ANS of Thorax Flashcards
features of sensory part of spinal nerves
Afferent
Enters posterior aspect of spinal cord
Cell body in spinal (dorsal root) ganglion
Ganglion=cluster of neural cell bodies outside the CNS
features of motor part of spinal nerves
Efferent
Exits anterior aspect of spinal cord
Cell body in spinal cord (grey matter)
function of dorsal rootlets
convey sensory information into spinal cord
function of ventral rootlets
convey motor information away from spinal cord
location of grey matter in spinal cord and function
ventral horn
contains cell bodies of lower motor neurons innervating voluntary muscles
diseases of grey matter in spinal cord
poliomyelitis
lateral horn
sympathetic system motor neurons cell bodies, present only in thoracic and lumbar areas
dorsal horn sends what kind of impulses
sensory impulses
white matter consists of
bundle of axons
white matter tracts down from..
up to the brain from sensory tracts and down from brain to neurons in grey matter e.g. spinothalamic, corticospinal
branches of spinal nerve
dorsal and ventral ramus
what structure does the dorsal ramus supply
supplies dorsal 1/3rd of the body wall, no contribution to limbs
what structures does the ventral ramus supply
supplies ventral 2/3rd of the body wall including the limbs
direction of sensory (afferent) impulses
towards CNS
Direction of motor (efferent) impulses
away from CNS
Somatic sensation
we are acutely aware of these; well localized (e.g. sharp pain, touch) Generally originate in body wall structures rather than internal organs
visceral sensation
: either imperceptible, only vaguely localizable, or only become perceptible in disease. From blood vessels and internal organs (viscera
voluntary motor impulses function
control skeletal muscle over which we have voluntary control
visceral motor impulses function
control muscle over which we do not normally have voluntary control
sympathetic nervous system
Alert, wary, increases heart rate & contractility, blood pressure rises Blood vessels to muscles dilate -ready for running away Pupil dilation •for good distant vision Bronchioles dilation Close sphincters
parasympathetic nervous system
Decreases heart rate and contractility Relaxes the gut tube muscle Pupil constriction Bronchioles constriction Open sphincters
are preganglionic fibres myelinated or unmyelinated in sympathetic nervous system
myelinated
are postganglionic fibres myelinated or unmyelinated in sympathetic nervous system
unmyelinated
location of thoracic splanchnic nerves
Greater - T5 T9
Lesser - T10, T11
Least - T12
3 types of splanchnic nerves
lumbar splanchnic
sacral splanchnic
thoracic
where does the thoracic sympathetic trunk track down to
Continuation of cervical trunk
Lies under the parietal pleura
Crosses the diaphragm
Continues as lumbar trunk
where does T1 join
joins inferior cervical ganglion to form Stellate Ganglion
preganglionic cell bodies of sympathetic cardiac plexus location
Preganglionic cell bodies
Lateral (grey) horn, upper thoracic cord
postganglionic cell bodies of sympathetic cardiac plexus location
Cervical & upper thoracic ganglia in the sympathetic trunk.
Post ganglionic fibres run to
SA & AV nodes, coronary vessels & cardiac muscle
preganglionic cell bodies of parasympathetic cardiac plexus location
Preganglionic fibres
vagus N. -relay in heart wall
postganglionic cell bodies of parasympathetic cardiac plexus location
Postganglionic fibres
SA & AV nodes, coronary vessels
main functions of cardiac plexus
Regulating heart rate Force of each contraction Cardiac output
function of sympathetic cardiac plexus
Increase heart rate
Increase force of contraction Dilate coronary arteries
function of parasympathetic cardiac plexus
Decreases heart rate Reduces force of contraction Constrict coronary arteries
how is the myocardiocyte death signalled in to the body
Pain fibres (visceral afferents) are stimulated
These run with sympathetic nerves
Somatic senses also enter at this level
The brain is unable to distinguish between visceral and somatic pain
pain in somatic regions
how is myocardiocyte referred to arm
Visceral afferents to lower cervical and upper thoracic segments of cord Referred to T1 – T4 dermatomes (arm)
how is myocardiocyte referred to arm
Afferents from pericardium run along the phrenic nerve
C 3, 4, 5 pain in neck & jaw
sympathetic function pulmonary plexus
Bronchodilation
Vasoconstriction
(NB – medications)
parasympathetic function pulmonary plexus
Bronchoconstriction
Mucus secretion
Vasodilation
Cough reflex (afferent)
