Head & Neck Anatomy Ch 8

Front 1

The nervous system - a network of neural structures that activates, coordinates, and controls all functions of the body.

Back 1

nervous system functions-
causes muscles to contract and even joint movements, involved in mastication and speech.

Front 2

The system stimulates glands to secrete and regulates many other systems such as the vascular system and digestive system.
allows sensation such as pain and touch

Back 2

neuron- is the cellular component of the nervous system, composed of a cell body and neural processes.

Front 3

nerve- a bundle of neural processes outside the central nervous system, in the peripheral nervous system.

Back 3

synapse- junction between two neurons or between a neuron and an effector organ, where neural impulses are transmitted.

Front 4

innervation- a supply of nerves to the body part.

Back 4

afferent nerve or sensory nerve -carries sensory information (taste, pain, and proprioception to the brain)

Front 5

efferent nerve or motor nerve - carries information to the muscles

Back 5

The plasma membrane of a neuron- has an unequal distribution of ions and electric charges between the two sides of the membrane.
the fluid- positive charge
the fluid inside- negative charge.
charge difference- resting potential
(measured in millivolts)

Front 6

action potential- a temporary reversal of the electric potential (less than a millisecond).

Back 6

To have the impulse cross the synapse to another cell requires the actions of chemical agents or neurotransmitters

Front 7

Anesthesia- loss of feeling or sensation resulting from the use of certain drugs or gases that serve as inhibitory neurotransmitters.

Back 7

major divisions of the nervous system, the central nervous system (CNS) includes both the brain and spinal cord.

Front 8

The system of membranes is the meninges, which has three layers:
dura mater
arachnoid mater
pia mater.

Back 8

major divisions of the brain include:
cerebrum
cerebellum
brainstem
diencephalon.

Front 9

cerebrum:
largest division
consists of two cerebral hemispheres.

Back 9

cerebellum:
second largest division of the brain

Front 10

brainstem-
include the medulla, pons, and midbrain.

Back 10

-medulla is closest to the spinal cord.
-pons connects the medulla with the cerebellum and with higher brain centers.
-midbrain includes relay stations for hearing, vision, and motor pathways.

Front 11

diencephalon- includes the thalamus and hypothalamus.
thalamus- central relay point for incoming nerve impulses.
hypothalamus- regulates homeostasis

Back 11

the peripheral nervous system (PNS)- composed of all the nerves stretching their pathways among the CNS and the receptors, muscles, and glands.

Front 12

PNS is divided into:
afferent nervous system or sensory nervous system
efferent nervous system or motor nervous system

Back 12

afferent: A nerve cell from the eye to the brain and carrying visual information

efferent: A nerve cell leading from the brain to the muscles controlling the eye’s movement

Front 13

somatic nervous system (SNS) is a subdivision of the efferent division of the peripheral nervous system and includes all nerves controlling the muscular system and external sensory receptors.
The SNS involves both receptors and effectors.

Back 13

autonomic nervous system (ANS) is the other subdivision of the efferent division of the peripheral nervous system.
This system operates without any conscious control as the caretaker of the body.
Autonomic fibers are efferent nerves, and they always occur in two-nerve chains: the first nerve carries autonomic fibers to a ganglion, where they terminate near the cell bodies of the second nerve

Front 14

sympathetic nervous system is involved in “fight-or-flight responses”

parasympathetic nervous system is involved in “rest-or-digest”

Back 14

The cranial nerves are an important part of the PNS. All 12 paired cranial nerves are connected to the brain at its base and pass through the skull by way of fissures or foramina.

Front 15

The first (I) cranial or olfactory nerve transmits smell from the nasal mucosa to the brain and thus functions as an afferent nerve.
The nerve enters the skull through the perforations in the cribriform plate of the ethmoid bone to join the olfactory bulb in the brain.

Back 15

The second (II) cranial or optic nerve transmits sight from the retina of the eye to the brain and thus functions as an afferent nerve.
The optic nerve enters the skull through the optic canal of the sphenoid bone on its way from the retina.

Front 16

The third (III) cranial or oculomotor nerve serves as an efferent nerve to some of the eye muscles that move the eyeball.
lies in the lateral wall of the cavernous sinus and exits the skull through the superior orbital fissure of the sphenoid bone on its way to the orbit.

Back 16

The small fourth (IV) cranial or trochlear nerve also serves as an efferent nerve for one eye muscle, as well as proprioception, similar to the oculomotor nerve but without any parasympathetic fibers.

Front 17

the trochlear nerve runs in the lateral wall of the cavernous sinus and exits the skull through the superior orbital fissure of the sphenoid bone on its way to the orbit.

Back 17

The fifth (V) cranial or trigeminal nerve has both an efferent component for the muscles of mastication, as well as some other cranial muscles, and an afferent component for the teeth, tongue, and oral cavity, as well as most of the skin of the face and head.
The ophthalmic nerve (division) provides sensation to the upper face and scalp.
The maxillary and mandibular nerves (divisions) provide sensation to the middle and lower face, respectively.

Front 18

The ophthalmic nerve or division enters through the superior orbital fissure.
The maxillary nerve or division enters by way of the foramen rotundum.
The mandibular nerve or division passes through the skull by way of the foramen ovale.

Back 18

The sixth (VI) cranial or abducens nerve or abducent nerve serves as an efferent nerve to one of the muscles that moves the eyeball, similar to the oculomotor and trochlear nerves.

Front 19

The seventh (VII) cranial or facial nerve carries both efferent and afferent components.
The nerve carries an efferent component for the muscles of facial expression and for the preganglionic parasympathetic innervation of the lacrimal gland (relaying in the pterygopalatine ganglion) as well as the submandibular and sublingual salivary glands (relaying in the submandibular ganglion).

Back 19

The eighth (VIII) cranial or vestibulocochlear nerve serves as an afferent nerve for hearing and balance.
This nerve conveys signals from the inner ear to the brain.

Front 20

The ninth (IX) cranial or glossopharyngeal nerve carries an efferent component for the pharyngeal muscle, the stylopharyngeus muscle, and the preganglionic gland parasympathetic innervation for the parotid salivary gland (relaying the otic ganglion).
The nerve also carries an afferent component for the oropharynx and for taste and general sensation from the base of the tongue, and thus is the afferent limb of the gag reflex.

Back 20

After supplying the ear, parasympathetic fibers leave the skull through the foramen ovale of the sphenoid bone as the lesser petrosal nerve.

Front 21

The tenth (X) cranial or vagus nerve carries a large efferent component for the muscles of the soft palate, pharynx, and larynx and for parasympathetic fibers to many organs in the thorax and abdomen including the thymus gland, heart, and stomach.
The nerve carries a smaller afferent component for a small amount of skin around the ear and for taste sensation for the epiglottis.

Back 21

The eleventh (XI) cranial or accessory nerve functions as an efferent nerve for the trapezius and sternocleidomastoid muscles, muscles of the soft palate and pharynx.

Front 22

The twelfth (XII) cranial or hypoglossal nerve functions as an efferent nerve for both the intrinsic and extrinsic muscles of the tongue.
exits skull through: hypoglossal canal in the occipital bone.

Back 22

*The hypoglossal nerve is important to dental professionals because it innervates the tongue