Exam 3 - Spinal Cord Flashcards
The spinal cord begins as a continuation of the medulla oblongata (the most inferior portion of the brain stem) extending
from the foramen magnum of the occipital bone to its termination as the conus medullaris between L1 - L2.
I.E. spine runs from Medulla to L2 (conus medullaris)
Where does the spinal cord terminate?
conus medullaris between L1 - L2
What surrounds the spinal cord?
The spinal meninges (singular = meninx) surround the spinal cord, and are continuous with the cranial meninges, which encircle the brain
The three meninges, from outermost inward, are:
Dura mater (DOO-ra MĀ-ter) Arachnoid mater Pia mater (PĒ-a MĀ-ter)
The arachnoid is continuous with the…
arachnoid mater of the brain
Between the dura mater and the arachnoid mater is the______, which contains interstitial fluid
thin subdural space
the subdural space is full of?
interstitial fluid
Contains blood vessels that supply oxygen and nutrients to the spinal cord.
Pia mater
Is a thin transparent connective tissue layer that adheres to the surface of the spinal cord and brain
Pia mater
Between the arachnoid mater and the pia mater is a space filled with cerebrospinal fluid called the…
subarachnoid space
Membranous, thickened extensions of the pia mater that project laterally and fuse with arachnoid mater and inner surface of dura mater
Denticulate ligaments
Suspend the spinal cord within its dural sheath, protecting it against sudden displacement
Denticulate ligaments
Delicate strands of tissue emanating from the arachnoid mater
Arachnoid trabeculae
Span the subarachnoid space, connecting the arachnoid and the pia
Arachnoid trabeculae
Look at picture of slide 9… remember what he said about the arachnoid villae being near the dural sinuses***
Good job
In adults the spinal cord extends from the medulla oblongata (the inferior part of the brain) to the ____ of the second lumbar vertebra
superior border
The cervical enlargement and lumbar enlargement accommodate nerves to and from the…
upper and lower limbs, respectively
Inferior to the lumbar enlargement the spinal cord tapers to a conical-shaped portion termed the conus medullaris, which in adults ends at the level of…
the IV disc between vertebrae L1 & L2
The _______ is an extension of the pia mater that arises from the conus medullaris to anchor the spinal cord to the coccyx
filum terminale
Nerves that arise from the inferior part of the spinal cord do not immediately leave the vertebral column, but rather continue in the vertebral canal in fine strands collectively termed the ….
cauda equina (horse’s tail)
Lumbar puncture AKA
spinal tap
Lumbar puncture AKA spinal tap
After administration of a local anesthetic, long needle is inserted into the ____
subarachnoid space
Lumbar puncture AKA spinal tap
Patient lies on side with vertebral column flexed (similar to fetal position), which increases distance between….
spinous process of the vertebrae
Lumbar puncture AKA spinal tap
Uses of spinal tap?
Withdraw CSF for diagnostic purposes Introduce antibiotics Introduce contrast media **** Introduce anesthetics Administer chemotherapy Measure CSF pressure
Spinal nerves are the paths of communication between the spinal cord and…
the nerves innervating specific regions of the body
Spinal Nerves:
___ bundles of axons connect each spinal nerve to a segment of the cord
-Each bundle is called a ___, which in turn is composed of smaller bundles of axons called rootlets
-The roots are The posterior (or dorsal) root The anterior (or ventral) root
Two
root
Spinal Nerves:
-Each bundle is called a root, which in turn is composed of smaller bundles of axons called ____
-The roots are:
Two types
rootlets
The posterior (or dorsal) root The anterior (or ventral) root
Spinal Nerves:
-Each bundle is called a root, which in turn is composed of smaller bundles of axons called ____
-The roots are:
Two types or pathways?
rootlets
The posterior (or dorsal) root The anterior (or ventral) root
External Cord Anatomy
Each posterior root has a swelling, the posterior (dorsal) root ganglion, which contains….
the cell bodies of sensory neurons.
