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Questions and Answers
What is the primary function of the spinal cord?
What is the primary function of the spinal cord?
How many pairs of cervical nerves are there?
How many pairs of cervical nerves are there?
The spinal cord terminates at the level of L3 in the human body.
The spinal cord terminates at the level of L3 in the human body.
False
The phrenic nerve originates from C1 to C3.
The phrenic nerve originates from C1 to C3.
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What are the three major branches that spinal nerves split into after exiting the central nervous system?
What are the three major branches that spinal nerves split into after exiting the central nervous system?
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What are the three layers of the meninges?
What are the three layers of the meninges?
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The _______ is an extension of the pia mater that anchors the spinal cord to the coccyx.
The _______ is an extension of the pia mater that anchors the spinal cord to the coccyx.
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The _________ plexus supplies almost the entire nerve supply to the shoulders and upper limbs.
The _________ plexus supplies almost the entire nerve supply to the shoulders and upper limbs.
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What condition results from a lesion of the median nerve?
What condition results from a lesion of the median nerve?
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Match the following anatomical features with their descriptions:
Match the following anatomical features with their descriptions:
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Match each type of spinal nerve with the number of pairs:
Match each type of spinal nerve with the number of pairs:
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Which structure protects the spinal cord?
Which structure protects the spinal cord?
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The anterior rami can form large nerve networks known as plexuses.
The anterior rami can form large nerve networks known as plexuses.
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The spinal cord integrates excitatory postsynaptic potentials (EPSPs) and inhibitory postsynaptic potentials (IPSPs).
The spinal cord integrates excitatory postsynaptic potentials (EPSPs) and inhibitory postsynaptic potentials (IPSPs).
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Which nerve specifically innervates the diaphragm?
Which nerve specifically innervates the diaphragm?
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What is the fluid that surrounds and protects the spinal cord?
What is the fluid that surrounds and protects the spinal cord?
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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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CSF can only be withdrawn and not injected during a lumbar puncture.
CSF can only be withdrawn and not injected during a lumbar puncture.
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At which lumbar vertebrae levels are lumbar punctures typically performed?
At which lumbar vertebrae levels are lumbar punctures typically performed?
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The spinal nerves are part of the __________ nervous system.
The spinal nerves are part of the __________ nervous system.
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Which agents can be introduced during a lumbar puncture?
Which agents can be introduced during a lumbar puncture?
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Match the following spinal nerves with their descriptions:
Match the following spinal nerves with their descriptions:
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The perineurium surrounds individual fascicles of spinal nerves.
The perineurium surrounds individual fascicles of spinal nerves.
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What is the purpose of measuring CSF pressure during a lumbar puncture?
What is the purpose of measuring CSF pressure during a lumbar puncture?
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What is a reflex?
What is a reflex?
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The gray matter of the spinal cord is the integrating center for spinal reflexes.
The gray matter of the spinal cord is the integrating center for spinal reflexes.
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What type of reflex causes contraction of a muscle that has been stretched?
What type of reflex causes contraction of a muscle that has been stretched?
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The _____ reflex causes relaxation of the muscle attached to the stimulated tendon.
The _____ reflex causes relaxation of the muscle attached to the stimulated tendon.
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Which of the following terms refers to two or more synapses in a reflex arc?
Which of the following terms refers to two or more synapses in a reflex arc?
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Match the following reflexes with their descriptions:
Match the following reflexes with their descriptions:
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Which nerve is the largest arising from the lumbar plexus?
Which nerve is the largest arising from the lumbar plexus?
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The sciatic nerve is actually composed of three separate nerves.
The sciatic nerve is actually composed of three separate nerves.
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The crossed-extensor reflex helps maintain balance during a withdrawal reflex.
The crossed-extensor reflex helps maintain balance during a withdrawal reflex.
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The term _____ refers to the same side in reflex terminology.
The term _____ refers to the same side in reflex terminology.
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What is the origin of the sciatic nerve?
What is the origin of the sciatic nerve?
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The _____ conducts nerve impulses between the brain and the body.
The _____ conducts nerve impulses between the brain and the body.
