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Questions and Answers
What is one of the primary functions of the spinal cord?
What is one of the primary functions of the spinal cord?
The spinal cord begins at the level of the lumbar vertebrae.
The spinal cord begins at the level of the lumbar vertebrae.
False
What is the function of cerebrospinal fluid in relation to the spinal cord?
What is the function of cerebrospinal fluid in relation to the spinal cord?
Provides cushioning and protection
The three layers of the meninges are the dura mater, arachnoid mater, and __________.
The three layers of the meninges are the dura mater, arachnoid mater, and __________.
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Match each structure with its correct description:
Match each structure with its correct description:
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What level does the spinal cord typically terminate?
What level does the spinal cord typically terminate?
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The cervical enlargement correlates with sensory input and motor output to the lower extremities.
The cervical enlargement correlates with sensory input and motor output to the lower extremities.
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Name the fluid that protects the spinal cord.
Name the fluid that protects the spinal cord.
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How many pairs of cervical nerves are there?
How many pairs of cervical nerves are there?
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The thoracic region has 5 pairs of spinal nerves.
The thoracic region has 5 pairs of spinal nerves.
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What is the function of the phrenic nerve?
What is the function of the phrenic nerve?
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The ______________ plexus supplies the nerve supply to the shoulders and upper limbs.
The ______________ plexus supplies the nerve supply to the shoulders and upper limbs.
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Match the following spinal nerve types with their descriptions:
Match the following spinal nerve types with their descriptions:
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What immediate branches do spinal nerves divide into after exiting the vertebral column?
What immediate branches do spinal nerves divide into after exiting the vertebral column?
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The coccygeal region contains two nerve pairs.
The coccygeal region contains two nerve pairs.
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Which plexus is responsible for innervating the diaphragm?
Which plexus is responsible for innervating the diaphragm?
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What is the primary purpose of a lumbar puncture?
What is the primary purpose of a lumbar puncture?
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Antibiotics can be injected into the subarachnoid space during a lumbar puncture.
Antibiotics can be injected into the subarachnoid space during a lumbar puncture.
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Where is the most common site for a lumbar puncture?
Where is the most common site for a lumbar puncture?
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The protective covering of spinal nerves is called the ______.
The protective covering of spinal nerves is called the ______.
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Match the following terms with their descriptions:
Match the following terms with their descriptions:
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How many pairs of spinal nerves are there in the human body?
How many pairs of spinal nerves are there in the human body?
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Spinal nerves emerge from the spinal cord at irregular intervals.
Spinal nerves emerge from the spinal cord at irregular intervals.
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Spinal nerves connect the CNS to ______, muscles, and glands.
Spinal nerves connect the CNS to ______, muscles, and glands.
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What is a common result of injury to the long thoracic nerve?
What is a common result of injury to the long thoracic nerve?
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Erb’s palsy can occur in adults after traumatic events.
Erb’s palsy can occur in adults after traumatic events.
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What is commonly referred to as bumping one’s funny bone?
What is commonly referred to as bumping one’s funny bone?
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The _____ nerve is the largest unprotected nerve in the human body.
The _____ nerve is the largest unprotected nerve in the human body.
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Match the injury or condition with its symptoms:
Match the injury or condition with its symptoms:
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Which nerve supplies the medial half of the hand?
Which nerve supplies the medial half of the hand?
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Carpal tunnel syndrome is associated with a common repetitive motion injury.
Carpal tunnel syndrome is associated with a common repetitive motion injury.
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What type of injury occurs when the nerves of the brachial plexus are violently stretched?
What type of injury occurs when the nerves of the brachial plexus are violently stretched?
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What does the lumbar enlargement primarily handle?
What does the lumbar enlargement primarily handle?
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In the spinal cord, the white matter is located on the inside and the gray matter is on the outside.
In the spinal cord, the white matter is located on the inside and the gray matter is on the outside.
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What is the role of the posterior root in the spinal cord?
What is the role of the posterior root in the spinal cord?
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Epidural anesthesia is commonly administered to women about to go into _____.
Epidural anesthesia is commonly administered to women about to go into _____.
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What do the anterior roots of the spinal cord primarily conduct?
What do the anterior roots of the spinal cord primarily conduct?
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The posterior root ganglion contains the cell bodies of motor neurons.
The posterior root ganglion contains the cell bodies of motor neurons.
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Match the following components of the spinal cord with their functions:
Match the following components of the spinal cord with their functions:
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The internal anatomy of the spinal cord allows ____ and ____ information to be processed in an organized way.
The internal anatomy of the spinal cord allows ____ and ____ information to be processed in an organized way.
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What is the primary function of the femoral nerve?
What is the primary function of the femoral nerve?
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The sciatic nerve consists of two separate nerves: tibial and common fibular.
