BIOL 1593 Module 10 - Central and Somatic Nervous System

What 2 things protect the spinal cord?

meninges, cushion of cerebrospinal fluid

What are the meninges?

three coverings composed of connective tissue that run continuously around the spinal cord and brain

What are the 3 layers of the meninges?

dura mater (outermost), arachnoid mater (middle), pia mater (innermost)

List, in order from the outside, the coverings of the spinal cord, and name the spaces adjacent to them.

epidural space, dura mater, subdural space, arachnoid mater, subarachnoid space, pia mater

In an adult, the spinal cord is a continuation of the ______.

medulla oblongata

At which vertebra does the spinal cord terminate?

second lumbar

What is the end portion of the spinal cord called?

cauda equina

How are the spinal nerves named and numbered?

region and level of the spinal cord from which they emerge

What are the 31 pairs of spinal nerves?

8 cervical, 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal

What are the names of the 2 features that divide the white matter of the spinal cord into right and left sides?

anterior/ventral median fissure, posterior/dorsal median sulcus

What does grey matter primarily consist of?

cell bodies of neurons and neuroglia, and unmyelinated axons and dendrites of association and motor neurons

Grey matter in the spinal cord is divided into what 3 areas?

anterior/ventral horn, lateral horn, and posterior/dorsal horn

What does white matter primarily consist of?

bundles of myelinated axons of motor and sensory neurons

White matter is divided into ________, each containing bundles of nerve axons that have a common origin or destination and carry similar information.

columns (anterior/ventral, lateral, and posterior/dorsal)

Bundles of nerve axons in the CNS are called ______, whereas in the PNS bundles of nerve axons are called ______.

tracts; nerves

Sensory (ascending) tracts conduct nerve impulses toward the _________. Motor (descending) tracts conduct impulses down the _______.

brain; cord

Spinal nerves connect the CNS to which 3 things?

sensory receptors, muscles, and glands

Spinal nerves connect to the spinal cord through a(n) _________ and a(n) ______ root, which correspond to the _________ and ________ horns.

posterior; anterior; posterior; anterior

The posterior root contains ________ axons and the anterior root contains _______ axons.

sensory; motor

The ventral/anterior horns in the _______ and _______ spinal cord are larger/wider because a greater number of muscles are controlled by these neurons. These areas are called ______.

cervical; lumbar; enlargements

The cervical enlargement contains nerves that supply the ________.

upper limbs

The lumbar enlargement, which is smaller than the cervical enlargement, contains nerves that supply the ________.

lower limbs

A spinal nerve is covered with an outer layer of fibrous connective tissue called the _______. Within the nerve, axons are further bundled into _______. These bundles are covered in a layer of fibrous connective tissue called the ______. Individual axon are then covered in a layer of loose connective tissue called the _______.

epineurium; fascicles; perineurium; endoneurium

Numerous __________ exist within the coverings of the spinal nerves.

blood vessels

What is a plexus?

a network of spinal nerve branches just outside of the spinal cord

What are the 4 principle plexuses?

cervical, brachial, lumbar, sacral

What parts of the body does the cervical plexus supply?

skin and muscles of the head, neck, and upper part of the shoulders; connects with some cranial nerves; and supplies the diaphragm

What parts of the body does the brachial plexus supply?

upper extremities and a number of neck and shoulder muscles

What parts of the body does the lumbar plexus supply?

anterolateral abdominal wall, external genitals, and part of the lower extremities

What parts of the body does the sacral plexus supply?

buttocks, perineum, and part of the lower extremities

What are the 2 main functions of the spinal cord in the maintenance of homeostasis?

conduct impulses to and from the brain (white matter tracts), recieve and integrate incoming and outgoing information (grey matter)

________ information travels up the spinal cord to the brain along two main routes on each side of the cord. These routes are called pathways or tracts.

Sensory

_______ information travels from the brain down the spinal cord to effectors (muscles and glands) along two main descending tracts

Motor

What are spinal reflexes?

rapid, predictable, automatic responses that occur without any brain involvement (i.e. involve the spinal cord only); reflexes help to maintain homeostasis by permitting the body to make rapid adjustments to homeostatic imbalances

The gray matter of the spinal cord serves as an _________ for spinal reflexes.

integrating centre

What is a reflex arc?

the simplest type of pathway; circuit of a reflex that involves a sensory input and motor output, or an afferent branch and an efferent branch, and an integrating center to connect the two branches

What are the 5 components of a reflex arc?

Receptor

Sensory neuron (afferent pathway)

Integrating centre neuron

Motor neuron (efferent pathway)

Effector

What are the 4 principle parts of the brain?

Brain stem

Diencephalon

Cerebellum

Cerebrum

What 2 structures protect the brain?

cranial bones and cranial meninges

What are the 3 cranial meninges?

dura mater, arachnoid mater, pia mater

Blood flows to the brain mainly through blood vessels that branch from the _____________ circle at the base of the brain. _______ return blood from the head to the heart.

cerebral arterial (circle of Willis); veins

The brain comprises about ___% of body weight but uses about ___% of the oxygen. The amount of oxygen used varies with the degree of ________.

2; 20; mental activity

What is meant by the expression blood-brain barrier?

It refers to the highly selective nature of the capillaries in most parts of the brain. Many substances that could leak out of capillaries in other parts of the body are prevented from doing so in the brain.

