Exam 3 - Brain, Cranial Nerves, Nervous System, Spinal Nerves

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Cerebrum

Cerebrum

2 Hemispheres, 4 Lobes Each Side

Frontal, Parietal, Temporal, Occipital

Gyri

Wrinkles of the Brain

Sulci

Valleys of the Brain between Gyri

Fissures

Deeper Valleys of the Brain Separating Lobes

Telencephalon

The Cerebrum of the Brain

Tel, Di, Mes, Met, My

Diencephalon

Thalamus, Hypothalamus, Epithalamus

Middle Most Vesicle of the Brain

Tel, Di, Mes, Met, My

Mesencephalon

Midbrain

Directly Below the Diencephalon

Tel, Di, Mes, Met, My

Metencephalon

Pons and Cerebellum

Below Mesencephalon, Above Myelencephalon

Tel, Di, Mes, Met, My

Myelencephalon

Medulla Oblongata - CARDIAC, VASOMOTOR, RESPIRATORY, and REFLEXES

Bottom Most Vesicle of the Brain, Above Brain Stem

Tel, Di, Mes, Met, My

Gray Matter

Neuron Cell Bodies, Dendrites and UNMYELINATED Axons

White Matter

MYELINATED AXONS

Cranial Meninges

3 Connective Tissue Layers Covering Skull

Composed of the Dura, Arachnoid and Dura Mater

Dura Mater

Tough, Outer Membrane (Superficial C. Meninges)

Composed of the Meningeal and Periosteal Layers

Arachnoid Mater

Middle Web-like Fibers (Middle C. Meninges)

Pia Mater

Layer Clinging to Brain (Deep C. Meninges)

Lateral Ventricles

Sheep-Horn Ventricles

Connected to 3rd via Interventricular Foramen

3rd Ventricle

Connect to 4th Ventricle via Cerebral Aqueduct

4th Ventricle

Connected to Central Canal + Subarachnoid Space

Cerebrospinal Fluid (CSF)

Fills Ventricles in Brain

‘Reduces’ Brain’s Weight, Liquid Cushion

Transport Nutrients, Shield from Chemical Fluctuations

Choroid Plexus

Creates CSF, Made by Ependymal Cells Located in Pia Mater

CSF Circulation

Continuously Formed and Reabsorbed

(Flows from Arachnoid Villi into Dural Venous Sinuses)

Hydrocephalus

Excessive CSF Condition, Megamind

Blood-Brain Barrier (BBB)

Regulates what Substances Enter the Brain’s Interstitial Fluid

Helps Prevent Neurons to Toxic Substances

Cerebrum

Origin of all Complex Intellectual Function

• Intelligence / Reasoning

• Thought, Memory, Judgement

• VOLUNTARY Motor, Visual and Auditory

Corpus Callosum

White Matter Tract Connecting Left + Right Hemispheres

Longitudinal Fissure

Deep Sulcus Separating Left and Right Hemispheres

Frontal Lobe

PRECENTRAL GYRUS - VOLUNTARY MOVEMENT

Concentration, Communication, Personality etc…

Parietal Lobe

POSTCENTRAL GYRUS - SENSORY FUNCTIONS

Temporal Lobe

Hearing and Smell

Occipital Lobe

Vision / Visual Memory

Insular Lobe

Memory and Taste

Primary (Somatic / Voluntary) Motor Cortex

Motor Homunculus, Controls Skeletal Muscle Activity on Opposite Side of Body

Broca and Wernicke Area

Controls Speech and Language Comprehension Respectively

Premotor Cortex (Somatic / Voluntary Motor Association)

Coordinated Learned Activities (Muscle Memory)

Primary Somatosensory Cortex

Receives Somatic Sensory Information (Touch / Feel)

Sensory Homunculus, Posterior to Motor Cortex

Homunculus

Larger Gyri Provide for More Detailed Movement

Association Tracts

Relay Impulses to Same Hemisphere

Commissural Tracts

Relay Impulses to Opposite Hemisphere

BLUE

Projection Tracts

Link Cerebral Cortex to Inferior Brain + Spinal Cord

GREEN

Right Hemisphere

The Emotional and Creative Brain

Left Hemisphere

The Logistical and Analytical Brain

Cerebral (Basal) Nuclei

Deep Gray Matter in Cerebrum that Regulate Motor Output

Pineal Gland

Secretes Melatonin

Regulates Day-Night Cycles

Helps Circadian Rhythm

Infundibulum

Stalk of the Pituitary Gland

The Midbrain

Holds…

• CN III (Oculomotor)

• CN IV (Trochlear)

• Cerebral Peduncles

• Cerebral Aqueduct

• Tectum

  • Superior Colliculi

  • Inferior Colliculi

The Brainstem

Holds…

• Midbrain

• Pons

• Medulla Oblongata

The Pons

Does…

• Sensory + Motor Tracts

• Respiratory Center (RR)

• Cranial Nerve Nuclei

  • CN V (Trigeminal)

  • CN VIII (Vestibulocochlear)

