MMSC200 Exam 2 Chapter 10

nervous system

• memory and movement

• voluntary and involuntary activities

• complex: 100 billion nerve cells called neurons (a type of parenchymal cells)

• active interactions between neurons (pass on information from one to another)

• nerves carry electrochemical messages

• external and internal receptors

central and peripheral nervous system

• central nervous system

  • brain

  • spinal cord

• peripheral nervous system

  • cranial nerves

  • spinal nerves

  • plexuses

  • peripheral nerves throughout the body

nervous system

afferent and efferent nerve fibers

• cranial and spinal nerves

  • sensory nerves (afferent nerve fibers) carry messages toward the brain

  • motor nerves (efferent nerve fibers) carry messages from the brain

• sensory receptors in organs and glands

  • sight

  • hearing and balance

  • smell

• mixed nerves may carry both sensory and motor fibers.

linkage between central and peripheral nervous system

simple reflex arc

autonomic nervous system

• involuntary nervous system

• carries impulses from the central nervous system to organs; motor nerve

• sympathetic nerves stimulate body under stress

• parasympathetic nerves balance sympathetic system

  • slow heart rate

  • lower blood pressure

cranial nerves

structure of nervous system

Main Idea:
The nervous system is divided into the Central Nervous System (CNS) and the Peripheral Nervous System (PNS). The CNS processes information, while the PNS carries information to and from the CNS.

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1. Central Nervous System (CNS)

Includes:

• Brain

• Spinal Cord

Function:

• Interprets sensory information

• Makes decisions

• Sends commands to the body

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2. Peripheral Nervous System (PNS)

Includes:

• Cranial nerves

• Spinal nerves

Function:

• Connects the CNS to the rest of the body

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Sensory (Afferent) Division

Direction: Body → CNS

Function:

• Carries information from sense organs (eyes, ears, skin, etc.) to the brain and spinal cord.

• Allows the CNS to receive information about the environment.

Remember:
Afferent = Arrives at the CNS

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Motor (Efferent) Division

Direction: CNS → Body

Function:

• Carries commands from the brain and spinal cord to muscles and glands.

Remember:
Efferent = Exits the CNS

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Motor Division Branches 1. Somatic Nervous System (Voluntary)

Controls:

• Skeletal muscles

Function:

• Responsible for conscious movements such as walking, writing, and lifting objects.

Example:

• Choosing to raise your hand in class.

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2. Autonomic Nervous System (Involuntary)

Controls:

• Cardiac muscle (heart)

• Smooth muscle (organs)

• Glands

Function:

• Regulates automatic body functions without conscious effort.

Sympathetic Division

"Fight or Flight"

• Increases heart rate

• Dilates pupils

• Increases breathing rate

• Prepares body for stress or emergencies

Parasympathetic Division

"Rest and Digest"

• Slows heart rate

• Stimulates digestion

• Conserves energy

• Returns body to a calm state

Vagus Nerve:

• Major nerve of the parasympathetic system

• Helps regulate heart rate, digestion, and other internal organ functions

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Quick Memory Trick

CNS = Control Center (brain & spinal cord)

PNS = Communication Network

Afferent = Arrives at CNS

Efferent = Exits CNS

Sympathetic = Stress ("Fight or Flight")

Parasympathetic = Peace ("Rest and Digest")

nerve cells (neurons)

• microscopic

• collected into macroscopic nerves

• carry electrical messages all over the body

movement of nervous pulse

Main Idea:
A neuron is a specialized nerve cell that receives, processes, and sends electrical and chemical signals throughout the body.

Key Parts and Functions:

• Dendrites: Receive incoming signals from other neurons.

• Cell Body (Soma): Contains the nucleus and processes information received by dendrites.

• Nucleus: Controls the activities of the neuron.

• Axon Hillock: Area where the nerve impulse begins.

• Axon: Carries the nerve impulse away from the cell body.

• Myelin Sheath (Schwann Cells): Insulates the axon and speeds up signal transmission.

• Nodes of Ranvier: Gaps in the myelin sheath that allow the impulse to jump from node to node, increasing speed.

• Axon Terminals: End branches of the axon that communicate with other cells.

How a Signal Travels:

1. Dendrites receive a message from another neuron.

2. The cell body processes the information.

3. The nerve impulse begins at the axon hillock.

4. The impulse travels down the axon.

5. Myelin and nodes of Ranvier help the signal move quickly.

6. At the axon terminal, neurotransmitters are released into the synapse.

Synapse (Bottom Left Diagram):

• The axon terminal releases neurotransmitters stored in vesicles.

• Neurotransmitters cross the tiny gap called the synapse.

• They bind to receptors on the dendrite of the next neuron.

• This starts a new nerve impulse in the receiving neuron.

Important Concept: Neural communication occurs through a combination of:

• Electrical signals within a neuron.

• Chemical signals (neurotransmitters) between neurons.

Remember:
Dendrites → Cell Body → Axon Hillock → Axon → Axon Terminal → Neurotransmitters → Next Neuron. This is the direction that information flows through a neuron.

multiple sclerosis

a chronic autoimmune condition where the immune system mistakenly attacks the protective myelin sheath surrounding nerve fibers in the brain and spinal cord

most common autoimmune disorder affecting the central nervous system

demyelinating disease in which the insulating covers of nerve cells in the brain and spinal cord are damaged

this damage disrupts the ability of parts of the nervous system to communicate, resulting in a wide range of sign sand symptoms, including physical, mental, and sometimes psychiatric problems

neurotransmitters

• acetycholine: neuromuscular synapse

• dopamine: perception of pleasurable effects

  • opioids, nicotine, amphetamine, ethanol and cocaine increase dopamine release

  • dysfunction involved in Parkinson disease, schizophrenia

• epinephrine and norepineprhine: ‘fight or flight’, increase heart rate

• serotonin: regulation of mood, happiness, sleep/wake cycles

myasthenia gravis

• weaknesses, serious

• chronic neuromuscular disease that leads to fluctuating muscle weakness and fatigue

• muscle weakness is caused by circulating autoimmune antibodies that block acetylcholine receptors at the postsynaptic neuromuscular junction, inhibiting the excitatory effects of the neurotrasmitter acetylcholine on neuromuscular junctions

• symptoms

  • weakness of voluntary muscles

  • blepharoptosis

  • diplopia (double vision)

cluster of nerve fibers

Main Idea:
A peripheral nerve is made up of many individual nerve fibers (axons) bundled together and protected by layers of connective tissue.

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Components of a Peripheral Nerve Axon

• The long extension of a neuron.

• Carries nerve impulses away from the cell body.

Myelin Sheath

• Fatty covering surrounding many axons.

• Insulates the axon and speeds up nerve impulse transmission.

Endoneurium

• Connective tissue surrounding each individual nerve fiber (axon).

• Provides support and protection.

Fascicle

• A bundle of many nerve fibers grouped together.

