9 cranial nerves

Name the cranial nerves and their Roman numeral.

I Olfactory; II Optic; III Oculomotor; IV Trochlear; V Trigeminal; VI Abducens; VII Facial; VIII Vestibulocochlear; IX Glossopharyngeal; X Vagus; XI Accessory Nerve; XII Hypoglossal.

What is Cranial Nerve I called, and what does it do?

Olfactory nerve; transmits the sense of smell.

Scientists trying to make neurons divide often study the body's only mitotic neurons. What are they?

Olfactory receptors.

What is Cranial Nerve II called, and what does it do?

Optic nerve; transmits visual information from the eye's retina.

What is Cranial Nerve III called, and what does it do?

Oculomotor nerve; controls most extrinsic eye muscles and has parasympathetic innervation in the iris/pupil and ciliary body/lens control.

What is Cranial Nerve IV called, and what does it do?

Trochlear nerve; supplies one of the extrinsic eye muscles.

What is Cranial Nerve V called, and what does it do?

Trigeminal nerve; main sensory nerve of the face.

What hole does Cranial Nerve V pass through in the skull?

Foramen ovale.

Irritation of Cranial Nerve V is called what?

Trigeminal neuralgia; excruciating facial pain from nerve inflammation.

What is Cranial Nerve VI called, and what does it do?

Abducens nerve; controls the lateral rectus eye muscle.

What is Cranial Nerve VII called, and what does it do?

Facial nerve; innervates muscles of facial expression and salivary glands.

A person who cannot blink or smile may have damage to what nerve?

Facial nerve, Cranial Nerve VII.

A person who cannot easily taste sweet, sour, or salty substances has damage to what nerve?

Facial nerve, Cranial Nerve VII.

The primary gustatory/taste cortex is located in which lobe of the brain?

Temporal lobe, in the insula.

Bell's palsy is damage to what nerve, and what other disorder does it look like?

Damage to the facial nerve; it must be distinguished from a stroke.

What is Cranial Nerve VIII called, and what does it do?

Vestibulocochlear nerve; transmits hearing and balance.

What is Cranial Nerve IX called, and what three things does it do?

Glossopharyngeal nerve; signals the pharynx to constrict during swallowing with CN X, innervates the top of the tongue, and carries information from baroreceptors.

What is Cranial Nerve X called, and what four things does it do?

Vagus nerve; provides parasympathetic supply to organs, moves the larynx during speech, signals the pharynx to constrict during swallowing with CN IX, and carries information from baroreceptors.

Which cranial nerve travels into the abdomen?

Vagus nerve, Cranial Nerve X.

The majority of all parasympathetic fibers are from what cranial nerve?

Vagus nerve, Cranial Nerve X.

What is Cranial Nerve XI called, and what does it do?

Accessory nerve; enters the skull through the foramen magnum, leaves through the jugular foramen, and supplies the shoulder muscles.

What is Cranial Nerve XII called, and what does it do?

Hypoglossal nerve; supplies the under surface of the tongue.

What does damage to Cranial Nerve XII cause?

Impairment of speech.

Where does the spinal cord begin and end?

It begins at the foramen magnum and goes to L1-L2. In infants, it ends at L4-L5 because it does not grow as fast as the rest of the body.

What is the spinal cord called beyond L1-L2?

Cauda equina, meaning horse's tail; these nerves exit through the intervertebral foramina.

Where does the sacral plexus exit the spinal cord?

The sacral plexus is made of spinal nerves exiting from L4 to S5.

What spinal nerve has a number that does not correspond to a vertebra?

C8; there is a spinal nerve C8 even though there is no C8 vertebra.

Cross section of the spinal cord: what structures should you label?

Central canal, grey matter, white matter, posterior median sulcus, anterior median fissure, dorsal horn, ventral horn, dorsal root, dorsal root ganglion, ventral root, and spinal nerve.

Define a ganglion/ganglia.

A group of neuron cell bodies.

Are ganglia motor or sensory?

Some are motor and some are sensory.

Are ganglia in the CNS, PNS, or both?

PNS only.

Where are the cell bodies of the sensory neurons of the spinal nerves located?

