Spinal Cord Structure and Functions Quiz
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Questions and Answers

What is the primary function of the spinal cord in relation to reflexes?

  • It regulates endocrine functions.
  • It processes reflexes. (correct)
  • It generates voluntary movements.
  • It enhances cognitive functions.

Which layer of the meninges is closest to the spinal cord?

  • Cerebrospinal fluid
  • Dura mater
  • Pia mater (correct)
  • Arachnoid mater

Where does the spinal cord begin in relation to the brain stem?

  • At the cervical enlargement
  • At the thoracic spine
  • At the level of the spinal canal
  • At the foramen magnum (correct)

What is the significance of the cervical enlargement of the spinal cord?

<p>It correlates with sensory and motor output to the upper extremities. (A)</p> Signup and view all the answers

Which of the following structures is involved in protecting the spinal cord?

<p>Vertebrae (A)</p> Signup and view all the answers

What part of the spinal cord anchors it to the coccyx?

<p>Filum terminale (B)</p> Signup and view all the answers

What are the lower spinal nerves collectively known as?

<p>Cauda equina (A)</p> Signup and view all the answers

Which of the following best describes the arrangement of impulses in the spinal cord's functions?

<p>Conducts sensory impulses to the brain and motor impulses to effectors. (B)</p> Signup and view all the answers

How many pairs of cervical nerves are there?

<p>8 pairs (D)</p> Signup and view all the answers

Which plexus provides nerve supply to the skin and muscles of the neck and diaphragm?

<p>Cervical plexus (A)</p> Signup and view all the answers

Which spinal nerves give rise to the phrenic nerve?

<p>C3–C5 (A)</p> Signup and view all the answers

What is the primary function of the anterior ramus of spinal nerves?

<p>Providing motor innervation to limbs (C)</p> Signup and view all the answers

What kind of injuries can result from a lesion of the median nerve?

<p>Carpal tunnel syndrome (B)</p> Signup and view all the answers

How many pairs of thoracic nerves are present in the human body?

<p>12 pairs (A)</p> Signup and view all the answers

Which of the following best describes the function of dermatomes?

<p>Carry sensory nerve impulses to the brain (B)</p> Signup and view all the answers

Which plexus is mainly involved in supplying the upper limbs?

<p>Brachial plexus (B)</p> Signup and view all the answers

What primary function does the lumbar enlargement serve?

<p>Motor output and sensory input to and from the legs (C)</p> Signup and view all the answers

Which statement about the internal anatomy of the spinal cord is correct?

<p>White matter is on the outside, and gray matter is on the inside. (A)</p> Signup and view all the answers

What is contained within the posterior root ganglion?

<p>Sensory neuron cell bodies (D)</p> Signup and view all the answers

How do the anterior (ventral) root and rootlets function?

<p>They carry efferent impulses to muscles and glands. (C)</p> Signup and view all the answers

What is a characteristic of the posterior (dorsal) root?

<p>It contains only sensory axons. (A)</p> Signup and view all the answers

During epidural anesthesia, which anatomical layer is penetrated?

<p>Ligamentum flavum (D)</p> Signup and view all the answers

What is filled with cerebrospinal fluid (CSF) in the spinal cord?

<p>Central canal (C)</p> Signup and view all the answers

What type of information is primarily processed in the spinal cord's gray matter?

<p>Both sensory and motor information (B)</p> Signup and view all the answers

What role do reflexes play in relation to homeostasis?

<p>They help maintain homeostasis. (C)</p> Signup and view all the answers

Which term describes a reflex arc that involves only one synapse?

<p>Monosynaptic (B)</p> Signup and view all the answers

What characterizes the crossed-extensor reflex?

<p>It maintains balance during withdrawal. (A)</p> Signup and view all the answers

Which reflex causes a muscle to relax as a result of tendon stimulation?

<p>Tendon reflex (B)</p> Signup and view all the answers

What response is typical in adults when the sole of the foot is stimulated in the Babinski reflex?

<p>Flexion (curling) of the big toe. (D)</p> Signup and view all the answers

What is meant by reciprocal innervation in a reflex arc?

