Chapter 7 Flashcards
Through where does medulla oblongata leave the skull?
Medulla oblongata of occipital bone
Neurocranial side
Inside of cranium
When medulla oblongata leaves the skull it is called the
Spinal cord
Where does integration of information take place?
CNS, collects sensory info from PNS
Three groups of structures in peripheral nervous system
- 12 pairs of Cranial nerves: part of PNS, can carry sensory and motor info , some carry both)
- Spinal nerves: nerves that bundle and exit out of the spine
- Ganglia:cell bodies with dendrites in PNS. Relay station. Junction box for pns communications.
Cranial nerves branch off what?
Directly off the brain
What passes through foramen?.
Blood vessels, arteries and cranial nerves enter and leave
Pneumonics for 12 cranial nerves
Oh
Oh
Oh
To
Touch
And
Feel
Very
Green
Vegetables
A
H
Olfactory nerve I
Think about furthermost structure of face. Nose
Sensory only
Olfactory nerves actually exit skull through
Olfactory foramina of cribiform plate of ethmoid bone. Go through those openings and receptors protrude onto surface of olfactory epithelium that we find in superior region of nasal cavity. Receptors hang off roof of epithelium of nasal cavity
Cribiform plate has large collection of teeny, tiny holes called
Olfactory foramina
Optic nerve 2
Sensory only
Info comes from retina
Optic nerve travels through
Optic canal of sphenoid bone and into back of eye
Left and right optic nerve 2 cross over importance
Important for processing sensory visual information
Optic chiasma
Crossing over of optic nerves .
Oculomotor III
Movement of eye
Skeletal muscle and involuntary movement like dilation of pupils
Carries motor info
What kind of muscle makes up iris in eye?
Smooth ciliary muscle
When eye dilates it is what kind of innervation?
Sympathetic innervation
When pupil constricts it is what kind of innervation?
Parasympathetic
Which skeletal muscles are controlled by oculomotor nerve?
Superior rectus
Inferior rectus
Medial rectus
Inferior oblique
Trochlear IV
Controls superior oblique muscle
Innervates an extrinsic eye muscle that loops through a pulley-shaped ligament in orbit
Depresses eye and turns laterally
Trochlea means
Pulley
Largest of cranial nerves
Trigeminal nerve V
Three divisions of trigeminal nerve V
Opthalmologic,
Maxillary,
Mandibular
Trigeminal nerve V
Innervates large areas of face, involved with muscles of mastication
Trigeminal neuralgia
Most painful,
Artery pressed again nerve
Abducens VI
Contracts lateral rectus
Three cranial nerves involved with eye movement are
Oculomotor III
Trochlear IV
Abducens VI
3 IV and VI
Facial nerve VII
Info from anterior 2-3 of tongue
Express emotions , zygomaticus major and minor, risorious, buccinator,
Vestibulocochlear VIII
Controls hearing and equilibrium, has 2 divisions
Cochlear
Collects sensory info from inner ear, collects info in inner ear
Functions of inner ear
Perception of sound and balance
Vestibule
Turns sensory information into static equilibrium
So if head is down or back. Uses otoliths that float in gelatinous mass when you move your head
Divisions of vestibulocochlear nerve?
Vestibular
Cochlear
What controls dynamic equilibrium
3 Semicircular canals perceive rotation
Glossopharyngeal IX
Muscles of swallowing (tongue and pharynx)
Sensory information through taste buds and posterior 1/3 of tongue
Vagus nerve X
Huge 90% of nerve fibers carried on parasympathetic nervous system come from vagus nerve
Parasympathetic nerve
Controls heart rate, innervates digestive viscera,
Some sensory info from taste buds around epiglottis
Hypoglossal nerve XII
Below tongue,
Tongue movement,
Glosso
Tongue
Accessory nerve XII
Innervates sternocleidomastoid muscle and trapezius
Sterno
Sternum
Cleido
Clavicle
Mastoid
Mastoid process
White matter on spinal cord is on
Outside
Spinal cord is collection of
Neurons and glial cells
Motor neurons exit and sensory neurons enter
Ventral root function
Carries motor info out to body, somatic or voluntary motor movement & autonomic motor neurons. Can move skeletal, smooth or cardiac muscles, or stimulate glands
Efferent direction after processing in brain
Function of dorsal root?
