Podcast
Questions and Answers
What are the two types of conduction pathways in the spinal cord?
What are the two types of conduction pathways in the spinal cord?
Afferent and efferent pathways.
Most 'thinking, processing, and decision-making' occurs at the level of the spinal cord.
Most 'thinking, processing, and decision-making' occurs at the level of the spinal cord.
False (B)
What are responses that do not involve the brain and are characterized by a fast reaction to a stimulus?
What are responses that do not involve the brain and are characterized by a fast reaction to a stimulus?
Reflexes.
From where does the spinal cord extend inferiorly?
From where does the spinal cord extend inferiorly?
What are the four main parts of the spinal cord?
What are the four main parts of the spinal cord?
At which vertebral level does the spinal cord typically end, and what is this terminal structure called?
At which vertebral level does the spinal cord typically end, and what is this terminal structure called?
What is the term for the bundle of spinal nerve roots that extend inferiorly from the end of the spinal cord?
What is the term for the bundle of spinal nerve roots that extend inferiorly from the end of the spinal cord?
Which spinal cord enlargement contains neurons innervating the upper limbs?
Which spinal cord enlargement contains neurons innervating the upper limbs?
Which spinal cord enlargement contains neurons innervating the lower limbs?
Which spinal cord enlargement contains neurons innervating the lower limbs?
Define a nerve.
Define a nerve.
What are the three connective tissue wrappings around a nerve and its components, from outermost to innermost?
What are the three connective tissue wrappings around a nerve and its components, from outermost to innermost?
How many pairs of spinal nerves are there?
How many pairs of spinal nerves are there?
How are spinal nerves typically named?
How are spinal nerves typically named?
What structures merge to form spinal nerve roots?
What structures merge to form spinal nerve roots?
What type of neurons does the posterior root contain? What structure within this root contains their cell bodies?
What type of neurons does the posterior root contain? What structure within this root contains their cell bodies?
What type of neurons does the anterior root contain?
What type of neurons does the anterior root contain?
Where do the anterior and posterior roots join to form a spinal nerve?
Where do the anterior and posterior roots join to form a spinal nerve?
Spinal nerves contain only sensory neurons or only motor neurons.
Spinal nerves contain only sensory neurons or only motor neurons.
What structures protect the spinal cord?
What structures protect the spinal cord?
What structure houses the spinal cord?
What structure houses the spinal cord?
Through what opening does the spinal cord pass within the vertebrae?
Through what opening does the spinal cord pass within the vertebrae?
Through what opening does each spinal nerve exit the vertebral column?
Through what opening does each spinal nerve exit the vertebral column?
What is the innermost, delicate meninx adhering to the spinal cord?
What is the innermost, delicate meninx adhering to the spinal cord?
What are the denticulate ligaments?
What are the denticulate ligaments?
What is the filum terminale?
What is the filum terminale?
What is the middle, web-like meninx external to the pia mater?
What is the middle, web-like meninx external to the pia mater?
What are the arachnoid trabeculae?
What are the arachnoid trabeculae?
What space lies deep to the arachnoid mater, and what flows through it?
What space lies deep to the arachnoid mater, and what flows through it?
What is the tough, outermost meninx?
What is the tough, outermost meninx?
What potential space is located between the dura mater and the arachnoid mater?
What potential space is located between the dura mater and the arachnoid mater?
What space is located between the dura mater and the vertebra, and what does it contain?
What space is located between the dura mater and the vertebra, and what does it contain?
What procedure involves obtaining CSF for medical diagnosis, and where is it typically performed relative to the spinal cord?
What procedure involves obtaining CSF for medical diagnosis, and where is it typically performed relative to the spinal cord?
List the structures a needle passes through during a lumbar puncture to reach the subarachnoid space.
List the structures a needle passes through during a lumbar puncture to reach the subarachnoid space.
What components make up gray matter in the spinal cord?
What components make up gray matter in the spinal cord?
What types of neurons are primarily housed in the posterior horns of the gray matter?
What types of neurons are primarily housed in the posterior horns of the gray matter?
What types of neuron cell bodies are housed in the anterior horns of the gray matter?
What types of neuron cell bodies are housed in the anterior horns of the gray matter?
What types of neuron cell bodies are housed in the lateral horns, and in which spinal cord segments are they present?
What types of neuron cell bodies are housed in the lateral horns, and in which spinal cord segments are they present?
What structure is the horizontal band of gray matter surrounding the central canal?
What structure is the horizontal band of gray matter surrounding the central canal?
What are groups of cell bodies within the CNS called?
What are groups of cell bodies within the CNS called?
Sensory nuclei are located in which horn of the spinal gray matter?
Sensory nuclei are located in which horn of the spinal gray matter?
