Anatomy: Ch. 14/16

Posterior part of brain stem

Language
Attention
Fear
Motor Learning
Fine Movement

Superior to brain stem

Consists of: thalamus, hypothalamus, and epithalamus

Superior portion of brain

Voluntary actions of the boy

Superficial to deep:

Dura mater
Arachnoid mater
Pia mater

Somatic: tactile/touch
(pressure, tickle, vibration)

Visceral: conditions with internal organs

Smell
Taste
Hear
Vision
Equilibrium/balance

1) Stimulation of sensory receptor: stimulus must occur within receptor's field/region, to produce a response

2) Transduction of the stimulus: converts stimulus energy into a graded potential (not propagated). Sensory receptors are selective and transduce one type of stimulus

3) Generation of Nerve Impulses: when graded potential in neuron reaches threshold, it riggers one or more nerve impulses, then propagates towards CNS. (When PNS to CNS, first order neurons)

4) Integration of Sensory Input: Particular regions of CNS receives/integrates impulses (cerebral cortex)

1) Free nerve endings (1st order sensory neurons)

2) Encapsulated nerve endings of (1st order sensory neurons)

3) Separate cells synapsing with 1st order sensory neurons

1) Generator potentials


2) Receptor potentials

1) Exteroceptors

2) Intero/visceroreceptors


3) Proprioceptors

1) Mechanoreceptors

2) Thermoreceptors

3) Nocireceptors

4) Photoreceptors

5) Chemoreceptors

6) Osmoreceptors

Adaptation of receptors (generator/receptor potential decreases)

Pressure, touch, small

Meant to detect CHANGES.

Pain, body position, chemical composition of blood

Triggers as long as stimulus persists.

conscious or subconscious awareness of changes in the ex/internal environment

conscious awareness and interpretation of sensations and is primarily a function of the cerebral cortex

each unique type of sensation (touch, pain, vision, hearing)

1) Tactile

2) Thermal

3) Pain

4) Proprioreceptive

1) Touch: (skin/subcutaneous)
-Rapidly Adapting: meissner corpuscles, found in hair follicle/ fingertipes/clitoris/etc
-Slowly Adapting: merkel discs (fingertipes/lips/external genitalia) AND ruffini corpuscles (deep dermis, ligaments, tendons)


2) Pressure: occurs with deformation of tissue. Has meissner corpuscles, merkel discs, and pacinian meissner corpuscle (rapid adapt). Found in joints, periosteum, urinary bladder.


3) Vibration: rapid repetitive signals from tactile receptors. Includes the pacinian corpuscles (high freq) and Meissner corpuscles (low freq).


4) Itch: stimulation of free nerve endings by chemicals.

5) Tickle: by free nerve endings; signals are sent different to the cerebellum between you touching and someone else touching you

Detects cold and warmth
-Cold receptor are in the stratum basale of epidermis and connect to myelinated A fibers (few with unmyelinated C fibers) 10-40 degrees C.
-Warm receptors: less abundant, in dermis and attached to unmyelinated C fibers. 32-48 degrees C.

Activates pain receptors!

FOR SURVIVAL, makes you aware of tissue damage.

-Nocireceptors are for pain, found everywhere but brain.

Nocireceptors are VERY slow adapters, pain mediating chemicals are lingering.

Fast pain: occurs <0.1s after stimulus. Myelinated A fibers. Acute/sharp/prick. Not found in deeper tissues


Slow pain: 1+s after stimulus and will increase in intensity. Unmyelinated C fibers. Can be in skin or deeper organs

stimulations of receptors in skin

stimulations in deeper tissue like joints, tendons, skel musc, fascia

nocireceptors in visceral organs

Not localized, diffuses and affecting areas above or far from source

lets us know where our body is spatially. Proprioreceptors are embedded in muscles and tendons. Proprios adapt slowly -- sending signals to the brain to always maintain equilibrium

-Weight discrimination: know how much it take to lift up an apple

-3 TYPES

1) Muscle spindles

2) Tendon organs

3) Joint kinesthetics (within synovial joint capsules)

Conducts impulses from facial somatic receptors into brain stem/spinal cord. If from the head, propagates with cranial nerves to brain stem. If from the posterior of the head, propagates along the spinal nerves into the spinal cord

Conducts impulses from the brain stem/spinal cord to the thalamus

Axons decussate to opposite side in brain stem/spinal cord, reaching to opposite side's thalamus

Conducts impulses from thalamus to the primary somatosensory area of cortex on the same side

Regions within CNS where neurons synapses with other neurons that are part of a particular sensory/motor pathway (for signal to get from one CNS region to other CNS region)

1) Posterior column-medial lemniscus pathway

2) Antero-lateral pathway

3) Trigeminothalamic pathway

The size in the somatosensory region is proportional with its corresponding body part.

