Module 2 Nervous System A&P for SLH

Central Nervous System

• Brain & spinal cord

• Command center that receives and processes info and control the response

Peripheral Nervous System

Cranial and Spinal nerves coming off brain stem and spinal cord throughout the body

Transmits sensory info to the CNS from the body and carries motor commands from the CNS to the body

Somatic nervous system

 Carries sensory info and motor (voluntary) commands from CNS to skeletal muscles

• Carries sensory information from peripheral organs to CNS

Autonomic Nervous System

Involuntary inner organs

Sympathetic: fight or flight

• Parasympathetic: rest and digest

• Enteric: functions of the GI tract

Efferent vs Afferent

When motor commands go from the brain to the muscles

Afferent neurons carry sensory information toward the central nervous system (brain) , while efferent neurons carry motor commands away from the central nervous system (to muscles).

Nerve impulses

electrical signals that travel through neurons to transmit information throughout

the nervous system, producing a specific response or function

Internruron

Connect similar neurons. Process info, not sending it

Motor Neuron

Transmits motor impulses from CNS to the body to be executed by muscles

Sensory Neuron

Transmits sensory information from sensory receptors to the CNS to be processed

Dendrite

Receives signals, send it to soma

Axons

Transmits signal through a neuron, covered in myelin (helps speed of signal sending)

Axon terminals

Where the axon comes to an end

Synapse

Specialized junction that allows a neuron to pass a signal to another cell

Glial Cells

 Support & nourish neurons

 Oligodendrocytes

 lays down myelin on axons in the CNS

Schwann cells

 lays down myelin on axons in the PNS

Microglia

immune defense and removal of cellular waste

Neurons

Signal sending/receiving cells in brain

Central sulcus

 separates the hemisphere from front and back

Lateral sulcus/Sylvian fissure

 separates temporal lobe from frontal and parietal lobes

 Parieto-occipital sulcus

 parietal and occipital lobes

Gray matter

 information processing, decision- making, memory storage, muscle control

• Made up of densely packed neuronal cell bodies/ neuron soma

White matter

Connects different gray matter areas and allows communication

between them through myelinated axons

• Made up of axons, white because mylin

• Inner part of cerebral hemisphere

Cerebral cortex

the visible surface of the brain (gray matter/outer layer)

-Outer portion of the cerebrum

-Most sophisticated part of brain

-Contains gyri and sulci

Laterilzation

When control of a function is dominated by 1 hemisphere relative to the other

Specialization

Control of a function is dominated by a particular region in the brain, regardless of hemisphere

Corpus Collosum

A white matter pathway that connects the 2 cerebral hemispheres

• Allows for communication between the left and right hemispheres

Frontal Lobe

• Function: higher level cognitive skills, decision-making, problem solving, executive functioning, initiation of movement and inhibition of impulses

•  Linked to personality

Pre-frontal cortex

 Large anterior-most mass of frontal lobe

Primary motor cortex

Part of the frontal lobe responsible for voluntary movement

• Generates the motor signal that is sent to the brainstem and spinal cord through neurons

• Important regions control muscles involved in speech production and swallowing

Somatopic Organization of the Cortex

Representation of different areas of the brain's cortex correspond to different parts of your body.

• Primary motor cortex → controls voluntary movement

• Primary somatosensory cortex → processes sensations such as touch, pressure, pain, and temperature

Broca’s area

 Left of frontal lobe 

Planning and organizing motor behavior required for speech production

• expressive language what we say vs receptive language- what we understand and take in

Temporal lobe

 Conscious perception of auditory and smell info (hearing)

• Located laterally/inferiorly of each cerebral hemisphere (below the lateral fissure)

• Contains Wernicke's area

• Contains hippocampus: memory

Wernicke’s Area

Understanding and processing language (receptive language)

Primary Auditory Cortex

 Receives afferent signals of auditory stimuli (hearing)

Left hemisphere: receives auditory signals of speech sounds and transmits to Wernicke's Area to be processed for comprehension

Right hemisphere: receives auditory signals from the environment and transmits them to area just posterior for processing of non-speech sounds 

Parietal Lobes

Conscious perception of touch, pressure, vibration, pain, temperature, and taste

Contains supramarginal gyrus and angular gyrus

Somatosensory Cortex

Receives and processes sensory information from the body

• Touch, Pressure, Pain, Temperature, and proprioception (body position)

• through the PNS to the primary sensory/ somatosensory cortex in the CNS

Basal ganglia

Group of neurons within cerebellum cortex part of the subcortical structures of the brain.