Posterior root ganglion.

Most synapses are in what part of the nervous system?

CNS.

Define sensory neurons.

Sensory neurons carry sensory information into the spinal cord through the posterior root.

Where do sensory neurons come into the spinal cord?

Through the posterior root.

Where is the cell body of a sensory neuron?

Posterior root ganglion.

Where do sensory neurons synapse in the spinal cord?

In the posterior horn and grey matter.

What pathway do sensory neurons take to the brain?

A branch enters the dorsal column pathway in the white matter.

In what part of the brain do sensory neurons terminate?

Thalamus.

Axons in the dorsal column pathway go to what part of the brain?

Thalamus.

Regarding lower motor neurons, where is their cell body?

Anterior horn of the gray matter.

Regarding lower motor neurons, where does their axon exit the spinal cord?

Anterior root.

Regarding lower motor neurons, where do they synapse?

In a muscle.

Where are the cell bodies of interneurons?

Dorsal half of the gray matter in the spinal cord.

Where do interneurons synapse?

On the cell body of the motor neuron.

What is another name for interneurons?

Association neurons.

The complexity of the CNS can be attributed to what?

Interneurons.

Where is the site of neuronal integration?

Grey matter.

What is the correct path of a simple spinal reflex?

Receptor -> afferent neuron -> integration center -> efferent neuron -> effector.

What types of sensory information are conveyed toward the brain in the spinothalamic tracts?

Pain and temperature.

What region of the brain interprets signals for touch and temperature?

Somatosensory association area.

What are the 3 nerves that form a simple reflex arc?

Sensory neuron, lower motor neuron, and interneuron.

Give an example of a withdrawal reflex.

Touching a hot stove: sensory input enters the spinal cord, association neurons send information to lower motor neurons, the muscle contracts, and the hand is removed before the brain knows it.

Simple reflex behavior involves how many nerves?

Three nerves.

Does a simple reflex involve the brain?

No brain involvement.

Are simple reflexes automatic or voluntary events?

Automatic events.

Define reflexes.

Rapid, involuntary responses involving both motor and sensory neurons.

Are reflexes motor, sensory, or both?

Both motor and sensory.

Are reflexes fast or slow?

Rapid/fast.

Are reflexes voluntary or involuntary?

Involuntary.

Do reflexes involve one or multiple synapses?

Multiple synapses.

What is an example of a three-neuron reflex?

Knee-jerk reflex.

How does a sensory signal get from a finger to the brain?

Sensory touch -> spinal nerve -> posterior root ganglion -> posterior root -> posterior horn -> tract -> thalamus.

What is the difference between a nerve and a tract?

Inside the brain, nerves are called tracts; outside the brain, they are called nerves.

What is an upper motor neuron?

A neuron with its cell body in the brain that synapses on a lower motor neuron in the spinal cord.

What is a lower/somatic motor neuron?

A neuron with its cell body in the spinal cord that synapses on skeletal muscle.

What region of the brain contains the upper motor neurons?

Primary motor cortex.

When the nerves leave the spinal cord, they travel together in what?

A plexus.

Give one example of a plexus.

Brachial plexus in the armpit; it innervates muscles of the arm.

Starting at the spinal cord and proceeding laterally, the subdivisions of a plexus are in what order?

Rami, trunks, divisions, cords.

What do proprioception neurons sense?

The amount of force and movement in muscles and joints.

What tract do proprioception nerves travel in?

Spinocerebellar tract.

What is an example of a test for proprioception?

Close eyes and touch finger to nose.

What are symptoms of an upper motor neuron disease?

Cannot move extremity on their own, paralysis, but reflexes are present.

What are symptoms of a lower motor neuron disease?

Cannot move extremity on their own, paralysis, and reflexes are not present.

How many spinal nerves are there?

31 pairs.

What region of the spinal cord do spinal nerves exit?

Outside of the vertebral canal; cervical, thoracic, lumbar, and sacral regions.

Are spinal nerves motor, sensory, or both?

Both motor and sensory.

What do lower motor neurons do?

Carry motor commands to skeletal muscles.