External Cord Anatomy
The anterior (ventral) root and rootlets contain axons of motor neurons, which conduct nerve impulses from…
the CNS to effectors (muscles and glands).
the bump on the external cords means what?
if it has a bump it is full of cell bodies therefore it is a POSTERIOR (DORSAL) root ganglion
The ___ matter of the spinal cord is shaped like the letter H, or a butterfly, and is surrounded by white matter
The gray ____ forms the crossbar of the H
gray
commissure
______ contain cell bodies of somatic motor neurons and motor nuclei that provide nerve impulses for the contraction of skeletal muscles.
Anterior horns
______ contain somatic and autonomic sensory nuclei. The gray commissure connects gray matter of the right and left sides.
Posterior gray horns
The ______extends the length of the spinal cord, and is continuous with the fourth ventricle in the medulla oblongata of the brain
central canal
The central canal extends the length of the spinal cord, and is continuous with the ____ in the medulla oblongata of the brain
fourth ventricle
Anterior to the gray commissure is the anterior (ventral) white commissure, which connects….
the white matter of the right and left sides of the spinal cord
Lateral gray horns are present only in….
the thoracic and upper lumbar, (T1 – L2 or T1 – L3) and sacral (S2 – S4) segments of the spinal cord.
______ contain cell bodies of autonomic motor neurons that regulate activity of smooth muscle, cardiac muscle, and glands.
Lateral gray horns
____ receives and integrates incoming and outgoing information
Gray matter
Poliomyelitis is caused by the poliovirus
Onset is marked by fever, severe headache, stiff neck and back, deep muscle pain and weakness
Polio
The virus produces damage and paralysis by destroying cell bodies of motor neurons in the anterior horn of the spinal cord and in nuclei of cranial nerves. It can cause death from respiratory or heart failure if the virus invades neurons in centers that control breathing and heart function
Polio vaccines have virtually eradicated polio in the U.S., but it still exists in other parts of the world
Polio
Polio damages what and where?
How can it cause death?
The virus produces damage and paralysis by destroying cell bodies of motor neurons in the anterior horn of the spinal cord and in nuclei of cranial nerves.
It can cause death from respiratory or heart failure if the virus invades neurons in centers that control breathing and heart function
The anterior and posterior gray horns divide the white matter into three broad areas called columns:
Anterior (ventral) white columns
Posterior (dorsal) white columns
Lateral white columns
Bundles of myelinated axons, called ____, have a common origin or destination, and carry similar information up or down the spinal cord
tracts
____ comprise axons that conduct nerve impulses toward the brain
Sensory (ascending) tracts
_____ carry nerve impulses down the spinal cord
Motor (descending) tracts
____ matter tracts ascend to or descend from the brain.
____ matter processes information input and output.
White
Gray
____ matter tracts ascend to or descend from the brain.
____ matter processes information input and output.
White: ascend or descend
Gray: input / output
Spinal nerves and the nerves that branch from them are part of the ______
They connect the _____ to sensory receptors, muscles, and glands in all parts of the body—i.e. spinal nerves connect the PNS to the CNS
There are ___ pairs of spinal nerves
peripheral nervous system
central nervous system
31
Spinal nerves are named and numbered according to….
the region and level of the vertebral column from which they emerge
Naming Spinal Nerves:
The first cervical pair emerges between the….
All other spinal nerves emerge through _____ between adjoining vertebrae
occipital bone and the atlas
intervertebral foramina
Spinal Nerves are named in sequence:
List # of pairs and their names
8 pairs of cervical nerves are named C1 – C8
12 pairs of thoracic nerves named T1 – T12
5 pairs of lumbar nerves named L1 – L5
5 pairs of sacral nerves named S1 – S5
1 pair of coccygeal nerves named Co1
Most spinal nerves exit ___ to the vertebra of the same number, the exception being …. ?
inferior
Exception: cervical nerves due to the fact that C1 exits superior to the atlas (which is the first cervical vertebra)
Spinal nerve names correlate with exit from vertebral column:
Spinal nerves do not necessarily exit the spinal cord in the same plane as….