<p>Simultaneous contraction of one muscle and relaxation of its antagonist. (C)</p> Signup and view all the answers

In which condition is the patellar reflex likely to be blocked?

<p>Damage in the corticospinal tracts. (D)</p> Signup and view all the answers

Which description accurately defines contralateral reflex actions?

<p>They occur on the opposite side of the stimulus. (A)</p> Signup and view all the answers

What is primarily collected during a lumbar puncture?

<p>Cerebrospinal fluid for diagnostic purposes (A)</p> Signup and view all the answers

What is the correct anatomical location for performing a lumbar puncture?

<p>Between the 3rd and 4th lumbar vertebrae (D)</p> Signup and view all the answers

Which substances can be introduced into the subarachnoid space during a lumbar puncture?

<p>Drugs like antibiotics, analgesics, or contrast media (A)</p> Signup and view all the answers

What is the primary function of the femoral nerve?

<p>To control flexor muscles of the hip joint and extensor muscles of the knee joint (B)</p> Signup and view all the answers

What is the function of spinal nerves in the peripheral nervous system?

<p>To connect the CNS to sensory receptors, muscles, and glands (C)</p> Signup and view all the answers

Which of the following describes the origin of the sciatic nerve?

<p>L4–S3 (C)</p> Signup and view all the answers

What structure surrounds the fascicles of spinal nerves?

<p>Perineurium (B)</p> Signup and view all the answers

How many pairs of spinal nerves are there in the human body?

<p>31 pairs (D)</p> Signup and view all the answers

Which statement is true about the composition of the sciatic nerve?

<p>It is comprised of the tibial and common fibular nerves. (A)</p> Signup and view all the answers

What is a primary role of gray matter within the spinal cord?

<p>Receiving and integrating incoming and outgoing information (C)</p> Signup and view all the answers

Which of the following statements about the lumbar puncture procedure is accurate?

<p>It is performed at the level of the lumbar cord termination. (C)</p> Signup and view all the answers

What is the primary role of the anterior and posterior roots in relation to spinal nerves?

<p>To attach a spinal nerve to a segment of the spinal cord (A)</p> Signup and view all the answers

Where does the sciatic nerve typically split into its two divisions?

<p>Usually at the knee (C)</p> Signup and view all the answers

What type of information is primarily conducted by white matter tracts in the spinal cord?

<p>Both sensory and motor information to and from the brain (B)</p> Signup and view all the answers

What type of muscle does the obturator nerve primarily control?

<p>Adductor muscles of the hip joint (D)</p> Signup and view all the answers

What consequence does the propagation of nerve impulses in the spinal cord have for overall physiology?

<p>Affects the balance of neural input and output in the body (A)</p> Signup and view all the answers

Flashcards

Functions of the Spinal Cord

The spinal cord processes reflexes, integrates excitatory and inhibitory signals, and acts as a pathway for sensory and motor impulses.

Protection of the Spinal Cord

The spinal cord, enclosed within the vertebral column, is protected by bone, connective tissue, and cerebrospinal fluid.

Meninges Layers

The meninges are three layers of protective membranes: Dura mater, Arachnoid Mater, and Pia Mater.

Spinal Cord Location

The spinal cord begins as an extension of the medulla oblongata at the foramen magnum and terminates at the level of L2.

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Filum Terminale Function

The filum terminale is a pia mater extension that anchors the spinal cord to the coccyx.

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Cauda Equina

The cauda equina are the root nerves of the lower spine that angle down alongside the filum terminale.

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Spinal Cord Enlargements

Enlargements in the cervical and lumbar regions of the spinal cord correspond to the sensory and motor innervation of the upper and lower extremities.

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Spinal Cord Overview

The spinal cord, protected by bone, connective tissue, and cerebrospinal fluid, is responsible for reflexes, signal integration, and conduction of sensory and motor information.

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What is the lumbar enlargement responsible for?

The lumbar enlargement is responsible for motor output (signals to muscles) and sensory input (signals from the body) related to the legs.

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Where is gray matter located in the spinal cord?

The gray matter is located inside the spinal cord, while the white matter is on the outside.