Perineurium

• Connective tissue surrounding each fascicle.

• Helps protect and organize groups of nerve fibers.

Epineurium

• Outermost connective tissue layer surrounding the entire nerve.

• Protects the whole nerve and holds fascicles together.

Blood Vessels

• Supply oxygen and nutrients to the nerve tissue.

• Remove waste products.

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Layers from Innermost to Outermost

1. Axon

2. Myelin Sheath

3. Endoneurium (around each axon)

4. Perineurium (around each fascicle)

5. Epineurium (around the entire nerve)

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Easy Memory Trick

Think of a nerve like a cable:

• Axon = wire

• Myelin sheath = wire insulation

• Endoneurium = wrapping around one wire

• Perineurium = wrapping around a bundle of wires

• Epineurium = outer covering of the entire cable

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Exam Tip

Endoneurium → Around one nerve fiber
Perineurium → Around one fascicle (bundle)
Epineurium → Around the whole nerve

Mnemonic: E-P-E = Endoneurium, Perineurium, Epineurium (smallest → largest covering).

Matters

grey matter: nerve cell bodies

white matter: axons covered with myelin sheets (no cell bodies)

central and peripheral nervous system

Main Idea:
The nervous system has two major divisions: the Central Nervous System (CNS), which serves as the control center, and the Peripheral Nervous System (PNS), which carries information between the CNS and the rest of the body.

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1. Central Nervous System (CNS)

Includes:

• Brain

• Spinal Cord

Functions:

• Receives sensory information

• Processes and interprets information

• Makes decisions

• Sends commands to the body

Protection of the CNS:

• Meninges: Three protective membranes surrounding the brain and spinal cord.

• Cerebrospinal Fluid (CSF): Fluid that cushions, nourishes, and protects the CNS.

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2. Peripheral Nervous System (PNS)

Includes all nerves outside the brain and spinal cord

Components: Cranial Nerves

• 12 pairs

• Originate from the brain

• Control functions of the head, neck, and some internal organs

Spinal Nerves

• 31 pairs

• Originate from the spinal cord

• Carry sensory and motor information throughout the body

Plexuses

• Networks of intersecting spinal nerves

• Help distribute nerve signals to different body regions

Peripheral Nerves

• Extend throughout the body

• Connect the CNS to muscles, organs, and sensory receptors

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Autonomic Nervous System (Part of the PNS)

Controls involuntary functions such as:

• Heart rate

• Blood pressure

• Digestion

• Breathing

Sympathetic Division

"Fight or Flight"

• Prepares body for stress or emergencies

• Increases heart rate and energy use

Parasympathetic Division

"Rest and Digest"

• Conserves energy

• Slows heart rate

• Promotes digestion

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Quick Comparison

Central Nervous System (CNS)	Peripheral Nervous System (PNS)
Brain and spinal cord	All nerves outside CNS
Processes information	Transmits information
Control center	Communication network
Protected by meninges and CSF	Includes cranial, spinal, and autonomic nerves

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Memory Trick

CNS = Command Center 🧠

PNS = Pathways and Nerves 🔌

12 Cranial Nerves + 31 Spinal Nerves = Major Components of the PNS

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Test Tip

Know these numbers:

• 12 pairs of cranial nerves

• 31 pairs of spinal nerves

meninges

Main Idea:
The meninges are three layers of connective tissue that surround and protect the brain and spinal cord (CNS). They help cushion the nervous system and contain cerebrospinal fluid (CSF).

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The Three Meningeal Layers 1. Dura Mater

"Tough Mother"

• Outermost meningeal layer

• Thick, tough, and durable

• Provides strong protection for the brain and spinal cord

• Located directly beneath the skull

Function:

• Protects the CNS from injury

• Forms partitions and venous sinuses that help drain blood from the brain

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2. Arachnoid Mater

"Spider-like Layer"

• Middle meningeal layer

• Thin, web-like membrane

• Located between the dura mater and pia mater

Function:

• Helps cushion and protect the CNS

• Forms the upper boundary of the subarachnoid space

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3. Pia Mater

"Gentle Mother"

• Innermost meningeal layer

• Thin and delicate

• Closely adheres to the surface of the brain and spinal cord

• Follows all folds and grooves of the brain

Function:

• Protects and nourishes nervous tissue

• Contains many blood vessels that supply the brain and spinal cord

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Spaces Between the Layers Subdural Space

• Located between the dura mater and arachnoid mater

• Contains a small amount of lubricating fluid

Subarachnoid Space

• Located between the arachnoid mater and pia mater

• Filled with cerebrospinal fluid (CSF)

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Cerebrospinal Fluid (CSF)

Functions:

• Cushions the brain and spinal cord

• Absorbs shock from impacts

• Helps transport nutrients

• Removes waste products

• Maintains a stable environment for nervous tissue

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Order from Outside to Inside

Skull → Dura Mater → Arachnoid Mater → Subarachnoid Space (CSF) → Pia Mater → Brain

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Memory Trick "D-A-P"

• Dura mater = Durable

• Arachnoid mater = Arachnid (spider-web)

• Pia mater = Pliable/Personal (sticks directly to the brain)

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Exam Tip

Know:

• Dura mater = outermost

• Arachnoid mater = middle

• Pia mater = innermost

• CSF is found in the subarachnoid space

Meninges and spinal fluid (CSF)

Main Idea:
The brain is protected by three membranes called the meninges and by cerebrospinal fluid (CSF), which cushions and supports the central nervous system.

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Meningeal Layers (Outside → Inside) 1. Dura Mater

• Outermost layer

• Thick and tough

• Located directly beneath the skull

• Provides strong protection for the brain

2. Arachnoid Mater

• Middle layer

• Web-like appearance

• Creates the upper boundary of the subarachnoid space

3. Pia Mater

• Innermost layer

• Very thin and delicate

• Closely attached to the surface of the brain

• Contains blood vessels that nourish nervous tissue

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Subarachnoid Space

Location:

• Between the arachnoid mater and pia mater

Contains:

• Cerebrospinal fluid (CSF)

Importance:

• The CSF-filled space acts as a protective cushion around the brain and spinal cord.

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Cerebrospinal Fluid (CSF) Functions:

✅ Cushions the brain and spinal cord from injury

✅ Absorbs shock during movement

✅ Supplies nutrients to nervous tissue

✅ Removes waste products

✅ Helps maintain a stable environment for neurons

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Structures Shown in the Diagram

Skull

• Hard outer protection

Dura Mater

• Tough outer meningeal layer

Arachnoid Mater

• Middle, web-like layer

Subarachnoid Space

• Contains CSF

Pia Mater

• Thin inner layer attached to the brain

Blood Vessels

• Carry oxygen and nutrients to brain tissue

Brain

• Main organ of the central nervous system

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Order to Memorize

Skull → Dura Mater → Arachnoid Mater → Subarachnoid Space (CSF) → Pia Mater → Brain

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Memory Trick "DAP"

• Dura = Durable

• Arachnoid = Arachnid (spider-web)

• Pia = Personal (sticks directly to the brain)

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Exam Tip

The most commonly tested fact is:

👉 CSF is located in the subarachnoid space between the arachnoid mater and pia mater.

meninges (from outside to inside)

• dura mater

• arachnoid (spinal fluid is contained in the subarachnoid space)

• pia mater

• Main Idea:
  The meninges are three protective membranes that surround the brain and spinal cord. They provide protection, support, and a space for cerebrospinal fluid (CSF).

