Chapter 13. Part 2: Spinal Nerves, and Somatic Reflexes

How many spinal nerves are there in order from superior to inferior?

8 cervical 12 thoracic 5 lumbar 5 sacral 1 coccygeal

Which describes a mixed nerve?

A nerve containing both sensory and motor nerve fibers

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.

Anterior

Which branch of the spinal nerve is indicated by the arrow

Anterior ramus

What structure is indicated by the arrow?

Anterior root

A nerve fiber refers to which part of the neuron?

Axon

The cluster of nerves circled on the figure is the____plexus.

Brachial

Which is the name of a plexus?

Brachial, Cervical, Sacral, Lumbar

The first cervical spinal nerve emerges above vertebrae____

C1

A spinal cord injury above segment____will lead to respiratory failure

C4

What are four possible effectors of a reflex?

Cardiac muscles, smooth muscle, skeletal muscles, gland.

The cluster of nerves indicated on the figure is the___plexus

Cervical

The anterior rami of Spinal Nerves form which nerve plexuses?

Cervical, lumbar, sacral

Which rami connect the anterior rami to the sympathetic chain?

Communicating

Which rami of spinal nerves T1-L2 connect to the sympathetic chain ganglia?

Communicating

Which branches of the spinal nerve is indicated by the arrow?

Communicating rami

In which reflex does a contralateral extensor muscle contract?

Crossed extension

Which reflex is ipsilateral?

Crossed extensor reflex

A___is an area of skin innervated by a spinal nerve.

Dermatome

Which carries the sensory nerve to the effector in the reflex arc?

Efferent nerve fiber

What is the relationship between efferent neurons and the CNS?

Efferent neurons carry impulses away from the CNS

What is the loose connective tissue surrounding an individual nerve fiber called?

Endoneurium

The connective tissue layer indicated by the arrow is the____

Epineurium

The dense irregular connective tissue layer enclosing an entire nerve is called the____

Epineurium

Which is composed of dense irregular connective tissue?

Epineurium

The crossed___reflex is contralateral

Extension

____fibers are working muscle fibers outside a muscle spindle.

Extrafusal

True or false: A reflex involving one or more interneurons is a monosynaptic reflex.

False: Polysnaptic

The bundle indicated by the blue arrow is a____and contains several nerve fibers.

Fascicle

What is the circled structure?

Fascicle

Within a nerve, nerve fibers are gathered into bundles called____

Fascicles

A quick contraction of flexor muscles in response to a painful stimulus is called a___reflex

Flexor

A___is a cluster of neuron cell bodies found outside of the CNS.

Ganglion

A____nerve fiber innervates widespread organs such as muscles, skin, glands, viscera, and blood vessels

General

A___nerve fiber innervates widespread organs such as muscles, skin, glands, viscera, and blood vessels.

General

Which stimulus causes a muscle to reflexively contract?

Increased stretch

The____center of a reflex arc is located within the gray matter of the spinal cord or brain stem.

Integrating

All spinal nerves except C1 pass through a____foramen to emerge from the vertebral column.

Intervertebral

____muscle fibers are modified muscle fibers within a muscle spindle

Intrafusal

A special fiber innervates which of the following?

Localized organs in the head (eyes, ears, olfactory and taste receptors, etc.

The cluster of nerves indicated on the figure is the____plexus

Lumbar

What branch of a spinal nerve innervates the meninges?

Meningeal

Spinal Nerves are described as______nerves because they carry both afferent and efferent signals.

Mixed

Which type of reflex arc consists of only an afferent neuron and an efferent neuron?

Monosynaptic

A____nerve is a nerve containing only fibers outgoing nerve signals from the CNS

Motor

An anterior roots of a spinal nerve contains axons of somatic_____neurons.

Motor

The anterior root of a spinal nerve contain axons of which neurons?

Motor

What is an efferent fiber?

Motor nerve fiber

Which type of stretch receptor embedded in skeletal muscle?

Muscle spimdle

A____is a cordlike organ composed of numerous nerve fibers (fascicles) bound together by connective tissue.

Nerve

What is a drop in blood pressure due to loss of sympathetic stimulation to the blood vessels called?

Neurogenic shock

What are two examples of nerves that carry only sensory information?

Optic and Olfactory nerve

What is the paralysis of both lower limbs called?

Paraplegia

The connective tissue layer indicated by the arrow is the____

Perineurium

Within a nerve, each fascicle is wrapped in a layer called a______

Perineurium

The structure indicated by the arrow is called the____root ganglion.

Posterior

Which ramus of a spinal nerve innervates the local muscles, joints, and skin on the back?

Posterior

Which spinal nerves carry sensory nerve signals?

Posterior

Which branch of the spinal nerve is indicated by the arrow?

Posterior ramous

Which are considered a distal branch of a spinal nerve?

Posterior ramus, Anterior ramus

Which structure is indicated by the arrow?

Posterior root

Which is somatosensory stimulus?

Pressure, temperature, pain, touch, stretch

What is quick, involuntary, stereotyped response to a stimulus is called?

Reflex

What is the neural pathway that mediates a reflex called?

Reflex arc

A___is a rapid, involuntary response to a stimulus.

Reflexes

The structures indicated by the circle are called____

Rootlets

Which are the closest to the spinal cord?

Rootlets

Moving peripherally from the spinal cord, which anterior and posterior structures form the spinal nerve?

Roots

What is the cluster of nerves indicated on the figure called

Sacral plexus

In the PNS, the____cells form a neurilemma and the myelin sheath around an axon.

Schwann

Nerve fibers of peripheral nerves are encased in which cells?

Schwann

A_____nerve is a peripheral nerve carrying nerve signals to the CNS

Sensory

The posterior root of Spinal Nerve carries______nerve fibers

Sensory

The somas of which neurons are found within the posterior root ganglion?

Sensory

What is an afferent fiber?

Sensory nerve fiber

What are the four components of a monosynaptic somatic reflex arc?

Skeletal muscle Afferent nerve fiber Receptor in skin, muscle, or tendon Efferent nerve fiber

Where are the receptors for somatic reflexes found?

Skin, muscle, and tendons

A somatic fiber innervates which of the following?

Skin, skeletal muscles, bones, and joints

The typical location for muscle____is at the ends of a muscle, near the tendons.

Spindles

A____reflex occurs in response to excessive tension on a tendon

Tendon

The intercostal nerves arise from the anterior rami of the___spinal nerves

Thoracic

True or False: The flexor reflex uses an ipsilateral reflex arc.

True

____fibers are nerve fibers that innervate blood vessels, glands, and internal organs.

Visceral

What is hemiplegia?

paralysis of one side of the body

What is a tendon organ?

proprioceptors located in a tendon near its junction with a muscle

Paralysis of all four limbs is called___

quadriplegia

What are the properties of a reflex?

require stimulation, quick, involuntary, stereotyped