What type of sensory signals do somatic sensory nuclei receive?
What type of sensory signals do somatic sensory nuclei receive?
What type of sensory signals do visceral sensory nuclei receive?
What type of sensory signals do visceral sensory nuclei receive?
Motor nuclei are located in which horns of the spinal gray matter?
Motor nuclei are located in which horns of the spinal gray matter?
What type of muscle do somatic motor nuclei (in anterior horn) innervate?
What type of muscle do somatic motor nuclei (in anterior horn) innervate?
What types of tissues do autonomic motor nuclei (in lateral horn) innervate?
What types of tissues do autonomic motor nuclei (in lateral horn) innervate?
What type of axons primarily make up white matter?
What type of axons primarily make up white matter?
Sensory pathways in the spinal cord ascend toward the brain.
Sensory pathways in the spinal cord ascend toward the brain.
Motor pathways in the spinal cord ascend toward the brain.
Motor pathways in the spinal cord ascend toward the brain.
Conduction pathways in the spinal cord are typically paired, meaning there is both a left and a right tract.
Conduction pathways in the spinal cord are typically paired, meaning there is both a left and a right tract.
Where are the axons and cell bodies typically located for neurons involved in spinal cord tracts?
Where are the axons and cell bodies typically located for neurons involved in spinal cord tracts?
Most spinal pathways involve a chain of how many neurons?
Most spinal pathways involve a chain of how many neurons?
What does it mean for a pathway to decussate?
What does it mean for a pathway to decussate?
If a pathway decussates, the brain processes information for which side of the body?
If a pathway decussates, the brain processes information for which side of the body?
If a pathway does not decussate, it works on which side of the body?
If a pathway does not decussate, it works on which side of the body?
What are the two main categories of general sense receptors that transmit input through the spinal cord?
What are the two main categories of general sense receptors that transmit input through the spinal cord?
What do tactile receptors detect?
What do tactile receptors detect?
What do proprioceptors detect?
What do proprioceptors detect?
What do visceral sensory receptors detect?
What do visceral sensory receptors detect?
What type of sensory information do somatosensory pathways carry?
What type of sensory information do somatosensory pathways carry?
What type of sensory information do viscerosensory pathways carry?
What type of sensory information do viscerosensory pathways carry?
What are the typical roles of the primary, secondary, and tertiary neurons in a sensory pathway?
What are the typical roles of the primary, secondary, and tertiary neurons in a sensory pathway?
What type of effectors do motor pathways control?
What type of effectors do motor pathways control?
What are the two main neurons involved in motor pathways starting in the brain?
What are the two main neurons involved in motor pathways starting in the brain?
Where does the upper motor neuron originate and synapse?
Where does the upper motor neuron originate and synapse?
Where is the lower motor neuron located, and what does it directly excite?
Where is the lower motor neuron located, and what does it directly excite?
The direct (pyramidal) motor pathway controls what type of muscles?
The direct (pyramidal) motor pathway controls what type of muscles?
In the lateral corticospinal tract, where do the upper motor neuron axons decussate?
In the lateral corticospinal tract, where do the upper motor neuron axons decussate?
What types of movements are primarily controlled by the lateral corticospinal tracts?
What types of movements are primarily controlled by the lateral corticospinal tracts?
In the anterior corticospinal tracts, where do the upper motor neuron axons typically decussate?
In the anterior corticospinal tracts, where do the upper motor neuron axons typically decussate?
What types of muscles are primarily innervated by the anterior corticospinal tracts?
What types of muscles are primarily innervated by the anterior corticospinal tracts?
Where do the upper motor neurons of indirect motor pathways originate?
Where do the upper motor neurons of indirect motor pathways originate?
What functions does the lateral pathway (indirect) regulate?
What functions does the lateral pathway (indirect) regulate?
What functions does the medial pathway (indirect) regulate?
What functions does the medial pathway (indirect) regulate?
Reticulospinal tracts originate from the reticular formation and help control what?
Reticulospinal tracts originate from the reticular formation and help control what?
Tectospinal tracts originate from the superior and inferior colliculi and regulate what responses?
Tectospinal tracts originate from the superior and inferior colliculi and regulate what responses?
Vestibulospinal tracts originate from the vestibular nuclei and help maintain what?
Vestibulospinal tracts originate from the vestibular nuclei and help maintain what?
Prompt use of steroids after a spinal cord injury may help preserve muscle function.
Prompt use of steroids after a spinal cord injury may help preserve muscle function.
Early use of antibiotics has reduced deaths from pulmonary and urinary infections after spinal cord injuries.
Early use of antibiotics has reduced deaths from pulmonary and urinary infections after spinal cord injuries.
What potential future therapy might help regenerate CNS axons after spinal cord injury?