What does the blood-brain barrier (BBB) do?

protects brain cells from harmful substances and pathogens by serving as a selective barrier to prevent the passage of many substances from the blood to the brain

What is cerebrospinal fluid (CSF) and what does it do?

a clear, colourless liquid that protects the brain and spinal cord against chemical and physical injuries; and carries oxygen, glucose, and other needed chemicals from the blood to neurons and neuroglia

What are the CSF-filled cavities in the brain called and how many are there?

ventricles; 4

At its superior end, the central canal of the spinal cord is continuous with what structure in the brain?

4th ventricle

What are the functions of the cerebrospinal fluid?

provide mechanical/physical protection, provide chemical protection, supply nutrients, remove waste

Where is cerebrospinal fluid produced?

in a network of capillaries called the choroid plexus, which is found in the brain ventricles

What 3 areas does CSF circulate through?

subarachnoid space, ventricles, and central canal

Which cells control which substances enter the CSF by creating a barrier between the blood and CSF?

ependymal cells

What absorbs most of the CSF?

the arachnoid villi of the superior sagittal blood sinus

What are the 3 regions of the brain stem?

Medulla oblongata

Pons

Midbrain

The medulla oblongata is continuous with the upper part of the spinal cord and contains portions of both _______ and _______ tracts.

motor and sensory

Nuclei in the medulla are reflex centers for the regulation of what 8 functions/actions?

heart rate, respiratory rate, vasoconstriction, swallowing, coughing, vomiting, sneezing, and hiccupping

What are 3 vital reflexes controlled by the medulla?

heart rate, respiratory rate, vasoconstriction

What structure links the spinal cord to the brain and parts of the brain to one another?

pons

The pons relays nerve impulses related to ______ skeletal movements from the cerebral cortex to the ________.

voluntary; cerebellum

What important nuclei help control respiration and the respiratory centre in the medulla are found in the pons?

pneumotaxic and apneustic nuclei

The midbrain conveys _______ impulses from the cerebrum to the cerebellum and spinal cord, sends sensory impulses from the spinal cord to the ______, and regulates _______ and _______ reflexes.

motor; thalamus; auditory and visual

The midbrain helps to regulate muscle _________, alerts the _________to incoming sensory signals, and is responsible for maintaining __________ and ________ from sleep.

tone; cortex; conciousness and awakening

What is the reticular activity system (RAS) responsible for?

sensation, consciousness, attention, and the sleep-wake cycle

What 3 things comprise the diencephalon?

thalamus, hypothalamus, pineal gland

The thalamus contains nuclei that serve as relay stations for all sensory impulses, except __________, to the cerebral cortex.

smell

The thalamus also registers the conscious recognition of the sensations of _________ and _________, and some awareness of __________ and __________. It plays an essential role in __________ and the acquisition of __________, which is called cognition.

pain and temperature; light touch and pressure; awareness; knowledge

The hypothalamus is a major regulator of ______.

homeostasis

What are 6 major functions of the hypothalamus?

control the autonomic nervous system (ANS) and the pituitary gland, and regulate emotion, hunger and thirst, temperature, and circadian rhythm

What does the does the pineal gland secrete and influence?

melatonin; diurnal cycles

The cerebellum has 2 hemispheres and a central, constricted _____.

vermis

What attaches the cerebellum to the brain stem?

three pairs of cerebellar peduncles

What are the functions of the cerebellum?

coordinate skeletal muscle contractions and to maintain normal muscle tone, posture, and balance

What is the largest part of the brain?

cerebrum

What abilities does the cerebrum provide?

the ability to read, write, speak, plan, and create

The superficial gray matter layer of the cerebrum is called the ______ and contains _____.

cerebral cortex; billions of neurons

What are grooves and ridges of the cerebral cortex called?

fissures (deep grooves), sulci (shallow grooves), and gyri (ridges)

Cerebral white matter contains tracts that connect the brain with ....

with itself and other parts of the nervous system.

What separates the brain into hemispheres?

longitudinal fissure

What is the bundle of white nerves that connects the cerebral hemispheres internally?

corpus callosum

What are the 4 lobes of the cerebrum called and what are they named after?

frontal, parietal, temporal, occipital; bones that cover them

What is the name of the fifth part of the cerebrum?

insula

What are the paired masses of grey matter in each cerebral hemisphere called and what are they responsible for?

basal ganglia; helping to control muscular movement

In what 2 parts of the brain is the limbic system found?

in the cerebral hemispheres and diencephalon

What does the limbic system function in and is associated with?

functions in emotional aspects of behaviour and memory, and is associated with pleasure and pain

What are the 3 functional areas of the brain?

Sensory areas that enable perception.

Motor areas that enable movement.

Association areas that enable memory, emotion, and so on.

______ pathways relay action potentials from sensory receptors to the cerebral cortex

Somatic sensory

______ pathways relay signals from the brain stem to the skeletal muscles.

Somatic motor

What are 5 important sensory areas of the cerebral cortex?

Somatosensory area, visual area, auditory area, gustatory area, olfactory area

How many pairs of cranial nerves are there?

12

3 cranial nerves are soley composed of sensory fibers, 5 only composed of motor fibers, and the remaining 4 are _________ and contain both.

mixed nerves

What is the mnemonic for remembering the cranial nerves?

On old Olympus' towering tops, a Finn and a German viewed some hops.

What are the 12 cranial nerve pairs?

olfactory, optic, oculomotor, trochlear, trigeminal, abducens, facial, auditory/vestibulocochlear, glossopharangeal, vagus, spinal accessory, hypoglossal