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Match the following nerves to their functions:
Match the following nerves to their functions:
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What is the primary role of gray matter in the spinal cord?
What is the primary role of gray matter in the spinal cord?
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The main purpose of the spinal cord is to maintain homeostasis.
The main purpose of the spinal cord is to maintain homeostasis.
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The _____ tracts in the spinal cord only conduct information to the brain.
The _____ tracts in the spinal cord only conduct information to the brain.
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What type of paralysis results from a transection at the upper cervical area?
What type of paralysis results from a transection at the upper cervical area?
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An abnormal Babinski sign indicates a normal neurological response.
An abnormal Babinski sign indicates a normal neurological response.
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What condition is characterized by demyelination of oligodendroglia?
What condition is characterized by demyelination of oligodendroglia?
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Paralysis with no function from the neck down is referred to as _________.
Paralysis with no function from the neck down is referred to as _________.
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Match the following conditions with their characteristics:
Match the following conditions with their characteristics:
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What is a potential cause of spinal cord compression?
What is a potential cause of spinal cord compression?
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The extent of paralysis depends only on the degree of spinal cord section.
The extent of paralysis depends only on the degree of spinal cord section.
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Which infection is characterized by skin blisters and pain due to the herpes zoster virus?
Which infection is characterized by skin blisters and pain due to the herpes zoster virus?
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Study Notes
Chapter 13: The Spinal Cord and Spinal Nerves
- This chapter identifies and describes the 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 in the body.
- It also explains spinal reflex arcs.
- The spinal cord processes reflexes, integrates EPSPs and IPSPs, and 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).
- The meninges consist of three layers: dura mater, arachnoid mater, and pia mater.
External Spinal Cord Anatomy
- The spinal cord begins as an extension of the medulla oblongata at the foramen magnum and ends at the level of L2.
- The spinal cord has two enlargements: cervical (C4-T1) and lumbar (between L1 and L4).
- The cervical enlargement controls sensory input and motor output to the upper extremities, while the lumbar enlargement handles these functions for the legs.
- Two bundles of axons called roots connect each spinal nerve to a segment of the cord. Posterior roots contain sensory axons, and anterior roots contain motor axons.
- The cauda equina are the roots of the lower spinal nerves that angle downwards alongside the filum terminale.
Internal Spinal Cord Anatomy
- In the spinal cord, white matter is on the outside and gray matter is on the inside.
- Structures include the posterior/anterior gray horns, gray commissure, anterior/posterior white commissure, anterior/posterior white funiculi and central canal.
Sensory and Motor Processing
- The spinal cord's internal anatomy allows for the organized processing of sensory and motor information.
- Spinal nerves connect the CNS to sensory receptors, muscles, and glands.
Spinal Cord Segments (Table 13.1)
- Cervical segments are relatively large in diameter, with a large oval shape and relatively large amounts of white matter, and small lateral gray horns in lower segments,.
- Thoracic segments have a small diameter, with relatively small amounts of gray matter, except for C1-C4.
- Lumbar segments are nearly circular, with very large anterior and posterior gray horns and small lateral gray horns.
- Sacral segments are relatively small with relatively large amounts of gray matter. Anterior and posterior gray horns are large and thick.
- Coccygeal are similar to lower sacral segments but are smaller.
Spinal Nerves
- Spinal nerves connect the central nervous system to sensory receptors, muscles, and glands of the peripheral nervous system.
- 31 pairs of spinal nerves.
- Anterior and posterior roots connect spinal nerves to a segment of the spinal cord.
Connective Tissue of Spinal Nerves
- Spinal nerves have layers of connective tissue coverings.
- The outermost layer is the epineurium
- The perineurium surrounds nerve fascicles
- The endoneurium surrounds individual nerve fibers (axons).
Peripheral Nerves
- Spinal nerves exit the spinal column at intervertebral foramina, and branch into anterior and posterior rami.
- Rami communicantes connect spinal nerves to sympathetic ganglia.
Peripheral Nerve Plexuses
- Nerve plexuses are formed from anterior rami of spinal nerves.