What potential future therapy might help regenerate CNS axons after spinal cord injury?
What is a dermatome?
What is a dermatome?
Adjacent dermatomes have distinct, separate boundaries with no overlap.
Adjacent dermatomes have distinct, separate boundaries with no overlap.
How can dermatomes help localize damage to spinal nerves?
How can dermatomes help localize damage to spinal nerves?
What is referred visceral pain, and how are dermatomes involved? Give an example.
What is referred visceral pain, and how are dermatomes involved? Give an example.
What condition involves the reactivation of the chickenpox virus?
What condition involves the reactivation of the chickenpox virus?
Where does the shingles virus travel when reactivated, and what are the symptoms?
Where does the shingles virus travel when reactivated, and what are the symptoms?
What is a nerve plexus?
What is a nerve plexus?
What are the four main nerve plexuses that occur bilaterally?
What are the four main nerve plexuses that occur bilaterally?
Most thoracic spinal nerves form large plexuses.
Most thoracic spinal nerves form large plexuses.
What is the benefit of nerve fibers branching and joining within a plexus?
What is the benefit of nerve fibers branching and joining within a plexus?
Cervical plexuses are formed from the anterior rami of which spinal nerves?
Cervical plexuses are formed from the anterior rami of which spinal nerves?
What general areas do the branches of the cervical plexus innervate?
What general areas do the branches of the cervical plexus innervate?
What important nerve arises from the cervical plexus (specifically rami of C3-C5) and what muscle does it innervate?
What important nerve arises from the cervical plexus (specifically rami of C3-C5) and what muscle does it innervate?
Brachial plexuses are formed from the anterior rami of which spinal nerves?
Brachial plexuses are formed from the anterior rami of which spinal nerves?
What are the five main components (levels of organization) of the brachial plexus, from medial to lateral?
What are the five main components (levels of organization) of the brachial plexus, from medial to lateral?
Which rami unite to form the superior, middle, and inferior trunks of the brachial plexus?
Which rami unite to form the superior, middle, and inferior trunks of the brachial plexus?
Each trunk of the brachial plexus divides into what?
Each trunk of the brachial plexus divides into what?
Which divisions converge to form the posterior cord of the brachial plexus?
Which divisions converge to form the posterior cord of the brachial plexus?
Which division forms the medial cord of the brachial plexus?
Which division forms the medial cord of the brachial plexus?
Which divisions converge to form the lateral cord of the brachial plexus?
Which divisions converge to form the lateral cord of the brachial plexus?
What are the 5 major terminal branches arising from the cords of the brachial plexus?
What are the 5 major terminal branches arising from the cords of the brachial plexus?
What muscles does the axillary nerve primarily innervate, and where does it provide sensory input?
What muscles does the axillary nerve primarily innervate, and where does it provide sensory input?
What muscles does the median nerve primarily innervate, and where does it provide sensory input?
What muscles does the median nerve primarily innervate, and where does it provide sensory input?
What muscles does the musculocutaneous nerve primarily innervate, and where does it provide sensory input?
What muscles does the musculocutaneous nerve primarily innervate, and where does it provide sensory input?
What muscles does the radial nerve primarily innervate, and where does it provide sensory input?
What muscles does the radial nerve primarily innervate, and where does it provide sensory input?
What muscles does the ulnar nerve primarily innervate, and where does it provide sensory input?
What muscles does the ulnar nerve primarily innervate, and where does it provide sensory input?
Injury to the axillary nerve, perhaps from compression in the axilla or a fracture of the humeral neck, would cause difficulty with what arm movement?
Injury to the axillary nerve, perhaps from compression in the axilla or a fracture of the humeral neck, would cause difficulty with what arm movement?
Injury to the radial nerve, perhaps from a humeral shaft fracture, would primarily cause paralysis of which muscle group?
Injury to the radial nerve, perhaps from a humeral shaft fracture, would primarily cause paralysis of which muscle group?
Improper use of crutches can injure which part of the brachial plexus or its nerves, leading to 'crutch palsy'?
Improper use of crutches can injure which part of the brachial plexus or its nerves, leading to 'crutch palsy'?
Compression of the median nerve in the carpal tunnel leads to what syndrome?
Compression of the median nerve in the carpal tunnel leads to what syndrome?
Fractures or dislocations of the elbow can easily injure which nerve?
Fractures or dislocations of the elbow can easily injure which nerve?
Lumbar plexuses are formed from the anterior rami of which spinal nerves?
Lumbar plexuses are formed from the anterior rami of which spinal nerves?
What is the main nerve arising from the posterior division of the lumbar plexus, and what muscles does it primarily innervate?
What is the main nerve arising from the posterior division of the lumbar plexus, and what muscles does it primarily innervate?
