Ch.14 Spinal Nerves/ Cord Flashcards
Where does the Spinal Cord end?
L1Vertebrae
(past L1) the inferior end tapers (narrows) to form the
conus medullaris
How many pairs of Cervical Nerves
8 Pairs
How many pairs of thoracic nerves are there
12 pairs
How many pairs of sacred Nerves?
5 pairs
How many pairs of coccygeal nerves
1 pair
How many Spinal Nerves are there?
31
spinal nerve roots extend inferiorly from the what
conus medullaris
The spinal nerve roots that extend inferiorly from the conus medullaris are called the
Cauda Equina (the “horses tail”).
Area deep to arachnoid through which CSF flows
Subarachnoid space
Anterior horn
Lateral horn
Posterior horn
are the 3 horns of what
Gray matter
Gray matter is composed of three horns:
(1/3)
(contains cell bodies of somatic motor neurons)
Anterior horn
Gray matter is composed of three horns:
Contains cell bodies of autonomic motor neurons
only present in parts T1-L2
Lateral horn
(contains sensory axons and cell bodies of interneurons)
Posterior horn
What contains unmyelinated axons connecting left and right gray matter
Gray Commissure
groups of cell bodies in CNS
Nuclei:
Sensory nuclei in posterior horn contain what
interneurons
What nuclei receive signals from skin, muscles and joints
site of synapse in posterior horn between somatosensory neurons and the interneurons
Somatic sensory nuclei:
What nuclei receive signals from blood vessels, viscera
Visceral sensory nuclei:
Motor nuclei in
anterior + lateral horns
contain what neurons?
Motor Nuerons
Somatic motor nuclei (anterior) innervate what muscle?
skeletal muscle
Autonomic motor nuclei (lateral) innervate what?
smooth muscle, heart, glands
Sit between posterior gray horns and posterior median sulcus
(White matter is organized into three pairs of funiculi)
Posterior funiculus
sits between anterior gray horns and anterior median fissure
(White matter is organized into three pairs of funiculi)
Anterior funiculus
Which pathways transmit ascending information from sensory receptors to the CNS
Spinal pathways are** sensory or motor
**
Sensory pathways
Which pathways transmit descending information from the brain to muscles and glands
Spinal pathways are** sensory or motor
Motor Pathway
most pathways decussate …. what does that mean?
Common pathway characteristics
axons cross midline so brain processes information for contralateral side
uncrossed pathways work on the ipsilateral side of body
decussate = cross
uncrossed pathways work on what side of the body?
Common pathway characteristics
ipsilateral side of body
(ipsilateral=same side)
Signals for proprioception, touch, temperature, pressure, pain
(2 Types) of General Sense Receptors = Somatic + Visceral
Somatic Sensory:
(Posterior)
located in skin and mucous membranes (monitor “texture”)
(Somatic Sensory: Signals) - Signals for proprioception, touch, temperature, pressure, pain
Tactile receptors:
What receptors are located within joints, muscles and tendons which detect stretch and pressure relative to position and movement of the skeleton and skeletal muscles.
(Somatic Sensory: Signals) - Signals for proprioception, touch, temperature, pressure, pain
Proprioceptors:
Sensory Pathways use a series of how many neurons to relay signal to brain)
2 or 3 neurons to relay signal to brain
Secondary (2nd order is a)
Sensory Pathways (use a series of 2 or 3 neurons to relay signal to brai
primary (1st order) neuron
secondary (2nd order)
tertiary neurons (3rd order neuron)
Interneuron
- Posterior funiculus-medial lemniscal pathway
- Anterorlateral pathway
- Spinocerebellar pathway
3 major types of what kind of Pathways
3 Major Types of Somatosensory Pathways
What pathway
transmits signals of proprioception and tactile receptors (touch, pressure, & vibration) with a 3 neuron chain?
Posterior Funiculus–Medial Lemniscal
Anterolateral (spinothalamic)
Spinocerebellar
Posterior Funiculus–Medial Lemniscal pathway
Within the cord, axon is in the posterior funiculus
fasciculus cuneatus (upper limb) or its fasciculus gracilis (lower limb)
In what type of Pathway?
