Anatomy of the Spinal Cord and Spinal Nerves Flashcards
what is the nervous system divided into?
central nervous system (brain and spinal cord)
and peripheral nervous system (cranial nerves + spinal nerves and autonomic nerve trunks with their associated ganglia)
spinal cord conducts…
conducts information to and from the brain through axonal tracts
the spinal cord connects with spinal nerves, it processes…
it processes afferent information from muscles, tendons, joints, ligaments, blood vessels skin and viscera and discharges efferent commands that control muscles and regulate glands
spinal cord is a reflex centre producing…
producing subconscious respsonses of muscles and regulate glands
the spinal cord is a direct continuation of…
the brain stem (medulla oblongata)
where does the spinal cord leave the skull from?
leaves the skull from the foramen magnum and runs through the vertebral column
from medulla oblongata to the level of 6th/7th lumbar vertebrae
centre of the spinal cord contains?
contains a central canal filled with CSF and lined with ependymal cells
spinal cord is divided into?
into segments
reason for dividing of spinal cord into segments?
is the attachment of dorsal and ventral roots
each dorsal or ventral root is made of?
made of thousands of axons
axons of each root are bound together laterally and they form spinal nerves
dorsal roots convey? and ventral roots carry?
dorsal roots convey sensory (afferent) input to the spinal cord and ventral roots carry motor (efferent) roots to the muscles and glands
each segment gives rise to?
to paired spinal nerves
what is the spinal ganglion present on?
present on each dorsal root
cell bodies outside the brain and spinal cord are called…
ganglion
paired spinal nerves emerge from the spinal cord through where?
through spaces formed between the vertebrae
Dorsal branches of spinal cord (medulla spinalis) innervate?
epaxial tissues
ventral branches of spinal cord innervate?
innervate hypaxial tissues, which include limbs
spinal ganglion on the dorsal root just prior to?
just prior to its union with the ventral root at the level of intervertebral foramen
at the thoraco-lumbar junction, how are segments positioned?
segments are positioned within corresponding vertebrae
how many sacral segments are located within the L5 vertebra?
three
where does functional spinal cord terminate at?
terminates at L6/L7
the end of the spinal cord is the?
the conus medullaris
what is the cauda equina?
it is the bundle of spinal nerves remaining after the termination of the spinal cord
what does the cauda equina consist of?
consists of the spinal nerves L6-Cd5 and includes those that form the sciatic (L6-S1) and pudendal (S2-3) nerves
what is the filum terminale?
it is a glial continuation persisting beyond the functional end of the spinal cord (contains no neural fibres, only fibrous connective tissue: strand of glial and ependymal cells) it stabilises the spinal cord by attaching distally to bony coxes
what is the brachial nerve plexus?
it is a complex, interwoven network of nerves
the cervical enlargement involves cord segments C6-T2 from which nerves forming the brachial plexus arise
what is the brachial plexus formed by?
formed by the ventral branches of spinal nerves C6, C7, C8, T1 and T2
large somatic nerve plexus gives origin to?
gives origin to the nerves that supply the thoracic limb
lumbar nerve plexus?
it is a complex interwoven network of nerves
lumbar enlargement with a similar relationship to the lumbosacral plexus involved cord segments L5-S1 plexus
what is the lumbar nerve plexus formed by?
formed by the ventral branches of spinal nerves L4, L5, L6, L7 and S1 (may reach S3)
gray matter - spinal cord cross section?
consists of neurons, neuroglia rich blood supply
gray due to perikaryal (cell body)
neuron cell bodies, dendrites, axons
white matter, of spinal cord?
myelinated and nonmyelinated axons
white due to the lipid composition of the myelin
gray matter of spinal cord divided into?
divided into horns, dorsal, ventral and lateral or named columns
dorsal horn contains?
contains cell bodies of the interneurons on which afferent neurons terminate
ventral horn contains?
contains cell bodies of the efferent motor neurons supplying skeletal muscles
autonomic nerve fibres supplying?
supplying cardiac and smooth muscle and exocrine glands originate from lateral horns
white matter of the spinal cord is organised into?
into tracts (funiculus)
tracts are grouped into?
into columns that extend the length of the cord
each of these begins or ends within a particular area of the brain and each is specific in the type of information that it transmits
spinal nerves (bundles of axons) connect with?
they connect with each side of the spinal cord by a dorsal root and ventral root
afferent fibres carrying incoming signals enter the spinal cord through the?
through the dorsal root
efferent fibres carrying outgoing signals leave through the?
through the ventral root
cell bodies of afferent neurons at each levels are?
they are clustered to for dorsal root ganglion
spinal nerves carry both what fibres?
they carry both afferent and efferent fibres
where does the first cervical spinal nerve leave the spinal cord?
lateral vertebral foramina
which roots of the spinal cord carry afferent information?
dorsal roots
why must be ventral branches for brachial plexus?
because limbs are in ventral direction and must be last vertebrae of cervical
thick bundle of elongated nerve roots within the lower vertebral canal is known as the?
known as the cauda equine