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  Meningeal Layers (Outside → Inside) 1. Dura Mater

  • Outermost layer

  • Tough, thick, fibrous membrane

  • Located directly beneath the skull

  • Provides the greatest protection

  2. Arachnoid Mater

  • Middle layer

  • Thin, web-like membrane

  • Named after its spiderweb appearance

  • Creates the upper boundary of the subarachnoid space

  Subarachnoid Space

  • Located between the arachnoid mater and pia mater

  • Contains cerebrospinal fluid (CSF)

  Important Fact: 👉 CSF is contained in the subarachnoid space.

  3. Pia Mater

  • Innermost meningeal layer

  • Thin and delicate

  • Closely adheres to the surface of the brain and spinal cord

  • Contains blood vessels that nourish nervous tissue

  ---

  Cerebrospinal Fluid (CSF) Functions:

  ✅ Cushions the brain and spinal cord

  ✅ Protects against injury and shock

  ✅ Delivers nutrients

  ✅ Removes waste products

  ✅ Helps maintain a stable environment for neurons

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  Layer Order to Memorize

  Skull → Dura Mater → Arachnoid Mater → Subarachnoid Space (CSF) → Pia Mater → Brain

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  High-Yield Exam Facts

  • Dura mater = outermost layer

  • Pia mater = innermost layer

  • CSF is located in the subarachnoid space

  • The meninges surround both the brain and spinal cord

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  Memory Trick

  "DAP"

  • Dura = Durable

  • Arachnoid = Arachnid (spider-web layer)

  • Pia = Personal (stuck directly to the brain)

  One-Sentence Summary

  The meninges consist of the dura mater, arachnoid mater, and pia mater, and cerebrospinal fluid (CSF) is found in the subarachnoid space between the arachnoid and pia mater. 🧠📚

cerebrospinal fluid (CSF)

ultrafiltrate of plasma (water, glucose, sodium, chloride, protein

20 mL/hr made reasborbed by arachnoid villin

adult volume: 160 mL

infant volume: 60 mL

Main Idea:
Cerebrospinal fluid (CSF) is a clear, colorless fluid that circulates around and through the brain and spinal cord, providing protection, support, and nourishment to the central nervous system (CNS).

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Where is CSF Found? Around the Brain and Spinal Cord

• In the subarachnoid space between the arachnoid mater and pia mater.

• Surrounds the entire brain and spinal cord.

Inside the Brain

• Found within the ventricles (fluid-filled chambers of the brain).

• Flows through connected ventricles and around the CNS.

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Functions of CSF 1. Protection

• Cushions the brain and spinal cord.

• Acts as a shock absorber against injury.

2. Buoyancy

• Helps support the weight of the brain.

• Prevents the brain from pressing heavily against the skull.

3. Nutrient Transport

• Delivers nutrients and essential substances to nervous tissue.

4. Waste Removal

• Carries away metabolic waste products from the brain and spinal cord.

5. Homeostasis

• Maintains a stable chemical environment for neurons to function properly.

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Structures Shown in the Diagram Cerebrum

• Largest part of the brain

• Responsible for thinking, memory, sensation, and voluntary movement

Cerebellum

• Coordinates balance, posture, and movement

Ventricles

• Internal cavities within the brain containing CSF

Membranes Around the Brain and Spinal Cord

• Meninges that contain and protect the CSF

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Flow of CSF (Simple Version)

1. Produced in the brain's ventricles

2. Circulates through the ventricles

3. Flows into the subarachnoid space

4. Surrounds the brain and spinal cord

5. Is reabsorbed into the bloodstream

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High-Yield Exam Facts

✅ CSF is found in the ventricles of the brain

✅ CSF is found in the subarachnoid space

✅ CSF cushions and protects the brain and spinal cord

✅ CSF helps transport nutrients and remove waste

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Memory Trick

CSF = "Cushion, Support, and Flow"

• Cushions the CNS

• Supports the brain

• Flows around the brain and spinal cord

One-Sentence Summary

Cerebrospinal fluid (CSF) circulates through the ventricles and subarachnoid space, where it cushions, protects, nourishes, and supports the brain and spinal cord. 🧠💧📚

spinal tap (lumbar puncture) to obtain cerebrospinal fluid (CSF)

Main Idea:
A lumbar puncture (spinal tap) is a procedure in which a needle is inserted into the subarachnoid space of the lower back to collect or measure cerebrospinal fluid (CSF).

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What the Diagram Shows

• Needle inserted between the L3 and L4 vertebrae.

• Needle passes through the meninges into the subarachnoid space.

• The subarachnoid space contains cerebrospinal fluid (CSF).

• The spinal cord has already ended above this area, making the procedure safer.

• The needle enters near the cauda equina (bundle of spinal nerve roots).

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Important Structures Cauda Equina

• Means "horse's tail"

• Bundle of spinal nerve roots below the end of the spinal cord

• Located in the lower vertebral canal

Subarachnoid Space

• Located between the arachnoid mater and pia mater

• Contains CSF

Distal End of the Spinal Cord

• Adult spinal cord ends around L1-L2

• Lumbar punctures are performed below this level to reduce the risk of spinal cord injury

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Why is a Lumbar Puncture Performed? Diagnostic Uses

• Test for meningitis

• Detect infections

• Detect bleeding around the brain

• Diagnose certain neurological diseases

Therapeutic Uses

• Administer medications

• Deliver anesthesia (spinal anesthesia)

• Measure CSF pressure

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Key Exam Facts

✅ Lumbar puncture collects cerebrospinal fluid (CSF)

✅ CSF is obtained from the subarachnoid space

✅ Procedure is commonly performed between L3-L4 or L4-L5

✅ The spinal cord ends near L1-L2, making lower insertion sites safer

✅ The cauda equina is found below the spinal cord

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Memory Trick "LP = Lower Puncture"

• Lumbar puncture

• Lower back

• L3-L4 or L4-L5

Remember:

Spinal Cord Ends → L1-L2
Lumbar Puncture → L3-L4 or L4-L5
CSF → Subarachnoid Space

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One-Sentence Summary

A lumbar puncture is performed in the lower back (usually between L3-L4 or L4-L5) to access cerebrospinal fluid located in the subarachnoid space surrounding the cauda equina. 🧠💉📚

neurons vs glial cells

neurons = parenchymal cells degenerate (die) as aging

glial = stromal cells may become cancer

four types of neuroglia (glia cells)

To maintain health of nervous system. They don’t transmit impulse, but are classified into stromal cells

1) Astrocytes (astroglial cells): transport water and salts between

capillaries and neurons. Regulate chemical compositions in neurons.

