Anatomy Exam 3

What is the reason for the cervical and lumbar enlargement?

1. Inferior to the lumbar enlargement the cord tapers to a conical tip called the Conus medullaris 2. A slender strand of fibrous connective tissue extends from the end of the cord down into the sacrum and is anchored at the coccyx. This strand is called the Filum terminale

Why is the blood brain barrier less intact in the hypothalamus?

A less intact blood brain barrier suggests that the endothelium is extremely permeable. This permeability exposes hypothalamic nuclei to circulating hormones and permits the diffusion of hypothalamic hormones into the circulation.

How does a reflex differ from a voluntary muscle movement?

A reflex is an immediate involuntary response, whereas voluntary motor movement is under conscious control and is voluntary.

In multiple sclerosis, there is progressive and intermittent damage to the myelin sheath of peripheral nerves. This results in poor motor control of the affected area. Why does destruction of the myelin sheath affect motor control?

Action potentials travel faster along myelinated fibers than along unmyelinated fibers. Destruction of the myelin sheath slows the time it takes for motor neurons to communicate with their effector muscles. This delay in response results in varying degrees of uncoordinated muscle activity. The situation is very similar to that of a newborn; the infant cannot control its arms and legs very well because the myelin sheaths are still being laid down for the first year. Since not all motor neurons to the same muscle may be demyelinated to the same degree, some fibers are slow to respond while others respond normally, producing contractions that are erratic and poorly controlled.

The deep crease on the anterior surface of the spinal cord is the

Anterior median fissure

Cranial blood vessels pass through the space directly deep to the

Arachnoid matter

Which neuronal tissue cell type is likely to be malfunctioning if the blood brain barrier (BBB) is no longer adequately protecting the brain?

Astrocytes

Lying within each hemisphere inferior to the floor of the lateral ventricles is/are the

Basal Nuclei

Astrocyte

Blood Brain Barrier

Interneurons

CNS situated between sensory and motor neurons Responsible for analysis of sensory input and coordination of motor output

Somatic motor neurons

Carries impulses to the CNS, axon is located in the CNS

Nerve fiber bundles on the ventrolateral surface of the mesencephalon are the

Cerebral Peduncles

What are two things normally found within the subarachnoid space?

Cerebral spinal fluid + arteries & veins

The expanded area of the spinal cord that supplies nerves to the pectoral girdle and upper limbs is the

Cervical enlargement

Prevertebral

Collateral ganglia

What purpose do collaterals serve in the nervous system?

Collaterals enable a single neuron to communicate with several other cells at the same time.

axon hillock

Connects initial segment to cell body

pseudounipolar neurons

Continuous dendritic and axon all processes—cell body off to one side Sensory neurons in PNS

Efferent tracts from the hypothalmus

Control involuntary motor activities, control autonomic function, and coordinate activities of the nervous and endocrine systems.

In some severe cases, a person suffering from stomach ulcers may need to have surgery to cut the branches of the vagus nerve that innervates the stomach. How would this help the problem?

Cutting off autonomic nervous system stimulation to the stomach through the vagus nerve decreases stimulation of digestive glands, thus reducing their secretion. This may diminish ulcers in the wall of the stomach.

The paired structures that contain cell bodies of sensory neurons and are associated with each segment of the spinal cord are the

Dorsal root ganglia

The is a strand of fibrous tissue that provides longitudinal support as a component of the coccygeal ligament.

Filum terminale

Preganglionic

First Neuron

Schwann cells (PNS)

Form myelin sheath in the peripheral nervous system

Astrocyte (CNS)

Forms the BBB

anaxonic neuron

Found only in CNS Special sense organs

Axons crossing from one side of the spinal cord to the other within the gray matter are found in the

Gray commissures

Bipolar Neurons

Have single dendrite, single axon with a soma in between. Important for sight, hearing and smell

The most important function of the cell body of a neuron is to

House organelles that produce energy and synthesize organic molecules

The primary link between the nervous and the endocrine systems is the

Hypothalmus

Why are there eight cervical spinal nerves but only seven cervical vertebrae?

In the cervical region, the first pair of spinal nerves, C1, exits between the skull and the first cervical vertebra. Thereafter, a numbered cervical spinal nerve exits after each cervical vertebra. For instance, nerve C2 exits after vertebra C1, nerve C3exits after vertebra C2, and so on until nerve C8, which exits after vertebra C7.

An 8-year-old girl cut her elbow when she fell while skating. The injury caused only minor muscle damage but partially severed a nerve in her arm. What is likely to happen to the severed axons of this nerve, and will the little girl regain normal function of the nerve and the muscles it controls?

