Lecture 5- Spinal cord and spinal nerves; autonomic nervous system Flashcards
Name the 4 main functions of the spinal cord
- final common pathway for the motor system
- conveys somatosensory information from the body
- conducts information for autonomic nervous system
- important centre for reflex activity
the spinal cord is a continuation of the ___ ____
medulla oblongata
the spinal cord ends at level ___ or __ which is known as ___ ____
- L1
- L2
- conus medullaris
describe the function of the filum terminale and where it descends from
- the filum terminale is a slender, fibrous thread that holds the spinal cord in place
- it descends from the conus medullaris
below L1/L2 the nerve root bundle that travel down the spinal cord is called ____ ____
- cauda equina
what is the Lumbrosacral enlargement?
- Lumbrosacral enlargement is when the spinal cord is bigger to accommodate for more motor neurons that are present
- more motor neurons needed in this area for the control of lower extremity muscles
spinal nerves go through the _____ ____
- intervertebral foramina
T/F: both layers of the dura mater (periosteal and meningeal) are present in the spinal cord
- False: only the meningeal layer is present in the spinal cord
the dura mater encloses the ___ __ and the ___ ___ and etends along each ___ ___
- spinal cord
- cauda equina
- nerve root
the dura extends along the nerve root and becomes continuous with the ______ of the spinal nerves
- epineurium
the epidural space is between the ___ and the ____
- dura
- periosteum
the epidural is filled with ___ ___ which provides ____
- fat tissue
- insulation from jarring forces
the ___ covers the whole spinal nerve root
- epineurium
the ____ covers the axons of each nerve within the neuron
- perineurum
the ___ ___ continues along the spinal nerve root and blends with the perineurim
- arachnoid mater
the ___ ____ ends inferiorly at S2 vertebra
- subarachnoid space
the CSF is present in the ____ ___ and in the ___ ___ of the spinal cord
- subarachnoid space
- central canal
what fluid protects the spinal cord from trauma
- CSF
what are 2 ways that the CFS protects the spinal cord
- Chemical= CSF provides a safe chemical environment for the nerves
- Mechanical= CSF cushions the nerves
where do you perform the lumbar puncture and what is considered a normal colour for the CSF
- performed in the subarachnoid space of lumbar cistern
- CSF should be clear NOT cloudy
what mater is thin, maliable and runs closest to the spinal cord
- pia mater
___ ___ are folds of the pia mater found within the spinal cord
- Denticulate ligaments
Denticulate ligaments stretch from ____ of ___ to attach to ___ and _____
- surface of cord
- arachnoid mater
- dura mater
what is the main function of the denticulate ligament
- to protect the spinal cord by suspending the spinal cord in the middle of the dural sheath
what is structures are located in the epidural fat
- plexus of veins and arteries
the ___ ___ ___ surrounds the spinal cord and acts as a safety mechanism for blood circulation
- spinal artery plexus
the anterior artery plexus has 1 ___ spinal artery and 2 ___ spinal arteries
- anterior
- posterior
T/F: posterior and anterior spinal arteries are reinforced by vertbral arteries
- F: reinforced by radicular arteries
Describe radicular arteries
- they arise from larger vessels
- enter the spinal cord via intervertebral foramen
- anastomse with the spinal arteries
- reinforce the posterior and anterior spinal arteries
describe the great radicular artery of adamkiewicz
- typically arises at lower thorocic vertebral level
- provides major blood supply to lumbar and sacral spinal cord
the prominent radicular artery is ________
- great radicular artery of adamkiewicz
What is the difference betweent he spinal cord and brain white and gray matter ditribution
- Spinal cord= inner gray matter and outer white matter
- bran= inner white matter and outer gray matter
the white matter of the spinal cord contains ____ and _____ axons
- ascending
- descending
What are the 3 horns of the gray matter
- dorsal horn
- ventral horn
- lateral horn
the dorsal horn is composed of ____ ____ and ____
- sensory neurons
- interneurons
the ventral horn is composed of ____ ____ of the ____ neuron and _____
- cell bodies
- motor
interneurons
the ventral horn contains _____ ___ cells
- anterior horn
the lateral horn is composed of ___ ___ of ____ ____ neurons
- cell bodies
- preganglionic sympathetic
the 3 areas of the white matter are…
- posterior funiculi
- anterior funiculi
- lateral funiculi
T/F: more white matter at cervical end of the spinal cord then lumbosacral end with both motor and sensory neurons
true
T/F: the 3rd cervical has more white matter then the 3rd lumbar
T
T/F: The 6th thoracic has less white mater then the 3rd sacral
F: the 6th thoracic has more white mater then the 3rd sacral
each nerve has two roots, what are they
- dorsal root
- ventral root
dorsal root consists _____ fibers carrying ___ information from ___ receptors in PNS to dorsal horn of spinal cord
- afferent
- sensory
- sensory
ventral root consists of ____ fibers which originate in the ____ ___ and travel periphery
- efferent
- ventral horn
stretch reflex is the simplest reflex also known as the ____ ____ ____
- monosynaptic stretch reflex
the stretch reflex is mediated at the ___ ____ level
- spinal cord
Explain the Stretch Reflex
- stretching of the muscle spindes causes stretching of the intrafusal fibers inside the muscle spindles which causes information to travels through dorsal root to active the motor neuron to contract the muscle (** If anyone of you has a better explanation please write it in haha**)
Explain Reciprocal Inhibition in the stretch reflex
- information is sent to the antagonist muscle to stop it from activating (** If anyone of you has a better explanation please write it in haha**)
