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Questions and Answers
Which is the name of a plexus?
Which is the name of a plexus?
- Brachial (correct)
- Cervical (correct)
- Sacral (correct)
- Lumbar (correct)
The anterior rami of spinal nerves form which nerve plexuses?
The anterior rami of spinal nerves form which nerve plexuses?
- Lumbar (correct)
- Brachial
- Sacral (correct)
- Cervical (correct)
The posterior root of spinal nerve carries______nerve fibers.
The posterior root of spinal nerve carries______nerve fibers.
sensory
Moving peripherally from the spinal cord, which anterior and posterior structures form the spinal nerve?
Moving peripherally from the spinal cord, which anterior and posterior structures form the spinal nerve?
The somas of which neurons are found within the posterior root ganglion?
The somas of which neurons are found within the posterior root ganglion?
An anterior root of a spinal nerve contains axons of somatic_____neurons.
An anterior root of a spinal nerve contains axons of somatic_____neurons.
Spinal nerves are described as______nerves because they carry both afferent and efferent signals.
Spinal nerves are described as______nerves because they carry both afferent and efferent signals.
Which ramus of a spinal nerve innervates the local muscles, joints, and skin on the back?
Which ramus of a spinal nerve innervates the local muscles, joints, and skin on the back?
The larger____ramus of a spinal nerve innervates the anterior and lateral skin and muscles of the trunk and gives rise to the nerves of the limbs.
The larger____ramus of a spinal nerve innervates the anterior and lateral skin and muscles of the trunk and gives rise to the nerves of the limbs.
The anterior root of a spinal nerve contains axons of which neurons?
The anterior root of a spinal nerve contains axons of which neurons?
How many spinal nerves are there in order from superior to inferior?
How many spinal nerves are there in order from superior to inferior?
What are the four components of a monosynaptic somatic reflex arc?
What are the four components of a monosynaptic somatic reflex arc?
Which type of reflex arc consists of only an afferent neuron and an efferent neuron?
Which type of reflex arc consists of only an afferent neuron and an efferent neuron?
A reflex involving one or more interneurons is a monosynaptic reflex.
A reflex involving one or more interneurons is a monosynaptic reflex.
Which branch of the spinal nerve is indicated by the arrow?
Which branch of the spinal nerve is indicated by the arrow?
Within a nerve, nerve fibers are gathered into bundles called____.
Within a nerve, nerve fibers are gathered into bundles called____.
What is a quick, involuntary, stereotyped response to a stimulus called?
What is a quick, involuntary, stereotyped response to a stimulus called?
What is an efferent fiber?
What is an efferent fiber?
Within a nerve, each fascicle is wrapped in a layer called a______.
Within a nerve, each fascicle is wrapped in a layer called a______.
What is the loose connective tissue surrounding an individual nerve fiber called?
What is the loose connective tissue surrounding an individual nerve fiber called?
Which is composed of dense irregular connective tissue?
Which is composed of dense irregular connective tissue?
A_____nerve is a peripheral nerve carrying nerve signals to the CNS.
A_____nerve is a peripheral nerve carrying nerve signals to the CNS.
A____nerve is a nerve containing only fibers outgoing nerve signals from the CNS.
A____nerve is a nerve containing only fibers outgoing nerve signals from the CNS.
The first cervical spinal nerve emerges above vertebrae____.
The first cervical spinal nerve emerges above vertebrae____.
All spinal nerves except C1 pass through a____foramen to emerge from the vertebral column.
All spinal nerves except C1 pass through a____foramen to emerge from the vertebral column.
Which rami connect the anterior rami to the sympathetic chain?
Which rami connect the anterior rami to the sympathetic chain?
Which rami of spinal nerves T1-L2 connect to the sympathetic chain ganglia?
Which rami of spinal nerves T1-L2 connect to the sympathetic chain ganglia?
What are the properties of a reflex?
What are the properties of a reflex?
The bundle indicated by the blue arrow is a____and contains several nerve fibers.
The bundle indicated by the blue arrow is a____and contains several nerve fibers.
Which structure is indicated by the arrow?
Which structure is indicated by the arrow?
The connective tissue layer indicated by the arrow is the____.
The connective tissue layer indicated by the arrow is the____.
In the PNS, the____cells form a neurilemma and the myelin sheath around an axon.
In the PNS, the____cells form a neurilemma and the myelin sheath around an axon.
A nerve fiber refers to which part of the neuron?
A nerve fiber refers to which part of the neuron?