Ex: people who read braille have a larger region in somatosensory area corresponding to fingertips

1) Posterior spinocerebellar tract

2) Anterior spinocerebellar tract


Neither are consciously perceived but critical for balance, posture, coordination of skilled movements.

Convey nerve impulses fro proprioceptors in trunk/lower limb form one side of the body to the same side of cerebellum.

1) Local circuit neurons

2) Upper motor neurons

3) Basal ganglia neurons

4) Cerebellar neurons

Provide input to LMNs via axons extending DIRECTLY to cerebral cortex

Provide input to LMNs from motor centers in brain stem.

1) Primary motor area: in the precentral gyrus of frontal lobe (executing voluntary movements)


2) Premotor area: contributes axons to descending motor pathways

Pyramidal Cells: UMNs, found in both primary motor/premotor areas.

1) Corticospinal pathways


2) Corticobulbar pathway

One of the 2 direct motor pathways. It subdivides into two...

1) Lateral corticospinal tract

2) Anterior corticospinal tract

Conducts impulses for the control of skel muscles in the head. Axons of UMNs from cerebral cortex form this tract. Some decussate, others don't. These axons terminate in the cranial nerves of the brain stem (oculomotor, trochlear, trigeminal, abducens, facial, glossopharyngeal, vagus, accessory, and hypoglossal.

Controls precise voluntary movements of the eyes, tongue, neck, chewing, facial expressions, and speech.

All other tracts!

Axons of the UMNs descend from various nuclei of brainstem into 5 major tracts of SC and terminate in local circuits or LMNs.

-5 types of indirect motor tracts! Rubrospinal, tectospinal, vestibulospinal, lateral reticulospinal, and medial reticulospinal.

1) Rubrospinal

2) Tectospinal

3) Vestibulospinal

4) Lateral reticulospinal

5) Medial reticulospinal

1) Initiation/termination of movements.

2) Suppresses unwanted movements by inhibitory effects from thalamus/superior colliculus

3) Influence muscle tone, by reducing. Damage to basal ganglia causes increase in muscle tone

4) Influences cortical function like sensory, limbic, cognitive, and linguistics

1) Monitors intensions for movement (from motor cortex/basal ganglia by pontine nuclei in pons -- red lines)

2) Monitors actual movement (input from proprioreceptors in joints and muscles -- blue line)

3) Compares the intended and performed movements

4) Sends out corrective feedback if there is a discrepancy between intended and performed movements. Info travels via thalamus to UMNs in cerebral cortex and goes directly to UMNs in brain stem motor centers (green lines)

1) Wakefulness
2) Sleepiness
3) Learning
4) Memory

Portions of the reticular formation that when active, sends many nerve impulses to areas of the cerebral cortex, both directly and via the thalamus.

Smell; there is no input from olfactory receptors that cause arousal. That is why people die in house fires :(

1) Rapid Eye Movement (REM)

2) NREM (Non-rapid Eye Movement)

1) Transition -- vetween wakefulness and sleep (lasts 1-7 minutes)

2) Light sleep -- eyes roll, fragments of dreams

3) Moderately deep sleep -- body temp/BP decrease, difficult to wake up, eyes moderately roll

4) Deepest sleep -- metabolism/temp drop, reflexes still intact, muscle tone decreased slightly. When sleepwalking occurs!

Capability for change associated with learning

-Frontal, parietal, temporal, occipital association areas

-Parts of limbic system (hippocampus, amygdala)

-Diencephalon

1) Immediate

2) Short-term

3) Long-term

Reinforcement that results from the frequent retrieval of a piece of info

What underlies some aspect of memory; transmission at some synapses within the hippocampus are enhanced, for hours/weeks after a brief period of high-freq stimulation

Neurotransmitter: glutamate

Part of the dura mater
Separates the 2 hemispheres

Part of the dura mater
Separates the 2 hemispheres of the cerebellum

Part of the dura mater
Separates the cerebrum from the cerebellum

Passes: oxygen, CO2, alcohol, anesthetics


Active Transport: water-solubles like glucose

Slow Transport: creatine, urea, most ions

Do not pass: proteins, antibiotic drugs

Flows in the subarachnoid space.

