Introduction to Neuroanatomy Flashcards
what does the vertebral column protect
spinal cord
what does cranial mean
‘head end’
what does caudal mean
tail end
what does rostral mean
towards the face
what does the CNS comprise of
the brain and spinal cord
what does the peripheral nervous system comprise of
all nervous tissue outside the CNS - primarily nerves
what are cranial nerves
nerves arising from the brain
what are spinal nerves
nerves arising from the spinal cord
what is the somatic nervous system
controls voluntary activities under conscious control
what is the autonomic nervous system
controls involuntary activities - not under conscious control
what is the cerebrum
largest part of brain - has left and right hemispheres (connected)
what is the surface of the cerebrum called
cerebral cortex - has a grey appearance
where is information processed
grey matter
what are the folds in the cerebral cortex called
gyri (singular gyrus)
what are the grooves in between the gyri called
sulci (singular sulcus)
what happens in the white matter
information is transmitted through bundles of fibres
what is a nucleus in the CNS
a collection of cell bodies
what are the 4 lobes of each cerebral hemisphere called
frontal (at the front), parietal (inbetween the occipital and frontal), occipital (at the back) and temporal (underneath)- named after the bones of the skull that over lie them
what part of the brain lies inferior to the posterior (occipital) part of the brain
cerebellum
what is the cerebellum composed of
a left and right hemisphere, highly folded cortex, contains white matter and nuclei
what is the role of the cerebellum
balance, coordination and movement
what is the role of the brain stem
relays info between cerebrum, spinal cord and cerebellum
- it gives rise to most of the cranial nerves
- contains centres that regulate breathing and consciousness
where is the spinal cord
it is continuous with the medulla of the brainstem - it is protected by the vertebral column - it is much shorter than the vertebral column and ends around L1 - L2
how many pairs of spinal nerves are attached to the spinal cord
31 - they carry info between the cord (CNS) and the periphery (e.g.skin, muscles). Each pair corresponds to a spinal cord segment
what kind of matter is in the spinal cord
grey matter made up of neuronal cell bodies, this is surrounded by white matter which contains tracts - bundles of axons that connect different parts of the CNS to each other
what are the cavities in the brain called
ventricles (there are 4), they are continuous with each other and filled with cerebrospinal fluid
what does the cerebrospinal fluid do
it surrounds the brain and spinal cord
- it provides nutrients to the brain
- it cushions the brain against trauma
- prevents delicate nerves and vessels from being compressed between the brain and then internal surface of the skull
what are the 3 meningeal layers
- dura mater
- arachnoid mater
- pia mater
what does the dura mater do
lines inner surface of the skull and vertebral column - thick and strong
what does the arachnoid mater do
lies deep into the dura, thin and loosely encloses the brain and spinal cord
what does the pia mater do
lies deep into the arachnoid - it is adhered to the surface of the brain and spinal cord - very thin - cant see with naked eye
what do the meninges do
protect the brain and provide a scaffold for blood vessels
what arteries supply the brain
the left and right internal carotid arteries and the left and right vertebral arteries
where and what is the circle of Willis
on the inferior surface of the cerebrum the arteries give rise to branches that form and interconnected ring (Circle of Willis)
what is anastomosis
where branches from separate arteries unite with each other - circle of willis is an example - allows for blood supply to an area to be maintained if one of the vessels gets blocked
what arteries does the circle of willis give rise to
3 cerebral arteries which supply the hemispheres, cerebellar arteries which supply the cerebellum, and arteries that supply the spinal cord
what arteries connect the cerebral arteries to each other
communicating arteries
what is the area called that an artery supplies
territory
what does the somatic nervous system control
skeletal muscle and sensory receptors
what does the autonomic nervous system control
smooth muscle, glands and cardiac muscle
what are the 2 parts of the autonomic nervous system
sympathetic NS - fight and flight
parasympathetic - rest and digest
the sensory component of the ANS conveys info from the internal environment from the viscera to the CNS - but it doesnt reach our conscious perception
what are viscera
organs
what is another name for sympathetic and parasympathetic nerves
visceral efferent nerves because they leave the CNS and travel to the periphery
what are some example of reactions to stimuli that the sympathetic NS causes
- fight, flight, fright, freeze
- heart rate increases
- bronchi dilate