Medulla Oblongata

Does…

• Cardiac Center (HR)

• Vasomotor Center

• Medullary Respiratory Center

• Nuclei for CNs IX - XII

Cerebellum

Continuously Receives Motor Plans + Sensory Feedback

• Left and Right Hemispheres

• Middle Separation - Vermis

• Cerebellar Cortex - Outer Gray Matter

• Arbor Vitae - Internal White Matter

The Limbic System

Controls Emotions (Just Know This)

Olfactory Nerve

CN I - Sense of Smell

1/3 Sensory Nerves

On Old Olympus Towering Tops A Finn Vs German Viewed A Hat

Optic Nerve

CN II - Sense of Vision

1/3 Sensory Nerves

On Old Olympus Towering Tops A Finn Vs German Viewed A Hat

Oculomotor Nerve

CN III - Controls Most Eye Movement, Eyelids, and Pupil Diameter (Light Sensors)

1/5 Motor Nerves

On Old Olympus Towering Tops A Finn Vs German Viewed A Hat

Trochlear Nerve

CN IV - Controls Superior Oblique Eye Muscles

1/5 Motor Nerves

On Old Olympus Towering Tops A Finn Vs German Viewed A Hat

Trigeminal Nerve

CN V - Somatic Sensation from Face + Chewing

1/4 Motor + Sensory Nerves

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Abducens Nerve

CN VI - Controls Lateral Eye Movement Only

1/5 Motor Nerves

On Old Olympus Towering Tops A Finn Vs German Viewed A Hat

Facial Nerve

CN VII - Controls Face Muscles, Provides Signals for Taste

1/4 Motor + Sensory Nerves

On Old Olympus Towering Tops A Finn Vs German Viewed A Hat

Vestibulocochlear Nerve

CN VIII - Senses Hearing, Balance and Equilibrium

1/3 Sensory Nerves

On Old Olympus Towering Tops A Finn Vs German Viewed A Hat

Glossopharyngeal Nerve

Cn IX - Taste and Touch from Tongue, Controls Swallowing, Controls Big Salivary Gland

1/4 Motor + Sensory Nerves

On Old Olympus Towering Tops A Finn Vs German Viewed A Hat

Vagus Nerve

CN X - Visceral (Autonomic) Sensation, Parasympathetic Nerve to Many Body Organs

1/4 Motor + Sensory Nerves

On Old Olympus Towering Tops A Finn Vs German Viewed A Hat

Accessory Nerve

CN XI - Controls Neck Muscles, Pharynx

1/5 Motor Nerves

On Old Olympus Towering Tops A Finn Vs German Viewed A Hat

Hypoglossal Nerve

CN XII - Controls Tongue Muscles

1/5 Motor Nerves

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Cervical Enlargement

Controls Nerves to Upper Limbs

Lumbar Enlargement

Contains Nerves to Lower Limbs

Spinal Nerves

31 Pairs of Spinal Nerves

• 8 Cervical

• 12 Thoracic

• 5 Lumbar

• 5 Sacral

• 1 Coccygeal (Coccyx / Tailbone)

Spinal Cord Meninges

• Pia Mater - Inner Most, Sticks to Spinal Cord

• Arachnoid Mater - Middle, Web-Like Layer

• Dura Mater - Outer Most, Tough Layer

Gray Matter in Spinal Cord

Anterior Horns - Bottom Bump

Lateral Horns - Side Bump

Posterior Horns - Top Bump

Sensory Nuclei

Located in the Posterior Horn

• Somatic Sensory - Receive Signals from Skin, Muscles, Joints

• Visceral Sensory - Receive Signals from Blood Vessels / Visceral Organs

Motor Nuclei

Located in Anterior and Lateral Horns

• Somatic Motor - ANTERIOR HORNS - Skeletal Muscle

• Autonomic Motor - LATERAL HORNS - Smooth / Cardiac Muscle

Spinal Cord White Matter

Funiculus = WHITE MATTER

• (4) Anterior Funiculus - Sensory + Motor Tracts

• (5) Lateral Funiculus - Sensory + Motor Tracts

• (6) Posterior Funiculus - Sensory Tracts called Fasciculi

Sensory Pathways

Ascend to the Brain

Motor Pathways

Descend from the Brain

• Controls Skeletal Muscles

• Includes 2 Neurons

  • Upper Motor - Contacts Lower Motor Neuron

  • Lower Motor - Located in Cranial Nerve Nucleus or Anterior Horn of Spinal Cord

Sensory Pathway to Brain

• PRIMARY - Cell Body in Posterior Root

• SECONDARY - Is an Interneuron to Thalamus
  TERTIARY - 3rd Order - Is an Interneuron to 1st Degree Sensory Cortex