Sensory information, routes info in afferent direction towards brain
Dorsal root ganglion made of
Unipolar, sensory cell bodies packaged in connective tissue
Sensory information arrives from
Periphery of body, through unipolar sensory neurons and then through axon heading to spinal cord, connecting with interneurons that get info all the way up into cortex of frontal lobe
Has lots of axon bundles
Ventral nerve
Nerve
Many axons of neurons bundled together into a thick tube. Held together by layers of connective tissue
Spinal reflex
Pat on patellar tendon
Sets off sensory stretch receptors because it pulls on quadriceps tendon
Sensory information travels down unipolar neuron
Info at the end of axon branches into synaptic knobs
In very simple reflex,Motor info travels back out, makes quadriceps contract and extend
In the polysynaptic reflex, the axon synapses with the interneurons..
Tells hamstring to not move.
Types of reflexes
Monosynaptic: one synapse
Polysynaptic reflexes:more than one synapse
Sensory stretch receptors types
Golgi sensory organ,
Spinal organ
Sensory stretch receptors function
Measure tension in muscle tissues and tendons.
Let you exert more force or cause you to stop exerting if that tendon could be destroyed
Unipolar neurons have how many cytoplasmic extensions?
One
Which systems are involved in reflexes
Peripheral nervous system, CNS, connection between neurons in the CNS and spinal cord
And interneuron
Explain the structure of a nerve
A spinal nerve has different components
At the smallest level
Axons surrounded by an endonerium fascia,
These groups of axons make fascicles surrounded by a perineurium and groups of fascicles are surrounded by and epineurium
Endonerium
Surrounds individual axon and schwann cells
Fascicle
Bundle of axons together
Perineurium
Wrap around fascicles , made of dense connective tissue
Peri
Around the edge
Epineurium
Wraps around all fascicles
Endo
To the inside
Nerve plexus
Nerves criss cross and information enters and leaves.
Dense connections of nerves
Satellite cells in dorsal root ganglion
Packed tightly around edges of cell bodies of sensory neurons in dorsal root ganglion
What is the function of Schwann cells in the peripheral nervous system
They myelinate the axons so that you can get saltatory conduction for faster transmission of action potentials
Satellite cells
Support the neurons
Dermatomes
Map to specific regions on the spinal cord.
If someone has a loss of sensation on one or more of the dermatomes, it can help find location of spinal injury.
Provides sensory neurons for sensation of touch on face
Trigeminal V
Plexuses in body
Cervical
Brachial
Lumbar
Sacral
Brachial
Upper arm
Lumbar
Lower back
Sacrum
Posterior between hip bones
Why are plexuses important?
Injuries and trauma can cause problems because there’s so many nerves in there.
Have to be avoided during surgeries
Bursitis
Inflammation of bursa
Bursae
Closed, fluid filled sacs that work as cushions and gliding surfaces to reduce friction between tissues of the bodym
Largest nerve in body
Sciatic nerve
Sciatic nerve
Bundling of tibial nerve and fibular nerve
Supplies entire lower limb except for the anteromedial thigh
Largest branch of sacral plexus
Sciatica
Pain, weakness, numbness, tingling in leg. Caused by pressure on sciatic nerve. Shooting pain from lower buttock down to leg
Phrenic nerve
Part of C3,C4& C5 regroup to form phrenic nerve
Innervates the diaphragm.pulls pleura of lungs down to create vacuum.
Controls ability to breathe
C3-C4
Breathe no more
Which reflex is particularly important for maintaining balance?
Crossed-extensor reflexes
Which branches of a spinal nerve only contain autonomic fibers?
Rami communicantes
Reflexes that come from practice and repetition are known as
Acquired reflexes
If a patient has difficulty using the pincer grasp to pick up small objects, which nerve is injured?
Median nerve
Hilton’s law states that
Any nerve serving a muscle that causes a movement at the joint Also innervates the joint and the skin over the joint
The pinching motion is highly dependent on impulses transmitted by the
Median nerve
The brachial plexus is formed by the ventral rami from
C5-T1
Median nerve
Descends through arm to anterior forearm. Branches to skin and most flexor muscles.
