introduction to the nervous system Flashcards
the nervous system is divided into 2 groups which are?
CNS
Peripheral nervous system
the peripheral NS is divided into how many groups? what are their names?
Somatic NS
Autonomic NS
the autonomic nervous system us responsible for what? what are its subdivisions?
involuntary control of visceral organs
Parasympathetic NS–> Rest and digestion
Sympathetic NS –> Fight or flight
what is the role of the somatic nervous system?
voluntary control of sensory and motor functions
area of the skin innervated by a given spinal nerve
dermatome
a group of muscles innervated by a given spinal nerve
myotome
what nerve plexus is responsible for the upper limbs? where does it range?
brachial plexus
from C5-T1
what nerve plexus is responsible for the lower limbs? where does it range?
Lumbosacral Plexus
L1-S4
what region is affected near the nipple?
T4
what happens if nerve on T6 is affected?
nerves going to the skin above the xiphoid process will be affected
what region is covered by T10?
umbilicus
why is it clinically significant to understand region of skin innervation?
it enables us to understand certain spinal cord injuries particularly, the level of the injury, if it’s complete or incomplete.
what is the conus medullaris?
it is the tapered lower end of the spinal chord. it is at that point the the filum terminale begins.
what is the filum terminale
it is the prolongation of the spinal chord. its purpose is to serve as an anchor.
what is the causa equina?
it is a bundle of spinal nerves. it begins at L2 and goes all the way down to the very last vertebrae of the coccyx.
how does the spinal cord ressemble at the embryo stage?
it fills out the vertebral column
Identifiy the stage at which the spinal chord ends
- L3
- L1-L2
birth
adult
what do spinal chord enlargments correponds with?
what are the 2 enlargements found on the spinal cord?
they correspond with their respective plexuses.
cervical enlargement with the brachial plexus
lumbar enlargement with the lumbosacral plexus
what is the neuron?
it is the basic unit of the NS
how do neurons communicate?
through chain-like connections that send electrical impulse to one another.
where is the posterior horn identified on the spinal cord?
the posterior horn is found on the gray matter, its the winged shaped structure
where is the posterior horn identified on the spinal cord?
the anterior horn is found on the gray matter it is the more rounded structure.
what is the gray matter composed of
cell bodies
what does the cervical enlargement give rise to?
gives rise to nerves on the upper limbs.
it occurs between C5-T1
what does the lumbar enlargement give rise to?
gives rise to the nerves of the lower limbs.
occurs at L1-S4
what is the name of the biggest fold in the spinal cord?
anterior median fissure
what part of the spinal cord represents the line of attachment between the dorsal and ventral spinal roots
the posteo-lateral Sulcus & the Anterolateral Sulcus
what is the white matter composed of?
axon’s & myelin
what are spinal meninges?
a membrane that surrounds, supports and protect the spinal cord and spinal nerve roots
how are the spinal nerves divided
you have the dorsal rootlets- that merge into the dorsal root into the dorsal ganglion (on the posterior side
on the anterior side you have ventral rootlets that merge into ventral roots.
the dorsal and ventral root merge to form the spinal nerves which divides back into the dorsal ramus and ventral ramus
what is the main function of the dorsal rami
responsible for innervation of the skin of the back, intrinsic muscles of the bac
what are the 3 Layers of meninges of the spinal cord?
- dura matter
- arachnoid matter
- pia matter
what ligament can be observed through the meninges of the spinal cord at the level of the pia?
denticulate ligaments
how would you describe the dura matter?
its can be seen as though matter
what meninges matter is described to look cob-web-like?
arachnoid matter
what is the pia matter described as?
what can be observed at that depth?
the tender mother
at the same depth we can observe the dendiculate ligament & the filum terminale
how does the spinal nerve exit the vertebral column?
the spinal nerve exits through the intervertebral foramen & bifurcates into the ventral and dorsal ramus
relative to the cervical vertebrae, where is the cervical spinal nerves located
above the vertebrae
how many cervical spinal nerves are there?
8 spinal nerves but only 7 cervical vertebrae
where do the spinal nerves for the thoracic and lumbar vertebrae exit?
the exit below the vertebrae
where do the sacral spinal nerves exit from?
they exit through the anterior and posterior sacral foramina below the corresponding sacral segments
what nerves bring sensory information from periphery to CNS via the dorsal root?
afferent nerves
what nerves transmit motor commands from the CNS to the periphery via ventral roots?
efferent nerves
what trick is used to recall spinal nerve signaling?
in the Dor(Sal) out the Vent(ral)
what is often found in the epidural/extradural space?
fatty tissue
what is the space between the dura mater and the pia mater
subdural space
what is the subarachnoid space
spinal fluid
what is the clinical significance of the meningeal
lumbar tap is executed at the lumbar levels, due to thoracic vertebrae overlap
ideally puncture at l4/l5
