Exam 2: Basic Neuroanatomy

Question 1

The Nervous System

Answer 1

Approximately 100 billion neurons in the
nervous system, and each of these neurons
may communicate directly with as many as
2,000 other neurons; This provides at least 1 trillion points of communication.

Question 2

Divisions of the Nervous
System

Answer 2

Central Nervous System (CNS); Peripheral Nervous System (PNS)

Question 3

Central Nervous System

Answer 3

Brain (cerebrum, cerebellum, subcortical
structures, brainstem) and spinal cord; All components housed within bone (skull or vertebral column)

Question 4

Peripheral Nervous System

Answer 4

12 pairs of cranial nerves and 31 pairs of spinal
nerves as well as sensory receptors; Components are housed outside of the bone

Question 5

Autonomic nervous system (ANS)

Answer 5

Governs involuntary activities of the visceral muscles
(i.e., glandular secretions, heart and digestive
functions). Comprised of: Sympathetic System and Parasympathetic System.

Question 6

Sympathetic System

Answer 6

Subsystem that responds to
stimulation through energy expenditure (i.e., increase in blood pressure, dilation of pupils, goosebumps;
“fight or flight response”)

Question 7

Parasympathetic System

Answer 7

System that counters the responses of the sympathetic system (i.e., slowing heart rate, reducing blood pressure, pupillary constriction, etc.)

Question 8

Somatic Nervous System

Answer 8

Somatic nervous system governs the
aspects of bodily function that are under
our conscious and voluntary control.

The motor component of the somatic
system is divided into 2 parts:
◦ Pyramidal system-largely responsible for
initiation of voluntary motor acts
◦ Extrapyramidal system-responsible for
background tone and movement supporting the
primary motor acts

Question 9

Nervous system is comprised of:

Answer 9

◦ Neurons-functional building blocks of the
nervous system; function is to transmit
information
◦ Glial Cells- critical players in the development of
synapses; provide structural support for neuron,
and play an important role in storing information
in long term memory

Question 10

General structure of the neuron includes:

Answer 10

◦ Soma: cell body
◦ Dendrite: transmits information towards
the soma
◦ Axon: transmits information away from
the soma

Question 11

Two ways neurons respond to stimulation

Answer 11

The neuron’s response is the mechanism for
transmitting information through the
nervous system:
◦ Excitation-stimulation that causes an increase of
activity of the tissue stimulated
◦ Inhibition- stimulation to a neuron that reduces
the neuron’s output

Question 12

Important landmarks of the neuron:

Answer 12

Axon Hillock
Myelin Sheath
Nodes of Ranvier
Telodendria
Synaptic Vesicles
Neurotransmitters
Synaptic Cleft

Question 13

Axon hillock

Answer 13

Junction of axon with soma

Question 14

Myelin Sheath

Answer 14

White, fatty wrapping of axon; functions to speed up neural conduction

Question 15

Nodes of Ranvier

Answer 15

Areas between myelinated segments; also important in conduction

Question 16

Telodendria

Answer 16

Long, thin projections at axon endpoint; have terminal buttons at the end

Question 17

Synaptic Vesicles

Answer 17

Found within terminal (end) buttons and contain neurotransmitters

Question 18

Neurotransmitters

Answer 18

Compounds responsible for activating next neuron in chain of neurons

Question 19

Synaptic Cleft

Answer 19

Gap between 2 neurons where neurotransmitter released

Question 20

Synapse

Answer 20

-When neuron is stimulated, axon discharges
neurotransmitter into synaptic cleft
-Adjacent neuron responds
-Information enters generally at dendrite and
exits at axon

Question 21

Neurons can either be:

Answer 21

◦ Presynaptic – those “upstream” from the
synapse
◦ Postsynaptic – stimulated by presynaptic
neurons

Question 22

Different types of neurons

Answer 22

-Monopolar (unipolar)-neurons with a single,
bifurcating process arising from soma
-Bipolar-have 2 processes
-Multipolar-more than 2 processes

Question 23

Cerebrum

Answer 23

-Largest structure of nervous system
-Weighs about 3 lbs
-Made up of billions of neurons
-Divided into left and right hemispheres
-Wrapped in 3 meningeal linings
-Most highly evolved and organized structure of the
human body

