Question 1

There are 31 pairs of spinal nerves. Twelve are in the thorax or chest region and eight are in the cervical or neck region.

Accepted Answer

Additionally, five are in the lumbar or lower back region; five are in the sacral or hip region; and one is in the coccygeal or tailbone region.

Question 2

The 12 pairs of thoracic nerves are distributed in the thorax and lumbar regions because all spinal nerves are distributed by region from the neck to the toes.

Accepted Answer

The 12 thoracic nerves are distributed only to the thoracic or chest area. Similarly, the five lumbar nerves are distributed to the lower back region. Note that distribution of spinal nerves is to their appropriate region.

Question 3

Which nerve supplies the muscle that moves the eye downward and laterally?

Accepted Answer

Although the optic and oculomotor involve other aspects of the eye and sight, the trochlear nerve is responsible for downward and lateral movement of the eye. The innervated muscle is the superior oblique.

Question 4

The sympathetic nervous system is also known as the craniofacial outflow. A term commonly used to describe the sympathetic nervous system is the "fight-or-flight-mechanism."

Accepted Answer

The sympathetic system, commonly known as the "fight-or-flight mechanism," is also called the thoracolumbar outflow. The craniosacral outflow is another term for the parasympathetic system. Both the parasympathetic and the sympathetic systems comprise the anatomic nervous system.

Question 5

The olfactory and optic are the only cranial nerves that are not paired because they are centrally located in the intravertebral foramina.

Accepted Answer

All twelve cranial nerves are paired. They attach directly to the brain, each with a separate function. Unrelated to their paired status is their exit from the spinal canal through the intervertebral foramina.

Question 6

Each of the following is a parasympathetic function EXCEPT one. Which is the EXCEPTION?

Accepted Answer

Decreased salivary flow occurs with stimulation of the sympathetic nervous system which is also referred to as the "fight-or-flight-mechanism". Conversely, parasympathetic function increases digestive mechanisms, including salivary flow. Appropriately called the vegetative system, the parasympathetic nervous system slows down the heart and respiration while increasing blood supply to the digestive system.

Question 7

The autonomic nervous system is composed of preganglionic and postganglionic neurons. These neurons diverge (separate) in a ganglion within the nervous system.

Accepted Answer

The preganglionic and postganglionic neurons synapse, or join, in a ganglion outside the central nervous system. A ganglion is an accumulation of cell bodies of the postganglionic neurons outside the CNS.

Question 8

Which part of the spinal cord is arranged in the shape of a butterfly?

Accepted Answer

The gray matter resides centrally in the spinal cord and consists of cell bodies of both motor and sensory neurons. The white matter, composed of myelinated axons, surrounds the gray matter. The dorsal root ganglion is a collection of sensory neuron cell bodies.

Question 9

The mental nerve supplies sensation to the floor of the mouth, the lingual mandibular gingivae, and the anterior two-thirds of the tongue. The mental nerve is joined by the chorda tympani, a branch of the facial nerve, to supply the submandibular and sublingual salivary glands.

Accepted Answer

Both statements correctly describe the lingual nerve, one of the largest branches of the mandibular division of the trigeminal nerve. The mental nerve is a small branch of the inferior alveolar nerve.

Question 10

The parasympathetic nervous system is called the craniosacral outflow because fibers from this system come off the brain and spinal cord at the sacral level.

Accepted Answer

This statement correctly describes the origin of the term craniosacral outflow. Similarly, the sympathetic nervous system comes off the spinal cord at the 12 thoracic levels and the first two lumbar levels; thus the name thoracolumbar outflow.

Question 11

The ophthalmic division is a branch of which nerve?

Accepted Answer

The ophthalmic division is a main branch of the trigeminal nerve. It is the first branch, usually denoted as V₁. The maxillary division (V₂) and the mandibular division (V₃) are the remaining of the three main trigeminal branches.

Question 12

Each of the following cranial nerves has sensory function EXCEPT one. Which is the EXCEPTION?

Accepted Answer

The hypoglossal nerve supplies only motor neurons to most of the intrinsic and extrinsic muscles of the tongue. An exception is the palatoglossus, which is supplied by the vagus nerve (X) as well as portions of the spinal accessory nerve (XI) that run with the vagus nerve.

Question 13

During times of stress incoming light is blocked to protect the eyes. This is accomplished by dilation of the pupils, a function of the sympathetic nervous system.

Accepted Answer

During times of stress the pupils dilate to enhance vision by letting in more light. This is a function of the sympathetic nervous system.

Question 14

The spinal nerve divides into a dorsal and a ventral primary ramus. This division occurs in the grey matter.

Accepted Answer

At the point where the dorsal and ventral roots meet is the beginning of the spinal nerve. At this point the spinal nerve divides into a small dorsal primary ramus and a larger ventral primary ramus. This division occurs some distance after the roots have left the grey matter of the spinal cord.

Question 15

Sensation to the skin of the lower lip and chin is supplied by which nerve?

Accepted Answer

The mental nerve is a small branch of the inferior alveolar nerve, which comes out of the mental foramen laterally to supply the skin of the lower lip and chin as well as the mucosa of the lip and labial gingiva. The mylohyoid is a small motor branch of the inferior alveolar nerve. The lingual nerve supplies sensation to the floor of the mouth, the lingual mandibular gingivae, and the anterior two-thirds of the tongue. The auriculotemporal supplies the areas above and in front of the ear.

Question 16

The facial nerve innervates each of the following structures EXCEPT one. Which is the EXCEPTION?

Accepted Answer

The soft palate is innervated by the trigeminal nerve (V), the vagus nerve (X), and the spinal accessory nerve (XI). The facial nerve (VII) innervates the remaining structures.

Question 17

The maxillary division of the trigeminal nerve follows the same pathway as the maxillary artery. The maxillary nerves and arteries generally have the same names.

Accepted Answer

The maxillary division of the trigeminal nerve (V₂) follows the same pattern of distribution and very similar nomenclature to those of the maxillary artery. Both the artery and the nerve are distributed to the maxillary teeth and oral cavity, the nasal cavity, the skin of the cheek, the midface, and temporal region.

Question 18

Each of the following cranial nerves is involved in motor or sensory eye innervation EXCEPT one? Which is the EXCEPTION?

Accepted Answer

Cranial nerve I, the olfactory, provides sensory neurons from the nose to the brain. Cranial nerve II, the optic nerve, provides special sense of sight from the eye to the brain. The oculomotor, cranial nerve III, supplies motor neurons that move the eye and contract the pupil. The trochlear nerve, IV, supplies the muscle that moves the eye downward and laterally. The abducens, cranial nerve VI, supplies the muscle that moves the eye laterally.

Question 19

Sensation to the maxillary labial gingiva is supplied by the nasopalatine nerve because this nerve branches off the infraorbital as it travels to supply the maxillary anterior teeth.

Accepted Answer

The anterior superior alveolar nerve, the second branch of the infraorbital, supplies the maxillary labial gingiva. The nasopalatine nerve supplies the nasal septum and gingiva lingual to the anterior maxillary teeth.

Question 20

The tenth cranial nerve has motor innervations to the root of the tongue and epiglottis. It supplies both motor and sensory innervation to the muscles of the pharynx and larynx.

Accepted Answer

The tenth cranial nerve, the vagus, provides only sensory innervation to the root of the tongue and epiglottis. This includes taste and general sensations arising from the root of the tongue.

Quiz 34: Nervous System