Illustrated: spinal nerve L1 exits the vertebral column inferior to L1 vertebra, but it exits the spinal cord on a plane between T11 & T12 vertebrae
their corresponding vertebrae
Look at L1 on slide 32 of ppt
Spinal nerve names correlate with exit from vertebral column:
During early childhood, both the spinal cord and vertebral column grow longer as part of overall growth
Spinal cord elongation stops about age ____, but _____ growth continues
4 or 5 years
vertebral column
Spinal nerve names correlate with exit from vertebral column :
The consequence is the observed ____, and the fact that in adults, the spinal cord does not…
offset
extend the entire length of the vertebral column
Spinal nerve names correlate with exit from vertebral column :
The resulting cauda equina comprises roots of the….
lower lumbar, sacral, and coccygeal nerves
Several rootlets emerge from the dorsal and ventral surfaces of the spinal cord
The rootlets converge to form the….
The dorsal and ventral nerve roots unite at…
Each spinal nerve divides almost immediately into….
dorsal and ventral roots of the spinal nerves
their points of exit from the vertebral canal to form a spinal nerve
a dorsal primary ramus and a ventral primary ramus
The rootlets converge to form the….
dorsal and ventral roots of the spinal nerves
The dorsal and ventral nerve roots unite at…
their points of exit from the vertebral canal to form a spinal nerve
Each spinal nerve divides almost immediately into….
a dorsal primary ramus and a ventral primary ramus
Spinal nerves technically comprise only that brief interval between union of the dorsal and ventral roots, and subsequent division into
dorsal and ventral rami
Spinal nerves technically comprise only that brief interval between union of the ____, and subsequent division into dorsal and ventral rami
dorsal and ventral roots
Individual axons (myelinated or unmyelinated) are covered by an _____
Groups of axons comprise a ____
Each fascicle is wrapped in ____
The entire nerve is covered by an _____
endoneurium
fascicle
perineurium
epineurium
The _______ is a white matter motor pathway starting at the cerebral cortex that terminates on lower motor neurons and interneurons in the spinal cord, controlling movements of the limbs and trunk.
corticospinal tract
Each nerve divides into several branches just after passing through its ____
Each branch is a _____
Rami are the terminal branches of ____
intervertebral foramen
ramus (= branch; rami is plural)
spinal nerves
____ innervates deep muscles and skin of the dorsal surface of the trunk
The posterior (dorsal) ramus
_______ serves muscles and structures of the upper and lower limbs and the skin of the lateral and ventral surfaces of the trunk
The anterior (ventral) ramus
The ____ branch of each spinal nerve reenters the vertebral canal to supply the vertebrae and associated structures
meningeal
Other branches form the ____ and contribute to the trunk ganglia of the autonomic nervous system
rami communicantes
Except for most thoracic nerves, the ____ of spinal nerves do not go directly to the body structures they supply
Rather, they form networks on both the left and right sides of the body by joining with….
This network of axons is called a ____
anterior rami
…other axons from anterior rami of adjacent nerves
plexus (meaning braid, or network)
Principal plexuses:
Cervical plexus
Brachial plexus
Lumbar plexus
Sacral plexus
(Also, a smaller coccygeal plexus)
Nerves emerge from the ____
The nerve names are often descriptive of the general regions they serve, or the course they take
plexuses
Each of the nerves may have several branches, each named for…
the specific structure they innervate
There is no “thoracic plexus” corresponding to the cervical plexus, lumbar plexus, etc.
True
______ of spinal nerves T2 – T12 are called intercostal nerves. Another name for them is thoracic nerves.
Anterior rami
These nerves connect directly to the structures they supply, which are:
Thoracic Nerves or Intercostal Nerves which supply:
- intercostal muscles
- abdominal muscles
- skin overlying those muscles
_____ of the intercostal nerves supply the deep back muscles and skin of the posterior aspect of the thorax
The posterior rami
_____ are formed from the anterior rami of spinal nerves
They are paired (left and right)
Plexuses have ___ of varying numbers, depending on the complexity of the plexus
They contain both….