Question 24

Anatomy of the Cerebrum: Meningeal Linings

Answer 24

-The triple layer meningeal lining serves
important protective and nutritive functions
-3 meningeal layers:
◦ Dura mater-tough bilayered lining; most superficial
◦ Arachnoid mater-lacey, spider-like structure where many blood vessels for the brain pass
◦ Pia mater- thin, membranous covering that closely contours the brain; major arteries and veins serving surface of brain course within this layer

Question 25

Traumatic Brain Injury

Answer 25

TBI is one of leading causes of death in individuals under 24 years of age ◦ Transportation-related injuries exceed falls, assaults, sports, firearms ◦ Seatbelts reduce death due to MVA by 50% ◦ Use of helmets reduced frequency of TBI in motorcycle accidents by 20 to 50%; up to 85% for bikes

Question 26

Ventricles

Answer 26

Spaces within the brain through which CSF (cerebral spinal fluid) flows ◦ Right lateral ventricle ◦ Left lateral ventricle ◦ Third ventricle ◦ Fourth ventricle -Within each ventricle is a choroid plexus, an accumulation of tissue that produces CSF -These cavities are suited to act as buffers for the delicate brain tissue

Question 27

Cerebrospinal Fluid

Answer 27

Central Nervous System (CNS) is bathed in cerebrospinal fluid (CSF) ◦ Provides cushion for delicate and dense neural tissue as well as some nutrient delivery and waste removal. -CSF is the clear, fluid product of the choroid plexus in each ventricle -The volume in CNS is ~125mL, replenished every 7 hours -Fluid is under constant pressure that changes with body position -Life-threatening conditions develop should something occlude the pathway of CSF

Question 28

Circulation of CSF

Answer 28

-Begins in each of the lateral ventricles  coursing through foramina of Monro to 3rd ventricle. -Then flows to cerebral aqueduct to 4th ventricle, where drains into subarachnoid space and freely circulates around brain and spinal cord. -Courses around cerebellum and cerebrum to exit through arachnoid granulation in sinuses of dura mater -Absorbed by venous system

Question 29

Layers of Cerebrum

Answer 29

Cerebrum consists of 2 cerebral hemispheres, roughly equal halves of brain ◦ Cortex refers to the outer surface of the brain; contains 2 basic cell types: -Pyramidal cells-involved in motor function (project to more distant regions) -Nonpyramidal cells-involved in sensory function (connect to more local regions) There are 6 Layers of Cerebrum ◦ Outmost layer=glial cells and axons ◦ 2nd and 3rd layer=pyramidal cells ◦ 4th layer= nonpyramidal cells ◦ 5th and 6th layer=pyramidal cells

Question 30

Landmarks of Cerebrum

Answer 30

Cerebral longitudinal fissure, Gyrus, Sulcus, Lateral Sulcus (Sylvian Fissure), Central Sulcus (Rolandic Sulcus)

Question 31

Cerebral longitudinal fissure

Answer 31

Separates left and right cerebral hemispheres

Question 32

Gyrus

Answer 32

A ridge on the cerebral cortex

Question 33

Sulcus

Answer 33

infolding valleys that separate gyri ◦ (if the groove is deeper or more pronounced it is termed a fissure

Question 34

Lateral Sulcus (Sylvian Fissure)

Answer 34

divides temporal from frontal & anterior parietal

Question 35

Central Sulcus (Rolandic Sulcus)

Answer 35

separates the frontal and parietal lobes entirely

Question 36

Frontal Lobe

Answer 36

-Largest of the lobes -Predominates in planning, initiation, and inhibition of voluntary motion, as well as cognitive function Some key areas: ◦ Broca’s Area-speech motor planning in dominant hemisphere ◦ Motor Strip (a.k.a. pre-central gyrus)-site of initiation of voluntary motor movement

Question 37

Parietal Lobe

Answer 37

-Primary reception sight for body (somatic) sense -All senses that reach consciousness terminate within parietal lobe -Integrates info related to vision, audition, and somatic sense Key areas: ◦ Postcentral gyrus-sensory counterpart to the motor strip, primary site of sensory output; receives sensation from various parts of body ◦ Supramarginal gyri-some involvement in motor planning for speech ◦ Angular gyri-important in comprehension of written material