• They help start, stop, and regulate movement. (DOES NOT CREATE)

• Disorders: Parkinsons disease- tremors and slow movement

Supramarginal gyrus

Language/phonological processing, and sensory information

-in parietal lobe

Angular gyrus

Language comprehension, reading, writing, visual and language information
- located in parietal lobe

Occipital lobe

Visual stimuli & hearing

Insula

 Involved in the control of speech, language, breathing, and swallowing

•  part of the limbic system (emotions, memory, etc.)

• Under frontal and parietal lobes

Subcortical Nuclei

 Deep gray matter structure that helps regulate movement sensation, emotion, memory, and body function.

Cranial nerves

- 12 pairs of nerves that control sensation and movement of head, neck, and face (sensory and motor) 

• 10 of 12 in brainstem

Cranial Nerve V- Trigeminal

•  touch, pressure, and pain from mid and upper face and maxillary and motor

• motor: muscles of jaw movements

• sensory: lower face/teeth, outer ear and anterior 2/3 tongue (touch, temp, pain)

• if damaged:  Impaired mastication, Impaired oral sensation, Potential difficulties with feeding and swallowing

Cranial Nerve VII- Facial

Sensory: parts of external ear, taste for anterior 2/3rd of tongue

• Motor: muscles of facial expression

• Carries autonomic motor fibers to glands that secrete tears and saliva

• Aids in muscles of articulation

• if damaged: bells palsy ex

Sensory Nerve VIII- Vestibulocochlear

•  Balance/coordination of head in space

• Cochlear: Auditory/ hearing

• Carries auditory and vestibular(coodination) info from the inner ear to the brainstem

Cranial Nerve IX- GlossoPharyngeal

(tongue)(throat)

• Has voluntary and autonomic motor and sensory

components

• Motor: Innervates the stylopharyngeus muscle (in neck for swallowing)

• Autonomic motor: salivary gland secretion

• Sensory: parts of external ear, eardrum, upper part of pharynx

• Autonomic sensory: taste for posterior 1/3rd of tongue

Cranial Nerve X-Vagus

• Motor: pharynx muscles, larynx, tongue

• Autonomic motor: stimulation of mucous glands 

• Sensory: for pharynx, larynx, meninges, parts of the external ear and eardrum

• Autonomic sensory: sensation from gut/bowels

Cranial Nerve XI- Spinal Accessory

a motor nerve that controls specific movements in the neck and shoulders

• motor neurons are in the upper part of the spinal cord rather than the brainstem

• It innervates 2 muscles of the head and neck: Sternocleidomastoid muscle and Trapezius muscle

Cranial Nerve XII- Hypoglossal

Intrinsic and extrinsic muscles of tongue movement

Internal carotid arteries

travel upward through the neck and enter the skull.

They primarily supply the front and middle portions of the brain

• Anterior cerebral artery (ACA)

• Middle Cerebral Artery (MCA)

Middle Cerebral Artery

Blood vessel supplying blood to lateral frontal, parietal, and temporal lobes (needed for speech and language)

• Part of internal carotid arteries

Vertebral arteries

travel upward through the vertebrae of the neck and enter the skull.

The two vertebral arteries join together to form Basilar artery

Basilar artery

Supplies blood to: Brainstem, Cerebellum, Inner ear

Eventually divides into the posterior cerebral arteries (PCAs).

Circle of Willis

a circular network of arteries located at the base of the brain.

provide collateral circulation, an alternate route for blood to reach brain tissue if one pathway becomes narrowed or blocked.

Like a roundabout connecting multiple roads:

Internal carotid system ↔ Circle of Willis ↔ Vertebrobasilar system

Spinal Nerves

Part of the PNS: 31 pair of nerves that act as communication lines from spinal cord and rest of the body

Motor: info from brain (CNS) to muscles & glands

Sensory (afferent) fibers: info from body to the brain (CNS)

Cortical Innervation Patterns

• tells us whether a motor nucleus receives commands from one side or both sides of the brain

• Describes how the motor cortex sends signals to motor

nuclei

Mostly bilateral

The two Cortical Innervation Patterns

• Bilateral: Motor nucleus receives input from both sides of

the motor cortex

• Contralateral: Motor nucleus receives primarily opposite

side cortical input

Ventricles

four interconnected cavities (spaces) inside the brain that produces and circulates cerebrospinal fluid.

Cerebral spinal fluid

 clear liquid that surrounds and protects the brain and spinal

cord, removes waste and provides nourishment

CSF Path

flows through the two lateral ventricles> third ventricle> fourth ventricle>

spinal cord and brain> reabsorbed into bloodstream

Cerebellum

Back part of the brain that helps make movements smooth, coordinated, and accurate.

• Disorders: stroke- problems talking, walking and with coordination