2) Microglia (microglial cells): phagocytic cells protecting neurons from

infections and disposing debris.

3) Oligodendroglia (oligodendroglial cells): produce and form the myelin sheath around nerve fibers.

4) Ependymal cells

a) GK: upper garment

b) Line the membraneswithin the brain and spinal cord where CSF circulates

glioblastoma multiforme (GBM)

Most common and most aggressive malignant primary brain tumor.

• It involves glial cells and accounting for 52% of all brain tissue tumor cases.

• Common symptoms of the disease include seizure, nausea and vomiting, headache, memory loss, and hemiparesis.

• The single most prevalent symptom is a progressive memory, personality, or neurological deficit due to temporal and frontal lobe involvement. The kind of symptoms produced depends highly on the location of the tumor, more so than on its pathological properties.

• About 50% of the people diagnosed with GBM die within one year, while 90% within three years

brain

Definition: Three protective layers (dura mater, arachnoid mater, and pia mater) that surround and protect the brain and spinal cord.

Function: Protect the CNS and contain cerebrospinal fluid (CSF).

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Thalamus

Definition: A relay center located near the middle of the brain.

Function: Receives sensory information (except smell) and sends it to the appropriate areas of the cerebral cortex.

Think: "Sensory relay station."

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Hypothalamus

Definition: A small region located below the thalamus.

Function: Maintains homeostasis by regulating:

• Body temperature

• Hunger

• Thirst

• Sleep

• Emotions

• Hormone production (through the pituitary gland)

Think: "Body's thermostat and control center."

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Pituitary Gland

Definition: Small endocrine gland attached to the hypothalamus.

Function: Produces hormones that regulate:

• Growth

• Metabolism

• Reproduction

• Other endocrine glands

Nickname: "Master gland."

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Frontal Lobe

Definition: Front portion of the cerebrum.

Function:

• Voluntary movement

• Planning and decision-making

• Problem solving

• Personality

• Speech production

Think: "Movement and personality."

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Parietal Lobe

Definition: Upper middle region of the cerebrum.

Function:

• Processes touch, pressure, pain, and temperature

• Interprets sensory information from the body

Think: "Sensory lobe."

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Occipital Lobe

Definition: Rear portion of the cerebrum.

Function:

• Processes visual information

Think: "Vision center."

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Temporal Lobe

Definition: Side portion of the cerebrum near the ears.

Function:

• Hearing

• Smell

• Memory

• Language comprehension

Think: "Hearing and memory."

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Pons

Definition: Part of the brainstem located above the medulla.

Function:

• Relays information between brain regions

• Helps regulate breathing

• Involved in sleep and arousal

Think: "Bridge" between brain areas.

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Cerebellum

Definition: Structure located at the back of the brain beneath the cerebrum.

Function:

• Balance

• Coordination

• Posture

• Fine motor control

Think: "Balance and coordination center."

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Medulla (Medulla Oblongata)

Definition: Lowest portion of the brainstem, connecting the brain to the spinal cord.

Function: Controls vital involuntary functions:

• Heart rate

• Blood pressure

• Breathing

• Swallowing

Think: "Keeps you alive."

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Super Quick Memory Chart

Structure	Main Function
Thalamus	Sensory relay
Hypothalamus	Homeostasis
Pituitary Gland	Hormone control
Frontal Lobe	Movement, personality
Parietal Lobe	Touch and sensation
Temporal Lobe	Hearing and memory
Occipital Lobe	Vision
Cerebellum	Balance and coordination
Pons	Breathing and communication
Medulla	Heart rate and breathing
Meninges	Protect brain and spinal cord

Easy Mnemonic for the Lobes

"F-POT"

• Frontal = Functions (thinking, personality)

• Parietal = Pressure/touch

• Occipital = Optical (vision)

• Temporal = Tunes (hearing) and memory

cerebrum

• sulcus: depression, groove in the surface of the cerebral cortex

• gyrus: sheet of nerve cells producing a rounded fold on the surface of the cerebrym

gyri and sulci lay on cerebral cortex

Main Idea:
The surface of the brain is highly folded. These folds increase the surface area of the cerebral cortex, allowing for more neurons and greater brain function.

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Gyrus (plural: Gyri)

Definition:
A gyrus is a raised ridge or fold on the surface of the brain.

Function:

• Increases the surface area of the cerebral cortex.

• Allows more neurons to fit within the skull.

• Helps improve information processing.

Think: A "hill" or "ridge" on the brain's surface.

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Sulcus (plural: Sulci)

Definition:
A sulcus is a shallow groove or furrow between gyri.

Function:

• Separates adjacent gyri.

• Helps organize different functional regions of the brain.

Think: A "valley" between brain folds.

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Why Are Gyri and Sulci Important?

✅ Increase the surface area of the cerebral cortex

✅ Allow more neurons to fit into the brain

✅ Improve the brain's processing capacity

✅ Help separate different functional brain regions

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Visualizing It

• Gyrus = Raised fold (hill)

• Sulcus = Groove (valley)

In the diagram:

• The rounded raised area is the gyrus.

• The indentation between folds is the sulcus.

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Memory Trick

"Gyrus = Grows Up" ⛰

• Gyri stick up.

"Sulcus = Sink" ⬇

• Sulci go down.

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Exam Tip

Professors often ask:

Q: What is the difference between a gyrus and a sulcus?

A: A gyrus is a raised fold of the cerebral cortex, while a sulcus is a groove or depression between gyri.

One-Sentence Summary

Gyri are the raised folds of the cerebral cortex, and sulci are the grooves between them; together they increase the brain's surface area and allow for greater processing power. 🧠📚

cerebrum

a) Largest section of brain

b) Surface area is called cerebral cortex

c) Manages speech, vision, smell, movement. hearing, and thought

afferent and efferent nerve fibers

Cranial and spinal nerves

a) Sensory nerves (Afferent Nerve Fibers) carry messages

toward the brain

b) Motor nerves (Efferent Nerve Fibers) carry messages

from the brain.

• Sensory receptors in organs and glands

a) Sight

b) Hearing and balance

c) Smell

sensory and motor areas of cerebral cortex

Main Idea:
The cerebral cortex contains specialized areas that control movement (motor cortex) and process sensations (sensory cortex). Different body parts are represented in different regions of these cortices.

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Motor Cortex (Precentral Gyrus) Definition:

The motor cortex is located in the frontal lobe and controls voluntary skeletal muscle movements.

