and vertebral column.
Which nerves give rise to the two divisions of the autonomic nervous system?
The cranial nerves and sacral spinal nerves give rise to the parasympathetic division, and the lumbar and thoracic spinal nerves give rise to the sympathetic division.
Parasympathetic division
travels through cranial nerves and sacral spinal nerve and produces the rest and digest maintenance responses to store and conserve energy.
Sympathetic division
travels through thoracic and lumbar spinal nerves and produces the fight or flight responses to mobilize energy reserves and prepare for activity to deal with stress.
bipolar neurons
two extensions from cell body, one dendrite & one axon. Found in special sense organs.
axon hillock
where cell body tapers into the axon, site where the action potential originates.
Which branch of the right subclavian artery carries blood to the brain?
The right vertebral artery
Identify these motor branches and describe the regions they innervate for the Temporal branch of the facial nerve:
The side of the scalp and forehead; the region of the face lateral to the eye
What are the two divisions of the autonomic nervous system?
The sympathetic and parasympathetic divisions
Which division increases heart rate and other body functions in response to an emergency?
The sympathetic division
Which central nervous system nerves supply these divisions?
The sympathetic division nerves arise from the thoracic and lumbar spinal nerves, and the parasympathetic division nerves arise from the cranial nerves and the sacral spinal nerves.
Which lobe is located below this sulcus?
The temporal lobe
Describe the route taken by the sciatic nerve:
It travels from the lower back through the buttock and down the posterior part of the leg.
Oligodendrocytes
wrap cytoplasmic processes around the axons of neurons ▪ Forms a white fatty insulation material called a myelin sheath
List the major plexuses and state which spinal nerves give rise to them.
• The cervical plexus derives from C01-C04.• The brachial plexus derives from C05-C08 and T01. • The lumbosacral plexus derives from T12-S04. Alternately, the lumbar plexus derives from T12-L04 and the sacral plexus derives from L04-S04.
Receptor
detects stimulus
Interneurons
(association) between sensory and motor neurons, only in CNS.
soma
(cell body or perikaryon) contains nucleus and organelles
What is formed by the fusion of the two vertebral arteries?
The basilar artery
pseudounipolar neurons
appear to have one extension off the cell body. This extension branches forming a long axon with dendrites on one end and axon terminals on the opposite end.• Most sensory neurons of the PNS.
Central nervous system (CNS)
brain and spinal cord
Special sensory afferent fibers
carries impulses from nose, eye, tongue, and ear.
What are the functions of the sensory fibers of the facial nerve?
Transmit sensory signals from the taste buds in the anterior region of the tongue and proprioceptive signals from the muscles in the face and scalp
myelin sheath
insulation formed by glial cells wrapping around the axon
Synapse
junction between two neurons or a neuron and muscles, glands or cells Structure of a synapse
Afferent
neuron - relays info to CNS
Control center
region of the CNS that processes sensory information and sends motor commands.
motor output
response to stimuli by activating effector organs.
Internodes
segments of myelin
Membrane potential
separation of charge across the plasma membrane measured in volts
axon
single long process, transmits action potential away from soma
Satellite cells
surround cell bodies of neurons a. Isolates cell body and regulates exchange of nutrients and waste
Schwann cells
surrounds and protects axons in the PNS ▪ Forms myelin sheath around some axons of PNS
Depolarization
the membrane potential becomes less negative. When neurons are stimulated Na+ channels open and Na+ rushes into the cell.
Presynaptic neuron
transmits impulse towards the synapse.
Cranial nerve 07 (VII)
Facial
Cranial nerve 12 (XII)
Hypoglossal
To which regions of the brain and brain stem do these sensory fibers relay input?
Pons and gustatory cortex
Superior cervical (vagal) cardiac branch of the vagus nerve
Contributes to the cardiac plexus that innervates the heart; contains sympathetic fibers
Cranial nerve 10 (X)
Vagus
What is the function of the corpus callosum?
It is a commissure that connects the gray matter of the two cerebral hemispheres, allowing communication between the two sides of the brain and enabling integrated function.
What is the function of the hypothalamus?
It maintains homeostasis and is the main visceral control center of the brain.
axolemma
plasma membrane of an axon
Postsynaptic cell (neuron, muscle, gland, ect):
receives information from the presynaptic neurons.
Axon terminals
of the presynaptic neuron release neurotransmitters.
Neurilemma
outer layer that contains Schwann cell cytoplasm
Pons
It acts as a relay center between the higher brain centers and the spinal cord and contains nuclei responsible for breathing rhythms.
Cerebellum
It fine-tunes body movements and manages balance and posture.
Midbrain (mesencephalon)
It regulates vision, hearing, motor control, alertness, and thermoregulation.
Why do you think that damage to both vagus nerves is often fatal?
Since it regulates heart rate and breathing, loss of both nerves would prevent the body from self- resuscitation
Which region of the cerebral cortex will receive sensory input from this cranial nerve?
Somatosensory cortex and gustatory cortex
Which nerve is responsible for turning your head side to side to see what your friends have ordered?
Spinal accessory (XI)
What are the large, purple, segmented structures at the bottom of the view?
The hippocampi
Which sulcus defines the lateral border of the parietal lobe?