Question 38

Temporal Lobe

Answer 38

Site of auditory reception and is very important for auditory and receptive language processing Key areas: ◦ Superior temporal gyrus-important in both SLP and Audiology because along it runs..... - Heschl’s Gyrus (where all auditory information is projected) - posterior portion of Wernicke’s area (important in language decoding

Question 39

Occipital Lobe

Answer 39

Posterior limit of brain; Responsible for receiving visual stimulation, as well as some of the higher-level visual processing

Question 40

Insula

Answer 40

-AKA the Island of Reil -Located deep to a region of cerebrum known as the operculum -Believed to be involved in consciousness and play a role in emotion and the regulation of the body's homeostasis

Question 41

Limbic System

Answer 41

Not an anatomically distinct region but is composed of: ◦ Uncus (formed by amygdala) ◦ Thalamus ◦ Parahippocampal gyrus ◦ Cingulate gyrus ◦ Olfactory bulb and tract ◦ Hippocampus ◦ Dentate gyrus Related to functional relationships to: ◦ Motivation ◦ Sex drive ◦ Emotional behavior ◦ Affect

Question 42

Myelinated Fibers

Answer 42

Gray matter of the cortex is predominately made up of neuron bodies, whereas white matter represents myelinated axon fibers -These fibers make up the communication link between neurons (without them there would be no neural function) There are 3 types of fibers: ◦ Projection Fibers ◦ Association Fibers ◦ Commissural Fibers

Question 43

Projection Fibers

Answer 43

Connects cortex with distant locations

Question 44

Association Fibers

Answer 44

Provides communication between regions of the same hemisphere

Question 45

Commissural Fibers

Answer 45

Runs from one location on a hemisphere to the corresponding location on the opposite hemisphere (mainly the corpus callosum)

Question 46

Anatomy of the Subcortex: Basal Ganglia

Answer 46

-Group of large nuclei that partially surround the thalamus -Important in the control of movement; regulates voluntary motor activities -Functions in starting, stopping, and monitoring arm swinging and gait Made up of: ◦ Caudate nucleus ◦ Putamen ◦ Globus Pallidus

Question 47

Anatomy of the Subcortex: Hippocampus

Answer 47

-Involved in memory forming, organizing, and storing -As a limbic system structure, it is important in forming new memories and connecting emotions and senses, such as smell and sound, to memories -Sends memories out to appropriate cerebral hemisphere for long-term storage and retrieval -Also appears to be specialized to recognize faces of individuals

Question 48

Anatomy of the Subcortex: Diencephalon

Answer 48

Structures of the Diencephalon: ◦ Thalamus ◦ Hypothalamus ◦ Epithalamus ◦ Subthalamus Function: ◦ Relays sensory information between brain regions ◦ Controls many autonomic functions of the PNS ◦ Connects structures of the endocrine system with the nervous system ◦ Works in conjunction with the limbic system to generate and manage emotions and memories

Question 49

Specific Functions of Diencephalon

Answer 49

-Directing sense impulses throughout the body -Autonomic function control -Endocrine function control -Motor function control -Homeostasis -Hearing, vision, taste -Touch perception

Question 50

Thalamus

Answer 50

-Large, dual-lobed mass of grey matter -Involved in sensory perception and regulation of motor functions -As a limbic system structure, it connects areas of the cortex involved in perception and movement with related parts of the brain and spinal cord -As a regulator of sensory information, it controls sleep and awake states of consciousness

Question 51

Hypothalamus

Answer 51

-Control center for many autonomic functions of PNS -Connections with structures of endocrine and nervous systems enable maintenance of homeostasis ◦ Blood vessel connection between hypothalamus and pituitary gland ◦ Allows for control of pituitary hormone secretion -As a limbic system structure, influences emotional responses

Question 52

Epithalamus

Answer 52

Secretion of melatonin by the pineal gland (involved in circadian rhythms), and regulation of motor pathways and emotions

Question 53

Subthalamus

Answer 53

Involved in the control of striated muscle

Question 54

Circle of Willis

Answer 54

-The arrangement of the brain’s arteries into the Circle of Willis creates redundancies to ensure constant blood supply to the brain -If one part of the circle or one of the arteries supplying the circle is blocked or narrowed, blood flow from the other blood vessels can often preserve the cerebral perfusion

