Introduction to the Spinal Cord and Spinal Nerves Flashcards
2 important functions of the spinal cord and its attached spinal nerves
- pathway for sensory and motor impulses
* responsible for reflexes
what is another word for anterior
ventral
what is another word for posterior
dorsal
what is another word for dorsal plate
alar plate (dorsal horn/sensory)
what is another word for ventral plate
basal plate (ventral horn/motor)
what are the 3 layers of the meningeal coverings
- Dura mater
- arachnoid mater
- pia mater
what are the three spaces in the spinal cord
subdural
subarachnoid
epidural
what is the intervertebral foramen
hole between vertebrae: where spinal cords exit out into the body
what is the difference between roots and rami
roots carry either motor or sensory while rami carry both motor and sensory
what are the 4 plexuses in the spinal cord and where are they located
- cervical (C1-C8)
- thoracic (T1-T12)
- lumbar (L1-L5)
- sacral (S1-S5)
what is the dorsal root attributed with (sensory or motor)
sensory
what is the ventral root attributed with (sensory or motor)
motor
define dermatome
area of skin innervated by the sensory fibers of a single nerve root
define myotome
a group of muscles that is primary innervated by the motor fibers of a single nerve root
what are the three ways that spinal nerves are distributed in the body
- intercostal nerves (anterior rami)
- dorsal rami (epaxial/back)
- nerves plexuses (anterior rami)
what are the major terminal branches (peripheral nerves)
- musculocutaneous
- median
- ulnar
- radial
- axillary
what is a reflex
rapid, automatic, involuntary reactions of muscles or glands to a stimulus
what are the components of a reflex arc
- the neural wiring of a single reflex
- always begins at a receptor in the PNS
- communicates with the CNS
- ends at a peripheral effector (muscle or gland)cell
define ipsilateral
when both the receptor and effector organs of the reflex are on the same side of the spinal cord
define contralateral
when the sensory impulses from a receptor organ cross over through the spinal cord to activate effector organs in the opposite side limb
what does the golgi tendon reflex do
prevents skeletal muscles from tensing excessively
what are the 2 division of the nervous system
CNS and PNS
what are the components of the CNS
spinal cord and brain
derived from epiblast
what are the components of the PNS
(everything outside the CNS)
- includes cranial nerves, spinal nerves and their roots and branches, peripheral nerves, and neuromuscular junctions
- primarily derived from neural crest precursor cells and epiblast
what are the 2 functional division of the nervous system
somatic and autonomic
what is the role of the sensory nervous system
- afferent
- receives sensory info from receptors and transmits it to the CNS. Somatic and visceral sensory components detect different types of stimuli
what is the role of the motor nervous system
- efferent
- initiates and tramsits motor output from the CNS to effectors and controls muscle tissues and glands. Somatic and autonomic components exert voluntary and autonomic control
what is the different between somatic and visceral
somatic: touch, taste, smell, hearing, balance
visceral: blood vessels, internal organs
what is general sensory
transmit sensations from the body to the CNS
what is somatic motor fibers
transmit impulses to skeletal muscles
what do visceral sensory fibers do
transmit pain or subconscious visceral reflex sensations from hollow organs and blood vessels to the CNS
what do visceral motor fibers do
transmit impulses to smooth muscle and glandular tissues
what are the 4 types of CNS glial cells
astrocytes
ependymal cells
microglia
oligodendrocytes
what are astrocytes
star-like due to projections from their surface and help form the BBB, regulate tissue fluid composition, form structural network, assist neuronal development and occupy space of dying neurons
what are ependymal cells
ciliated simple cuboid or columnar cells lining the interal cavities of the brain and spinal cord to assist in the production of CSF
what are microglia
typically small with branches representing smallest percentages of CNS glial cells and act as protectors to infection or remove harmful substances
what are oligodendrocytes
large with bulbous body and slender extensions that en-sheath portions of axons creating a myelin sheath. it insulates and provides faster transport of signals along the axon
what are the 2 types of PNS glial cells
satellite and neurolemmocytes
what are satellite cells
surround cell bodies of sensory neurons and regulate continuous exchange of nutrients and waste products between neurons and their environment
what are neurolemmocytes/schwann cells
they ensheath PNS axons to form a myelin sheath and allow faster AP propagation within the PNS
what is the subdural space
fluid-filled space or potential space between dura mater and arachnoid
what is the subarachnoid space
- located between the arachnoid and pia mater and is filled with CNS
- enlargement is in the dural sac, caudal to the conus medullaris
what is the epidural space
area between the dura mater and the vertebral wall, containing fat and small blood vessels. The space is located just outside the dural sac which surrounds the nerve roots and is filled with CSF
what is the conus medularis
inferior tapering portion of the spinal cord
where spinal cord ends
ends between L1 and L2
what is the cauda equina
- collection of nerves at the base of the spinal column, near the first lumbar vertebra
- primary function= to send and receive messages between the lower limbs and the pelvic organs, which consist of the bladder, the rectum, and the internal genital organs
what is the dura mater
- composed mainly of tough fibrous tissue with some elastic fibers
- outermost covering membrane of the spinal cord
- tapers to coccygeal ligament
what is the arachnoid mater
- delicate, avascular membrane composed of fibrous and elastic tissue that lines the spinal dural sac and its dural root sheaths
- encloses the CSF-filled subarachnoid space containing the spinal cord, spinal nerve roots, and spinal ganglia
what is the pia mater
- intermost covering membrane of the spinal cord, thin and transparent, and closely follows all the surface features of the spinal cord
- meshwork of elastic and collagen fibers
- denticulate ligaments
- filum terminalis
what is the cervical plexus and what nerves are included
(C1-C4)
hypoglossal, accessory, lesser occipital, greater auricular, transverse cervical, ansas cervicalis, branch to brachial plexus, supraclavicular nerve, phrenic nerve
what is the brachial plexus and what nerves are included
(C5-T1)
pectoral, subscapular, nerve to subclavius, musculocutaneous, median, axillary, radial, thoracodorsal, long thoracic, ulnar
what is the lumbar plexus and what nerves are included
(L1-L4)
iliohypoglastric, ilioinguinal, genitofemoral, lateral femoral cutaneous, femoral, obturator
what is the sacral plexus and what nerves are included
(L4-S4)
superior gluteal, inferior gluteal, nerve to piriformis, sciatic nerve, posterior femoral cutaneous, pudendal