The lateral sulcus
Which branch of the left common carotid artery carries blood to the brain?
The left internal carotid artery
Which branch of the left subclavian artery carries blood to the brain?
The left vertebral artery
Graded Potential
a localized change in membrane potential that is short lived and dissipates as it travels. Can be stimulated by neurotransmitters binding to ligand gated channels, mechanical stress, or temperature change. If the stimulus is excitatory it will cause depolarization of the membrane
dendrites
branching extensions that contain receptors to detect neurotransmitters from other neurons.
Motor (efferent) neurons
carry commands from CNS to effector organs.
Sensory (afferent) neurons
carry sensory information from sensory receptors to CNS.
Neuroglia (glia)
cells that surround and support neurons
Ependymal cells
ciliated cells, line chambers filled with cerebrospinal fluid ▪ Monitor and maintain the composition of CSF ▪ Assist in the circulation of CSF
Autonomic efferent fibers
control involuntary cardiac muscle, smooth muscle and glands.
Action Potential
electrical impulse producing a brief reversal of the membrane potential that travels down the entire length of the axon from the axon hillock to the axon terminals. Rising (Depolarization) phase of the action potential- Na+ rushes in through voltage gated Na+ channelso Threshold Potential: V-gated Na+ Channels open at membrane potential of -55mV Falling (Repolarization) phase of the action potential- K+ rushes out through voltage gated K+ channels
axon terminals
enlarged distal ends of an axon that contain secretory vesicles filled with neurotransmitters (synaptic vesicles).
Synaptic cleft
fluid filled space where neurotransmitters are released
Nodes of Ranvier
gaps in the myelin sheath
Medulla oblongata
It relays messages between the brain and the spinal cord; controls involuntary functions of the respiratory, digestive, and pulmonary systems; and contributes to sensory functions.
Equilibrium potential
membrane potential at rest when the cell is not receiving information in the form of a graded potential or sending out information as an action potential. Resting potential is typically around -70 mV. Chemical gradients - higher [Na+] outside cell, higher [K+] inside cell
Efferent (motor) division
motor neurons carry commands away from CNS to effectors
multipolar neurons
multiple processes branching off the cell body, numerous dendrites and one axon
Microglia
oval cells with long thorny processes ▪ Remove cellular debris and pathogens
Cranial nerve 11 (XI)
Accessory
The sympathetic nerves form which three major plexuses?
Cardiac, celiac, and hypogastric
What are the functions of the motor fibers of the facial nerve?
Innervates facial, scalp, and neck muscles
What are the main roles of the limbic system?
It manages emotions and contributes to the processing of memory and smell.
Cerebrum
It regulates conscious thought, decision-making, speech, sensory perception, and memory.
Cranial nerve 01 (I)
Olfactory
Pharyngeal branch of the vagus nerve
Principle motor nerve of the pharynx
Superior laryngeal branch of the vagus nerve
Receives fibers from the superior cervical ganglion of the sympathetic trunk
Trapezius muscles
Rotation, retraction, elevation, depression of the scapulae; levitation of the clavicle; extends the neck; stabilizes the shoulder
Identify these motor branches and describe the regions they innervate for the Marginal mandibular branch of the facial nerve:
Runs along the lower jaw to the chin and the muscles below the lower lip
Do all the cranial nerves remain in the skull or do some travel out of the skull?
Some cranial nerves leave the skull.
Which brain system is responsible for processing emotions?
The limbic system
Look back through the exercise and make a list of all the cranial nerves that emerge from the midbrain:
The midbrain contains nuclei for the oculomotor nerve (III) and the trochlear nerves (IV).
Which cranial nerve is associated with motor control of the muscles of chewing as you take the first bite?
Trigeminal (V)
Look back through the exercise and make a list of all the cranial nerves that emerge from the medulla and pons:
Trigeminal (V), abducens (VI), facial (VII), vestibulocochlear (VIII), glossopharyngeal (IX), vagus (X), spinal (IX), hypoglossal (XII)
Which four cranial nerves are designated as mixed?
Trigeminal (V), facial (VII), glossopharyngeal (IX), vagus (X)
Which nerves would help you interpret the temperature of food in your mouth as hot or cold?
Trigeminal (V), glossopharyngeal (IX)
Which cranial nerve has parasympathetic fibers to control digestive activities of the stomach, liver, pancreas, and intestines?
Vagus (X)
Cranial nerve 08 (VIII)
Vestibulocochlear
After you finish this meal and decide to lie down for a short nap, which cranial nerve monitors your change in equilibrium?
Vestibulocochlear (VIII)
Which nerve is responsible for your sense of hearing as you hear the crunching of food in your mouth?
Vestibulocochlear (VIII)
Peripheral nervous system (PNS)
all nervous tissue outside CNS
Visceral afferent fibers
carries impulses from organs within ventral body cavities
Somatic afferent fibers
carries impulses from skin, skeletal muscles and joints
Efferent neuron
carries motor commands away from the CNS to the effector
Afferent (sensory) division
carry info from receptors to the CNS
sensory input
monitoring stimuli occurring inside and outside the body.
Effector
muscle or gland that responds to motor commands by producing the response.
Integration
processing of sensory input and formulation of motor commands.