- Major plexuses in the body include cervical, brachial, lumbar, sacral, and coccygeal plexuses.
Branches of a Spinal Nerve
- Shortly after exiting, spinal nerves branch into anterior and posterior rami and rami communicantes.
Dermatomes
- Specific skin segments are supplied by spinal nerves; these regions are called dermatomes.
Cervical Plexus
- Supplies skin and muscles of the head, neck, superior shoulders and upper chest; and diaphragm.
- Phrenic nerve supplies diaphragm.
Brachial Plexus
- Provides nerve supply for shoulders and upper limbs, including the median nerve (important for carpal tunnel syndrome).
- Lesions of the median nerve can cause carpal tunnel syndrome.
Nerve Plexuses (Long Thoracic Nerve)
- The long thoracic nerve emerges from the brachial plexus to supply the serratus anterior muscle.
- This nerve is susceptible to injury, which can result in "winged scapula."
Nerve Plexuses (Injury)
- Erb's palsy and similar injuries can occur from birth canal trauma.
- The ulnar nerve is large and unprotected, and damage can affect the 4th and 5th fingers, impairing abduction and adduction.
Median Nerve Injury & Carpal Tunnel Syndrome
- Median nerve injury, either at the plexus or elsewhere, can cause numbness, tingling, and pain in the palm and fingers, often associated with typing and hand motions.
- Carpal tunnel syndrome is a specific kind of median nerve injury.
Lumbar Plexus
- Lumbar plexus supplies motor and sensory innervation to the hip, thigh, and lower leg.
- Major nerves include the femoral and obturator nerves.
Sacral Plexus
- Sacral plexus lies inferior to the lumbar plexus and supplies the posterior hip, thigh and lower leg.
- The sciatic nerve, the largest nerve in the body, is a major nerve of the sacral plexus.
Spinal Cord Physiology
- Spinal cord pathways conduct nerve impulses to and from the brain.
- Gray matter integrates incoming and outgoing information to perform spinal reflexes.
Sensory and Motor Tracts
- Specific tracts within the spinal cord carry sensory information (ascending tracts) and motor commands (descending tracts).
Reflexes and Reflex Arcs
- Reflexes are rapid, involuntary responses to stimuli, crucial for homeostasis.
- Gray matter in the spinal cord acts as the integrating center for spinal reflexes.
Reflex Arcs: Components
- Sensory receptors, sensory neurons, integrating centers (in the spinal cord), motor neurons, and effectors (muscles or glands) are components of a reflex arc.
Types of Reflex Arcs
- Monosynaptic: Simplest reflex arc with one synapse. One example is the stretch reflex.
- Polysynaptic: More complex with multiple synapses. Some examples are the flexor reflex, crossed-extensor reflex and the tendon reflexes.
Stretch Reflex
- Causes muscle contraction in response to stretching.
Tendon Reflex
- Causes muscle relaxation in response to tension on the tendon.
Flexor (Withdrawal) Reflex
- Causes withdrawal of a limb from a painful stimulus.
Crossed-Extensor Reflex
- Maintains balance during a withdrawal reflex.
Important Spinal Reflexes
- Patellar reflex: Leg extension in response to patellar tendon stretch.
- Achilles reflex: Calf muscle contraction in response to Achilles tendon stretch.
- Babinski reflex: Normal in infants; abnormal in adults indicates corticospinal tract damage.
Spinal Cord Disorders
- Traumatic injuries (monoplegia, paraplegia, hemiplegia, quadriplegia) o Degree of injury (spinal cord section or compression) and location effect the outcome of damage
- Spinal cord compression: compression from bone, blood, abscess, tumor or ruptured disk.
- Degenerative diseases (ALS - Lou Gehrig's disease)
- Shingles: infection of peripheral nerves by herpes zoster virus (causing chicken pox).
- Poliomyelitis (Polio): viral infection causing paralysis.
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Description
Test your knowledge on the anatomy and functions of the spinal cord and spinal nerves. This quiz covers key components such as nerve pairs, meninges layers, and the role of various nerves. Perfect for students studying human anatomy or preparing for exams.