Function:

• Initiates movement

• Sends signals to muscles throughout the body

Important Fact:

• The left motor cortex controls the right side of the body

• The right motor cortex controls the left side of the body

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Somatic Sensory Cortex (Postcentral Gyrus) Definition:

The somatic sensory cortex is located in the parietal lobe and receives sensory information from the body.

Function:

Processes:

• Touch

• Pressure

• Pain

• Temperature

• Vibration

• Body position (proprioception)

Important Fact:

• The left sensory cortex receives information from the right side of the body

• The right sensory cortex receives information from the left side of the body

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Precentral Gyrus Definition:

A gyrus located immediately anterior (in front of) the central sulcus.

Function:

Contains the primary motor cortex.

Think: Pre = Before the central sulcus = Movement

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Postcentral Gyrus Definition:

A gyrus located immediately posterior (behind) the central sulcus.

Function:

Contains the primary somatic sensory cortex.

Think: Post = After the central sulcus = Sensation

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Cortical Homunculus Definition:

A map showing how different body parts are represented in the motor and sensory cortices.

Key Concept:

The amount of cortex devoted to a body part depends on:

• Fine motor control (motor cortex)

• Sensory sensitivity (sensory cortex)

---

Why Are the Hands and Face So Large?

The hands, lips, tongue, and face take up a large area because they:

• Require precise movements

• Have many sensory receptors

• Need greater cortical processing

Not because they are physically larger.

---

Body Arrangement on the Cortex Top of Cortex

• Toes

• Feet

• Legs

Middle

• Trunk

• Arms

• Hands

Lower Side

• Face

• Lips

• Tongue

---

High-Yield Exam Facts

✅ Motor cortex = Precentral gyrus

✅ Sensory cortex = Postcentral gyrus

✅ Motor cortex is in the frontal lobe

✅ Sensory cortex is in the parietal lobe

✅ Left hemisphere controls/receives input from the right side of the body

✅ Hands and face occupy large cortical areas

---

Memory Tricks

Motor = Move

• Precentral gyrus = Motor cortex

Sensory = Sense

• Postcentral gyrus = Sensory cortex

"PRE moves, POST feels."

---

One-Sentence Summary

The precentral gyrus contains the primary motor cortex responsible for voluntary movement, while the postcentral gyrus contains the primary somatic sensory cortex responsible for processing touch, pain, temperature, and other sensations from the body. 🧠📚

spinal cord (afferent and efferent nerves)

Gray matter: nerve cell bodies

White matter: Axons covered with myelin sheets

Main Idea:
Sensory information travels into the spinal cord through the dorsal root, while motor commands travel out of the spinal cord through the ventral root.

---

Dorsal Root (Sensory Root) Definition:

The dorsal root is the posterior (back) root of a spinal nerve that carries sensory (afferent) information into the spinal cord.

Function:

• Brings sensory signals from the skin, muscles, and organs to the CNS.

• Carries sensations such as:

  • Touch

  • Pain

  • Temperature

  • Pressure

Remember:
Dorsal = Sensory = Afferent

---

Dorsal Root Ganglion Definition:

A cluster of sensory neuron cell bodies located on the dorsal root.

Function:

• Houses the cell bodies of sensory neurons before they enter the spinal cord.

Exam Tip:
The dorsal root ganglion contains sensory neuron cell bodies.

---

Afferent Neuron (Sensory Neuron) Definition:

A neuron that carries information toward the CNS.

Function:

• Transmits sensory information from receptors to the brain and spinal cord.

Pathway:

Receptor → Afferent Neuron → Dorsal Root → Spinal Cord

Memory Trick:
Afferent = Arrives at the CNS

---

Ventral Root (Motor Root) Definition:

The anterior (front) root of a spinal nerve that carries motor (efferent) signals out of the spinal cord.

Function:

• Sends commands from the CNS to muscles and glands.

Remember:
Ventral = Motor = Efferent

---

Efferent Neuron (Motor Neuron) Definition:

A neuron that carries information away from the CNS.

Function:

• Sends motor commands to skeletal muscles.

• Produces movement.

Pathway:

Spinal Cord → Efferent Neuron → Muscle

Memory Trick:
Efferent = Exits the CNS

---

Gray Matter Definition:

The inner butterfly-shaped region of the spinal cord.

Function:

• Contains neuron cell bodies.

• Site where information is processed.

---

White Matter Definition:

The outer region of the spinal cord.

Function:

• Contains myelinated axons.

• Carries information up and down the spinal cord.

---

Central Canal Definition:

A small canal running through the center of the spinal cord.

Function:

• Contains cerebrospinal fluid (CSF).

---

High-Yield Exam Facts

✅ Dorsal root = sensory (afferent)

✅ Ventral root = motor (efferent)

✅ Dorsal root ganglion contains sensory neuron cell bodies

✅ Afferent neurons carry information TO the CNS

✅ Efferent neurons carry information AWAY from the CNS

---

Memory Trick

SAME DAVE

• Sensory = Afferent

• Motor = Efferent

Dorsal = Afferent
Ventral = Efferent

---

One-Sentence Summary

Sensory (afferent) neurons enter the spinal cord through the dorsal root and dorsal root ganglion, while motor (efferent) neurons exit the spinal cord through the ventral root to control muscles. 🧠➡💪

brain

Cerebellum (“little brain”)

a) Coordinates voluntary movements

b) Maintains balance coordination

Thalamus (Gk: chamber)

1) Relaying & processing sensory signals prior to sending them to cerebral cortex.

2) Regulation of alertness & consciousness.

hypothalamus

Controls body temperature, sleep, appetite, sexual

desire, and emotions

•Supervises the release of hormones from pituitary

gland.

•Integrates activities of sympathetic and

parasympathetic nervous systems

brain stem pons

Bridges cerebrum with cerebellum and medulla

•Passes on pulses from cerebellum and houses

nerves for face and eyes, including hearing, tasting,

eye movement, facial expression, chewing, swallowing and secretion of saliva.

•Lower part interacts with

Cranial nerve

cranial nerves are autonomic nerve system

Main Idea:
There are 12 pairs of cranial nerves that arise directly from the brain and brainstem. They control sensory functions, motor functions, or both in the head, neck, and some internal organs.

---

I. Olfactory Nerve

Function: Smell

Memory Aid: "Olfaction = Odor"

---

II. Optic Nerve

Function: Vision

Word Parts:

• Opt/o = eye, vision

• Optic/o = eye, sight

---

III. Oculomotor Nerve

Function: Most eye movements and pupil constriction

Word Part:

• Ocul/o = eye

---

IV. Trochlear Nerve

Function: Eye movement

Memory Aid: "Trochlea" means pulley, referring to how the eye muscle moves.