Plexuses
subunits
….motor and sensory neurons
Roots arise from the spinal cord
Trunks are formed by union of roots (fortunately this is only in the brachial plexus):
Superior trunk
Middle trunk
Inferior trunk
Divisions are the consequence of branching of trunks:
Anterior division
Posterior division
Nerves extend to the body part innervated
The ______ supplies the skin and muscles of the head, neck, superior portion of the shoulders and chest, and the diaphragm
cervical plexus
The _____ arise from the cervical plexuses and supply motor fibers to the diaphragm
phrenic nerves
Complete severing of the spinal cord above the origin of the phrenic nerves (C3, C4, and C5) causes….
…..respiratory arrest. Breathing stops because the phrenic nerves no longer send impulses to the diaphragm.
The ____ supplies the shoulders and upper limbs
brachial plexus
The _____ arises from the brachial plexus and supplies the muscles on the posterior aspect of the arm and forearm
radial nerve
Radial nerve injury is indicated by….
wrist drop, which is the inability to extend the wrist and fingers
Radial nerve injury can be caused by improperly administered intramuscular injections into the ____ muscle, or by a cast applied too tightly around the ____
deltoid
mid-humerus
The lumbar plexus supplies the….
anterolateral abdominal wall, external genitals, and part of the lower limbs
The sacral plexus supplies the….
buttocks, perineum, and lower limbs
_____ is the largest nerve in the body. It is actually two nerves bound by a common sheath of connective tissue, arising from the sacral plexus.
The sciatic nerve
Various branches of the sciatic nerve supply muscles of the….
leg, foot, and toes
Injury to the sciatic nerve results in sciatica, pain that may extend from…
the buttock down the posterior and lateral aspect of the leg and into the foot.
Sciatic Injury may be due to herniated disc, dislocated hip, osteoarthritis, pressure from the uterus during pregnancy, or an improperly administered gluteal intramuscular injection
Tis the Truest
____ are those that arise in the skin , and include tactile sensations (touch, pressure, vibration, tickling), thermal sensations (warmth, coolness), and pain
Cutaneous sensations
Maps of the afferent nerves that convey cutaneous sensations toward the CNS are of two types:
- Dermatomes
- Peripheral nerve fields (cutaneous nerves)
The maps differ because of plexuses
Dermatomes:
The skin is supplied by ____ that carry nerve impulses from the skin into the spinal cord and brain stem
somatic sensory neurons
Dermatomes:
Each spinal nerve contains sensory neurons that serve a specific segment of the body
The area of the skin that provides sensory input to the CNS via one pair of spinal nerves or cranial nerve V is called a…
dermatome (cranial nerve V is the trigeminal; it serves most of the skin of the face and the scalp)
Knowing which spinal cord segments supply each dermatome makes it possible to locate damaged regions of the spinal cord
Nerves supplying a specific dermatome may be damaged if the sensation is not perceived when the skin in a particular region is stimulated
True
Adjacent dermatomes typically overlap, except at the ____, which is the line of junction of dermatomes supplied from discontinuous spinal levels
axial line
axial line is what?
is the line of junction of dermatomes supplied from discontinuous spinal levels
____ is an acute infection of the peripheral nervous system caused by herpes zoster, the virus that also causes chickenpox
After recovery from chicken pox the virus retreats to a ____
The immune system usually prevents the virus from spreading if it is reactivated
Sometimes the virus leaves the ganglion and travels down sensory neurons of the skin by ____
This causes pain, skin discoloration, and typically a line of blisters on the skin coinciding with dermatomal distribution of the sensory nerve belonging to the….
Shingles
posterior root ganglion
fast axonal transport
….infected posterior root ganglion
The spinal cord has two principal functions in the maintenance of homeostasis:
- Nerve impulse propagation
- Information integration (processing)
The spinal cord has two principal functions:
- Nerve impulse propagation
- Information integration (processing)
Within the spinal cord, these functions are associated with either the….
_____ receives and integrates incoming and outgoing information
White matter tracts carry sensory impulses toward the brain, and motor impulses from the brain toward….
….gray matter or the white matter
Gray matter
….effectors
Name of a tract indicates . . .