What is the main nerve arising from the anterior division of the lumbar plexus, and what muscles does it primarily innervate?
What is the main nerve arising from the anterior division of the lumbar plexus, and what muscles does it primarily innervate?
Sacral plexuses are formed from the anterior rami of which spinal nerves?
Sacral plexuses are formed from the anterior rami of which spinal nerves?
Nerves from the anterior division of the sacral plexus tend to innervate which muscle group in the lower limb?
Nerves from the anterior division of the sacral plexus tend to innervate which muscle group in the lower limb?
Nerves from the posterior division of the sacral plexus tend to innervate which muscle group in the lower limb?
Nerves from the posterior division of the sacral plexus tend to innervate which muscle group in the lower limb?
What is the largest and longest nerve in the body, formed from both anterior and posterior divisions of the sacral plexus?
What is the largest and longest nerve in the body, formed from both anterior and posterior divisions of the sacral plexus?
The sciatic nerve is composed of which two divisions bound together?
The sciatic nerve is composed of which two divisions bound together?
The tibial nerve (from the anterior division of the sciatic) innervates which muscles in the thigh and leg?
The tibial nerve (from the anterior division of the sciatic) innervates which muscles in the thigh and leg?
Where does the tibial nerve primarily receive sensory signals from?
Where does the tibial nerve primarily receive sensory signals from?
The common fibular nerve (from the posterior division of the sciatic) innervates which muscle in the thigh before dividing?
The common fibular nerve (from the posterior division of the sciatic) innervates which muscle in the thigh before dividing?
The common fibular nerve splits into which two main branches?
The common fibular nerve splits into which two main branches?
What muscles does the deep fibular nerve innervate?
What muscles does the deep fibular nerve innervate?
Where does the deep fibular nerve provide sensory input?
Where does the deep fibular nerve provide sensory input?
What muscles does the superficial fibular nerve innervate?
What muscles does the superficial fibular nerve innervate?
Where does the superficial fibular nerve provide sensory input?
Where does the superficial fibular nerve provide sensory input?
Injury to the superior or inferior gluteal nerves, possibly from a poorly placed gluteal injection, would affect which main movements?
Injury to the superior or inferior gluteal nerves, possibly from a poorly placed gluteal injection, would affect which main movements?
What is sciatica, and what commonly causes it?
What is sciatica, and what commonly causes it?
Why is the common fibular nerve prone to injury, and what is a common cause?
Why is the common fibular nerve prone to injury, and what is a common cause?
Injury to the common fibular nerve (or its deep branch) causes paralysis of which muscle groups and results in what characteristic sign?
Injury to the common fibular nerve (or its deep branch) causes paralysis of which muscle groups and results in what characteristic sign?
Define reflexes.
Define reflexes.
A stimulus is required to initiate a reflex.
A stimulus is required to initiate a reflex.
The response in a reflex involves a long chain of many neurons, making it slow.
The response in a reflex involves a long chain of many neurons, making it slow.
The response in a reflex is always the same for a given stimulus because it is preprogrammed.
The response in a reflex is always the same for a given stimulus because it is preprogrammed.
Reflexes are voluntary responses that require conscious thought.
Reflexes are voluntary responses that require conscious thought.
Why are reflexes considered survival mechanisms?
Why are reflexes considered survival mechanisms?
What is a reflex arc?
What is a reflex arc?
List the five components of a typical reflex arc.
List the five components of a typical reflex arc.
What distinguishes a spinal reflex from a cranial reflex?
What distinguishes a spinal reflex from a cranial reflex?
What distinguishes a somatic reflex from a visceral reflex?
What distinguishes a somatic reflex from a visceral reflex?
What distinguishes a monosynaptic reflex from a polysynaptic reflex?
What distinguishes a monosynaptic reflex from a polysynaptic reflex?
What distinguishes an ipsilateral reflex from a contralateral reflex?
What distinguishes an ipsilateral reflex from a contralateral reflex?
What distinguishes an innate reflex from an acquired reflex?
What distinguishes an innate reflex from an acquired reflex?
What are the four common spinal reflexes mentioned?
What are the four common spinal reflexes mentioned?
Stretch and Golgi tendon reflexes rely on which type of sensory receptor?
Stretch and Golgi tendon reflexes rely on which type of sensory receptor?
What is a muscle spindle, and what does it detect?
What is a muscle spindle, and what does it detect?
What is the stretch reflex?
What is the stretch reflex?
What proprioceptor detects the stretch in a stretch reflex?
What proprioceptor detects the stretch in a stretch reflex?
In the stretch reflex, the sensory axon synapses directly with the alpha motor neuron of the same muscle.
