Nervous System Flashcards
What are the two branches of the nervous system?
Central and peripheral
What are the branches of the CNS?
The brain and spinal cord
What are the branches of the PNS?
Autonomic and somatic
What are the divisions of the autonomic?
Sympathetic and parasympathetic
what is the spinal cord protected by?
vertebrae
What does the spinal cord sit within?
Verterbral Canal
What is the vertebral canal formed by?
Stacking of individual tunnels in each vertebra
Where is the end of the spinal cord level with in children?
L3
Where is the end of the spinal cord level with in adults?
L1
What is the vertical tunnel running through the vertebra known as?
Vertical foramen
What does the outer section of the spinal cord consist of?
White matter
What does white matter contain?
The axons of neurons that form ascending and descending pathways
What is the inner section of the spinal cord made of?
Grey matter
What does grey matter consist of?
Where cell bodies of neurons are located and where synapses occur
Where do neurons from the body enter the spinal cord?
Dorsal horn
Where do neurons exit the spinal cord from?
ventral horn
What are the three tracts of the somatic nervous system?
lateral corticospinal tract, dorsal columns and anterolateral fascicutus
What does the lateral corticospinal tract do?
Carries descending motor tracts from the cerebral cortex
What are the dorsal columns for?
Sense of fine touch and proprioception
What does the anterolateral fasciutus do?
Carries pain and temperature sensory neurons
Where do autonomic nerves run?
Not within spinal cord - in collection of ganglia along side it
What type of control is the autonomic nervous system?
subconsious
What does the autonomic system generally innervate?
Smooth muscle of tissues or glands
What actions is the autonomic system involved with?
Temperature control, continence, secretions and gastic motility
Where do autonomic neurons arise?
from the spinal cord and directly from the brain
What does the sympathetic nervous system initiate?
The fight or flight response
Where are sympathetic cell bodies present?
In the thoracic and lumbar spinal cord segments
What do sympathetic cell bodies connect to?
A paravertebral ganglion chain or individual ganglia
What does the sympathetic nervous system innervate?
Heart, blood vessels, sweat glands, viscera and adrenal medulla
Where do parasympathetic neurons arise from?
Cranial nerves or lumbosacral spinal cord
What does the parasympathetic system stimulate?
Rest and digest functions
Where are parasympathetic ganglia located?
Close to target organ
What is the somatic nervous system responsible for?
Conscious control of the body
What do afferent somatic sensory nerves detect?
Pain, temperature, touch and proprioception
What do somatic efferent nerves motor to?
effector skeletal muscles
Where do somatic neurons project to?
Directly to their target cell via a single neuron
What are the two types of somatic nerves?
Spinal and cranial
What do spinal nerves carry?
peripheral nerves that carry axons of neurons of the somatic and autonomic nervous systems to and from spinal cord
Where does a spinal nerve exit the spinal cord?
Inferior to each vertebra level
What is the expception to the spinal nerves exiting the spinal cord inferior to each verterbrea level?
In the cervial region they exit superiorly so there is a spinal root both above and below to C7
How many spinal roots are there in total?
31
Where is there an additional spinal root?
At the coccyx
Dorsal (afferent) and ventral (efferent) roots unit to form a what?
Mixed segmental spinal nerve
What may a mixed segmental spinal nerve continue to form?
A nerve plexus or a single peripheral nerve
What is a lumbar plexus?
Made up of spinal nerves arising from the spinal cord below vertebrea T12-L5
Where does the femoral nerve arise from?
Spinal roots L2,L3 and L4
What does the femoral nerve supply?
Muscles and skin of the leg
What are dermatomes and myotomes representative of?
The distribution of somatic nerves
What is a distinct area of skin supplied by a spinal root known as?
dermatome
what is a distinct area of muscle supplies by a spinal root known as?
Myotome
What are the roles of the sciatic nerve with respect to muscles?
Motor to muscles of posterior thigh (the hamstrings that flex the knee)
Where does pain from sciatica radiate from?
The buttock down the leg
What are the roles of the sciatic nerve with respect to skin?
Sensory afferent from the skin over the lateral side of the leg (below the knee) and skin on sole and dorsum of foot
What are the roles of the femoral nerve with respect to muscles?
Motor to muscles of anterior thigh (the quads that extend the knee)
What are the roles of the femoral nerve with respect to skin?
Sensory afferent from anterior thigh and medial leg
How many cranial nerves are there?
12
What are the special senses?
Sight, Taste, Hearing, Smell, Balance
What does the left hemisphere of the brain control?
Logic and numbers and language. Processes sensory and motor pathways for the right side of the body
What does the right hemisphere of the brain control
Creativity, immagination and rythym and processes the sensory and motor pathways of the left side of the body
How are the two hemispheres joined?
By a neutral bridge of nerve fibre known as the CORPUS CALLOSUM
What are the three subdivisions of the brain?
Forebrain, midbrain and hindbrain
What are the three subdivisions of the forebrain?
Cerebral cortex, thalamus and hypothalmus
What are the three subdivisions of the hindbrain?
Medulla, pons and cerebellum
What makes up the brain stem?
Midbrain medulla and pons
What structure run through the brains stem?
Reticular formation
What is the recticular formation important for?
Controlling consciousness
What does the midbrain control?
Higher functions (eye movements and auditory system)
What does the medulla control?
Basic functions such as breathing and heart rate
What does the pons control?
Indistinct functions in conciousness and posture
What does the cerebellum consist of?
Two mounds of folded tissue posterioe to the brainstem
How is the cerebellum connected to the brainstem?
Three peduncles of neural tissue
What is the cerebellum concerned with?
motor functions and motor learning
Where does the cerebellum receive inputs from?
Ascending sensory pathways from body and descending motor pathways from cerebrum and other info from brainstem
WHat is the thalamus?
A relay point where all inputs to the cerebrum synapse before ascending to the cerebral cortex
What is the main function of the hypothalmus?
homeostasis
What is directly controlled by the hypothalamus?
Blood pressure, body temperature, fluid and electrolyte balance, body weight
How are heart rate, vasoconstriction, digestion and sweating controlled by the hypothalamus?
By inputs to the medulla
What does stimulation of the pituitary gland do?
Hormone release
What does most of the volume of the cerebral hemispheres consist of?
White matter
Where does grey matter exist?
Only on the surface of the hemispheres
What is the cerebral cortex the location of?
Higher fuctions e.g. intelligence, personality, planning, touch sensation
What are sulci?
Infoldings of the brain
What are gyri?
Sticky out bits between sulci - areas of functional grey matter
What is the CNS covered with?
The meninges
What is the meninges?
A layer of tissues
What is within the meninges?
cerbro spinal fluid that bathes the CNS
What is CSF produced by?
specialised epithelium - choroid plexus
Where is the choroid plexus found?
lining cavities within the brain called ventricles
What does the choroid plexus actively secrete?
Components of blood plasma in to the ventricles
Describe CSF
Clear fluid lower in proteins cells and most ions than plamsa
What does CSF have a higher concentration of than the plasma?
Sodium, chloride and magnesion
How are these ions transported in the to CNS
Active transport
Describe the pathway of CSF
Circulates through ventricles before exiting on to the surface of the brain (still within meninges) to bathe brain and spinal cord
What are ventricles linked by?
aqueducts
What is CSF reabsorbed by?
Venous circulation at specialised points called ARACHNIOID GRANULATIONS