The flexor withdrawal reflex is a _____ reflex
- polysynaptic
Explain the flexor withdrawal reflex
- medaites the withdrawal of a limb from a painful stimulus
- sensory neurons activate interneurons in the gray matter which excites the motor neurons inervating the ipsilateral limb flexor muscles
when the flexor withdrawal reflex happens what also occurs in the ipsilateral limb
- reciprocal inhibition of the ipsilateral extensor muscles occurs
Explain crossed extensor reflex
- activation of the flexor relfex simultaneouslt causes reflex activation of contralateral limb to take weight of body
- mediated by interneurons (which project across midline to contralateral anterior horn)
- excites motor neurons for contralateral limb extension
- inhibits motor neurons for contralalteral limb flexion
the cervical spinal nerves exit ___ the corresponding vertebra
- above
___ nerve root exits between C7 and T1 vertebra
- C8 nerve root
thoracic, lumbar and sacral spinal nerves exit ____ the corresponding vertebra
- below
Explain the rule of thumb with disc herniation
- for both cervical and lumbosacral disc herniation the affected spinal nerve typically corresponds to the lower of the adjacent two vertebrae
T/F: disc herniation typically corresponds to the upper of the adjacent two vertebrae
F: lower not upper
the most common nerves associated with cauda equina syndrome are
L4-L5 or L5-S1
Cauda equina syndrome may be caused by ___ disc herniation, ___ or other ____ causes
- central
- tumours
- medical
Cauda equina syndrome in S2-S5 creates ____ loss which produces ___ ____
- sensory
- saddle anesthesia
Cauda equina syndrome in S2-S4 nerve roots may cause ___ and ___ dysfunction
- bladder
- bowel
3 important nerve roots in the arm
- C5, C6, C7
C5= main weakness, reflex decreased, region of sensory abnormaility and disc involved
- deltoid, infraspinatus, bicep
- bicep, pecs
- shoulder, upper lateral arm, C4-C5
C6= main weakness, reflex decreased, region of sensory abnormaility and disc involved
- wrist extensors, biceps
- biceps, brachioradalis
- 1st and 2nd finger, lateral forearm
- C5-C6
C7= main weakness, reflex decreased, region of sensory abnormaility and disc involved
- triceps
- triceps
- 3rd finger
- C6-C7
3 important nerve roots in the leg
- L4, L5, S1
L4= main weakness, reflex decreased, region of sensory abnormaility and disc involved
- iliopsoas, quads
- patellar tendon
- knee, medial lower leg
- L3-L4
L5= main weakness, reflex decreased, region of sensory abnormaility and disc involved
- foot dorsiflexion, big toe extension, foot eversion and inversion
- non
- dorsum of foot, big toes
- L4-L5
S1= main weakness, reflex decreased, region of sensory abnormaility and disc involved
- foot plantar flexion
- achilles tendon
- lateral foot, small toes, sole
- L5-S1
what is the main function of the endocrine system
to maintain body homeostasis
the autonomic nervous system exerts control over the function of ___, ___ and ____
- inetrnal organs
- blood vessels
- glands
what is the basic organization of the ANS
- preganglionic neurons
- peripheral synapse in autonomic ganglia
- postganglionic neurons
T/F: sympathetic division responsible for situations in which energy needs to be expended
True
ANS prepares body for ___ or ___ phenomenon
- fight or flight
ANS causes for 5 things to happen, they are…
- increased HR
- raised BP
- sweating
- pupil dilation
- bronchodilation
redistribution of blood so that it leaves skin and GI tract and passes to brain, heart, and skeletal muscle is called ____ ____
- splanchnic vasoconstriction
for the preganglionic transmitters; ____ excites postganglionic neurons in sympathetic ganglia
- acetlchonine
for the postganlionic transmitters; most sympathetic postganglionic neurons release _____
- norepinephrine
T/F: sympathetic system origin is in the dorsal gray columns of spinal cord segments T1-L2
False: sympathetic system origin is in the LATERAL gray columns of spinal cord segments T1-L2
The cell bodies of ______ neurons of sympathetic division are in ______ nucleus in ______ horn of spinal cord
- preganglionic
- interomediolateral
- lateral
myelinated preganglionic fibers from lateral horn leave spinal cord via ______
- ventral nerve root
efferent fibers pass via ____ ____ _____to synapse in paravertebral ganglia (sympathetic trunk/chain ganglion)
- short white communicating ramus
paired paravertebral ganglia form a chain called ___ ___
- sympathetic trunk (chain
preganglionic neurons can travel ___ or ____ sympathetic trunk to synapse in other paravertebral ganglia
- up
- down
postganglionic neurons pass through ____ _____ _____
- gray communicating ramus
_______ neurons enter thoracic/lumbar spinal nerves and travel to target site
postganglionic neurons (efferent fibers)
some preganglionic neurons synapse in ____ ganglia located near aorta
- prevertebral
postganglionic neurons travel to _____ muscle and glands of ____ and pelvic viscera
- smooth
- abdominal
describe function of adrenal meddula
- directly innervated by preganglionic sympathetic neurons
- releases epinephrine and norepinephrine into bloodstream
autonomic responses are regulated by signals from
______ within effector organs
- internal receptors
T/F: afferent fibers from viscera enter spinal cord at dorsal horn and form reflex arcs
True
What are the 4 higher controls of the ANS
- hypothalamus
- midbrain, pons, medulla
- limbic system
- cerebral cortex
what is the role of the hypothalamus in the ANS
- integrates autonomic and endocrine systems, thus
regulating body homeostasis
what is the role of the mindbrain, pons and medulla in the ANS
- regulate cardiopulmonary responses
what is the role of the limbic system in the ANS
- has a role in relationship between emotions and ANS
what is the role of the cerebral cortex in the ANS
- modulates brainstem centres and their effect on body
- Helps with complex situations in sympathetic reaction