In the stretch reflex, the sensory axon synapses directly with the alpha motor neuron of the same muscle.
What happens to the antagonist muscle during a stretch reflex, and what is this phenomenon called?
What happens to the antagonist muscle during a stretch reflex, and what is this phenomenon called?
How is the stretch reflex classified?
How is the stretch reflex classified?
What is the function of the Golgi tendon reflex?
What is the function of the Golgi tendon reflex?
What proprioceptor detects excessive tension in the Golgi tendon reflex?
What proprioceptor detects excessive tension in the Golgi tendon reflex?
What is the withdrawal reflex?
What is the withdrawal reflex?
What type of receptor is typically excited in a withdrawal reflex?
What type of receptor is typically excited in a withdrawal reflex?
In the withdrawal reflex involving the leg (e.g., stepping on a tack), which muscles contract and which relax?
In the withdrawal reflex involving the leg (e.g., stepping on a tack), which muscles contract and which relax?
What is the crossed-extensor reflex?
What is the crossed-extensor reflex?
The crossed-extensor reflex is an ipsilateral reflex.
The crossed-extensor reflex is an ipsilateral reflex.
If the left leg is withdrawn due to a painful stimulus, what happens in the right leg during the crossed-extensor reflex?
If the left leg is withdrawn due to a painful stimulus, what happens in the right leg during the crossed-extensor reflex?
What does a hypoactive reflex indicate?
What does a hypoactive reflex indicate?
What does a hyperactive reflex indicate?
What does a hyperactive reflex indicate?
What is clonus, and when might it be observed?
What is clonus, and when might it be observed?
Flashcards
Conduction
Conduction
Link between brain and body for sensory/motor information.
Neural integration
Neural integration
Brain's analysis and response to sensory input.
Reflexes
Reflexes
Quick, brainless responses to stimuli.
Spinal Cord
Spinal Cord
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Spinal cord regions
Spinal cord regions
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Conus medullaris
Conus medullaris
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Cauda equina
Cauda equina
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Epineurium
Epineurium
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Perineurium
Perineurium
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Endoneurium
Endoneurium
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Rootlets
Rootlets
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Posterior root
Posterior root
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Posterior root ganglion
Posterior root ganglion
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Anterior root
Anterior root
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Spinal cord meninges
Spinal cord meninges
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Pia mater
Pia mater
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Denticulate ligaments
Denticulate ligaments
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Filum terminale
Filum terminale
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Arachnoid mater
Arachnoid mater
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Subarachnoid space
Subarachnoid space
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Dura mater
Dura mater
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Subdural space
Subdural space
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Epidural space
Epidural space
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Vertebral column
Vertebral column
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Intervertebral foramen
Intervertebral foramen
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Lumbar puncture
Lumbar puncture
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Adult Spinal Cord
Adult Spinal Cord
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Cell bodies, dendrites, unmyelinated axons, and glial cells.
Cell bodies, dendrites, unmyelinated axons, and glial cells.
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Posterior horns
Posterior horns
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Anterior horns
Anterior horns
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Lateral horns
Lateral horns
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Gray commissure
Gray commissure
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Nuclei
Nuclei
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Sensory nuclei
Sensory nuclei
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Somatic sensory nuclei
Somatic sensory nuclei
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Visceral sensory nuclei
Visceral sensory nuclei
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Motor nuclei
Motor nuclei
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Somatic motor nuclei
Somatic motor nuclei
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White matter
White matter
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Sensory pathways
Sensory pathways
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Study Notes
- Conduction involves afferent and efferent pathways, linking the brain and body structurally and functionally.
- Sensory input travels from the body to the brain.
- Motor commands travel from the brain to the body.
- Neural integration is minimal, mainly involving thinking, processing, and decision-making at the brain level.
- Reflexes are responses that do not involve the brain.
- Reflexes are fast reactions to a stimulus.
Spinal Cord Anatomy
- The spinal cord extends inferiorly from the brain's medulla through the vertebral canal.
- The spinal cord has four parts: cervical, thoracic, lumbar, and sacral.
- The spinal cord ends at the L₁ vertebra with the conus medullaris.
- Spinal nerve roots extend inferiorly, forming the cauda equina.
- The spinal cord has two widened regions with more neurons.
- The cervical enlargement contains neurons innervating the upper limbs.
- The lumbar enlargement contains neurons innervating the lower limbs.
Spinal Nerve Anatomy
- Nerves consist of cablelike bundles of axons.
- The connective tissue wrappings include:
- Epineurium, which surrounds the entire nerve.
- Perineurium, which surrounds fascicles (bundles of axons).
- Endoneurium, which surrounds individual axons.
- There are 31 pairs of spinal nerves.