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How does the location of white and gray matter differ in the brain and spinal cord?

The white matter in the brain is located on the inside, while the gray matter is on the outside. This is the opposite of the spinal cord.

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What is cerebrospinal fluid (CSF)?

Cerebrospinal fluid (CSF) is a clear, colorless fluid that fills the spaces within the brain and spinal cord. It helps to protect and nourish these organs.

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How does the internal anatomy of the spinal cord facilitate sensory and motor processing?

The internal anatomy of the spinal cord is organized in a way that allows for the efficient processing of sensory and motor information.

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What type of axons are found in the posterior (dorsal) root of a spinal nerve?

The posterior root of a spinal nerve contains only sensory axons, which carry signals from sensory receptors in the body to the central nervous system (CNS).

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What type of axons are found in the anterior (ventral) root of a spinal nerve?

The anterior root of a spinal nerve contains axons of motor neurons, which carry signals from the CNS to muscles and glands.

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What is epidural anesthesia?

Epidural anesthesia is a type of pain relief administered by injecting a local anesthetic into the epidural space, which is located between the dura mater and the ligamentum flavum. It's commonly given during labor to help manage pain.

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Peripheral Nerve

A bundle of nerves that exits the spinal cord and carries signals to and from the body.

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Branches of a Spinal Nerve

The three major branches of a spinal nerve are: Anterior ramus, Posterior ramus, and Rami communicantes.

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Nerve Plexus

A group of nerves that form a network, often located anterior to the spine, responsible for innervating specific body regions. Examples: Cervical plexus, Brachial plexus, Lumbar plexus.

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Dermatome

Areas of skin innervated by specific spinal nerves. Each dermatome represents a distinct sensory region.

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Cervical Plexus

Supplies nerves to the head, neck, diaphragm, and shoulders.

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Phrenic Nerve

The phrenic nerve, a major branch of the cervical plexus, is responsible for innervating the diaphragm.

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Brachial Plexus

Supplies nerves to the shoulders and upper limbs, including the hand and fingers.

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Carpal Tunnel Syndrome

A condition caused by compression of the median nerve, which often affects the wrist and hand.

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What is a Lumbar Puncture?

A procedure where a needle is inserted into the subarachnoid space to withdraw cerebrospinal fluid (CSF) for diagnosis or to relieve pressure, or to introduce drugs or contrast agents.

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Why is CSF Collected during a Lumbar Puncture?

The cerebrospinal fluid (CSF) is often collected during a lumbar puncture to diagnose conditions like meningitis or other central nervous system (CNS) diseases.

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What can be Injected during a Lumbar Puncture?

A lumbar puncture can be used to inject medications like antibiotics, chemotherapy drugs, or analgesics into the subarachnoid space.

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What is the Subarachnoid Space (SAS)?

The subarachnoid space (SAS) is the space between two layers of meninges - the arachnoid mater and pia mater, where cerebrospinal fluid circulates.

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Where is the Typical Lumbar Puncture Site?

The lumbar puncture site is usually between the 3rd and 4th (or 4th and 5th) lumbar vertebrae because the spinal cord ends above this region, minimizing the risk of injury.

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What is the Cauda Equina?

The cauda equina is a bundle of nerve roots extending from the spinal cord in the lower lumbar region.

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What are Spinal Nerves?

Spinal nerves connect the central nervous system (CNS) to sensory receptors, muscles, and glands, forming part of the peripheral nervous system.

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How Many Pairs of Spinal Nerves are There?

There are 31 pairs of spinal nerves, each named for the vertebral level they exit from. They consist of both anterior (motor) and posterior (sensory) roots.

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What is a reflex?

A rapid, involuntary, and unplanned response to a specific stimulus.

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What is a reflex arc?

The pathway that a reflex signal travels through, involving sensory neurons, interneurons, motor neurons, and an effector.

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What is the role of the spinal cord's gray matter in reflexes?

The integrating center of a reflex arc, where sensory input is processed and motor output is generated.

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What is the stretch reflex?

A reflex that causes a muscle to contract when it is stretched.

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What is the tendon reflex?

A reflex that causes a muscle to relax when the tendon attached to it is stretched.