Nerve Plexus

Network of Interweaving Anterior Rami

• 4 Main Plexuses Occurring Bilaterally

  • Cervical, Brachial, Lumbar, Sacral

Spinal Nerves Split

(DORSAL ROOT) Posterior Ramus - Controls Muscles and Skin of Back - BACK ROOT

(VENTRAL ROOT) Anterior Ramus - Forms Nerve Plexuses - FRONT ROOT

Rami Communicants - Small Branches of Autonomic Fibers

Reflex Arc

1. Stimulus

2. Afferent Pathway

3. Control Center

4. Efferent Pathway

5. Response

Classification of Spinal Reflexes

Is the Spinal Cord / Cranial the Control Center…

Somatic - Skeletal Muscle is the Effector

Visceral - Cardiac / Smooth Muscle is the Effector

• honestly i really dont fucking know

Monosynaptic Reflex - Stretch Reflex

Reflexive Contraction of a Muscle After it is Stretched

Polysynaptic Reflexes - Withdrawal Reflexes

Stimulus —> Nociceptor Sensory Neuron —> Spinal Cord —> Excites Interneurons

Interneurons —> Motor Neurons = Contraction on Muscles

Hypothalamus

Controls the ANS

Somatic Nervous System

• 1 Neuron Extends From CNS to Skeletal Muscles

  • Cell Bodies Located in Brainstem or Spinal Cord

  • Release ACh

Autonomic Nervous System

• Visceral Motor System

• Maintain Homeostasis

• Preganglionic and Postganglionic Neurons

Sympathetic NS - Part of ANS

Fight-or-Flight

Preganglionic Axons are Short

Postganglionic Axons are Long

Mass Activation of Activity

Parasympathetic NS - Part of ANS

Rest-and-Digest

The 3 D’s : Digestion, Defecation and Diuresis (Digest, Shit and Piss)

Preganglionic Axons are Long

Postganglionic Axons are Short

Localized Activity

Cranial Nerves of Parasympathetic NS

CN III - Oculomotor

CN VII - Facial (Glands in Face)

CN IX - Glossopharyngeal (Big Salivary Gland in Mouth)

CN X - Vagus (All Internal Organs)

Pelvic Splanchnic Nerves

Communicating Rami

• White Rami - Myelinated, PREGANGLIONIC Axons From T1 Vertebrae - L2 Vertebrae

• Gray Rami - Unmyelinated, POSTGANGLIONIC Axons From Trunk to all Spinal Nerves

Preganglionic Sympathetic

1. Short - Myelinated

2. ACh

3. Nicotinic Receptors

4. Sympathetic Chain Ganglia

Preganglionic Parasympathetic

1. Long - Myelinated

2. ACh

3. Nicotinic Receptors

4. Terminal Ganglia, Intramural Ganglia

Postganglionic Sympathetic

1. Long

2. Norepinephrine

3. Adrenergic (Vasomotor)

4. Target Organs (Heart, Smooth Muscle)

Postganglionic Parasympathetic

1. Short

2. ACh

3. Muscarinic

4. Target Organs

Sympathetic Splanchnic Nerves

PREGANGLIONIC Axons do not Synapse in Sympathetic Trunk

Terminate in Prevertebral Ganglia

Sympathetic Pathways (Preganglionic, Myelinated, Lateral Horn of Gray Matter)

• Spinal Nerve Pathway - Sweat Glands, Smooth Muscle of Erector Pilli?

• Postganglionic Sympathetic Pathway - Internal Organs, Sweat Glands of Head/Neck

• Splanchnic Nerve Pathway - Abdominal Visceral Organs

• Adrenal Medulla Pathway - Kidneys - Release Norepinephrine

Autonomic Nervous System Neurotransmitters (15.5a)

• ANS Uses ACh and Norepinephrine

  • Cells Releasing ACh = Cholinergic Neurons

  • Target Cells have Cholinergic Receptors

    • All Preganglionic and Postganglionic Neurons

  • Sympathetic Ganglionic Neurons - Sweat Glands

Cholinergic Receptors (15.5b)

• Nicotinic Receptors

  • Found on all Ganglionic Neurons and Adrenal Medulla Cells

  • When ACh Binds, N. Receptor opens Cation Channel

• Muscarinic Receptors

  • Found in Target Organs

  • All Receptors use Second Messengers

Adrenergic Receptors (15.5c)

Located in Target Organs

• Alpha Receptors - Stimulated by Norepinephrine

• Beta Receptors - Stimulated or Inhibited by Norepinephrine

Dual Innervation (15.6b)

• Organ Receives Input from both the Sympathetic and Parasympathetic Divisions

  • Organ may receive Same or Different Stimulus

    • Same Stimulus : Male Reproductive System

    • Different Stimulus : Pupil Size, HR and GI Tract Movement

Sympathetic Innervation (15.6c)

• Opposing Effects Without Dual Innervation (15.6)

  • Blood Vessels Constrict with Increased Sympathetic Activity

  • Blood Vessels Dilate with Decreased Sympathetic Activity

• Sympathetic Innervation ONLY

  • Sweat Glands of Trunk of Body

  • Arrector Pili Muscles in Skin

  • Adrenal Medulla Cells (Kidneys)

Vasomotor Center

Sympathetic Nervous System Only

Vasoconstriction - Increased Stimulation of SNS

Vasodilation - Decreased Stimulation of SNS