Its position in the white matter
Where it begins and ends
By extension, the direction of information flow
Example: lateral corticospinal tract A lateral white column Begins in the cortex (of the brain) Ends in the spinal cord Since flow is away from the brain, it is a motor (descending) tract
Name of a tract indicates . . .
Its position in the white matter
Where it begins and ends
By extension, the direction of information flow
Proprioception:
awareness of the postion and movement of muscles, tendons, and joints
Discriminative touch:
ability to feel exactly what part of the body is touched
Two-point discrimination:
ability to distinguish the touching of two different points on the skin which are close together
awareness of the postion and movement of muscles, tendons, and joints
Proprioception:
ability to feel exactly what part of the body is touched
Discriminative touch:
ability to distinguish the touching of two different points on the skin which are close together
Two-point discrimination:
Integration and response:
Sensory systems provide input to the CNS regarding the environment
_____ in several areas of the brain and spinal cord integrate the input
Responses are initiated. Most regulation of involuntary activities of smooth muscle, cardiac muscle, and glands is by the _____
_____ has a major role in controlling precise, voluntary muscular movements
Interneurons
autonomic nervous system
The cerebral cortex
The cerebral cortex has a major role in….
controlling precise, voluntary muscular movements
Motor output to skeletal muscles travels down the spinal cord in two types of descending pathways:
Direct
Indirect
DIRECT PATHWAYS:
These nerve impulses originate in the cerebral cortex
They cause precise, voluntary movement of skeletal muscles
Comprise the following tracts: ???
Lateral corticospinal tract
Anterior corticospinal tract
Corticobulbar tract
Where do direct pathway nerve impulses originate?
cerebral cortex
What do direct pathways cause?
They cause precise, voluntary movement of skeletal muscles
Lateral corticospinal tract
Anterior corticospinal tract
Corticobulbar tract
DIRECT PATHWAYS
Indirect pathways:
These impulses originate in….
the brain stem or other parts of the brain that govern automatic movements
They help coordinate body movements with visual stimuli, maintain skeletal muscle tone and contraction of postural muscles, regulate muscle tone in response to movements of the head
Indirect pathways
Indirect pathways Include the following tracts:
Rubrospinal tract Tectospinal tract Vestibulospinal tract Lateral reticulospinal tract Medial reticulospinal tract
Rubrospinal tract Tectospinal tract Vestibulospinal tract Lateral reticulospinal tract Medial reticulospinal tract
Indirect pathways
A ___ is a fast, involuntary, unplanned sequence of actions that occurs in response to a particular stimulus
reflex
Reflexes may be:
Innate (inborn)
Learned
The types of reflexes based on site of integration of stimuli are . . .
Spinal reflex, when integration takes place in spinal cord gray matter
Cranial reflex , when integration occurs in the brain stem
when integration takes place in spinal cord gray matter
Spinal reflex
when integration occurs in the brain stem
Cranial reflex
Somatic reflexes involve contraction of
skeletal muscles
Involve contraction of smooth muscle, cardiac muscle, and glands
Are not usually consciously perceived
Are not easy to initiate by clinical processes
Are also termed autonomic reflexes, since they are mediated by the autonomic nervous system
Visceral reflexes
Autonomic reflexes
visceral reflexes
The pathway followed by nerve impulses that produce a reflex is termed a
reflex arc (or reflex circuit)
Reflex arcs comprise very specific pathways as they propagate into, through, and out of the
central nervous system
Reflex arcs are of diagnostic value due to the property of having
specific pathways
A reflex arc includes the following five functional components:
Sensory receptor Sensory neuron Integrating center Motor neuron Effector
Sensory receptor :
The dendrite or sensory structure of the sensory neuron responds to a specific stimulus by producing a graded potential called a generator (or receptor) potential. If the potential reaches threshold, it will trigger one or more nerve impulses in the sensory neuron
True
…. of the sensory neuron responds to a specific stimulus by producing a graded potential called a generator (or receptor) potential. If the potential reaches threshold, it will trigger one or more nerve impulses in the sensory neuron
The dendrite or sensory structure
The gray matter within the central nervous system is the integrating center. The simplest reflex consists of the integrating center comprising just one synapse between sensory neuron and motor neuron, called a
monosynaptic reflex arc
Most reflex arcs are…
polysynaptic, involving more than two types of neurons and more than one CNS synapse
The integrating center sends impulses out of the CNS along a _____ to the part of the body that will respond
motor neuron
The ____ is the part of the body that responds, generally a muscle or gland.