Protects the brain and spinalcord from chemical and physical injuries

1) Mechanical protection: shock absorber

2) Chemical protection: provides optimal chemical environment for accurate neuronal signaling

3) Circulation: allows exchange of nutrients and waste products between blood and nervous tissue

Choroid plexuses (capillaries in walls of ventricles). These capillaries are coverd by ependymal cells that filter blood plasma and secrete.

Gradually reabsorbed into the blood by arachnoid villi that's in the sagittal sinus

1) Cardiovascular Center: regulates rate and force of heartbeat, diameter of BV

2) Medullary Rhythmicity Center: adjusts basic rhythm of breathing

3) Vomiting Center

4) Deglutition Center: swallowing (mouth into pharynx)

5) Gustatory: input from tastebuds of tongue

6) Cochlear: auditory input from the cochlea of the inner ear

7) Vestibular: equilibrium, associated with proprioceptors of inner ear

-Contains sensory and motor tracts

-Relay info from cerebral cortex to cerebellum

-Helps control breathing and equilibrium (along with the medulla)

-Contains cranial nerves

-Contains sensory/motor tracts

-Superior colliculi coordinates movement of head, eyes, trunk in response to visual stimuli

-Inferior colliculi coordinates to auditory stimuli

-Substantia nigra and red nucleus contribute to overall control of movement

-Smoothes and coordinates contractions of skeletal muscles

-Regulates posutre and balance

-Cognition and language processing

-Relays almost all sensory input (not smell) to cerebral cortex

-Motor functions relayed from basal ganglia/cerebellum to primary motor area

-Maintenance of conciousness

-Controls and integrates activities of the ANS

-Produces/releases hormones

-Regulates emotional and behavior

-Regulates thirst and hunger

-Controls body temperature

-Controls circadian rhythms

-Perception of sensory info

-Execute voluntary movements

-Integration like memory, personality, intelligence

-Initiate/terminate movement, suppress unwanted movements

-Regulate muscle tone

-Limbic system: emotions

1) Anterior nucleus

2) Medial nuclei

3) Lateral group

4) Ventral group

5) Intralaminar nuclei

6) Midline

7) Reticular

1) Mammillary

2) Tuberal

3) Supraoptic

4) Preoptic

-Controls ANS (cardiac/secretion of glands)

-Production of hormones: two connections with the pituitary

-Regulation of emotional and behavioral patterns

-Regulation of eating and drinking

-Control of body temp

-Regulaton of circadian rhythm/states of conciousness

-Superior/posterior part of thalamus

-Contains pineal gland and habenular nuclei

-Secretes melatonin, which sets the biological clock and makes someone more sleepy

-Involved in olfaction, associates emotions with smell

-Part of the diencephalon

-Monitors chemical composition of blood because there isn't a blood-brain barrier

-Regulates homeostasis like regulating BP, fluid balance, hunger, thirst.

-Site of HIV transmission?

-Gray matter region
-Folds: gyri
-Deep grooves: fissures
-Shallow grooves: sulci

1) Association tracts

2) Commissural tracts

3) Projection tracts

1) Globus Pallidus

2) Putamen

3) Caudate Nucleus

-Initiate/terminate movement

-Suppress unwanted movement

-Regulate muscle tone

-Influences cortical functions like limbic, cognitive and linguistics

-Associated with Parkinsons and schizophrenia

When there is a specialization occuring on either side of the brain

-Reasoning numerically, scientifically

-Spoken, written, and sign language

-Artistic/musical awareness

-Spatial/pattern perception

-Recognizing facial and emotion

-Discriminate different smells

-Generating mental images of sight, sound, touch, smell and comparing their relationships

1) Alpha waves

2) Beta waves

3) Theta waves

4) Delta waves

Olfactory (I)
Optic (II)
Oculomotor (III)
Trochlear (IV)
Trigeminal (V)
Abducens (VI)
Facial (VII)
Vestibulocochlear (VIII)
Glossopharyngeal (IX)
Vagus (X)
Hypoglossal (XI)
Accessory (XII)

Type: Sensory

Function: smell

Neuron: bipolar

Location:
nasal cavity to
unmyelinated axon to
olfactory foramina to
olfactory bulbs (gray matter) to

OR to axons in olfactory tracts which synapse with POlfactoryA in temporal lobe of cerebral cortex

Features: olfactory bulbs and tracts

Type: Sensory

Function: Vision

Neuron: bipolar

Location: Retina, rods, and cones initiate vision to
bipolar neurons to
ganglion cells to
optic foramen
X at optic chiasm to
synapse with axons in PVA in occipital lobe of cerebral cortex