In the process known as Wallerian degeneration, the axons distal to the injury site deteriorate, and macrophages migrate in to phagocytize the debris. The Schwann cells in the area divide and form a solid cellular cord that follows the path of the original axon. As the neuron recovers, its axon grows into the injury site, and the Schwann cells wrap around it. If the axon continues to grow into the periphery alongside the appropriate cord of Schwann cells, it may eventually reestablish normal synaptic contacts. If it stops growing or wanders off in some new direction, normal function will not return.

Which of the following is not a function of the neuroglia?

Information processing

The brachial plexus

Innervates the shoulder girdle and the upper extremity, is formed from the ventral rami of spinal nerves C5-T5, and is the source of the musculocutaneous, radial, median, and ulnar nerves.

Reflex

Involuntary motor response

Spinal cord begins at the base of the brain and extends to the

L1 or L2

Sympathetic

Long postganglionic fiber

Epidural Space

Loose connective tissue, adipose tissue

Obturator Nerve

Lumbar plexus

Proprioceptors

Monitor position/movement of joints

Multipolar Neurons

Most common type of neuron in CNS

oligodenrocyte

Myelin

Ganglia

Neuron Cell bodies in PNS

The middle layer of connective tissue that surrounds each peripheral nerve is the

Perineurium

reverberation

Positive Feedback

Autonomic motor neurons (arranged in a series)

Preganglionic: somas in CNS with axon extended out to fire at the postganglionic neurons which have their somas in a peripheral ganglion

Neuroglia found surrounding the cell bodies of peripheral neurons are

Satelite cells

afferent division

Sensory Information

collaterals

Side branches of axons

Fascicle

Single bundle of axons

Effector

Skeletal Muscle

Dermatome

Specific region of body surface

satellite cells (PNS)

Surround somas in the ganglia Regulate O2 & CO2 around neurons in the ganglia

Paravertebral

Sympathertic division

crisis

Sympathetic activation

How do sympathetic chain ganglia differ from both collateral ganglia and intramural ganglia?

Sympathetic chain ganglia are innervated by preganglionic fibers from the thoracolumbar regions of the spinal cord, and they are interconnected by preganglionic fibers and axons from each ganglion in the chain innervating a particular body segment. The collateral ganglia are part of the abdominal autonomic plexus anterior to the vertebral column. Preganglionic sympathetic fibers innervate the collateral ganglia as splanchnic nerves. Intramural ganglia are part of the parasympathetic division. They are located near or within the tissues of the visceral organs.

What anatomical mechanism is involved in causing a person to blush?

Sympathetic stimulation relaxes vessel walls, increasing blood flow to the skin.

Axons terminate in a series of fine extensions known as

Telodendria

The cortex inferior to the lateral sulcus is the

Temporal Lobe

Parasympathetic

Terminal Ganglia

The diencephalic components of the limbic system include the

Thalmus and hypothalmus

Why is it important that a spinal tap be done between the third and fourth lumbar vertebrae?

The adult spinal cord extends only as far as vertebra L1 or L2. Inferior to this point in the vertebral foramen, the meningeal layers enclose the relatively sturdy components of the cauda equina and a significant quantity of CSF.

What is the arachnoid layer made up of?

The arachnoid mater is the middle layer of the meninges, lying directly underneath the dura mater. It consists of layers of connective tissue

What is the purpose of the blood brain barrier (BBB)?

The blood brain barrier (BBB) is needed to isolate nervous tissue from the general circulation because hormones or other chemicals normally present in the blood could have disruptive effects on neuron function.

Which of the cranial nerves are responsible for all aspects of eye function?

The cranial nerves that collectively participate in eye function are N II, N III, N IV, N V, and N VI.

What is the role of the meninges in protecting the spinal cord?

The meninges provide a tough protective covering, longitudinal physical stability, and a space for shock-absorbing fluid

Karen falls down a flight of stairs and suffers spinal cord damage due to hyperextension of the cord during the fall. The injury results in edema of the spinal cord with resulting compression of the anterior horn cells of the spinal region. What signs would you expect to observe as a result of this injury?

The neurons for the anterior horn of the spinal cord are somatic motor neurons that direct the activity of skeletal muscles. The lumbar segments of the spinal cord control the skeletal muscles that are involved with the control of the muscles of the hip and lower limb. As a result of the injury, Karen would have poor control of most lower limb muscles, a problem with walking (if she could walk at all), and (if she could stand) problems maintaining balance.

Why are the effects of parasympathetic stimulation more specific and localized than those of the sympathetic division?

The parasympathetic division innervates only visceral structures served by some cranial nerves or lying within the thoracic and/or abdominopelvic cavities. The sympathetic division has widespread impact due to extensive collateral branching of preganglionic fibers, which reach visceral organs and tissues throughout the body.