Flex wrist,
Fingers, oppose the thumb
Innervates five intrinsic muscles of lateral Palm
Median nerve
Axillary nerve innervates
Deltoid and Teres minor muscles and skin, skin and joint capsule of shoulder
Provides cutaneous sensation in lateral forearm
Musculocutaneous nerve
Innervates most intrinsic hand muscles and the skin of the medial aspect of the hand. Causes hand and fingers to flex (with median nerve) adducts and abducts the medial fingers
Ulnar nerve
Crossed extensor reflex
Helps maintain balance
Made of ipsilateral withdrawal reflex and contralateral extensor reflex.
Ipsilateral causes you to lift injured foot, contralateral lets opposite leg support the weight being shifted
Superficial reflexes
Caused by gentle cutaneous stimulation depend on functional upper motor pathways and on cord level reflex arcs
Abdominal and plantar reflexes
Rami communicantes
Branches of a spinal nerve that only contain autonomic fibers
The cervical plexus is made of which ventral rami?
C1-C4
The lumbar plexus is made of which ventral rami?
L1-L4
Which component of a reflex arc responds to efferent impulses?
Effector
Which reflex tests the integrity of the spinal cord from L4 to S2?
Which structure belongs to the projection level of the motor control hierarchy?
Primary motor cortex
Which nerve when struck accounts for hitting your funny bone?
Ulnar nerve. Very vulnerable to injury.
Stretch reflex
Important in large extensor muscles that sustain upright posture and in postural muscles of the trunk
Tendon reflex
Causes muscle to relax and lengthen in response to tension
Plantar reflex
Tests integrity of spinal cord from L4 -S2.
Determines if corticospinal tracts are functioning properly.
Reflex arc parts
- Receptor
- Afferent neuron
- Interneuron and info processing in CNA
- Efferent neuron. Communicates with muscle or gland
Reflex
Subconscious stimulus response mechanism.
Can be superficial or deep
Why are reflexes tested?
To find abnormalities in reflex pathway. May indicate problems within PNS or CNA.
Tests contractions of muscles
Monosynaptic reflexes
Single synapse between afferent and efferent neuron
Ex. Patellar reflex
Muscle spindles
Receptors within muscles
Respond to stretch innervated by sensory neurons
Stretch reflex
Cause muscle contraction in response to increased muscle length
Polysynaptic tendon reflexes
Muscles relax and lengthen in response to tension
Which reflex maintains muscle tone?
Stretch reflex
Somatic reflexes
Activate skeletal muscle
Autonomic reflexes
Activate smooth, cardiac muscle, or glands
Motor system hierarchy
Pre-command (highest)
Projection (middle)
Segmental (lowest)
What occurs at the pre-command level of the motor control hierarchy?
Cerebellum and basal nuclei
Programs and instructions for motor control. Think muscle memory. Affected by sensory input auditory, vestibular or visual or spinal cord
What occurs at the projection level of the motor control hierarchy?
Gives instructions to the spinal cord’s motor neurons and sends a copy of that information to higher levels. Higher level checks commands
Motor cortex and brain stem
What occurs at the segmental level?
Central pattern generators
Spinal cord
Motor neurons in ventral horn contains CPGs that can be used for motor output
Reflexes that don’t interact with brain
Perceived by senses, go through spinal cord, come in contact with CPGs and cause motor output
Prevents over stretching of a muscle
Stretch reflex. Makes sure that muscles stays that length
Which of the following reflexes tests the integrity of the spinal cord from L4 to S2?
Drawing blunt object downward lateral aspect of foot causing curling of toes
When are stretch reflexes hypoactive?
Peripheral nerve damage or ventral horn injury of tested area.
Absent in diabetes mellitus, neurosyphilis, coma
When are stretch reflexes hyperactive?
Lesions of corticospinal tracts reduce the inhibitory effect of the brain on the spinal cord (like in stroke patients)
Damage of ulnar nerve can lead to
Sensory loss, paralysis and muscle atrophy.
Affect ability to make fist and grip objects.