*Can also pass optic chiasm and reach motor neurons in eye muscle*

Special Features: optic tracts

Type: Motor

Function:
Somatic Motor Neurons = movement of upper eyelid and eye ball

Parasympathetic Neuron: constriction of pupil

Neuron: n/a

Location: n/a

Special Features: proprioception from eyeball

Type: Motor

Function: movement of the eyeball

Neuron: n/a

Location:
Motor Neuron = trochlear nucleus to
superior orbital fissure of midbrain

Special Feature: proprioception for eyeball

Type: Mixed

Function:
Sensory = touch, pain, temperature, proprioception
Motor = chewing

Neuron: n/a

Location:
SENSORY
1) Ophthalmic: axons from upper eyelid, eyeball, lacrimal glands, nasal cavity, side of nose, forehead, anterior half of scalp that pass through superior orbital fissure

2) Maxillary: nose's mucosa, palate, parts of pharynx, upper teeth/lip, lower eyelid that pass through foramen rotundum

3) Mandibular: ant 2/3 of tongue (not taste), lower teeth, mandible skin, cheek and mucosa, side of head in front of the ear to foramen ovale

MOTOR
3) Mandibular= through foramen ovale for chewing

Special Features: largest cranial nerve with its three branches

Type: Motor

Function: eyeball movement

Neuron: n/a

Location:
Pons to
superior orbital fissure to
lateral rectus muscle (eyeball)

Type: Mixed

Function:
SENSORY
touch, pain, temperature, proprioception, and taste

MOTOR
(Somatic) facial expression
(Autonomic) secrete saliva and tears

Location: n/a

Special Features: n/a

Type: Sensory

Function:
1) Vestibular: equilibrium
2) Cochlear: hearing

Neuron: n/a

Location: semicircular canals to
vestibular ganglion to
vestibular nuclei in medulla and pons

OR some go thru inferior cerebellar peduncle to cerebellum

Special Features: 2 branches

Type: Mixed

Function:
SENSORY
taste, touch/pain/temperature from posterior 1/3 of tongue, monitoring of BP/O2/CO2 for breathing

MOTOR
(Somatic) elevates pharynx for swallowing/speech
(Autonomic) saliva secretion

Neuron: n/a

Location:
(Sensory) axons pass through jugular foramen to
medulla

(Motor) from medulla to
jugular foramen

Special Features: n/a

Type: Mixed

Function:
(Sensory): taste, touch, pain, temp, proprioception from epiglottis and pharynx, monitors BP/O2/CO2 for breathing rate, visceral sensations in thorax/abs

(Somatic): swallowing, coughing, voice

(Autonomic/Parasympathetic): smooth musc contraction/relaxation in organs/GI tract, slowing heart rate, secrete digestive fluids

Neuron: n/a

Location:
(Sensory) skin of extern. ear/baroreceptors in aorta/visceral receptors to
jugular foramen to
medulla/pons

(Somatic) runs briefly w/ accessory arises from medulla to
pharynx/larynx

Special Features: n/a

Special Feature: wide distribution

Type: Motor

Function: head, trapezius, sternocleidomastoid movement

Neuron: n/a

Location: anterior gray horn of C1-C5 through SC to
foramen magnum to
jugular foramen to
traps/sterno

Type: Motor

Function: movement of tongue, speech/kissing/swallowing

Neuron: n/a

Location: medulla to
hypoglossal canal to
muscles of tongue

Special Features: n/a

1) Free nerve endings

2) Encapsulated nerve endings

3) Separate cells

Pain, thermal, tickle, itch, and touch

Somatic and visceral, like pressure, vibration and some touch

Equilibrium, gustatory receptors in tastebuds, and photoreceptor in eye

1) Generator potential
2) Receptor potential

The intensity of the stimulus!

1) Exteroceptors

2) Interoceptors

3) Proprioceptors

1) Mechanoreceptors
2) Nociceptors
3) Thermoreceptors
4) Photoreceptors
5) Chemoreceptors
6) Osmoreceptors

1) Meissner corpuscles
2) Hair root plexuses

1) Merkel discs
2) Ruffini corpuscles

Pacinian corpuscle

1) Pacinian corpuscles
2) Meissner corpuscles

-Rapid repetitive sensory signals

-FREE NERVE ENDINGS!

1) Cold receptors

2) Warm receptors

Below 10c and above 48c

THE BRAIN

1) Fast pain

2) Slow pain

Often visceral pain, is felt in or just deep to skin around the stimulated organ. Big region!