A____is a cordlike organ composed of numerous nerve fibers (fascicles) bound together by connective tissue.
A____is a cordlike organ composed of numerous nerve fibers (fascicles) bound together by connective tissue.
Which branch of the spinal nerve is indicated by the arrow?
Which branch of the spinal nerve is indicated by the arrow?
____fibers are nerve fibers that innervate blood vessels, glands, and internal organs.
____fibers are nerve fibers that innervate blood vessels, glands, and internal organs.
What structure is indicated by the arrow?
What structure is indicated by the arrow?
The structure indicated by the arrow is called the____root ganglion.
The structure indicated by the arrow is called the____root ganglion.
Which are considered a distal branch of a spinal nerve?
Which are considered a distal branch of a spinal nerve?
A somatic fiber innervates which of the following?
A somatic fiber innervates which of the following?
A___nerve fiber innervates widespread organs such as muscles, skin, glands, viscera, and blood vessels.
A___nerve fiber innervates widespread organs such as muscles, skin, glands, viscera, and blood vessels.
A special fiber innervates which of the following?
A special fiber innervates which of the following?
A___is a rapid, involuntary response to a stimulus.
A___is a rapid, involuntary response to a stimulus.
What is an afferent fiber?
What is an afferent fiber?
The connective tissue layer indicated by the arrow is the____.
The connective tissue layer indicated by the arrow is the____.
Which describes a mixed nerve?
Which describes a mixed nerve?
A___is an area of skin innervated by a spinal nerve.
A___is an area of skin innervated by a spinal nerve.
What is the relationship between efferent neurons and the CNS?
What is the relationship between efferent neurons and the CNS?
A quick contraction of flexor muscles in response to a painful stimulus is called a___reflex.
A quick contraction of flexor muscles in response to a painful stimulus is called a___reflex.
Where are the receptors for somatic reflexes found?
Where are the receptors for somatic reflexes found?
What are four possible effectors of a reflex?
What are four possible effectors of a reflex?
The cluster of nerves circled on the figure is the____plexus.
The cluster of nerves circled on the figure is the____plexus.
What is the circled structure?
What is the circled structure?
What are two examples of nerves that carry only sensory information?
What are two examples of nerves that carry only sensory information?
A___is a cluster of neuron cell bodies found outside of the CNS.
A___is a cluster of neuron cell bodies found outside of the CNS.
Which type of stretch receptor is embedded in skeletal muscle?
Which type of stretch receptor is embedded in skeletal muscle?
The cluster of nerves indicated on the figure is the___plexus.
The cluster of nerves indicated on the figure is the___plexus.
What is the neural pathway that mediates a reflex called?
What is the neural pathway that mediates a reflex called?
The crossed___reflex is contralateral.
The crossed___reflex is contralateral.
Which carries the sensory nerve to the effector in the reflex arc?
Which carries the sensory nerve to the effector in the reflex arc?
Nerve fibers of peripheral nerves are encased in which cells?
Nerve fibers of peripheral nerves are encased in which cells?
Paralysis of all four limbs is called___
Paralysis of all four limbs is called___
What is the cluster of nerves indicated on the figure called?
What is the cluster of nerves indicated on the figure called?
What is the paralysis of both lower limbs called?
What is the paralysis of both lower limbs called?
The structures indicated by the circle are called____.
The structures indicated by the circle are called____.
The flexor reflex uses an ipsilateral reflex arc.
The flexor reflex uses an ipsilateral reflex arc.
The cluster of nerves indicated on the figure is the____plexus.
The cluster of nerves indicated on the figure is the____plexus.
Which is a somatosensory stimulus?
Which is a somatosensory stimulus?
Which stimulus causes a muscle to reflexively contract?
Which stimulus causes a muscle to reflexively contract?
Which spinal nerves carry sensory nerve signals?
Which spinal nerves carry sensory nerve signals?
The dense irregular connective tissue layer enclosing an entire nerve is called the____.
The dense irregular connective tissue layer enclosing an entire nerve is called the____.
Which are the closest to the spinal cord?
Which are the closest to the spinal cord?
____muscle fibers are modified muscle fibers within a muscle spindle.
____muscle fibers are modified muscle fibers within a muscle spindle.
What structure is indicated by the arrow?
What structure is indicated by the arrow?
A____nerve fiber innervates widespread organs such as muscles, skin, glands, viscera, and blood vessels.