Can lead to hyper extension and claw hand
Irritation of phrenic nerves caused
Spasms of diaphragm or hiccups
What happens if C3-C5 is destroyed?
Diaphragm is destroyed and respiratory arrest happens
Transection of sciatic nerve would cause
Impair lower limbs
No flexion, causes foot drop,
Intrinsic reflex
Rapid, predictable motor response to a stimulus. Maintain
Nerves in branchial plexus
Musculocutaneous nerve
Axillary nerve
Ulnar nerve
Radial nerve
Radial nerve function
Posterior muscles of arm and forearm
Maintaining posture is an example of which kind of reflex?
Intrinsic
Largest terminal nerve of the lumbar plexus
Femoral nerve. Motor branches innervate anterior thigh muscles
Sciatic nerve supplies entire lower limb except for
Anteromedial thigh
Pudendal neeve
Innervates muscles and skin of perineurium, stimulates erection and control urination
In traumatic blows to the head, the ethmoid bone can be broken or fibers passing through the ethmoid may be torn as the brain moves inside the cranium. The condition that results would be
Anosmia, loss of smell
Anosmia loss of smell caused by
Fracture of ethmoid bone or lesions of olfactory fibers, resulting in total or partial loss of smell
Damage to optic II nerve results in
Blindness in eye severed by nerve
Injury to one accessory XI nerve causes
SCM paralysis, head turns to one side
Shrugging shoulder becomes difficult
Vagus(X) nerve is important for maintaining
normal state of visceral organ activity
Supplies 4 of 6 extrinsic eye muscles
Oculomotor
Damage to this cranial nerve might lead to drooping of the eye and an eye that deviates laterally at rest
Oculomotor
Anopsia refers to
Visual defect
Damage to visual pathway beyond optic chiasma results in
Partial visual losses
Effect of injured or impaired glossopharyngeal IX nerves
Impair swallowing and taste
Oculomotor nerve paralysis
Eye can’t move up, down or inward. At rest eye rotates laterally because actions of two extrinsic eye muscles are unopposed
Upper eyelid droops and has double vision. Can’t focus on close objects
Damage to facial nerves results in
Bell’s Palsy, facial muscles are paralyzed on affected side. Partial loss of taste sensation
Abducens nerve paralysis
Eye can’t move laterally. At rest, eyeball rotates medially
Recurrent dryness of mouth may be an issue with which cranial nerve?
VII (facial)& IX (glossopharyngeal)
Innervates salivary glands
Inflammation of trigeminal nerve
Excruciating pain. Lasts for few seconds but can be a hundred times a day . Provoked by sensory stimulus like brushing teeth or breeze on face
Vagal nerve paralysis
Hoarseness and loss of voice. Difficulty swallowing, impaired digestive system motility
Hypoglossal nerve XII damage
Difficulties in speech and swallowing
Do people with vestibulocochlear nerve lesions adapt
Maintain balance by using visual cues. May not present overt symptoms. If it happens slowly
If a person complains of double vision which cranial nerves might be affected?
3,4,6 are responsible for eye movement. Eyes may position themselves in different directions
Damage to this nerve leads to difficulty with speech and swallowing
Hypoglossal.
Tongue deviates if one is affected
if two are affected cannot protrude tongue
Considered accessory to the Vagus and was formerly called the spinal accessory nerve
Accessory
Which nerves are implicated in difficulty swallowing?
IX glossopharyngeal, X vagus, XII hypoglossal
Which cranial nerve means The wanderer
Vagus (vagabond) extends beyond head and neck to thorax and abdomen
Impairment of which cranial nerves are responsible for loss of sense of taste
VII facial
, IX glossopharyngeal
,X vagus
Patellar reflex function
Type of stretch reflex, helps keep knees from buckling when you are standing upright
the patellar reflex overview
- Tapping patellar ligament stretches the quadriceps and excites it’s muscle spindles.
2.afferent impulses travel to spinal cord, where synapses occur with motor neurons and interneurons
3.the motor neurons send activating impulses to the quadriceps causing it to contract extending the knee.
- The interneurons make Inhibitory synapses with ventral horn neurons that prevent antagonist muscles (hamstrings) from resisting the contraction of the quadriceps
