Everything done in the nervous system involves 3 fundamental steps. What are they?

1. A sensory function detects internal and external stimuli.

2. An interpretation is made (analysis).

3. A motor response occurs (reaction).

1. What parts of the body does the CNS consist of?

2. What about the PNS?

1. Brain and spinal cord

2. Consists of all nervous tissue outside the CNS, including nerves, ganglia, enteric plexuses, and sensory receptors.

The SNS consists of:

1. ________ neurons that convey information from sensory receptors in the head, body wall and limbs towards the CNS.

2. ________ neurons that conduct impulses away from the CNS towards the skeletal muscles under voluntary control in the periphery.

1. Somatic sensory (afferent)

2. Somatic motor (efferent)

________ are small masses of neuronal cell bodies located outside the brain and spinal cord, usually closely associated with cranial and spinal nerves.

- Ganglia

Though there are several different types of neurons, what do most of them have?

1. Cell body

2. Axon

3. Dendrites

4. Axon terminals

1. ______ conduct impulses away from the cell body toward another neuron or effector cell.

2. The ______ is where the above joins the cell body.

3. The ______ is the beginning of #1.

4. The ______ is the junction between #2 and #3.

1. Axons

2. axon hillock*

3. initial segment

4. trigger zone

Two types of transport systems carry materials from the cell body to the axon terminals and back.

1. ________ conveys axoplasm in one direction only -- from the cell body toward the axon terminals.

2. ________ moves materials in both directions.

1. Slow axonal transport

2. Fast axonal transport

1. ________ supplies new axoplasm (the cytoplasm in axons) to developing or regenerating axons and replenishes axoplasm in growing and mature axons.

2. ________ that occurs in an anterograde (forward) direction moves organelles and synaptic vesicles from the cell body to the axon terminals. 

3. ________ that occurs in a retrograde (backward) direction moves membrane vesicles and other cellular materials from the axon terminals to the cell body to be degraded or recycled.

1. Slow axonal transport

2. Fast axonal transport

3. Fast axonal transport

Classifying Neurons

________ is based on the number of processes (axons or dendrites) extending from the cell body.

- Structural classification 

Classifying Neurons

________ have several dendrites and only one axon, and are located throughout the brain and spinal cord.

- Multipolar neurons

- The vast majority of the neurons in the human body are multipolar.

Classifying Neurons

________ have one main dendrite and one axon.

- Bipolar neurons

- They are used to convey the special senses of sight, smell, hearing and balance.

- As such, they are found in the retina of the eye, the inner ear, and the olfactory (olfact  = to smell) area of the brain.

Classifying Neurons

________ contain one process which extends from the body and divides into a central branch that functions as an axon and as a dendritic root.

- Unipolar (pseudounipolar) neurons

- Unipolar structure is often employed for sensory neurons that convey touch and stretching information from the extremities.

What are the 4 types of neuroglia in the CNS?

1. Astrocytes - support neurons in the CNS. Maintain the chemical environment (Ca2+ & K+)

2. Oligodendrocytes - produce myelin in CNS

3. Microglia - participate in phagocytosis

4. Ependymal cells - form and circulate CSF

What are the 2 types of neuroglia in the PNS?

1. Satellite cells - support neurons in PNS

2. Schwann cells - produce myelin in PNS

________ is the process of forming a myelin sheath which insulates and increases nerve impulse speed.

- Myelination

- It is formed Oligodendrocytes in the CNS and by Schwann cells in the PNS.

The outer nucleated cytoplasmic layer of the Schwann cell, which encloses the myelin sheath, is the ________.

- neurolemma (sheath of Schwann)

________ refers to the loss or destruction of myelin sheaths around axons. It may result from disease, or from medical treatments such as radiation therapy and chemotherapy.

- Demyelination

1. ________ of the brain and spinal cord is formed from aggregations of myelinated axons from many neurons.

2. ________ of the brain and spinal cord is formed from neuronal cell bodies and dendrites.