The sciatic nerve consists of two separate nerves: tibial and common fibular.
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Which two plexuses are mentioned in the content?
Which two plexuses are mentioned in the content?
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The origin of the obturator nerve is _____
The origin of the obturator nerve is _____
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Match the following nerves with their primary functions:
Match the following nerves with their primary functions:
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What type of information does gray matter in the spinal cord primarily handle?
What type of information does gray matter in the spinal cord primarily handle?
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White matter tracts in the spinal cord conduct nerve impulses to and from the brain.
White matter tracts in the spinal cord conduct nerve impulses to and from the brain.
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At which anatomical location does the sciatic nerve typically split into its two divisions?
At which anatomical location does the sciatic nerve typically split into its two divisions?
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Study Notes
Introduction to Chapter 13
- The chapter aims to identify and describe anatomical features of the spinal cord and spinal nerves.
- It discusses the functions of the spinal cord and spinal nerves and how they maintain homeostasis.
- It explains spinal reflex arcs.
Functions of the Spinal Cord
- Processes reflexes.
- Integrates EPSPs and IPSPs.
- Conducts sensory impulses to the brain and motor impulses to effectors.
Spinal Cord Anatomy
- Protected by bone (vertebrae).
- Protected by connective tissue (meninges).
- Protected by fluid (cerebrospinal fluid).
Meninges
- Composed of three layers: dura mater, arachnoid mater, and pia mater.
External Spinal Cord Anatomy
- The spinal cord begins at the foramen magnum and ends at the level of L2.
- The spinal cord has two enlargements: cervical and lumbar.
- The cervical enlargement correlates with sensory input and motor output to the upper extremities.
- The lumbar enlargement handles motor output and sensory input to and from the legs.
Spinal Cord Internal Anatomy
- White matter is on the outside of the spinal cord.
- Gray matter is on the inside of the spinal cord.
- In the brain, the white matter is on the inside, and the gray matter on the outside.
Sensory and Motor Processing
- The internal spinal cord anatomy allows sensory and motor information to be processed.
Comparison of Spinal Cord Segments
- Cervical segments have relatively large diameters and significant white matter.
- Thoracic segments have smaller diameters and less gray matter.
- Lumbar segments are nearly circular with large anterior and posterior gray horns and less white matter.
- Sacral segments are relatively small but have large amounts of gray matter.
- Coccygeal segments are much smaller.
External Cord Anatomy: Roots and Rootlets
- Two bundles of axons called roots connect each spinal nerve to a segment of the cord.
- The smaller bundles are called rootlets.
- Posterior (dorsal) roots and rootlets contain sensory axons that transmit nerve impulses from sensory receptors to the central nervous system.
External Cord Anatomy: Ganglion
- The posterior (dorsal) root has a swelling called the posterior (dorsal) root ganglion.
- Sensory neurons' cell bodies are located within the posterior (dorsal) root ganglion.
- The anterior (ventral) root and rootlets contain motor neurons' axons that transmit nerve impulses from the CNS to effectors (muscles and glands).
Epidural Anesthesia
- Commonly given to women in labor.
- A needle is placed between the bones of the posterior spine to the ligamentum flavum.
- The needle remains superficial to the dura mater.
- Local anesthetic is used to provide pain relief during a Cesarean section.
Lumbar Puncture
- A needle inserted into the subarachnoid space for withdrawing CSF or for introducing a drug or contrast agent.
- CSF is collected to diagnose meningitis or other CNS diseases.
- Agents such as antibiotics, chemotherapeutic agents, analgesics, or contrast media for radiographic procedures are injected.
- CSF pressure in the subarachnoid space (SAS) can be measured.
Spinal Nerves
- Spinal nerves connect the central nervous system (CNS) to sensory receptors, muscles, and glands.
- There are 31 pairs of spinal nerves.
- Anterior and posterior roots attach a spinal nerve to a segment of the spinal cord.
- Spinal nerves have connective tissue coverings: epineurium, perineurium, and endoneurium.
Peripheral Nerves
- Spinal nerves are arranged in fascicles surrounded by perineurium, with the entire nerve sheathed by epineurium.
Peripheral Nerves: Emergence and Branches
- 31 pairs of spinal nerves emerge from the cord at regular intervals (segments).
- Spinal nerves exit the vertebral column from the intervertebral foramina.
- Spinal nerves split into branches: anterior ramus, posterior ramus, and rami communicantes (connections to sympathetic ganglia).
Peripheral Nerves: Plexuses
- Anterior rami of spinal nerves form large plexuses (e.g., cervical, brachial, celiac, lumbar, sacral, coccygeal).
- The anterior rami either travel alone (intercostal nerves) or join to form plexuses.
Branches of Spinal Nerves
- Shortly after passing through the intervertebral foramen, a spinal nerve divides into several branches known as rami.