Cindy is in an automobile accident and injures her spinal cord. She has lost feeling in her right hand, and her doctor tells her that it is the result of swelling compressing a portion of her spinal cord. Which part of her cord is likely to be compressed?

The part of the cord that is most likely compressed is an ascending tract.

If a person has poor emotional control and difficulty in remembering past events, what area of the brain might be damaged or have a lesion?

The person might have a lesion in the limbic system.

Distinguish between the somatic nervous system and the autonomic nervous system.

The somatic nervous system controls skeletal muscle contractions, which may be voluntary or involuntary. The autonomic nervous system regulates smooth muscle, cardiac muscle, and glandular activity, usually outside our conscious awareness or control.

Compare the general effects of the sympathetic and parasympathetic divisions of the ANS.

The sympathetic division of the ANS stimulates metabolism, increases alertness, and prepares for emergency in "fight-or-flight." The parasympathetic division promotes relaxation, nutrient uptake, energy storage, and "rest-and-digest."

The effects of epinephrine and norepinephrine released by the adrenal glands last longer than those of either chemical when released at neuroeffector junctions. Why?

There are no enzymes to break down epinephrine and norepinephrine in the blood and very little in peripheral tissues.

How does the cauda equina form?

There is further growth of ventral/dorsal nerve roots

Spinal nerves are called mixed nerves because

They contain sensory and motor fibers

Oligodendeocytes (CNS)

Ties axons together Forms myelin sheath in the CNS

White Matter

Tracts and columns

Sensory and motor innervations of the skin of the lateral and anterior surfaces of the body are provided by the

Ventral Ramus

Patterns of interactions between neurons include which of the following?

Visual activities

Cutting the ventral root of the spinal nerve at L2 would interrupt the transmission of what type of information?

Voluntary motor output and ANS motor output

The neurotransmitter at all synapses and neuroeffector junctions in the parasympathetic division of the ANS is

acetylcholine

All preganglionic autonomic fibers release at their axon terminals, and the effects are always .

acetylcholine; excitatory

Epinephrine

adrenal medulla

Acetylcholine (ACh)

all preganglionic fibers

parallel processing

allows several neural pools to process information simultaneously. For example, stepping on a tack causes you to withdraw your foot, shift your weight, move your arms, feel the pain, and holler all at the same time.

The anterior nuclei of the thalamus

are part of the limbic system

The white ramus communicans

carries the preganglionic fibers into a nearby sympathetic chain ganglion.

The gray matter of the spinal cord is dominated by

cell bodies of neurons and neuroglia

Spinal Cord has two enlargements

cervical enlargement and lumbar enlargement

Phrenic Nerve

cervical plexus

What is the cauda equina?

collection of nerve roots at the inferior end of the vertebral canal

epidural space

contains adipose tissue

What is the Pia mater made of?

elastic and collagen fibers

Splanchnic nerves

include preganglionic fibers that go to collateral ganglia.

Reverberation

is a way for a circuit to exert positive feedback on the circuit. Once this process has started it can only be stopped by an inhibitory signal or by neuronal fatigue. These types or circuits are important for maintaining consciousness, muscular coordination, and normal breathing patterns.

How is the pia mater attached to the spinal cord?

is attached to it through a connection to the anterior fissure. The pia mater attaches to the dura mater through 21 pairs of denticulate ligaments that pass through the arachnoid mater and dura mater of the spinal cord.

serial processing

is used to relay information from one neural pool to another. This is seen when sensory information is relayed from one processing center to another.

divergent circuit

is used to spread information from one neuron too many. This permits a broad distribution of specific input. This is seen whenever sensory input is brought into the CNS

ependymal cells (CNS)

lines cavities produces CSF

Ventral Root

motor neuron axons

The only cranial nerves that are attacked to the cerebrum are the

olfactory

bipolar neurons

one Dendrite

Brachial Plexus

pectoral girdle/upper extremity

convergence

permits variable control of motor neurons by providing for both their voluntary and involuntary controls. For example, right now your diaphragm is being contracted by involuntary neuron activity, but you can also take voluntary control and take a very deep breath.

Microglia (CNS)

phagocytes

Splanchnic

preganglionic fibers to collateral ganglia

The large cells in the adrenal medulla, which resemble neurons in sympathetic ganglia,

release epinephrine and norepinephrine into blood capillaries.

pudendal nerve

sacral plexus

Visceral motor neurons in the CNS

send axons to synapse on peripherally located ganglionic neurons.

Sympathetic preganglionic fibers are characterized as being

short in length and myelinated.

Which of the following ganglia belong to the sympathetic division of the ANS?

sympathetic chain ganglia

Thoracolumbar

sympathetic division

Preganglionic fibers of the ANS sympathetic division originate in the

thoracic and lumbar spinal segments.

Postganglionic fibers of autonomic neurons are usually

unmyelinated