1. White matter (lipid part of myelin imparts the white appearance)

2. Gray matter (gray because it lacks myelin)

External Cord Anatomy

The outermost ________ forms a sac that encloses the entire cord.

- dura mater (tough mother)

External Cord Anatomy

The middle meninx is a delicate avascular covering called the ________. It is attached to the inside of the dura and forms the roof of the ________ in which cerebral spinal fluid (CSF) circulates.

- arachnoid mater

- subarachnoid space (SAS)

External Cord Anatomy

The transparent ________ is pressed up against the cord and is filled with blood vessels that supply nutrients.

- pia mater

External Cord Anatomy

The ________ or "horses tail" are the roots of the lower spinal nerves that angle down alongside the filum.

- cauda equina

1. In the spinal cord, the white matter is on the ______, and the gray matter is on the ______. 

2. In the brain the white matter is on the ______, and the gray matter is on the ______.

1. outside; inside

2. inside; outside

The pia mater has ___ pairs of ________ which attach it to the arachnoid and dura maters. 

- 21; denticulate ligaments

- Named for their tooth-like appearance, they are traditionally believed to provide stability for the spinal cord against sudden shock and displacement within the vertebral column.

Internal Cord Anatomy

1. ________ consist of somatic motor neurons.

2. ________ consist of somatic and autonomic sensory nuclei.

1. Anterior (ventral) gray horns

2. Posterior (dorsal) gray horns

- The posterior gray horn is the site of synapse between first-order sensory neurons coming in from the periphery, and second-order neurons which either ascend in the cord or exit back out as parts of reflex arcs.

The ________ are found only in the thoracic, upper lumbar, and sacral segments of the cord.

- lateral gray horns

A ______ is a bundle of neuronal axons that are all located in a specific area of the cord and all traveling to the same place (higher or lower in the brain or cord).

- tract

The ________ goes from the spinal cord to the brain – it is an afferent tract.

- spinothalamic tract

- The spinothalamic tract is an afferent tract that transmits sensations of pain, warmth, coolness, itching, tickling, deep pressure, and crude touch.

The _________ goes from the cortex of the brain to the spinal cord – it is an efferent tract.

- corticospinal tract

The ________ originates from an area in the brain which you probably don’t recognize; however, you can recognize the destination in the spine, and therefore deduce that it is a motor tract.

- vestibulospinal tract

________ emerge from the cord at regular intervals (called segments).  Except for the first cervical pair the spinal nerves leave the vertebral column from the intervertebral foramen between adjoining vertebrae – the first pair leaves between the skull and the first cervical vertebrae.

- 31 left-right pairs of spinal nerves

Cervical – 8 pairs, C1-C8

Thoracic – 12 pairs, T1-T12

Lumbar – 5 pairs, L1-L5

Sacral - 5 pairs, S1-S5

Coccygeal – 1 nerve pair

The ________, formed by the anterior rami of C1-C5, serves the head, neck, and diaphragm.

- cervical plexus

- The phrenic nerves arise from the cervical plexus to supply the major muscle of respiration ("C3,4,5 keep the diaphragm alive")

1. The ________ is formed by the anterior rami of C5-C8 and T1.  

2. It is divided into: ____ → ____ → ____ → ____ → ____.

1. brachial plexus

- The nerves from the brachial plexus supply the shoulders and upper limbs.

2. Roots → Trunks → Divisions → Cords → Branches (Risk Takers Don't Cautiously Behave)

The ________ is formed by the anterior rami of L1-L4 to supply the anterolateral abdominal wall, external genitalia, and part of the lower limbs.

- lumbar plexus

- The femoral and obturator nerves come from the lumbar plexus

The ________ is formed by the anterior rami of L4-L5 and S1-S4.  It supplies the buttocks, perineum, and part of the lower limbs.

- sacral plexus

- It gives rise to the largest nerve in the body, the sciatic nerve

The ________ is formed by the anterior rami of S4-S5 and the coccygeal nerves. It is a small plexus from which the anococcygeal nerve exits to supply a small area of skin in the coccygeal region.