- Rami supply muscles of the back.
Dermatomes
- Certain segments of the skin are supplied by spinal nerves.
- Dermatomes are areas of skin innervated by specific spinal nerves.
Cervical Plexus
- Supplies skin and muscles of the head, neck, superior part of shoulders, chest, and diaphragm.
- The Phrenic nerve is a primary component, supplying the diaphragm.
Brachial Plexus
- Supplies nerves to the shoulders and upper limbs.
- A lesion of the median nerve can result in carpal tunnel syndrome.
Nerve Plexuses: Long Thoracic Nerve
- Emerges from the brachial plexus to supply the serratus anterior muscle.
- The long thoracic nerve is susceptible to injury due to its long, relatively superficial course.
- An injury to this nerve can cause a "winged scapula."
Nerve Plexuses: Brachial Plexus Injuries
- Erb's palsy is a paralysis of the arm that occurs in infants when the head and neck are pulled to one side during childbirth.
- A similar injury can occur in adults from traumatic falls.
- Injuries to the brachial plexus or peripheral nerves can affect the median nerve, leading to numbness, tingling, and pain in the hand and fingers.
Nerve Plexuses: Ulnar Nerve
- The ulnar nerve is a major nerve in the brachial plexus, emerging from the medial and lateral cords.
- It supplies the medial half of the hand.
- Striking the medial epicondyle of the humerus (the “funny bone”) can damage the ulnar nerve.
- Damage results in abnormal sensations and the inability to abduct or adduct the little and ring fingers.
Lumbar Plexus
- Supplies nerves to the lower abdominal walls, anterior thigh muscles, and medial thigh skin.
- The femoral nerve and obturator nerve are key components of the lumbar plexus.
Sacral Plexus
- Supplies nerves to the buttocks, most of the posterior thigh, and the posterior leg and foot.
- The primary nerve is the sciatic nerve.
Spinal Cord Physiology
- The spinal cord maintains homeostasis through the propagation of nerve impulses and the integration of information.
- White matter tracts conduct nerve impulses to and from the brain.
- Gray matter receives and integrates incoming and outgoing information to perform spinal reflexes.
Sensory and Motor Tracts (review)
- Sensory and motor tracts are essential pathways for information transmission within the spinal cord.
Reflexes and Reflex Arcs
- A reflex is a fast, involuntary, unplanned response to a stimulus.
- Reflexes are vital for maintaining homeostasis.
- The spinal cord's gray matter serves as the integrating center for spinal reflexes.
General Components of a Reflex Arc
- A reflex arc is composed of sensory receptors, sensory neurons, interneurons, motor neurons, and effectors.
Reflex Arcs: Vocabulary Terms
- Ipsilateral refers to the same side of the body.
- Contralateral refers to the opposite side of the body.
- Monosynaptic refers to reflex arcs with only one synapse.
- Polysynaptic refers to reflex arcs with more than one synapse.
- Reciprocal innervation describes neural circuits simultaneously contracting one muscle and relaxing its antagonist.
Stretch Reflex
- Causes contraction of a muscle that has been stretched.
- Sensory neurons respond to muscle-spindle stretches.
- Motor neurons to the same muscle cause contraction.
Tendon Reflex
- Causes relaxation of the muscle attached to the stimulated tendon.
- Sensory neurons respond to tendon stretches.
- Motor neurons to the antagonist muscles are stimulated, leading to relaxation of the stretched muscle.
Flexor (Withdrawal) Reflex
- Causes withdrawal of a limb to avoid injury or pain.
- Sensory neurons respond to harmful stimuli.
- Motor neurons to flexor muscles are excited, while those to extensors are inhibited.
Crossed-Extensor Reflex
- Maintains balance during a withdrawal reflex by extending the opposite limb.
- Sensory pathway transmits information of the pain stimulus to the spinal cord.
Reflexes: Important Spinal Reflexes
- Patellar reflex: leg extends when patellar tendon is stretched.
- Achilles reflex: calf contracts when Achilles tendon is stretched.
- Babinski reflex: Normal in infants; abnormal extension indicate CNS damage.
Disorders of the Spinal Cord
- Traumatic injuries (monoplegia, paraplegia, hemiplegia, quadriplegia).
- Damage depends on the severity and location of spinal cord section or segment compression.
- Spinal cord compression is a disorder of the spinal cord caused by various issues.
- Degenerative diseases, like multiple sclerosis and amyotrophic lateral sclerosis (ALS), cause damage to the spinal cord.
- Shingles is an acute infection characterized by the herpes zoster virus affecting the PNS
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Description
Test your knowledge on the anatomy and functions of the spinal cord with this quiz. Explore key structures, their roles, and how cervical and thoracic nerves contribute to the body's motor and sensory functions. Perfect for students studying anatomy or related fields!