effector
The responsive action of the effector is called a ___.
reflex
If the effector is skeletal muscle, the reflex is a ____.
somatic reflex
If the effector is smooth muscle, cardiac muscle, or a gland, the reflex is an…
autonomic reflex (or visceral reflex)
It operates as a feedback mechanism to control muscle length by causing muscle contraction
Prevents injury from over-stretching, because muscle contracts when it is stretched
Monosynaptic, ipsilateral reflex arc
Stretch Reflex (patellar reflex)
What are the Events of stretch reflex?
-muscle spindle (stretch receptors) in the
-muscle signals stretch of muscle
motor neuron activated & muscle contracts
Brain sets ______ sensitivity as it sets muscle tone (degree of muscle contraction at rest)
muscle spindle
This reflex involves muscle spindles, which are..
…proprioceptors in skeletal muscle that participate in stretch reflexes.
The stretch reflex prevents…
…overstretching of the muscle by causing it to contract.
The stretch reflex prevents…
…overstretching of the muscle by causing it to contract
is the clinical correlate of the absence or decrease of patellar reflex or knee jerk
Westphal’s sign
Clinical significance (abbreviated):
- receptor damage, or lesions involving the dorsal columns of the spinal cord or cerebellum
- lesions present within the motor cortex of the brain or the pyramidal tracts
- interruption of motor impulse transmission in the femoral nerve
Westphal’s sign
It operates as a feedback mechanism to control muscle tension by causing muscle relaxation when muscle force becomes too extreme
Tendon Reflex
Polysynaptic, ipsilateral reflex
- activated by stretching of tendon
- inhibitory neuron is stimulated (polysynaptic)
- motor neuron is hyperpolarized and muscle relaxes
Tendon Reflex
Tendon Reflex:
Golgi tendon organs (tension receptors) are in tendon, at the _____ junction of skeletal muscles
- activated by stretching of ___
- ___ is stimulated (polysynaptic)
- motor neuron is _____ and muscle relaxes
musculotendonous
tendon
inhibitory neuron
hyperpolarized
Tendon Reflex:
Both tendon & muscle are protected… T or F?
_______ -causes contraction of ipsilateral muscle group
True
Reciprocal innervation (polysynaptic)
This reflex involves tendon organs, which are in tendons at the junction of the tendon and its muscle. They monitor tension. The tendon reflex prevents…
… application of excessive force to the muscle/tendon by causing muscle relaxation.
Flexor and Crossed Extensor Reflexes:
The _______ is ipsilateral and is a protective withdrawal reflex that moves a limb to avoid pain (also known as ____).
This reflex results in contraction of flexor muscles to move a limb to _____
flexor (withdrawal) reflex
nociceptive withdrawal reflex (NWR)
avoid injury or pain.
Flexor and Crossed Extensor Reflexes:
The _____, which is contralateral, helps to maintain balance during the flexor reflex.
This is a balance-maintaining reflex that causes a _____ of the joints of one limb and _____ of the joints in the opposite limb.
crossed extensor reflex
synchronized extension
flexion
crossed extensor reflex
The crossed extensor reflex, which is contralateral, helps to maintain balance during the flexor reflex.
This is a balance-maintaining reflex that causes a synchronized extension of the joints of one limb and flexion of the joints in the opposite limb.
flexor (withdrawal) reflex
The flexor (withdrawal) reflex is ipsilateral and is a protective withdrawal reflex that moves a limb to avoid pain (also known as nociceptive withdrawal reflex (NWR)).
This reflex results in contraction of flexor muscles to move a limb to avoid injury or pain.
