Please enable JavaScript.
Coggle requires JavaScript to display documents.
GROSS AND SYSTEM NEUROBIOLOGY, Where the cauda equina starts, Over 7…
GROSS AND SYSTEM
NEUROBIOLOGY
Describe the anatomical and functional divisions of the nervous system
General Functions
Sensory
Communicative
Integrative
Motor
So as to respond to both internal and external stimuli
Peripheral Nervous System
Nerve fibers
12 pairs of cranial nerves
Most comes from brain stem
31 pairs of spinal nerves
8 pairs
of cervical nerves
12 pairs
of thoracic nerves
5 pairs
of lumbar nerves
5 pairs
of sacral nerves
1 pair
of coccygeal nerves
Meal times, with dinner twice
Afferent
Carries information
to the CNS
Sensory stimuli and visceral stimuli
Efferent
Transmits information
from the CNS
to effector organs
Somatic nervous system
Fibers of the motor neurons that supply the skeletal muscles
Subjected to voluntary control
Autonomic nervous system (ANS)
Fibers that innervate smooth muscle, cardiac muscle, and glands
Involuntary
Sympathetic
Sympathetic division (Thoracolumbar divisions)
Preganglionic neurons are located between segments T1 and L2 of the spinal cord
The sympathetic chain ganglia runs alongside the spine
Each preganglionic fiber can synapse with more than one ganglionic neurons
Effect of autonomic nervous system on organs
Go memorise or remember slide 15
Liver, Adipose, pancreas, endocrine, genitals, brain activity don't have to memorise
Comparison
See slide 16
Type of receptors for neurotransmitters not needed
Parasympathetic
Sympathetic and parasympathetic nervous systems dually innervate most visceral organs.
This gives more precise control of an organ
Dual innervation:
innervation of a single organ by both branches of the autonomic nervous system
Times of sympathetic dominance:
“fight- or-flight” response
Times of parasympathetic dominance:
“rest-and-digest” response
Parasympathetic division (Craniosacral divisions)
Innervate organs of 3 main regions: cranial, trunk and pelvic
Long preganglionic and short postganglionic fibers
Central Nervous System
Brain and spinal
cord
Describe the general structure and functions of the sympathetic and parasympathetic division of the autonomic system
Pathways
General pathway of autonomic nerve
Preganglionic neuron:
Synapses with the cell body of the postganglionic fiber in a ganglion outside the CNS
Postganglionic neuron
Sends axons that end on the effector organ
Describe the basic structural and organizational features of the central nervous system
Central Nervous System
Brain and spinal cord
Gray matter – generic term for collection of cell bodies (soma) in the CNS
White matter – generic term for collection of CNS axons
Protection
Cranium and vertebral column
Meninges
Three meningeal membranes wrap, protect, and nourish the central nervous system
Dura mater
Arachnoid mater
Pia mater
Continuous with spinal meninges
Production of CSF
Produced by ependymal cells of the choroid plexuses
Circulate throughout ventricles
Exit 4th ventricle
Flow in subarachnoid space
Reabsorb into venous blood
Cerebrospinal fluid (CSF)
The brain floats in its own special CSF
Shock absorbing fluid
Surrounds and cushions the brain and spinal cord
Formed by choroid plexuses in ventricles (brain)
Functions
Cushions delicate neural structures
Supports brain
Transports nutrients, chemical messengers, and waste products
Collection
Lumbar puncture
Collect CSF from the subarachnoid space
Blood–brain barrier
Isolates CNS neural tissue from general circulation
Formed by network of tight junctions
Between endothelial cells of CNS capillaries
Highly selective blood–brain barrier regulates exchanges between the blood and brain
Allows chemical composition of blood and CSF to differ
Selectively isolate brain from chemicals in blood that might disrupt neural function
CNS capillaries only allow lipid soluble drugs to cross
Polar and ionised drugs can cross with transport system
Ventricles
4 main ventricles
Nourishment
The brain depends on constant delivery of oxygen and glucose by the blood
Only utilizes glucose but does not store it
Cannot produce ATP without O2
2% of body weight but ~ 13% - 15% of cardiac output
Brain damage results if deprived of O2
General functions
Subconsciously regulate homeostatic responses
Experience emotions
Voluntarily control movements
Perception of body and surroundings
Engage in other higher cognitive processes
Components of the brain
Brain stem
Origin of majority of peripheral cranial nerves
Cardiovascular, respiratory, and digestive control centers
Regulation of muscle reflexes involved with equilibrium and posture
Reception and integration of all synaptic input from spinal cord; arousal and activation of cerebral cortex
Role in sleep–wake cycle
Mid brain
Pons
Medulla
Spinal cord
Long, slender cylinder of nerve tissue
Extends from the brain stem
Extends through the vertebral canal and is connected to the spinal nerves
Enclosed by the protective vertebral column
The white matter is organized into tracts
Bundles of nerve fibers with a similar function
Dermatomes (not needed to study)
Area of skin supplied by a single spinal cord level, or on one side, by a single spinal nerve
Can be used to localized lesions to a specific spinal nerve or specific spinal level
Knowledge useful for neurological examination
Myotomes
Portion of a skeletal muscle innervated by a single spinal cord level, or on one side, by a single spinal nerve
Each skeletal muscle usually innervated by nerves from more than one spinal cord level
Testing movements at successive joints to help in localizing nerve or spinal cord lesions
Eg, shoulder joint innervated by C5 & C6 spinal nerves
Spinal nerves
T1 to L2
Simple distribution pattern of posterior and anterior rami
The dorsal roots carry afferent sensory axons
The ventral roots carry efferent motor axons.
Nerve plexus
Network of nerves that come together and then redistribute themselves out with a different distribution of nerves into the limbs
Either somatic or visceral
Combine fibers from different sources or level to form new nerves with specific targets or destinations
Each nerve exiting the plexus may contain fibers from different spinal nerves
Damage to a single spinal nerve is less likely to result in total paralysis of a muscle innervated by nerves from that plexus
Nerve Plexuses
Cerebellum
Maintenance of balance
Enhancement of muscle tone
Coordination and planning of skilled voluntary muscle activity
Hypothalamus
Regulation of many homeostatic functions, such as temperature control, thirst, urine output, and food intake
Important link between nervous and endocrine systems
Extensive involvement with emotion and basic behavioral patterns
Role in sleep–wake cycle
Thalamus
Relay station for all synaptic input
Crude awareness of sensation
Some degree of consciousness
Role in motor control
Basal nuclei (Basal ganglia)
Inhibition of muscle tone
Coordination of slow, sustained movements
Suppression of useless patterns of movement
Cerebral cortex
Sensory perception
Voluntary control of movement
Language
Personality traits
Sophisticated mental events, such as thinking, memory, decision
making, creativity, and self-consciousness
Frontal lobe
Complex cognitive, decision making, personality, social behavior
Sensory and motor homuculus
Somatotopic map
Relative proportion of somatosensory cortex devoted to reception of sensory input from each area
Distribution of motor output from the primary motor cortex to different parts of body
Precise distribution is unique for each individual
Use-dependent modification
Parietal lobe
Somatosensory
processing
Occipital lobe
Visual
Temporal lobe
Memory formation
Where the cauda equina starts
Over 7 pairs of vertebrae column
Ganglions
Cluster of neuronal cell bodies
Adrenal glands don't have postganglionic fibres
The vagus nerve is a major parasympathetic output, supplying to 75% of the thoracic and abdominal organs
Cervical plexus
C1 to C5
Brachial plexus
C5 to T1
Lumbar plexus
T12 to L4
Sacral plexus
L4 to S4