N261 Chapter 15: In-Depth Study of Sensory and Motor Tracts of the Spinal Cord

ascending sensory tracts

-originate at a sensory receptor

-ending in the cerebral cortex, cerebellum, or brainstem

descending motor tracts

-originate in the brain

-ending in spinal cord or brainstem

tracts within the spinal cord _____

relay sensory and motor information between the peripheral nervous system and higher centers within the central nervous system

all tracts involve both the brain and the spinal cord and the name of a tract often indicates its origin and destination

prefix: spino-

-starts in the spinal cord and ends in the brain

-ascending tract that carries sensory information

suffix: -spinal

-starts in the brain and ends in the spinal cord

-descending tract that carries motor commands

sensory information carried by a tract that synapses in the thalamus: conscious

sensory information carried by a tract that does not synapse within the thalamus: subconscious

three major somatosensory tracts:

-posterior columns

-spinothalamic tracts

-spinocerebellar tracts

posterior columns (dorsal columns) (medial lemniscal pathway)

carry highly localized information from receptors in the skin and musculoskeletal system about proprioception, fine touch, pressure, and vibration

posterior columns tracts:

-gracile fasciculus and cuneate fasciculus

-decussate in the medulla

gracile fasciculus sensations

proprioception, fine touch, pressure, and vibration from levels inferior to T6

gracile fasciculus destination

primary somatosensory cortex on side opposite of stimulus

cuneate fasciculus sensations

proprioception, fine touch, pressure, and vibration from levels at or superior to T6

cuneate fasciculus destination

primary somatosensory cortex on side opposite of stimulus

sensory homunculus

-sensory map

-proportions of body parts is proportional to the number of sensory receptors that region contains

spinothalamic tracts:

-lateral and anterior

-decussates in the spinal cord at the level of entry

lateral spinothalamic tracts sensations:

pain and temperature

lateral spinothalamic tract destination:

primary somatosensory cortex on side opposite of stimulus

anterior spinothalamic tract sensations:

crude touch and pressure

anterior spinothalamic tract destination:

primary somatosensory cortex on side opposite of stimulus

spinocerebellar tracts:

-posterior and anterior

-because neither of these tracts synapse within the thalamus, the information is not raised to the conscious level

posterior spinocerebellar tract sensations:

proprioception

posterior spinocerebellar tract destination:

cerebellar cortex on some side of stimulus

anterior spinocerebellar tract sensations:

proprioception

anterior spinocerebellar tract desination

cerebellar cortex, primarily on side of stimulus

Descending motor tracts:

corticospinal, subconscious motor pathways

corticospinal tracts

-provide conscious, voluntary control over skeletal muscles

-system begins at the primary motor cortex

-upper motor neurons synapse on lower motor neurons

powerful visceral memories:`

olfactory

hypothalamic satiety

eating, sleeping, drinking, sexual behavior

super chiasmatic nucleus

clock nucleus

hypothalamus

choroid plexus

produces CSF

cerebrum

consciousness

cerebellum

-motor coordination area

-ALL OUTPUT IS INHIBITORY

third ventricle connects lateral ventricles

cerebral aqueduct

connects the third and fourth ventricles

continuous with the spinal cord

if you poke into the third ventricle what will you be in?

thalamic nuclei

fourth ventricle leads into the

central canal of the spinal cord

THERE IS NO EPIDURAL SPACE IN THE BRAIN

CSF SHOULD BE CLEAR

endosteum

superior sagittal sinus

-major brain drain vein

-formed by the splitting of the dura mater

-attached to the crista gali

the dura mater stops at the level of the

corpus callosum

the brain feels like firm tofu

cerebral arterial circle

-circle of willis

-anastomoses

-alternative ways for blood to flow

the brain needs 2 things to survive:

glucose and oxygen

anastomosis

alternative way for blood to get where blood needs to go

confluence of sinuses

intersection of superior sagittal sinus, straight sinus, transverse sinuses, occipital sinus

hydrocephalus

accumulation of fluid in the spaces of the brain

cerebral hemispheres

receives sensory information from and generate motor commands to the opposite side of the body

cerebrum

consciousness

arcuate fibers

connect gyri

longitudinal fasciculi

connect the frontal lobe to the other lobes of the same hemisphere

internal capsule

A large collection of axons that connects the telencephalon with the diencephalon

major white commissure

corpus callosum

the thalamus is on either side of the

third ventricle

claustrum

plays a role in the subconscious processing of visual information

hippocampus

learning and memory

diencephalon

connects cerebral hemispheres to brain stem; consists of epithalamus, thalamus, and hypothalamus

corpora quadrigemina

located in the midbrain; contains reflex centers for vision and auditory reflexes

-tectum (roof)

superior colliculus

visual reflex

inferior colliculus

auditory reflex

suprachiasmatic nucleus

-light

pineal gland

circadian rhythm

serotonin is metabolized into melatonin

only nerve that comes from the dorsal brainstem

trochlear

limbic system nuclei

coodinate involuntary movements of skeletal muscles

substantia nigra

regulates activity of basal nuclei

pons

-help regulate respiration

-help coordinate involuntary skeletal muscle movements and muscle tone

apneustic center

Portion of the pons that increases the length of inspiration and decreases the respiratory rate

pneumotaxic center

inhibits inspiration

cerebellum

-adjusts postural muscles of the body to maintain balance

-programs and fine-tunes voluntary and involuntary movements

vermis

trunk coordination

folia of cerebellum

medulla oblongata

Part of the brainstem that controls vital life-sustaining functions such as heartbeat, breathing, blood pressure, and digestion.

essential for life

cranial nerves

components of the peripheral nerous system that connect to the brain

branches of the facial nerve

temporal, zygomatic, buccal, mandibular, cervical

the one nerve we cannot live without

vagus