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What is the flexor (withdrawal) reflex?

A reflex that causes a limb to withdraw from a painful stimulus.

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What is the crossed-extensor reflex?

A reflex that helps maintain balance during a withdrawal reflex by extending the opposite limb.

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What is the Babinski reflex?

A reflex that checks the integrity of the corticospinal tract.

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What is the femoral nerve?

The largest nerve emerging from the lumbar plexus. It innervates the flexors of the hip and extensors of the knee, as well as the skin of the anterior and medial thigh, and the medial side of the leg and foot.

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What is the obturator nerve?

A nerve originating from the lumbar plexus that supplies the adductor muscles of the hip joint and the skin over the medial aspect of the thigh.

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Describe the sciatic nerve.

The sciatic nerve is actually two nerves bound together: the tibial and common fibular nerves. It innervates the hamstring muscles and adductor magnus in the thigh.

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How are nerve impulses conducted in the spinal cord?

The spinal cord uses white matter tracts to transmit information to and from the brain.

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What is the role of the gray matter in the spinal cord?

The gray matter of the spinal cord is responsible for processing incoming sensory information and integrating it with outgoing motor signals.

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How does the spinal cord enable reflexes?

The spinal cord receives sensory information and integrates it with motor commands to create smooth and coordinated movements.

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What is the overall function of the spinal cord?

The spinal cord is a vital structure that allows communication between the brain and the body. It enables reflexes, coordinates movement, and regulates some autonomic functions.

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What happens to the spinal cord at its lower end?

The spinal cord doesn't terminate abruptly but continues as a thin filament called the filum terminale.

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Study Notes

Introduction

  • The chapter aims to identify and describe the anatomical features of the spinal cord and spinal nerves.
  • It also discusses the functions of the spinal cord and spinal nerves, and how they maintain homeostasis.
  • The chapter also covers spinal reflex arcs.
  • The spinal cord performs reflexes, integrates EPSPs and IPSPs, and conducts sensory and motor impulses.

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

  • The spinal cord is protected by bone (vertebrae), connective tissue (meninges), and fluid (cerebrospinal fluid).

Protection of the Spinal Cord

  • The spinal cord is protected by bone (vertebrae).
  • The spinal cord is protected by connective tissue (meninges).
  • The spinal cord is protected by fluid (cerebrospinal fluid).

Meninges

  • The meninges are composed of three layers: dura mater, arachnoid mater, and pia mater.

External Anatomy of the Spinal Cord

  • The spinal cord begins as an extension of the medulla oblongata at the foramen magnum and terminates at the level of L2.
  • The spinal cord has two enlargements: a cervical enlargement and a lumbar enlargement. These enlargements correlate with the sensory and motor output to the upper and lower extremities, respectively.
  • Two bundles of axons, called roots, connect each spinal nerve segment of the cord by even smaller bundles of axons called rootlets.
  • The posterior (dorsal) root and rootlets contain only sensory axons, transmitting nerve impulses from sensory receptors into the CNS.
  • Each posterior root has a swelling, the posterior (dorsal root ganglion), which contains the cell bodies of sensory neurons.
  • The anterior (ventral) root and rootlets contain axons of motor neurons, conducting nerve impulses to effectors (muscles and glands).
  • The cauda equina, or “horse's tail,” are the roots of the lower spinal nerves angling alongside the filum terminale,
  • The filum terminale, an extension of the pia mater, anchors the spinal cord to the coccyx.
  • The spinal cord's external anatomy shows pairs of spinal nerves emerging at regular intervals (segments) from the intervertebral foramen.

Internal Anatomy of the Spinal Cord

  • White matter is on the outside, and gray matter is on the inside of the spinal cord in the middle of the spinal cord.
  • The spinal cord internal anatomy includes spinal ganglion, lateral white funiculus, lateral gray horn, anterior root of spinal nerve, anterior gray horn, gray commissure, axon of interneuron, anterior white commissure, anterior white funiculus, anterior median fissure, posterior rootlets, axons of motor neurons, posterior gray horn, posterior median sulcus, posterior white funiculus, central canal, axon of sensory neuron, cell body of interneuron, cell body of autonomic motor neuron, cell body of sensory neuron, cell body of somatic motor neuron

Sensory and Motor Processing

  • Internal spinal cord anatomy organizes sensory and motor information.