---

V. Trigeminal Nerve

Function:

• Facial sensation

• Chewing

Memory Aid: "Tri" = three branches

Three Branches:

1. Ophthalmic

2. Maxillary

3. Mandibular

Think: "Born in threes"

---

VI. Abducens Nerve

Function: Moves the eye laterally (away from the nose)

Memory Aid: "Abduct = move away"

---

VII. Facial Nerve

Function:

• Facial expressions

• Taste (anterior tongue)

• Some ear sensation

Think: "Makes the face move"

---

VIII. Vestibulocochlear Nerve

Function:

• Hearing

• Balance

Memory Aid:

• Vestibule = balance

• Cochlea = hearing ("snail shell")

---

IX. Glossopharyngeal Nerve

Function:

• Taste

• Tongue sensation

• Swallowing

• Throat sensation

Word Parts:

• Gloss/o = tongue

• Pharyng/o = throat

---

X. Vagus Nerve

Function:

• Controls many autonomic functions

• Heart rate

• Blood pressure

• Digestion

• Breathing support

Memory Aid:
Vagus means "wandering nerve" because it travels throughout the body.

Very Important Exam Fact: The vagus nerve is the major nerve of the parasympathetic nervous system.

---

XI. Accessory Nerve

Function:

• Head movement

• Shoulder shrugging

• Neck muscles

---

XII. Hypoglossal Nerve

Function:

• Tongue movement

• Speech

• Swallowing

Word Part:

• Hypo = under

• Glossal = tongue

---

Brainstem Cranial Nerves

Many cranial nerves emerge from the:

• Pons

• Medulla Oblongata

---

Cranial Nerves in Order

Number	Name	Function
I	Olfactory	Smell
II	Optic	Vision
III	Oculomotor	Eye movement
IV	Trochlear	Eye movement
V	Trigeminal	Facial sensation, chewing
VI	Abducens	Eye movement
VII	Facial	Facial expression, taste
VIII	Vestibulocochlear	Hearing, balance
IX	Glossopharyngeal	Taste, swallowing
X	Vagus	Parasympathetic control
XI	Accessory	Head and shoulder movement
XII	Hypoglossal	Tongue movement

---

Easy Mnemonic (Names)

"Oh, Oh, Oh, To Touch And Feel Very Good Velvet, AH!"

1. Olfactory

2. Optic

3. Oculomotor

4. Trochlear

5. Trigeminal

6. Abducens

7. Facial

8. Vestibulocochlear

9. Glossopharyngeal

10. Vagus

11. Accessory

12. Hypoglossal

One-Sentence Summary

The 12 cranial nerves arise from the brain and brainstem and control smell, vision, eye movements, facial sensation and expression, hearing, balance, swallowing, autonomic functions, and tongue movement. 🧠📚

brainstem: medulla oblongata

“Long marrow”

•Below pons

•Connects spinal cord to brain

•Nerve tracts crossover

•Regulates:

a) Blood vessels (vasomotor sensor)

b) Heart rates

c) Respiratory system

spina bifida

• birth defect where there is incomplete closing of the backbone (vertebrae) and membranes around the spinal cord

• is believed to be due to a combo of genetic and environmental factors. not having enough folate in the diet during pregnancy also plays a significant role. mole cases can be prevented if the mother gets enough folate

  before and during pregnancy. Other risk factors include certain antiseizure

  medications, obesity, and poorly controlled diabetes.

  • Diagnosis may occur either before or after a child is born. Before birth if a blood

  test or amniocentesis finds a high level of alpha-fetoprotein (AFP) there is a

  higher chance of spina bifida. Ultrasound examination may also detect the

  problem.

  • There are three main types: spina bifida occulta, meningocele, and

  myelomeningocele..

  1) Occulta has no or only mild signs. Signs of occulta may include a hairy

  patch, dimple, dark spot, or swelling on the back at the site of the gap in the

  spine.

  2) Cystica with Meningocele typically causes mild problems with a sac of fluid

  present at the gap in the spine.

  3) Cystica with myelomeningocele, also known as open spina bifida, is the

  most severe form. Associated problems include poor ability to walk,

  problems with bladder or bowel control, hydrocephalus, and latex allergy.

amniocentesis

Definition:
Amniocentesis is a prenatal diagnostic procedure in which a needle is inserted through the mother's abdomen into the uterus to withdraw a sample of amniotic fluid surrounding the fetus.

---

When is it Performed?

• Usually between 14-16 weeks of pregnancy (as shown in the diagram).

• Used when there is concern about possible genetic or developmental abnormalities.

---

What is Collected? Amniotic Fluid

• Fluid that surrounds and protects the fetus.

• Contains fetal cells and chemicals produced by the fetus.

---

What Happens to the Sample? 1. Fluid Analysis

The amniotic fluid is tested for substances such as:

Alpha-Fetoprotein (AFP)

Definition: A protein produced by the fetus.

Purpose: Used to screen for certain developmental abnormalities, especially neural tube defects.

---

2. Fetal Cell Analysis

Fetal cells in the fluid are separated and grown in culture.

Karyotyping

Definition: The examination of chromosomes to determine their number and structure.

Purpose: Detects chromosomal abnormalities such as:

• Down syndrome (Trisomy 21)

• Trisomy 18

• Other chromosomal disorders

---

Structures in the Diagram Placenta

• Organ that provides nutrients and oxygen to the fetus.

Fetus

• Developing baby.

Uterus (Womb)

• Muscular organ where the fetus develops.

Cervix

• Lower opening of the uterus leading to the vagina.

Amniotic Fluid

• Protective fluid surrounding the fetus.

---

Why is Amniocentesis Performed?

✅ Detect genetic disorders

✅ Detect chromosomal abnormalities

✅ Evaluate fetal development

✅ Measure AFP levels

✅ Obtain fetal cells for chromosome analysis

---

High-Yield Exam Facts

✅ Amniocentesis = removal of amniotic fluid

✅ Performed around 14-16 weeks

✅ AFP is measured from amniotic fluid

✅ Fetal cells can be used for karyotyping

✅ Karyotyping examines chromosomes

---

Memory Trick

Amnio = Amniotic Fluid

AFP = Alpha-Fetoprotein

Karyotype = Chromosome Picture

---

One-Sentence Summary

Amniocentesis is a prenatal test performed around 14-16 weeks of pregnancy in which amniotic fluid containing fetal cells is collected to measure AFP levels and perform karyotyping for the detection of genetic and chromosomal abnormalities. 👶🧬📚

hydrocephalus

water on the brain

ventriculoperitoneal shunt placement

Definition:
A ventriculoperitoneal (VP) shunt is a surgically implanted tube that drains excess cerebrospinal fluid (CSF) from the brain's ventricles into the abdominal (peritoneal) cavity, where the fluid can be absorbed.

---

Why is a VP Shunt Needed? Hydrocephalus

Definition: A condition in which excess CSF accumulates in the ventricles of the brain.

Effects:

• Enlarged ventricles

• Increased intracranial pressure

• Brain tissue compression

Nickname: "Water on the brain"

---

Parts of the VP Shunt Ventricular Catheter

• Inserted into a ventricle of the brain.

• Collects excess CSF.

Valve

• Located behind the ear.

