Introduction To Neurosensory Flashcards
CNS broad overview
Contains the brain and spinal cord
is responsible for integrative and control centers and using information relayed from the peripheral nervous system
Sensory (Afferent) vs motor (efferent) Divisions
Sensory (afferent)
- somatic and visceral sensory nerve fibers
- relays information from the organs -> the brain
Motor (efferent)
- motor nerve fibers
- relays information from brain -> organs/ muscles
Motor (efferent) subdivisions
Automatic nervous system (ANS)
- involuntary
- conducts impulses from CNS to cardiac/smooth muscles and glands
Somatic nervous system
- voluntary
- conducts impulses from CNS to the skeletal muscles
General Anatomical differences of the ANS divisions
Sympathetic
- origins of fibers: T1-T12
- length of fibers: short preganglionic / long postganglionic
- ganglia location: close to spinal cord
Parasympathetic
- origin of fibers: cervical and sacral regions
- length of fibers: long preganglionic / short postganglionic
- ganglia location: in visceral effector organs
- sympathetic innervates structures in the body wall and viscera. Parasympathetics only innervate viscera*
Gary vs white matter
Gray matter
- contains neuron cell bodies
- makes up the outer portion of the brain and inner portion fo the spinal cord
- makes up the cortex and nucleus in the brain
White matter
- contains mostly myelinated axons
- makes up the outer portion of the spinal cord and inner portions of the brain
Terms synonymous with white matter
Nerve (PNS only)
Tracts (includes the following sub catagories)
- bundles
- capsules
- fascicles
- fasiciculus
- lemniscus
Decussation: crossing of fiber tracts within the same hemisphere
Commissure: crossing of fiber tracts between hemispheres
Petal and fugal suffix meanings
Petal = describes tracts of fibers going toward from the designated structure
Fugal = describes tracts of fibers going away form the designated structures
Two descriptions of gray matter
Ganglia/ganglion = gray matter in the PNS
- exception is basal ganglia which is a collection of cell bodies in the CNS used for primary motor control
Nucleus/ nuclei = gray matter in the CNS
Posterior vs anterior nerve roots
Both are part of the PNS
Posterior (dorsal) root: contains the sensory (afferent) ganglia
Anterior (ventral) root: contains the motor (efferent) ganglia
Which are true and which are false cranial nerves?
True = 3-12
False = 1-2
- are called false since they are actually direct extensions fo the brain itself
Basic divisions of the CNS
Telencephalon
- contains the cerebral cortex and both brain hemispheres
Diencephalon
- contains the hypothalamus, pituitary, thalamus
Cerebellum
- contains the cerebrum
Brainstem
- connects the brain to the spinal cord and contains the pons, medulla oblongata and the actual midbrain
Below midbrain vs above brainstem anatomical descriptions
Above midbrain
- rostral (anterior)
- dorsal (superior)
- caudal (posterior)
- ventral (inferior)
Below midbrain
- rostral (superior)
- dorsal (posterior)
- ventral (anterior)
- caudal (inferior)
Telencephalon (cerebral hemispheres)
- Contains gyri (ridges) and sulci (valleys)
- contains subcortical white matter include the internal capsule
- contains basal nuclei for primary motor functions
Diencephalon
Contains the thalamus and hypothalamus
Directly ventral to the telencephalon
Thalamus primary functions
Primary relay center
- all sensory information from the PNS -> cerebral cortex must pass through the thalamus
Receives inputs pertaining to most bodily sensory information, static positioning in real time and tension in muscles/ tendons
- all information signals are at first choppy and unorganized
The thalamus then relays these signals to the cerebral cortex which functions to smooth out the signals into smooth purposeful movements
Hypothalamus functions
Visceromotor functions
Influences visceral centered in brainstem and spinal cord
Plays role in sexual behavior, feeding, hormonal output of the pituitary and body temperature regulation.
What is the only sensory information that does NOT pass through the thalamus?
Olfactory
What organ specific centers are found in the brain stem?
Respiratory and cardiovascular centers.
Ventricle locations in the brain
1st and 2nd ventricle
- found on each side of the cerebral cortex (telencephalon)
3rd ventricle
- in the diencephalon and is connected with 1st/2nd
4th ventricle
- in the brainstem connected to the 3rd ventricle via the cerebral aquaduct
Which true cranial nerve ganglia is NOT found in the brainstem?
Accessory nerve (11) - this is found in the upper cervical spinal cord itself
Cerebellum primary functions
Chief mover in the motor system
Serves top coordinate activity of individual muscle groups to produce smooth, purposeful, synergistic movements.
3 primary functions of neurons
Impulse formation
Impulse conduction
Information processing
majority of neurons are multipolar
Other types of neurons that are not multipolar
Unipolar
- single process (axon)
- no dendrite
Bipolar
- single dendrite and single axon
Pseudounipolar
- single process (axon) that bifurcated into 2 processes (axons)
- no dendrite
Cells of the nervous system broad overview
CNS specific:
1) astrocytes
- help form BBB
- provide nutrients to CNS neurons
2) microglial cells
- immune cells of the CNS
3) oligodendrocytes
- myelinate CNS axons
4) ependymal cells
- make up the choroid plexus and price CSF
PNS specific:
1) Schwann cells
- myelinate PNS axons
2) Satellite cells
- provide nutrients to PNS axons
Afferent and efferent in the CNS vs the PNS
PNS:
- afferent = sensory
- efferent = motor
CNS
- afferent = axons moving towards a Structure
- efferent = axons moving away from a structure
Description terms of reflexes
Areflexia = lack of any reflex
Hyporeflexia = weakened reflex
Hyperreflexia = excessive reflex
Ways pathways can differ from each other
1) type of information carried
2) length of a pathway
- both physical length and amount of synapses
3) chemical coding of pathways
4) type of neurotransmitter used
5) whether information reaches the conscious perception (cerebral cortex and thalamus) or not
What does the term system mean in neuro sensory?
A series or group of neurons that all carry the same type fo information
Difference between upper motor and lower motor neurons
Upper
- project from the cerebral cortex -> spinal cord or brain stem
- cell bodies are found in the cerebral cortex
Lower
- project from brainstem of anterior horns of the spinal cord -> the target
- cell bodies are found in anterior horns or brainstem motor nuclei
Primary, secondary and tertiary neurons in somatosensory pathways
Primary:
- detects stimulus
- cell body in dorsal root ganglion
Secondary
- acts as relay
- cell body is in either spinal cord or brain stem
Tertiary
- sends information from thalamus -> cerebral cortex
- cell body is found in thalamus
General rules surround localized neuro sensory damage
1) Defects on the same side of the head and body
- lesion is likely in the cerebral hemisphere
2) Defects on one side of the head and opposite side of the body
- lesion is likely in brain stem
- called “ crosses deficits”
3) Defects of the body only with normal head function
- lesion is likely in the spinal cord
- there are exceptions but >90% follow this*