- Spinal nerve names begin with the first letter of the spinal cord region to which they attach, followed by a number (e.g., T7).
- Rootlets merge to form spinal nerve roots.
- The posterior root contains sensory neurons.
- The posterior root ganglion contains the cell bodies of these neurons.
- The anterior root contains motor neurons.
- Spinal nerves form where the roots join.
- Sensory and motor neurons are in each spinal nerve.
- Spinal nerves are classified as mixed nerves.
Protection
- The spinal cord is protected by bone, meninges, and cerebrospinal fluid.
- The vertebral column houses the spinal cord.
- The spinal cord passes through the vertebral canal.
- Spinal nerves exit through each intervertebral foramen.
Spinal Cord Meninges
- Pia mater is a delicate layer adhering to the spinal cord.
- It is made of elastic and collagen fibers.
- Denticulate ligaments are lateral extensions of the pia mater that help suspend the spinal cord.
- The filum terminale is the pia mater anchoring the inferior end of the spinal cord to the coccyx.
- Arachnoid mater is a web-like layer external to the pia mater.
- Arachnoid trabeculae are fibrous extensions of the membrane.
- The subarachnoid space is an area deep to the arachnoid through which CSF flows.
- Dura mater is a tough, outermost layer.
- It is a layer of dense irregular connective tissue that stabilizes the spinal cord. -- The subdural space is between the dura and arachnoid.
- The epidural space is between the dura and vertebra.
- Adipose, areolar connective tissue, and blood vessels are housed here.
Clinical Information: Lumbar Puncture
- A lumbar puncture procedure obtains CSF for medical diagnosis.
- The needle passes through the skin, back muscles, ligamentum flavum, epidural space, dura mater and arachnoid mater into subarachnoid space.
- The adult spinal cord ends at L₁.
- Lumbar puncture occurs below this, just above or below L₄.
- The spinous process of L₄ is at the highest points of iliac crests.
Gray Matter
- The gray matter is made of neuron cell bodies, dendrites, and unmyelinated axons; also glial cells.
- Masses of gray matter project from the center of the spinal cord.
- Posterior horns house axons of sensory neurons and cell bodies of interneurons.
- Anterior horns house cell bodies of somatic motor neurons.
- Lateral horns house cell bodies of autonomic motor neurons.
- Only present in parts T1-L2.
- Gray commissure is a horizontal band of gray matter surrounding the central canal.
- It contains unmyelinated axons connecting the left and right gray matter.
- Nuclei are groups of cell bodies.
- Sensory nuclei in the posterior horn contain interneurons.
- Somatic sensory nuclei receive signals from the skin, muscle, and joints.
- Visceral sensory nuclei receive signals from blood vessels and viscera.
- Motor nuclei in the anterior and lateral horns contain motor neurons.
- Somatic motor nuclei (anterior) innervate skeletal muscle.
- Autonomic motor nuclei (lateral) innervate smooth muscle, the heart, and glands.
White Matter
- White matter consists of myelinated axons traveling to and from the brain.
Regions of White Matter
- The posterior funiculus sits between the posterior gray horns and the posterior median sulcus.
- It contains sensory tracts (axon bundles called fasciculi).
- The lateral funiculus sits on the lateral sides of the spinal cord.
- It contains sensory (ascending) and motor (descending) tracts.
- The anterior funiculus sits between the anterior gray horns and the anterior median fissure.
- The left and right anterior funiculi are interconnected by the white commissure.
- It contains sensory (ascending) and motor (descending) tracts.
Conduction Pathways
- Spinal pathways are sensory or motor.
- Sensory pathways ascend toward the brain.
- Motor pathways descend from the brain.
- Pathways are paired, with a left and a right tract.
- Cell locations vary:
- Axons are in spinal cord tracts.
- Cell bodies are in ganglia, spinal cord gray horns, and brain gray matter. Pathways are made of a chain of two or more neurons.
- Most pathways decussate, meaning axons cross the midline so brain processes information for the contralateral side.
- Uncrossed pathways work on the ipsilateral side of the body
Sensory Pathways
- Sensory input transmitted through the spinal cord originates from general sense receptors. This input has two categories.
- Somatic sensory (somatosensory) receptors receive touch, pressure, vibration, and texture input
- Tactile receptors detect characteristics of an object.
- Proprioceptors detect stretch in joints, muscles, and tendons.
- Visceral sensory receptors detect changes (e.g., stretch) in an organ. Categories of sensory pathways include the following:
- Somatosensory pathways carry signals from the skin, muscles, and joints.
- Viscerosensory pathways carry signals from viscera.
- A series of neurons relays signals to the brain.
- A primary (1st order) neuron has a peripheral ending, a cell body in the posterior root ganglion, and an axon leading to the secondary neuron.