Step on tack (pain fibers send signal to spinal cord
Interneurons branch to different spinal cord segments
Motor fibers in several segments are activated
More than one muscle group activated to lift foot off of tack
Flexor (withdrawal) Reflex
Lifting right foot requires extension of left leg to maintain one’s balance
Pain signals cross to opposite spinal cord
Contralateral extensor muscles are stimulated by interneurons to hold up the body weight
Reciprocal innervation - when extensors contract flexors relax, etc
Crossed Extensor Reflex
This reflex results from the gentle stroking of the lateral outer margin of the sole.
Plantar flexion reflex (Babinski)
The ______ is dorsiflexion of the great toe with or without lateral fanning of the other toes. It normally occurs in children under 1 ½ years of age due to incomplete myelination of fibers in the corticospinal tract.
Babinski sign
Presence of the Babinski sign after age 1 ½ is abnormal and indicates an interruption of the _____ as the result of lesion of the tract.
The normal response (“no Babinski”) after age 1 ½ is curling under of all the toes (illustration a).
corticospinal tract
____ is a stretch reflex with a rapid decrease in resistance when attempting to flex a joint. Generally observed during a neurological examination, it is one of the characteristic responses of an upper motor neuron lesion, indicating damage to the pyramidal tract.
Clasp Knife reflex (clasp knife response)
In this reflex, a spastic limb resists passive motion and then suddenly gives way, similarly to the motion of the blade of a jackknife.
Although seemingly a stretch reflex when flexing a joint, force from the muscle during the attempt to flex a joint is actually thought to be caused by the tendon reflex of the antagonistic muscle of that joint, which is an extensor muscle that becomes stretched. In upper motor neuron lesions, muscle tonus may increase, and resistance of muscle to stretch increases. However, if sufficient force is applied, limb resistance suddenly decreases.
Clasp Knife reflex (clasp knife response)
The predictability of reflexes makes them useful in the diagnosis of disease
Diagnostic value of reflexes
Diagnostic value of reflexes:
Diagnostic value of reflexes
Diagnostic value of reflexes:
Damage or disease anywhere along a reflex arc can cause the reflex ____
____ reflexes can usually be tested by tapping or stroking the body surface
to be absent or abnormal
Somatic
Diagnostic value of reflexes:
____ reflexes are not practical diagnostic tools since it is difficult to stimulate most visceral receptors because they are deep inside the body (one exception being the _______
Autonomic
pupillary light reflex—pupils of both eyes decrease in diameter when either is exposed to light)
Hyperactive reflexes suggest central nervous system disease
Decreased reflexes are found in?
- Damage to relevant spinal segments
- Diseases of muscles
- Diseases of the neuromuscular junction
- Loss of sensation
Paralysis of one limb only.
Monoplegia
Paralysis of both upper limbs or both lower limbs.
Diplegia
Paralysis of both lower limbs.
Paraplegia.
Paralysis of the upper limb, trunk, and lower limb on one side of the body.
Hemiplegia.
Paralysis of all four limbs.
Quadriplegia.
Partial transection of the spinal cord on either the right or left side.
Hemisection.
Loss of reflex function.
Areflexia.
Injection of an anesthetic drug into the epidural space in order to cause a temporary loss of sensation.
Epidural block.
Inflammation of the meninges due to an infection.
Meningitis.
Inflammation of the spinal cord.
Myelitis.
A procedure in which a CT scan or X-ray image of the spinal cord is taken after injection of a radiopaque dye to diagnose abnormalities such as tumors and herniated intervertebral discs.
Myelography.
Loss of sensation in a region due to injection of a local anesthetic.
Nerve block.
Attacks of pain along the entire course or a branch of a sensory nerve.
Neuralgia.
Inflammation of one or several nerves due to a variety of causes.
Neuritis.
An abnormal sensation, such as burning, pricking, tickling, or tingling resulting from a disorder of a sensory nerve.
Paresthesia.
Attacks of pain along the entire course or a branch of a sensory nerve.
Neuralgia.
Inflammation of one or several nerves due to a variety of causes.
Neuritis.
An abnormal sensation, such as burning, pricking, tickling, or tingling resulting from a disorder of a sensory nerve.
Paresthesia.
If there is a plexus it is an ___ rami
anterior
only anterior rami can have….
plexuses