1) Muscle spindles (slow)
2) Tendon organs (slow)
3) Joint-Kinesthetics receptor (rapid)

1st Order: takes impulses from somatic receptors. Facial stimuli travel down by cranial nerves into the brain stem. The rest of the body are propogated by spinal nerves into the spinal cord

2) 2nd Order: conducts impulses from brainstem/spinal cord to the thalamus and decussate. So signals reach to the opposite side of the thalamus

3) 3rd Order: conducts impulses from thalamus to the primary somatosensory area of the cortex (same side)

1) Posterior Column-Medial Lemniscus

2) Anterolateral Pathway

3) Trigeminothalamic Pathway

1) First order neurons of (trunk, limbs)

2) Reaches spinal cord.

3) Ascends to medulla (same side) , where the cell bodies are in the posterior root ganglia. The axons form gracile and cuneate fasciculus
-Cuneate: touch, pressure, vib, concious proprioception of upper trunk/limbs, neck and posterior head go to cuneate nucleus.
-Gracile: touch, pressure, vibs from lower libs/trunk are in the gracile axon and go to gracile nucleus

4) Second order neurons cause decussation, entering the medial lemniscus (bridge).

5) In thalamus, 2nd order neurons synapse w/ 3rd order neurons

6) Third's axons go to Primary Somatosensory Area of the cerebral cortex

1) First order connects with limb/trunk/neck/post head to spinal cord.

2) Synapse with 2nd order in the posterior gray horn of spinal cord.

3) 2nd order axons cross over in spinal cord, and ascend the spinothalamic tract.

4) 2nd order neurons end in thalamus, synapse w/ 3rd order.

5) Third's axons project to Primary Somatosensory Area on same side

1) First order neurons of face/nasal/oral/teeth go to the pons via trigemino nerves

2) Some 1st synapse with 2nd in the pons. Other 1st descend the medulla and synapse with those 2nd.

3) Axons in 2nd order decussate in the medulla or pons, and ascend the trigeminothalamic tract to the thalamus

4) In thalamus, 2nd synapse with 3rd.

5) 3rd's axons project into Primary Somatosensory Area of cerebral cortex (same side)

1) Posterior Spinocerebellar tract

2) Anterior Spinocerebellar tract

LMNs have cell bodies in 1) brain stem or 2) spinal cord.

The brainstem LMN's axons will extend into cranial nerves to innervate muscles of the face and and head.

The spinal cord's LMNs axons will extend into the spinal nerves and innervate the skeletal muscles of the limb and trunk.

1) Local circuit neurons
2) Upper motor neurons
3) Basal ganglia neurons
4) Cerebellar neurons

1) Direct motor pathway

2) Indirect motor pathway

Pyramidal pathways aka DIRECT MOTOR PATHWAYS.

Pyramidal cells are UMNs located in the primary motor area and premoter area of cortex.

Consists of 2 pathways: corticospinal and corticobulbar.

1) Corticospinal

2) Corticobulbar

1) Rubrospinal
2) Tectospinal
3) Vestibulospinal
4) Lateral reticulospinal
5) Medial reticulospinal

Sends nerve impulses from the red nucleus (receives input from cortex and cerebellum) to contralateral skeletal muscles for precise, voluntary movements of distal upper limbs

Sends nerve impulses from the superior colliculus to contralateral skeletal muscles for movement of head/eye/trunk in response to auditory/visual stimuli

Sends nerve impulses from vestibular nucleus (which gets its input from inner ear) to ipsilateral skeletal muscles of trunk/proximal limbs for posture and balance during head movements

Reticular formation to ipsilateral skeletal muscles of trunk and proximal parts of limbs for maintaining posture, muscle tone for continuous movement

1) Initiate and terminate movements

2) Suppresses unwanted movements by inhibiting thalamus/superior colliculus

3) Influences muscle tone. Globus pallidus sends impulses to reticular formation reducing muscle tone, so damage to basal ganglia causes increase in muscle tone

4) Influences cortical function like sensory, limbic, cognitive, and linguistic. Ex: initiates and ends memory, attention, and planning

1) Monitors intentions for movement. Motor cortex and basal ganglia sends impulses to pontine nuclei.

2) Monitors actual movement. Done by receiving input from proprioceptors in joints/muscles that reveals what is happening, impulses travel by anterior/posterior spinocerebellar tracts

3) Compares the command signals (intended movement) with sensory info (actual movement)

4) Sends our corrective feedback if there is a discrepancy in intended and performed movement. Thatlamus to UMNs of cortex to UMNs in brain stem (leads to learning new skills)