- A secondary (2nd order) neuron is an interneuron that receives primary input and extends to a tertiary neuron or to the cerebellum.
- A tertiary (3rd order) neuron is an interneuron that receives secondary neuron input and extends to the somatosensory cortex of the parietal lobe in the cerebrum.
Posterior Funiculus-Medial Lemniscal Pathway
- Signals about proprioception, touch, pressure, and vibration use a three-neuron chain.
- The primary neuron relays a signal from the skin to the brainstem.
- The peripheral receptor has an axon in the spinal nerve, posterior root, and spinal cord. Within the cord, the axon runs inside of fasciculus cuneatus or fasciculus gracilis.
- In the medulla, the axon contacts a secondary neuron.
- A secondary neuron relays the signal from the medulla to the thalamus.
- The cell body is in either the nucleus cuneatus or the nucleus gracilis of the medulla.
- The axon decussates and joins medial lemniscus. On thalamus, the axon contacts tertiary neuron
- A tertiary neuron relays a signal to the primary somatosensory cortex (postcentral gyrus). Signals related to crude touch, pressure, pain, and temperature use a three-neuron chain.
- A primary neuron relays the signal from skin to the spinal cord.
- The axon is in the spinal nerve and posterior root.
- The axon contacts the secondary neuron in the spinal cord posterior horn. A secondary neuron relays the signal from the spinal cord to the thalamus.
- Axon decussates and ascends in contralateral white matter where the anterolateral spinothalamic tract or the lateral spinothamalic tract run.
- Axon contacts a tertiary neuron in the thalamus.
- The tertiary neuron relays the signal from the thalamus to the cerebral cortex.
- Axon contacts the target neurome in appropriare part of primary somatosensory cortex. Provides signals about proprioception through a two neuron chain
- The primary neuron relays a signal from skin to the spinal cord.
- Axon is in spinal nerve and poseteriour root. The spinal cord’s posterior horn contains the axon that contacts the secondary spinal cord.
- The secondary neuron has relayed signals from the spinal cord toward cerebellum.
- Some secondary neuron axons move accross, while others stay ispsilateral
- Axons rise in ascending spinal cord to the spinal track. Contacts cell within the cerebellum.
Motor Pathway Information
- Controls effectors such as skeletal muscles
- Starts at Brian and has at least 2 neurons:
-
- The uper motor neuron in the brain/cortex/cercereal regions: This neurons exites the lower motor neurons from areas
- lower motor neurons in the craneal nerve or spinal cord anterior horn: Excites the muscle to do the task
Direct (Pyramidal) pathway
- Is a way between the brain and the muscles to the motor region and function
- Begins with “upper” motor neurons, in the “ primary” motor area in the cerciral reigon
- The Acros course through internal capsule, cerer rai, reduncles, corticospinal cracts.
- The Axons is in charge of synapsis with the lower motor in terior nor region
- lower motorneurons then extend to the muscle for execution.
Direct (pyramidal) pathway
- Contains
– Lateral corticospinal tracts
- With upper-motor neurons , axons decussate within medulla's pyramids
- Axons form a white tracts in literal fundiculi and contacts lower motor nuercjss
- Allows lowers neurons to innervate for the limbs, for mobility – Anterior corticospinal tracts
- Has upper motor neuron’s, creating white tracs in the anterior
funculi
- Axons Decussate at level of segmented spinal cord- and contact the interrveurons, lower motor neurons
- Axons will inneravte the axial muslces to skeleton if that neuron type
Indirect Pathway
- Contains complicated route to spial cord, via brainstem and spine connecting
Lateral Pathway
- Tone in flxor limb muscles
- Comrises of rudiospinal tracts originating in the midbrain
Medial Pathway
- Muscle tone and movement for head , heck , proximal ,trunk
- Also reculsposinal, tectosopinal, vertisbulostina; tracrts, from vistibular
Clinical Applications for Spinal Cord Injuries
- Prompt steroid given use help presecrve muscle function
- Early Antibiotics for for number of health , from unrin and pulimonay, reduce the unmber of deaths
- Neuro Steams Cells help with rerendering cons axons from spinal region
General Distribution of Spinal Nerves
After intervetrbal foramen
- Splints into multipole branches, inner actons that innervate the antero and lateral limbs with , upper and limb areas.
- Post Ramus does the innervare to skin for muscles and back
- Antieror amsu = larges and branches
Communicatoines rmai, connect between spinak nerve and trunks with glanglium and trunk
DERMATONES
- Seme gment of skin that supllies signals to spinal nerve to inner acting signal
REFERRED VISION
-
can help localize to one or mor
-
Appendicitis; pain - often referred to spinal segment 7 10 89t
Shingles
- When virus reactivates in dorsal root ganglion
- Reacting travels through sensors and inner actions to dermatome
Results: Burning and lighting pain.