Comparison of Various Spinal Cord Segments

  • Cervical segments are relatively large and oval, with large amounts of white matter.
  • Thoracic segments have small diameters with relatively small amounts of gray matter.
  • Lumbar segments are nearly circular with large amounts of gray matter, and relatively less white matter.
  • Sacral segments are relatively small but have large amounts of gray matter, and small white matter.
  • Coccygeal segments resemble lower sacral segments but are markedly smaller.

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 spinal nerves to spinal cord segments.
  • Spinal nerves have connective tissue coverings: epineurium, perineurium, and endoneurium.

Peripheral Nerves

  • Peripheral nerves are the communication paths between the spinal cord and specific body regions.
  • Spinal nerves emerge from the cord at regular intervals.
  • Branching includes the anterior rami, posterior rami, and rami communicantes.
  • Spinal nerves form major nerve plexuses, all located anterior to the spine.

Branches of a Spinal Nerve

  • A spinal nerve, after passing through its intervertebral foramen, divides into several branches known as rami.

Dermatomes

  • Certain skin segments are supplied by spinal nerves that carry somatic sensory nerve impulses to the brain.

Cervical Plexus

  • The cervical plexus supplies skin and muscles of head, neck, superior shoulders, chest, and diaphragm.
  • The phrenic nerve is crucial for diaphragm function in this plexus.

Brachial Plexus

  • The brachial plexus provides almost all nerve supply to the shoulders and upper limbs.
  • Lesion of the median nerve can result in carpal tunnel syndrome.

Nerve Plexuses

  • The long thoracic nerve emerges from the brachial plexus to supply the serratus anterior muscle.
  • Damage can cause a “winged scapula.”
  • Injuries to the brachial plexus are relatively common, including Erb's palsy (waiter's tip) and ulnar nerve palsy.

Lumbar Plexus

  • The lumbar plexus supplies the lower abdominal wall, external genitalia, and lower limbs.
  • Important nerves include the femoral and the obturator nerve.

Sacral Plexus

  • The sacral plexus is important for supplying the buttock, perineum, and lower limbs.
  • The sciatic nerve is a major component.

Spinal Cord Physiology

  • The spinal cord plays a crucial role in maintaining homeostasis by propagating nerve impulses and integrating information.
  • White matter tracts conduct nerve impulses to and from the brain.
  • Gray matter receives and integrates incoming and outgoing information.

Sensory and Motor Tracts

  • Sensory and motor tracts are defined, and their functions are described.

Reflexes and Reflex Arcs

  • Reflexes, fast involuntary responses, aid in homeostasis.
  • Gray matter acts as the integrating center for spinal reflexes, with sensory receptors, sensory neurons, neurons, interneurons, motor neurons, and effectors.

Reflex Arcs: Vocabulary Terms

  • Ipsilateral, contralateral, monosynaptic, and polysynaptic terms are defined in reference to reflex arcs.
  • Reciprocal innervation is described.

Stretch Reflex

  • The stretch reflex explains how a muscle contracts when stretched.

Tendon Reflex

  • The tendon reflex describes the relaxation of a muscle when its tendon is stimulated.

Flexor (Withdrawal) Reflex

  • Describes the withdrawal of a limb in response to pain.

Crossed-Extensor Reflex

  • Describes the reflex that maintains balance during a withdrawal reflex.

Reflexes

  • Describes the patellar reflex, Achilles reflex, and Babinski reflex.

Disorders

  • Spinal cord trauma, compression, degenerative diseases (e.g., multiple sclerosis, ALS), and shingles, and poliomyelitis are discussed. The extent of paralysis depends on the location and level of damage.

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Description

Test your knowledge on the anatomy and functions of the spinal cord with this comprehensive quiz. Engage with questions about reflexes, meninges, and spinal nerves, while exploring the significance of the cervical enlargement. Perfect for students studying biology or human anatomy.

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