Posterior Funiculus–Medial Lemniscal
Anterolateral (spinothalamic)
Spinocerebellar
Posterior Funiculus–Medial Lemniscal pathway
transmits signals of proprioception and tactile receptors (touch, pressure, & vibration) with a 3 neuron chain
Posterior Funiculus–Medial Lemniscal
Anterolateral (spinothalamic)
Spinocerebellar
Posterior Funiculus–Medial Lemniscal pathway
transmits stimuli related to crude touch, pressure, pain, and temperature with a three-neuron chain
Posterior Funiculus–Medial Lemniscal
Anterolateral (spinothalamic)
Spinocerebellar
Anterolateral (spinothalamic) pathway
primary neuron relays signal from skin to spinal cord
secondary neuron relays signal from spinal cord to thalamus
(anterior spinothalamic tract or the lateral spinothalamic tract)
tertiary neuron relays signal from thalamus to cerebral cortex
Posterior Funiculus–Medial Lemniscal
Anterolateral (spinothalamic)
Spinocerebellar
Anterolateral (spinothalamic) pathway
Anterolateral (spinothalamic) pathway
primary neuron relays signal from skin to what
spinal cord
Anterolateral (spinothalamic) pathway
secondary neuron relays signal from spinal cord to what
thalamus
anterior spinothalamic tract or the lateral spinothalamic tract
Anterolateral (spinothalamic) pathway
tertiary neuron relays signal from thalamus to what
cerebral cortex
transmits stimuli from proprioceptors to the cerebellum
Spinocerebellar pathway
axon ascends in either the
anterior spinocerebellar tract (trunk & lower limbs) or
posterior spinocerebellar tract (trunk & upper limbs)
Spinocerebellar pathway/
Anterolateral (spinothalamic) /
Posterior Funiculus–Medial Lemniscal
in what type of pathway
Spinocerebellar pathway
Spinocerebellar pathway
anterior spinocerebellar tract (trunk & lower or upper limbs)?
lower limbs
Spinocerebellar pathway
posterior spinocerebellar tract (trunk & lower/upper limbs)
upper limbs
Motor is ascending or descending?
descending
What control effectors such as skeletal muscles
Motor (descending) pathways
include at least two neurons
What pathway includes at least 2 neurons
Motor Pathways
- Upper motor neuron
- Lower motor neuron
1/2 Neuron of Motor (descending) pathways
Excite or inhibit lower motor neurons
Upper Motor Neurons
2/2 Neuron of Motor (descending) pathways
Always excites skeletal muscle
Upper/lower motor neurons
Lower Motor Neurons
What tract
-decussates (crosses) within medulla’
- innervate limb muscles for skill movements
lateral corticospinal tracts
The lateral corticospinal tract inervates what for skill movement
- innervate limb muscles for skill movements
+crosses within medulla
How many Spinal nerves are there
formed from the union of an anterior root and a posterior root - dont need 2 know
31
anterior root is many axons of motor or sensory neurons
Motor
posterior root is many axons of motor or sensory neurons
Sensory
Posterior Ramus and Anterior Ramus are the 2 branches of the
Spinal Nerves
2 Branches of Spinal Nerves:
Posterior Ramus: : innervates the skin and deep muscles of the back
Anterior Ramus: innervates the anterior and lateral portions of the trunk and the limbs
What Branch of the Spinal Nerve ?
innervates the skin and deep muscles of the back
Innervate: supply (an organ or other body part) with nerves.
Posterior or anterior ?
Posterior Ramus:
What Branch of the Spinal Nerve ?
Innervates the anterior and lateral portions of the trunk and the limbs
Innervate: supply (an organ or other body part) with nerves.
Anterior Ramus:
A segment of skin supplied by single spinal nerve
-Can help localize damage to one or more spinal nerves
Dermatomes
What can help localize damage to one or more spinal nerves
Dermatomes
Four main plexuses occur bilaterally:
Plexus: branching network of vessels or nerves.
cervical plexus
brachial plexus
lumbar plexus
sacral plexus
What Plexus is formed Formed from the anterior rami of C1–C4 spinal nerves
Cervical Plexus
What nerve is formed from rami of C3-C5; innervates the diaphragm
(C3-4-5 keeps the diaphragm alive)
Phrenic Nerve:
What cervicals keep the Diaphragm alive?
(Phremic Nerve)
C3
C4
C5- keep that diagraphm alive
Phrenic Nerves - formed from Rami
What Plexus is Formed from the anterior rami of spinal nerves C5–T1.
Extends laterally from the neck into axilla (arm pit).
Innervates anterior and posterior parts of the upper limbs.
Innervate: supply (an organ or other body part) with nerves.
Brachial Plexuses
- Axillary nerve: to deltoid,; sensory input from superolateral arm
2.Median nerve: sensory input from palmar side and dorsal tips of most fingers
3.Musculocutaneous nerve
4.Radial nerve:
- Ulnar nerve: two medial fingers .