- rash/ blusters across skins of derma tone
Plaxus Never/ Networks
- Interweaving antero rmai of Spinal never, to
- From the four spinal segments, form cervical , brachial Lumio and sacral
INSTERCOSTAL NERVES
- Located in anterior rmai of spinal nerves (T1-511)
- 2 Is sub costal nerve, anterior to ribs
- T1 - anterior rmai, has - part goes to brahcol nerves, pare goes to the intercostal
- Also - T2 - anterior - inner actres intersotal muslces interstal region. Get info for a ill and medial
T9 - T6, have inner actions on interstotal and for signals and interconals T1-T 2 - Anterior ranmus inveravte muslces, and receive overskin signals to abdomen
PLAXUS FOR CERVICAL
- Anterior rmai for 71 to 74 segments has some axons
- To give for portions with head and show ders
BRACIAL PLEXUDES
- Anterior , rmai of $7 5 is the -10
- This network extends from fiber laterally to exit - Made of interior mar, trunks, cord divisions. The runks unite
- Anterior for fibers extending and made in later with Xila – superior to trukcs – MIDDLE
- INFERIOR
To divide interior/ posterior divisions for
- Divisions Converge for cords that extend, via artery Posteror - 65 -71 parts of nerves cord = has portion from the interior runks Medial Cord has portion of nerves cord Lateral- Has portion from -v 5 10
Major terminal branches = give 5 major cord signals. Also
-
Axilary nerve - Sensory from superlateral to arm,
-
Median Nerve 2 Most muslces , lateral, lunbricals (not pinkie) and dorsla tops-fist most fingers
Mucuocuteneous , snesoty input to lateral forearm for anterior arm muslces aswell Radia - to posteruims, posre, terui, for radial, and hand
Ulnar neve
- For the anterior and - forearm , also, the palmers
Clinical Axilaryl issues
-
Can be damaged to compress axils
-
The radial causes extensor
-
Posterior cord is caused my by Crutes - axillary and
If middle = hand, unler = fractures
LUMBO SUCARL
-
Has Lumbor lumbus - for anterior - 14 of nerv
-
Fromoral,
-
Obturator nerve ( innervates medial, muslces but no input)
-
Smaller neves ( for abdominal with - geneteial)
SACRAL
- For - 1 for segment Antero for - innavetes flaxor Also sciate, for largest division
- 7 billia and common and fimbria and innervate, and are connected: DEEP- The tibial with common and fimbria
- SPLITS
CLINICAL IMPACTS
-
Injury glueril for neves Causes - Extremity with hermination to disk Common fimbria
-
Muscler Paraysosi cause of fracture that help person the unable to divert
Spinal cord
- Rapid premeditated,
- Involuntary
Stimulus is that what is needed to start for
- Rapid, has chain in neuron, what
- Involuntary Survival Meesum and aware of deimeteal Response
Components of the reflex
- Refelx
- Nerual
- Reposes
- Copyright
- Stimulates has
- skin activates signal
- Never signal
- Never and cord
- Efficter, 3 questions from what makes a C S,F S,F
SOMTIC
- The plywers of refeic SOMETIME RECEPTORS - IN s, k, muscle
AFTERENETI
-
CARES for information to horm and cord
-
INTEGRTATION
-
DETERMINE for
-
EFERENET CArries Muscles AFFFECYTOS
Spinal, cranial C, B is intergratioN Somatic OR visceral The effector of the
Innate
Horm and is , what
- A-I of reflex and if develp
COMMON SPINLA REFLXUES
- Also GOlgi, and WITHDEREWS - EXT
- STETCH
muscles. It contains
intract muscle
-
1 N and wrappeons orm by sensory Axonal extra
-
I is - fusetel
-
SPANDL is stretched, SENRY is that is connected to spinal COrd
-
Reflexive
-
It is detected for priorto
-
Spindle Sensory Alpa exite and - cause conteacs Also at the motor - the musclces
CLASSIFIED as - SPIL, and INATTE
COLGIA
- PREVENT CONTRACTIONS
- DETECT TENSION They are proproiceot, wih sensty ending at junction
- Their - AXS, with a
- Some - innerons inhibit or
- Inner - MUSCLES
- Som e - Inner action to the muscles
Withdrawl
- Puls for for pinalfuls with pain stimun and a stimuus
- EXIE AND SIGNL for cord
- CONTAC - and inner actions will, e and Excite with contact. And with draeon cord
- Simultneolsy , ,other, will excide. For
7 Cross SENSOE
It is conjucten Wich, e
TESTER
-
can TEST
-
Hypeactive
-
Hypractice
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