• Controls the rate of CSF drainage.

• Prevents too much fluid from being removed.

Shunt Tubing

• Runs underneath the skin from the head to the abdomen.

• Carries CSF away from the brain.

Peritoneal Cavity

• Space within the abdomen.

• Absorbs the drained CSF into the body.

---

How It Works

1. Excess CSF builds up in the ventricles.

2. The shunt catheter collects the CSF.

3. Fluid passes through the valve.

4. Tubing carries the fluid under the skin.

5. CSF drains into the peritoneal cavity.

6. The body absorbs the excess fluid.

---

Structures Shown in the Diagram Enlarged Left Ventricle

• Indicates excess CSF accumulation.

Cranium Entry Site

• Point where the shunt enters the skull.

Valve (Behind Ear)

• Regulates CSF flow.

Tubing Under Skin

• Connects the brain to the abdomen.

Peritoneal Cavity

• Final drainage site for the fluid.

---

High-Yield Exam Facts

✅ VP = Ventriculoperitoneal

✅ Used to treat hydrocephalus

✅ Drains CSF from the ventricles

✅ Fluid is transported to the peritoneal cavity

✅ Valve controls drainage rate

---

Memory Trick

VP Shunt

• V = Ventricle (where fluid comes from)

• P = Peritoneal cavity (where fluid goes)

Brain ➜ Tube ➜ Abdomen

---

One-Sentence Summary

A ventriculoperitoneal (VP) shunt is a device used to treat hydrocephalus by draining excess cerebrospinal fluid from the brain's ventricles to the peritoneal cavity, where it can be safely absorbed. 🧠➡🩺➡🫃📚

hydrocephalyus

• meaning "water", and

  kephalos, meaning "head") is a medical condition in which

  there is an abnormal accumulation of cerebrospinal fluid

  (CSF) in the brain.

  • This causes increased intracranial pressure inside the

  skull and may cause progressive enlargement of the head

  if it occurs in childhood, potentially causing convulsion,

  tunnel vision, and mental disability. It was once informally

  called “water on the brain”.

  • Hydrocephalus can be caused by congenital or acquired

  factors. Congenital causes include Spina Bifida, Arnold–

  Chiari malformation, craniosynostosis, Dandy–Walker

  syndrome, and Vein of Galen malformations.

  • Acquired causes include hemorrhage, meningitis, head

  trauma, tumors, and cysts.

Alzheimer Disease (AD)

• Accounts for 60% to 70% of cases of dementia (mental inability).

  • It is a chronic neurodegenerative disease that usually starts slowly

  and gets worse over time. The disease process is associated with

  plaques and tangles in the brain, as well as loss of neurons and

  synapses in cerebral cortex . Examination of brain tissue is

  needed for a definite diagnosis.

  • The most common early symptom is difficulty in remembering

  recent events (short-term memory loss). As the disease advances,

  symptoms can include problems with language, disorientation

  (including easily getting lost), mood swings, loss of motivation, not

  managing self care, and behavioral issues. Gradually, bodily

  functions are lost, ultimately leading to death. The average life

  expectancy following diagnosis is three to nine years.

  • The cause of Alzheimer's disease is poorly understood. About

  70% of the risk is believed to be genetic with many genes usually

  involved. Mental and physical exercise, and avoiding obesity may

  decrease the risk, There are no medications or supplements that

  decrease risk. 26.6 million people worldwide had Alzheimer's in

  2006; this number may quadruple by 2050. It is becoming one of

  the most financially costly disease.

amyotrophic lateral sclerosis (ALS)

• also known as Lou Gehrig's disease

  •no + muscle+ nourishment, indicating muscle

  wasting from degeneration of motor neurons.

  •It involves the death of neurons, characterized by

  stiff muscles, muscle twitching, and gradually

  worsening weakness due to muscle wasting. This

  results in difficulty speaking, swallowing, and

  eventually breathing (causing death). The average

  survival from onset to death is three to four years

  •The cause is not known. About 5–10% of cases

  are inherited. About half of these genetic cases

  are due to one of two specific genes.

epilepsy

• greek for "to seize, possess, or afflict“.

  Symptoms include unconscious and uncontrolled

  movement.

  B. Patients suffer from chronic recurrent seizures.

  Epileptic seizures are the result of excessive and

  abnormal cortical nerve cell activity in the brain.

  Seizures are episodes that can vary from brief and

  nearly undetectable to long periods of vigorous

  shaking.

  C. 65 million individuals affected (1 % people worldwide).

  a) Younger patients: genetic, congenital, and

  developmental conditions

  b) Over 40: tumors are more likely.

  c) At any age, some people develop epilepsy as the

  result of brain injury, stroke, brain tumor, and

huntington disease

• can be passed on to children in family. A child of an

  affected parent typically has a 50% chance of inheriting the disease

  (dominant autosomal inheritance).

   Huntington's disease is an incurable neurodegenerative genetic disorder

  that affects muscle coordination and leads to mental decline (dementia),

  behavioral symptoms, uncontrollable movements of arms, legs, and

  face.

   Complications include pneumonia, and heart disease. Life expectancy to

  around twenty years from the point at which symptoms begin

parkinson disease

a disorder of the central nervous

system that results from the loss of cells in a basal ganglia

that normally produce dopamine, a chemical messenger

responsible for transmitting signals within the brain and allows

for coordination of movement.

2) Loss of dopamine causes neurons to fire without normal

control, leaving patients less able to direct or control their

movement. Common symptoms include cognitive impairment,

muscle rigidity, tremors, shuffling gait, changes in speech,

mild memory loss, dementia, mood disorders, depression,

anxiety, sleep difficulties, loss of sense of smell, constipation,

speech and swallowing problems, unexplained pains, and

drooling.

3) The exact cause of Parkinson's disease is unknown, although

research points to a combination of genetic and environmental

tourette’s syndrome

Associated with excessive dopamine,

Tourette’s syndrome is an inherited

neuropsychiatric disorder, with onset

in childhood, characterized by multiple

physical (motor) tics including

provisional, transient and persistent

(chronic).

• Common tics of eye blinking, coughing,

throat clearing, sniffing, and facial

movements. Extreme Tourette's in

adulthood is a rarity, and Tourette's

does not adversely affect intelligence or

life expectancy.

• Genetic and environmental factors play

a role in the etiology of Tourette's, but

the exact causes are unknown.

bell palsy

Nerve that controls muscles on one side of the face is

damaged by inflammation.

2) The cause of Bell palsy is not clear. Most cases are thought

to be caused by the herpes virus .

3) The nerve damage may also affect the sense of taste and

the way tears and saliva are made. This condition comes on

suddenly, often overnight, and usually self-resolve on its

own within a few months

traumatic disorders

• Cerebral concussion (“shake together”):

  • Temporary brain dysfunction after injury

  There may be no evidence of structural damage

  to brain tissue or loss of consciousness

  Rest is very important to allow the brain to heal

  • Usually clears within 24 hours

  • Cerebral contusion (“break into pieces”):

  • Bruising of brain tissue through direct trauma to

  head.