5 major terminal branches of Brachial Plexus
5 major terminal branches of Brachial Plexus
What nerve goes into the deltoid
gives sensory input from superolateral arm
Axillary Nerve
5 major terminal branches of Brachial Plexus
What Nerve gives sensory input from palm and dorsal tips from most fingers (except pinky)
Median Nerve
5 major terminal branches of Brachial Plexus
Which nerve is responsible for 2 medial fingers
Ulnar Nerve
Brachial Plexus Injuries
difficulty abducting the arm
Axillary nerve injury
causes paralysis of extensor muscles of forearm, wrist, fingers
Radial nerve injury:
injury that may be compressed in Carpal Tunnel Syndrome
Median nerve injury
What plexus is Formed from the anterior rami of spinal nerves L1–L4.
Lumbar Plexuses
Nerves from Lumbar Plexus
What Nerve innervates anterior thigh muscles
Femoral nerve
Nerves from Lumbar Plexus
innervates medial thigh muscles
Obturator nerve:
What Plexus is Formed from the anterior rami of spinal nerves L4–S4.
Sacral Plexuses
What injury may be caused by herniated intervertebral disc
characterized by extreme pain down posterior thigh and leg
Sciatica (injury to sciatic nerve):
What is Sciatica caused by? Characterized by what?
intervertebral disc
characterized by extreme pain down posterior thigh and leg
What is a rapid, preprogrammed involuntary responses of muscles or glands to a stimulus.
Reflex
Is a Reflex volunatary or Involuntary?
Involuntary
1.A stimulus activates a sensory receptor
- The sensory neuron transmits a nerve signal to the CNS
- Information is processed by interneurons
4.Motor neuron transmits impulse to effector
5.Effector responds
5 Steps of Reflex
What are the 5 Steps of a Reflex?
1.A stimulus activates a sensory receptor
2. The sensory neuron transmits a nerve signal to the CNS
3. Information is processed by interneurons
4.Motor neuron transmits impulse to effector
5.Effector responds
sensory neurons synapse directly with motor neurons
monosynaptic or polysynaptic:?
monosynaptic
One or more interneurons positioned between sensory and motor neurons
monosynaptic or polysynaptic?
polysynaptic
receptor and effector are on the
- same side of the body
- opposite sides
ipsilateral or contralateral:
Both
These are What kind of Reflexes?
- Stretch reflex
- Golgi tendon reflex
- Withdrawal reflex
- Crossed-extensor reflex
4 Common Spinal Reflexes
Reflexive contraction of a muscle after it is stretched
Stretch (or tendon tap) is detected by a muscle spindle
These are What kind of Reflexes?
Stretch reflex
Golgi tendon reflex
Withdrawal reflex
Crossed-extensor reflex
Stretch reflex
Stretch reflex: step 2
When stretched, what fires impulses that are conducted to the spinal cord
spindle’s sensory axon
Stretch reflex: step 2
When stretched, spindle’s sensory axon fires what?
that are conducted to what part of the body?
impulses that are conducted to the spinal cord
Stretch reflex:
In spinal cord, the sensory axon excites alpha motor neurons of the same muscle, causing what?
contraction (monosynaptic)
Stretch reflex:
Are Contractions monosynaptic or polysynaptic?
monosynaptic
Stretch reflex: step 5
Simultaneously, the sensory axon excites interneurons that inhibit motor neurons of antagonist muscle
monosynaptic or polysynaptic?
(polysynaptic reciprocal inhibition)
Step 5
Which reflex Prevents muscles from contracting excessively
Golgi tendon organs detect excessive tension
What kind of Reflexes?
Stretch reflex
Golgi tendon reflex
Withdrawal reflex
Crossed-extensor reflex
Golgi tendon reflex
What detects excessive tension
Golgi tendon organs
What inhibit motor neurons of same muscle
+ prevents damage
Golgi tendon reflex
Golgi tendon reflex
Which Reflex
Withdraws a body part away from a painful stimulus
Withdrawal reflex
Simultaneously, other interneurons reciprocally inhibit motor neurons of extensors (antagonist) so that extensor muscles (e.g., quadriceps) relax and withdrawal happens quickly
Withdrawal reflex
Which reflex
Allows the opposite side limb to support body weight while the hurt limb withdraws
Crossed-extensor reflex
Reflex testing
: diminished or absent;
Hypoactive reflexes or Hyperactive reflexes:
May indicate damage to spinal cord, or muscle disease, or damage to neuromuscular junction
Hypoactive reflexes
abnormally strong response
Hypoactive reflexes or Hyperactive reflexes:
May indicate damage to brain or spinal cord, especially if accompanied by clonus
Hyperactive reflex:
May indicate damage to spinal cord, or muscle disease, or damage to neuromuscular junction
Hypoactive reflexes or Hyperactive reflexes:
Hypoactive reflexes
May indicate damage to brain or spinal cord, especially if accompanied by clonus
Hypoactive reflexes or Hyperactive reflexes:
Hyperactive reflex