- peripheral blood vessels constrict so blood is diverted to skeletal muscles
- pupils dilate
- hair stands on end
- sweat glands are stimulated
what are some example of reactions to stimuli that the parasympathetic NS causes
- Rest and digest
- heart rate decreases
- bronchi constrict
- glands stimulated
- gut activity is stimulated (peristalsis)
- pupils constrict
where are sympathetic first neuron bodies found
in the thoracic and upper lumbar segments of spinal cord
where are parasympathetic first neuron bodies found
in the brain stem and sacral spinal cord
what happens once the parasympathetic and Sympathetic axons leave the CNS
they synapse with a second neuron whose cell body lies in a Ganglion (a collection of cell bodies outside the CNS)
what is a preganglionic neuron
the first neuron whose axon leaves the CNS to synapse with another neuron whose body is in the ganglion
what is a postganglionic neuron
this is the neuron whose cell body lies in the ganglion, postganglionic neurons travel to target organs
what lengths are the post and pre ganglionic axons in the ParaSNS and SymNS
- the SymNS has a short preganglionic axon and a long postganglionic axon
- the ParaSNS has a long preganglionic axon and a short postganglionic axon
which is more widely distributed SymNS or ParaSNS
the sympathetic system is far more widely distributed than the parasympathetic - this is because they have to reach hair follicles and sweat glands so have to reach all parts of the body
Why are sensory autonomic fibres also called visceral afferent fibres
because they convey information from the viscera back to the CNS
what do sensory autonomic fibres do
- they monitor our internal environment e.g. blood pressure and send info to CNS, these elicit reflex responses (unconcious) which maintain the internal environment
what do sensory autonomic fibres do
- they monitor our internal environment e.g. blood pressure and send info to CNS, these elicit reflex responses (unconscious) which maintain the internal environment
- they send information back about distention, stretch spasm or ischaemia of viscera that causes pain or discomfort - this does reach consciousness
- Visceral afferents travel back to the CNS along paths of the sympathetic and PS nerves
what is ischaemia
when blood flow (and so oxygen) is reduced or restricted to parts of the body
how many pairs of cranial nerve pairs are there
12, they are numbered from I to XII `
where do the cranial nerves serve
the head and neck
they exit the skull by leaving through holes in the base of the skull called what
foramina (singular foramen)
what are cranial nerve nuclei
collections of cell bodies associate with the cranial nerves found in the brainstem
are the cranial nerves part of the peripheral NS
yes - they leave the CNS and travel to the periphery
can cranial nerves have more than one type of nerve fibre
yes - some are purely sensory and some are purely motor, some carry both sensory and motor fibres and some carry parasympathetic fibres
how many pairs of spinal nerves are there
31
how many pairs of cervical spinal nerves are there
8 - C1 to C8
how many pairs of throacic spinal nerves are there
12 - T1 to T12
how many pairs of lumbar spinal nerves are there
5 - L1 to L5
how many pairs of sacral spian lnerves are there
5 - S1 to S5
how many pairs of coccygeal spinal nerves are there
1 - Co1
what kind of nervous fibre do spinal nerves carry
- somatic motor fibres from CNS to body
- sympathetic fibres (autonomic motor) from the CNS to the body
- somatic sensory fibres from the body to the CNS
how do nerves exit the spinal cord
they pass through gaps formed between adjacent vertebrae called the intervertebral foramina
where do the cell bodies of the motor neurons lie
in the ventral horn of the spinal cord (grey matter)
what is the ventral (motor) root of the spinal nerve
when the axons leave the cord via a series of rootlets which merge together to form this, these motor fibres stimulate the voluntary contraction of skeletal muscle
where do the cell bodies of peripheral sensory neurons lie
in the dorsal root ganglia - visible with naked eye as small swellings- instead of having one axon they have 2 processes, one that projects peripherally into the spinal cord and one that projects centrally into the dorsal horn of the spinal cord (grey matter)
what is the pathway of information traveling from peripheral receptors (in the skin)
goes towards the dorsal root ganglia via the spinal nerve and then from the DRG to the dorsal horn via a series of rootlets
what do all 31 pairs of spinal nerves contain
sympathetic fibres - these stimulate sweat glands and the contraction of smooth muscle in peripheral blood vessels and hair follicles
what is a dermatome
the area of skin innervated by a single spinal nerve - see dermatome maps e.g. C6 spinal nerve has sensation over the thumb and part of the forearm
what is a myotome
the group of muscles innervated by a single spinal nerve