- coccygeal plexus

A ________ is a pathway that a nerve impulse follows to produce a reflex. Components of a reflex arc include a ________ and a ________, an ________ inside the cord, an exiting ________, and an ________ (which is usually some sort of muscle or a gland which makes something move or secrete “involuntarily”)

- reflex arc

- sensory receptor

- sensory neuron

- integrating center

- motor neuron

- effector

________ involved in reflex arcs are specifically adapted to perceive the stimulus and initiate an impulse.

- Sensory receptors

Reflex arcs can be ________ (all neurons and effectors on the same side of the body) or ________ (the receptors and afferent neurons are on the opposite side of the body as the efferent neurons and effectors.).

- ipsilateral

- contralateral

- The flexor (withdrawl) reflex is a good example of a contralateral reflex (stepping on a tack)

The ________ is considered normal in adults if they flex (curl) the big toe when the sole of the foot is stimulated. If the sole of the foot is stimulated and the patient extends the big toe, it would indicate damage in the corticospinal tract.

- Babinski, or plantar flexion reflex

During the first 3 weeks of gestation, the human embryo's neural tube flexes as it grows, forming the three primary brain vesicles colloquially called the ________, ________ and ________.  The 1st and 3rd vesicles further divide forming 5 secondary brain vesicles in a process called encephalization.

- forebrain

- midbrain

- hindbrain

1. The brain grows at an amazing rate during development; at times, as many as ________ neurons are added each second! At birth, the neonatal brain looks very much like that of an adult and almost all the neurons the brain will ever have are already present.

- 50,000

1. The ________ is the continuation of the spinal cord and consists of the medulla oblongata, pons and midbrain.

2. The ________ is the second largest part of the brain.

3. The ________ gives rise to the thalamus & hypothalamus.

4. The ________ is the newest (evolutionary) and largest part of the brain as a whole.

1. brain stem

2. cerebellum

3. diencephalon

4. cerebrum

- It is in the cerebral cortex that perception, thought, imagination, judgment, and decision making occur.

The ________ are continuous with the spinal meninges and mirror their structure and function – they also bear the same names:

- a tough outer ________

- a spidery ________

- and a thin, delicate ________

- cranial meninges

- dura mater

- arachnoid mater

- pia mater

The ________ is a strong sickle-shaped fold of dura mater which descends vertically in the longitudinal fissure and separates the two cerebral hemispheres.

- falx cerebri

The ________ is a small triangular process that separates the two cerebellar hemispheres.

- falx cerebelli

The brain represents only ___ of total body weight, but receives about ___ of the body’s blood supply and consumes ___ of the O2 and glucose (even when resting).

- 2%

- 20%

- 20%

________ is a clear fluid that circulates through the internal cavities in the brain (called brain ventricles) and spinal cord (the central canal) and also flows over and around the brain and cord in the subarachnoid space.  In essence, the brain "floats" in it.

- Cerebral spinal fluid (CSF)

- CSF absorbs shock and protects the brain and the cord. It also helps transport nutrients and wastes between blood and nervous tissues.

The majority of CSF production - 80 to 150 mL at any given time in an adult - comes from ________ in the ________ (networks of blood capillaries that line the ventricles).

- ependymal cells

- choroid plexuses

CSF is gradually reabsorbed back into the blood through the ________ (finger-like projections that extend into the dural sinuses).

- arachnoid villi

The ________ is superior to, but continuous with, the spinal cord. Developmentally, it does not represent a single structure, but rather a group of anatomical components considered collectively. What are it's three components?

- brain stem

- Midbrain, Pons, Medulla Oblongata

The ________ begins at the inferior border of the pons and extends to the foramen magnum. It contains all ascending and descending tracts extending between the spinal cord and cerebrum.

- medulla oblongata

The ______ lies directly above the medulla and anterior to the cerebellum (2.5 cm). It acts as a bridge connecting the spinal cord with the brain and parts of the brain with each other. 

- pons

The Medulla Oblongata

The nuclei associated with 5 of the 12 cranial nerves originates in the medulla. Which cranial nerves are they?