Question 55

Venous Drainage & Blockage

Answer 55

System of blood vessels called veins that provide the means of draining carbon dioxide-laden blood to the lungs from reoxygenation

Question 56

Obstruction in cerebrovascular supply typically occurs as:

Answer 56

◦ Thrombus: a foreign body (blood clot) that obstructs blood vessel ◦ Embolism: when a thrombus breaks loose from its site of formation and floats through bloodstream and causes occlusion

Question 57

Cerebellum

Answer 57

-Responsible for coordinating motor commands with sensory inputs to control movement -Communicates with brainstem, spinal cord, and cerebral cortex by means of superior, middle and inferior peduncles -Also plays significant role as memory for motor functions and even cognitive processing -Composed of 2 hemispheres (the vermis separates the two lobes)

Question 58

Tracts of Cerebellum

Answer 58

Dorsal spinocerebellar tract, Cuneocerebellar tract, Ventral spinocerebellar tract, Rostral spinocerebellar tract

Question 59

Dorsal spinocerebellar tract

Answer 59

communicates sensation of temperature, proprioception, and touch from lower body to ipsilateral cerebellum

Question 60

Cuneocerebellar tract

Answer 60

serves the same function as above but for the arms and upper trunk

Question 61

Ventral spinocerebellar tract

Answer 61

transmits proprioception info and pain sense from legs and lower trunk

Question 62

Rostral Spinocerebellar Tract

Answer 62

Serves the same as above for arms and upper trunk

Question 63

Anatomy of the Brainstem

Answer 63

-Medulla -Pons -Midbrain Cranial Nerves and their nuclei arise from the brainstem and basic bodily functions of life are maintained here

Question 64

Medulla Oblongata

Answer 64

A portion of the hindbrain that controls autonomic functions -Digestion -Heart and blood vessel function -Swallowing -Sneezing ◦ Motor and sensory neurons from midbrain and forebrain ◦ Relay of nerve signals between the brain and spinal cord ◦ Coordination of body movements

Question 65

Pons

Answer 65

Description ◦ Connects the cerebral cortex with the medulla oblongata ◦ Communication and coordination center between the two cerebral hemispheres ◦ Helps in transferring of messages between brain and spinal cord Function ◦ Arousal ◦ Controlling autonomic functions ◦ Relaying sensory information between cerebrum and cerebellum ◦ Sleep

Question 66

Midbrain

Answer 66

Midbrain and hindbrain make up the brainstem; Connects the hindbrain and the forebrain; Involved in auditory and visual responses as well as motor function

Question 67

Reticular Formation (also called Reticular Activating System)

Answer 67

Function: ◦ Arousal ◦ Attention ◦ Cardiac Reflexes ◦ Motor Functions ◦ Regulates Awareness ◦ Relays nerve signals to the cerebral cortex ◦ Sleep Location: ◦ The reticular formation is a group of nerve fibers located inside the brainstem (spans the medulla, pons and midbrain)

Question 68

Cranial Nerves

Answer 68

-Cranial nerves I through IV stem from midbrain -Cranial nerves V through VIII stem from pons -Cranial nerves IX through XII stem from medulla -Cranial nerves can be efferent, afferent or mixed

Question 69

Efferent

Answer 69

Transmit information from brain to spinal nerves.

Question 70

Afferent

Answer 70

Transmit info concerning the physical state of limbs and trunk to higher brain centers.

Question 71

Anatomy of the Spinal Cord

Answer 71

-Spinal cord if the information lifeline to and from the periphery of the body -Made up of a long mass of neurons, with both cell bodies and projections from (and to) those neurons -Gray portions are neuron cell bodies and white portions are the myelinated fibers of tracts that communicate info to and from brain -Efferent (motor) tracts, such as corticospinal tract, transmit information from brain to spinal nerves -Afferent (sensory) tracts, such as spinothalamic tract, transmit info concerning the physical state of limbs and trunk to higher brain centers

Question 72

More anatomy of spinal cord

Answer 72

-Begins at foramen magnum of skull and courses through the vertebral canal -Safely protected by long tube made up of connective tissue (the meningeal linings) 31 pairs of spinal nerves arise from regions related to the vertebra ◦ 8 pairs of cervical spinal nerves ◦ 12 pairs of thoracic nerves ◦ 5 pairs of lumbar and sacral nerves ◦ 1 pair of coccygeal nerves