A____nerve fiber innervates widespread organs such as muscles, skin, glands, viscera, and blood vessels.
Which branches of the spinal nerve are indicated by the arrow?
Which branches of the spinal nerve are indicated by the arrow?
The bundle indicated by the blue arrow is a____and contains several nerve fibers.
The bundle indicated by the blue arrow is a____and contains several nerve fibers.
In which reflex does a contralateral extensor muscle contract?
In which reflex does a contralateral extensor muscle contract?
The typical location for muscle____is at the ends of a muscle, near the tendons.
The typical location for muscle____is at the ends of a muscle, near the tendons.
What is hemiplegia?
What is hemiplegia?
A____reflex occurs in response to excessive tension on a tendon.
A____reflex occurs in response to excessive tension on a tendon.
____fibers are working muscle fibers outside a muscle spindle.
____fibers are working muscle fibers outside a muscle spindle.
What branch of a spinal nerve innervates the meninges?
What branch of a spinal nerve innervates the meninges?
The intercostal nerves arise from the anterior rami of the___spinal nerves.
The intercostal nerves arise from the anterior rami of the___spinal nerves.
Which reflex is ipsilateral?
Which reflex is ipsilateral?
A spinal cord injury above segment____will lead to respiratory failure.
A spinal cord injury above segment____will lead to respiratory failure.
What is a tendon organ?
What is a tendon organ?
What is a drop in blood pressure due to loss of sympathetic stimulation to the blood vessels called?
What is a drop in blood pressure due to loss of sympathetic stimulation to the blood vessels called?
The____center of a reflex arc is located within the gray matter of the spinal cord or brain stem.
The____center of a reflex arc is located within the gray matter of the spinal cord or brain stem.
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Study Notes
Spinal Nerves and Plexuses
- Plexuses include Brachial, Cervical, Lumbar, and Sacral regions.
- Anterior rami of spinal nerves form Cervical, Lumbar, and Sacral plexuses.
- Spinal nerves carry both sensory (afferent) and motor (efferent) signals; thus, they are classified as mixed nerves.
Structure and Function of Spinal Nerves
- Anterior roots contain axons of motor neurons, while posterior roots carry sensory nerve fibers.
- The posterior root ganglion houses the somas of sensory neurons.
- Each spinal nerve has a posterior ramus that innervates local back muscles, joints, and skin, and a larger anterior ramus for anterior and lateral trunk innervation and limb nerves.
Reflex Arcs
- A monosynaptic reflex arc includes receptor in skin/muscle/tendon, afferent nerve fiber, efferent nerve fiber, and skeletal muscle as the effector.
- Monosynaptic reflex arcs have only one afferent and one efferent neuron; those involving interneurons are classified as polysynaptic.
- Reflexes require stimulation, are quick, involuntary, and stereotyped responses to stimuli.
Nerve Fiber Types
- Efferent fibers are motor fibers carrying signals from the CNS; afferent fibers are sensory fibers sending signals to the CNS.
- General nerve fibers innervate widespread organs, while special fibers target localized organs, specifically in the head.
Connective Tissue Layers
- Nerve fibers are organized into bundles called fascicles, surrounded by connective tissue layers: endoneurium (individual fibers), perineurium (fascicles), and epineurium (entire nerve).
Neuroanatomy and Injury
- The first cervical spinal nerve emerges above the C1 vertebra; all spinal nerves except C1 exit through intervertebral foramina.
- Spinal nerves from T1-L2 connect to the sympathetic chain through communicating rami.
- Damage to spinal cord segments above C4 may lead to respiratory failure.
Reflex Responses
- A flexor reflex contracts flexor muscles in response to pain.
- Tenon reflexes respond to excessive tension in tendons, while crossed extension reflexes involve contralateral extensor muscle contraction.
- Specific regions of skin innervated by spinal nerves are called dermatomes.
Pathway and Physiological Functions
- A reflex arc includes an integrating center located in the spinal cord or brain stem which processes input and generates an output response.
- Neurogenic shock results from loss of sympathetic stimulation to blood vessels, leading to blood pressure drops.
Types of Paralysis
- Quadriplegia refers to paralysis of all four limbs, while paraplegia describes paralysis of the lower limbs only. Hemiplegia results in paralysis on one side of the body.
Sensory Perception and Reflex Conditions
- Somatosensory stimuli include pressure, temperature, pain, touch, and stretch, which can trigger reflex actions.
- Muscle spindles are sensory receptors located within muscles that respond to stretch.
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