  • Usually associated with skull fracture as well as

  edema and an increase in intracranial pressure.

  • Neurological deficits persist longer than 24 hours

cerebrovascular accident (CVA) commonly called:

• stroke

• is a disruption of normal

  blood supply to brain.

  Hemorrhagic — A blood vessel, such as the cerebral artery, breaks

  and bleeding occurs

  Embolic — A dislodged clot that travels to the cerebral arteries.

  Thrombotic — A blood clot in an artery heading to the brain

cerebral angiography

X-ray Tests

Cerebral angiography.

a) Provides images of blood vessels

and detects abnormalities such as

arteriovenous malformations and

aneurysms.

b) a contrast dye is delivered to carotid

artery. A series of radiographs are

taken as the contrast agent spreads

through the brain's arterial system,

then a second series as it reaches the

venous system.

c) This method may yield better images

than non-invasive methods such as

computed tomography angiography

and magnetic resonance angiography

computed tomography (CT)

X-ray Tests

• Cerebral angiography

• Computed tomography (CT) of

the brain. It is also called CT

scan.

a) Uses a series of x-rays of the

head taken from many different

directions.

b) It quickly evaluates swelling,

injuries, bleeding, and in

assessment of ventricle size

c) It uses a computer program

that performs a integral

calculation on the measured x-

ray series to estimate how

much of an x-ray beam is

absorbed in brain.

myelography

a) A type of radiographic examination

that uses a contrast medium to detect

pathology of the spinal cord,

including the location of a spinal cord

injury, cysts, and tumors.

b) The procedure often involves

injection of contrast dye into the

cervical or lumbar spine, followed by

several X-ray projections.

c) A myelogram may help to find the

cause of pain not found by an MRI or

CT.

MRI—Magnetic resonance Imaging

a) Magnetic resonance imaging (MRI) is

a noninvasive medical test that

physicians use to diagnose medical

conditions.

b) MRI uses a powerful magnetic field,

radio frequency pulses and a

computer to produce detailed

pictures of organs, soft tissues, bone

and virtually all other internal body

structures.

c) MRI can show tissue damage or

disease, such as infection or

inflammation, a tumor, stroke or seizure

PET - positron emission scan

Post seizure

1) Red/yellow = more activity

2) Green/blue = less activity

Use biologically active molecule (like

glucose analog) to produce 3-

dimensional image reflecting the

functional processes (activities) of brain

tissues.

EEG-Electroencephalography

most often used to

diagnose epilepsy. It records

electrical activity/waves of the

brain and detect seizure.

• For detecting sleep disorders,

coma, encephalopathies, brain

death, tumors, stroke and other

focal brain disorders.

acetylecholine

Neurotransmitter chemical released at ends

of nerve cells

afferent nerve

Carries messages toward the brain and

spinal cord

arachnoid membrane

Middle layer of the three membranes that

surround the brain and spinal cord

astrocyte

Glial cell that transports water and

salts from capillaries

autonomic nervous

system

Nerves that control involuntary body

functions of muscles, glands, and

internal organs

axon

Microscopic fiber that carries the

nervous impulse along a nerve cell

blood-brain barrier

Protective separation between the

blood and brain cells that keeps

substances (such as anticancer drugs)

from penetrating capillary walls and

entering the brain

brainstem

Posterior portion of the brain that

connects the cerebrum with the spinal

cord

cauda equina

collection of spinal nerves below the

end of the spinal cord

cell body

the part of a nerve cell that contains the

nucleus

central nervous

system (CNS)

the brain and spinal cord

cerebellum

the posterior part of the brain that

coordinates muscle movements and

maintains balance

cerebral cortex

Outer region of the cerebrum; contains

sheets of nerve cells; gray matter

cerebrospinal fluid

Circulates throughout the brain and spinal

cord

cerebrum

the largest part of the brain; responsible for

voluntary muscle activity, vision, speech,

taste, hearing, thought, and memory

cranial nerves

Twelve pairs; carry messages to and from

the brain with regard to the head and neck

(except the vagus nerve)

dendrite

Microscopic branching fiber of a nerve

cell; the first part to receive the nervous

impulse

dura mater

The thick, outermost layer of the

meninges surrounding and protecting the

brain and spinal cord

efferent nerve

Carries messages away from the brain

and spinal cord; motor nerve

ependymal cell

glial cell that lines the membranes within

the brain and spinal cord; helps form

cerebrospinal fluid

ganglion (plural:

ganglia)

Collection of nerve cell bodies in the

peripheral nervous system

glial cell (neuroglial

cell)

Supportive and connective nerve cell that

does not carry nervous impulses; can

reproduce itself

gyrus (plural: gyri

Sheet of nerve cells that produces a

rounded ridge on the surface of the

cerebral cortex; convolution

hypothalamus

The portion of the brain beneath the

thalamus; controls sleep, appetite, body

temperature, and pituitary gland secretions

medulla oblongata

the part of the brain just above the

spinal cord; controls breathing,

heartbeat, and size of blood vessels

meninges

Three protective membranes that

surround the brain and spinal cor

microglial cell

Phagocytic glial cell that removes waste

products from the central nervous

system

motor nerve

Carries messages away from the brain and

spinal cord to muscles and organs; efferent

nerve

myelin sheath

Covering of white fatty tissue that surrounds

and insulates the axon of a nerve cell;

speeds impulse conduction

nerve

Macroscopic cord-like collection of fibers

(axons and dendrites) that carry electrical

impulses

neuron

Nerve cell that carries impulses

throughout body; parenchyma of the

nervous system

neurotransmitter

Chemical messenger released at the

end of a nerve cell; stimulates or

inhibits another cell

oligodendroglial cell

Glial cell that forms the myelin sheath

covering axons

parasympathetic

nerves

Involuntary, autonomic nerves that

regulate normal body functions such as

heart rate, breathing, and muscles of the

gastrointestinal tract

parenchyma

Essential, distinguishing tissue of any

organ or system; for the nervous system,

neurons and nerves that carry impulses

peripheral nervous

system

Nerves outside the brain and spinal cord;

cranial, spinal, and autonomic nerves

pia mater

The thin, delicate inner membrane of the

meninges

plexus (plural:

plexuses)

A large, interlacing network of nerves

pons

The part of the brain anterior to the

cerebellum and between the medulla and

the rest of the midbrain

receptor

An organ that receives a nervous stimulus

and passes it on to afferent nerves; the

skin, ears, eyes, and taste buds are

receptors

sciatic nerve

The nerve extending from the base of the

spine down the thigh, lower leg, and foot

sensory nerve

Carries messages toward the brain and

spinal cord from receptor; afferent nerve

spinal nerves

Thirty-one pairs arising from the spinal

cord