Chapter 13: The Spinal Cord, Spinal Nerves and Somatic Reflexes

A ___ nerve is a peripheral nerve carrying nerve signals to the CNS.

Afferent

What are the regions of the spinal cord?

Cervical Thoracic Lumbar Sacral

What are the spinal cord regions in order from superior to inferior?

Cervical Thoracic Lumbar Sacral

The left and right sides of the gray matter in the spinal cord are connected by the gray ___.

Commissure

Which rami connect the anterior rami to the sympathetic chain?

Communicating

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

Communicating

The spinal cord contains ascending and descending nerve fibers that send information between the CNS and the periphery. This illustrates which function of the spinal cord?

Conduction

What are the functions of the spinal cord?

Conduction Neural Integration, Locomotion Reflexes

What is the epineurium composed of?

Dense irregular connective tissue

What are the extensions of the pia mater that anchors the spinal cord?

Denticulate ligaments

What is an area of skin innervated by a spinal nerve called?

Dermatome

The dural sheath around the spinal cord is formed from the ___ mater.

Dura

What is the order of the meninges from superficial to deep?

Dura Mater Arachnoid Mater Pia Mater

Which structure is indicated by the arrow in the figure?

Medullary Cone (Conus medullaris)

The ___ branch of the spinal nerve innervates the meninges.

Meningeal

The ___ are a series of fibrous connective tissue membranes covering the central nervous system.

Meninges

Spinal nerves are described as ___ nerves because they carry both afferent and efferent signals.

Mixed

An anterior roots of a spinal nerve contains axons of ___ neurons.

Motor

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

Motor

Within the spinal cord, what type of information do the descending tracts carry?

Motor

How many neurons are found in the descending tract?

2

It takes ___ neurons for a somatic response sensation nerve signal to complete the sensory pathway.

3

How many pairs of spinal nerves are there?

31

How many spinal nerve 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

Which describes a motor nerve?

A nerve containing only fibers carrying outgoing nerve signals from the CNS

What is a fasciculus in the spinal cord?

A tract of nerve fibers within a funiculus

The ___ horns of the spinal cord contain the cell bodies of outgoing somatic motor neurons.

Anterior

The ___ median fissure is a longitudinal groove on the ventral surface of the spinal cord.

Anterior

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 horns of the spinal cord contain the cell bodies of outgoing somatic motor neurons?

Anterior

The distal branches of a spinal nerve include which of the following?

Anterior and Posterior Rami

Which are made of gray matter?

Anterior, posterior, and lateral horns

The ___ mater is just below (deep to) the dura mater.

Arachnoid

The ___ mater that consists of layers of squamous to cuboidal cells with a loose mesh of fibers in the space below.

Arachnoid

The middle layer of the meninges is the ___ mater.

Arachnoid

The neural pathway that mediates a reflex is called a reflex ___.

Arc

Where does the spinal cord arise from the medulla oblongata?

At the Foramen Magnum

What factor accounts for the fact that the right side of the brain communicates with the left side of the body, and vice versa?

Decussation

Where is the epidural space around the spinal cord?

Between the vertebral bones and dural sheath

Which are the names of a plexus?

Brachial Cervical Coccygeal Lumbar Sacral

What is the white matter of the spinal cord?

Bundles of myelinated and unmyelinated axons found superficial to the gray matter

The first cervical spinal nerve emerges above vertebra ___.

C1

External to the neurilemma of a nerve fiber is the layer of loose connective tissue that surrounds a nerve fiber called a(n) ___.

Endoneurium

The connective tissue layer indicated by the arrow is the ___.

Epineurium

What is the dense irregular connective tissue layer enclosing an entire nerve called?

Epineurium

T/F: Severing a sensory nerve root will completely deaden sensation from a dermatome?

False

Within a nerve, nerve fibers are gathered into bundles called what?

Fascicles

A ___ is a tract of nerve fibers within a column of the spinal cord.

Fasciculus

What structure marks the superior end of the spinal cord?

Foramen magnum

A ___ is a cluster of neuron cell bodies found outside of the CNS.

Ganglion

Where are the neuron cell bodies, dendrites, and synapses found in the CNS?

Gray matter

All spinal nerves except C1 pass through a(n) ___ foramen to emerge from the vertebral column.

Invertebral

Some nerve tracts do not decussate and have their origin and destination on the same side of the body. These tracts are considered ___.

Ipsilateral

Which tract will have its origin and destination on the same side of the body?

Ipsilateral

In an adult, where does the spinal cord end? (At what vertebra)

L1

Which are purely sensory nerves?

Olfactory and optic nerves

Within a nerve, each fascicle is wrapped in which layer?

Perineurium

The ___ mater is the meningeal layer that is closely associated with the contours of the spinal cord.

Pia

The ___ median sulcus is a longitudinal groove on the dorsal surface of the spinal cord.

Posterior

The ___ roots are the spinal nerve roots that carry sensory nerve signals.

Posterior

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

Posterior

What are the three pairs of funiculi in the spinal cord?

Posterior Lateral Anterior

What are some somatosensory stimulus's?

Pressure Touch Pain Temperature Stretch

What are the components of a reflex arc in order?

Receptor Afferent Nerve Fiber Integration Center Efferent Nerve Fiber Effector

Which are properties of a reflex?

Require stimulation Quick Involuntary Stereotyped

Which are closest to the spinal cord?

Rootlets

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

Roots

Nerve fibers of peripheral nerves are encased in ___ cells.

Schwann

___ cells form a neurilemma and the myelin sheath around axons in the PNS.

Schwann

The posterior root of a spinal nerve carries ___ nerve fibers.

Sensory

The somas of ___ neurons are found within the posterior root ganglion.

Sensory

Within the spinal cord, which tracts carry information up to the brain?

Sensory

Which disease results from herpes virus residing in a posterior root ganglion?

Shingles

The first cervical spinal nerve emerges between which two structures?

Skull and vertebra C1

What are the possible effectors of a reflex response?

Smooth, cardiac, and skeletal muscle as well as glands

___ reflexes use receptors located in the skin, muscle, and tendons.

Somatic

In which does cerebrospinal fluid circulate?

Subarachnoid space

Where is the white matter in the spinal cord?

Superficial to the gray matter

The coccygeal ligament is formed from the fusion of which two structures?

Terminal filum and dura mater

What is the anterior median fissure of the spinal cord?

The longitudinal groove on the ventral surface of the spinal cord

What is the subarachnoid space?

The space between the arachnoid mater and pia mater. (cerebrospinal fluid is here)

The intercostal nerves arise from the anterior rami of the ___ spinal nerves.

Thoracic

In the CNS, bundles of axons that make up white matter are called ___.

Tracts

In the descending pathways, which motor neurons have their somas in the cerebral cortex or brain stem?

Upper

___ matter is composed of myelinated and unmyelinated axons and is superficial to the gray matter of the spinal cord.

White

In the spinal cord, the ___ canal is lined with ependymal cells and contains spinal fluid.

central