- CN VIII - XII

The Pons

1. Contains the nuclei associated with 4 pairs of cranial nerves: ______

2. Cranial nerve ___ emerges directly from the pons.

3. ___, ___, and ___ emerge from the space between the pons and the medulla.

1. V - VIII

2. V

3. VI, VII, VIII

The ________ extends from the pons to the diencephalon. The ________ passes through the midbrain connecting the 3rd ventricle above with the 4th ventricles below (both locations of CSF formation and circulation.)

- midbrain

- cerebral aqueduct

1. On the anterior part of the midbrain are found the “little feet” of the ________.

2. These contain axons of the ________, ________, and ________ which conduct nerve impulses from motor areas in the cerebral cortex to the spinal cord, medulla, and pons, respectively.

- cerebral peduncles

- corticospinal, corticobulbar, and corticopontine tracts

On the posterior part of the midbrain are four rounded elevations known as the superior and inferior colliculi which serve as reflex centers for certain visual and auditory reflexes, and also the startle reflex.

It is the origin of cranial nerves ___ and ___.

- III and IV

The ________, or “little brain”, is the second largest part of the brain and lies inferior to the cerebrum and posterior to the brain stem.

- cerebellum

- Separated from the cerebrum by the transverse fissure

During embryonic development, the ______ matter of the brain develops faster than the ______ matter - the cortical region rolls and folds on itself.  Convolutions and grooves are created in the cortex during this growth process.

- grey

- white

1. The ________ is the “seat of our intelligence”– it’s because of neurons in the cortex that we are able to read, write, speak, remember, and plan our life.

2. What is the largest part of the brain?

1. cerebral cortex

2. cerebrum (also known as newest part of the brain)

The ________ is superior and posterior to the thalamus. It consists of the ________ (secretes melatonin) and ________ (emotional responses to odors).

- epithalamus

- pineal gland

- habenular nuclei

The ________ functions to maintain consciousness, a state of wakefulness in which an individual is fully alert, aware, and oriented. Inactivation of this produces sleep, a state of partial consciousness.

- Reticular Activating System (RAS)

The prominent ________ separates the cerebrum into right and left cerebral hemispheres. The ________ further divides the anterior frontal lobe from the more posteriorly situated parietal lobe.

- longitudinal fissure

- central sulcus

The lateral ________ separates the frontal lobe from two laterally placed ________, hanging like ear muffs off the sides. A fifth part of the cerebrum, the _______, cannot be seen at the surface of the brain because it lies within the lateral cerebral sulcus, deep to the parietal, frontal, and temporal lobes.

- cerebral sulcus (fissure)

- temporal lobes

- insula

1. CN I is the ________ nerve (sense of smell).

2. CN II is the ________ nerve (sense of sight).

3. CN III, IV, and VI ________ that allow us to move our _____.

1. olfactory

2. optic

3. innervate the extraocular muscles; eyes (III also supplies motor input to our eyelid muscles and facilitates pupillary constriction)

1. CN V is the ______ nerve (the major sensory nerve of the face).

2. CN VII is the ______ nerve. It has 5 large somatic branches. (Bell's Palsy nerve)

3. CN VIII is the ______ nerve. (inner ear)

1. trigeminal

2. facial (innervate muscles for facial expression, also carries some taste sensations)

3. vestibulocochlear (inner ear; damage to this nerve can cause ringing, vertigo, or deafness)

1. CN IX is the _______ nerve. (taste sensations as well as ANS impulses to salivary glands and the mechanoreceptors of the carotid; senses changes in blood pressure)

2. CN X is the _______ nerve. ("the wanderer," carries most of the parasympathetic motor efferents to the organs of the thorax and abdomen)

3. CN XI is the ______ nerve. This nerve supplies somatic motor innervation to the Trapezius and Sternocleidomastoid muscles.

4. CN XII is the ________ nerve. This is a very large nerve (a lot of resources) to be devoted solely to the tongue – it takes a lot more coordination than you might guess to chew, talk, and swallow without injuring our tongue.

1. glossopharyngeal

2. vagus

3. spinal accessory

4. hypoglossal