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HSF - Anatomy - Innervation of the heart

Anatomy Exam 2
Nervous system subdivisions
CNS includes
brain and spinal cord
PNS includes
Cranial Nerves and ganglia
• Spinal nerves and ganglia
Spinal Nerve roots
Dorsal and Ventral
Dorsal root of spinal nerve
contains visceral and somatic AFFERENT fibers
contains cell bodies of somatic and visceral afferent nerve fibers
Ventral root of spinal nerve
contains somatic and visceral efferent fibers
Lateral Horn
contains cell bodies visceral efferent fibers
Ventral Horn
contains somatic efferent fibers
Spinal nerve contains
both sensory and motor nerve fibers
functional components of spinal nerve
General Somatic Afferent
General Visceral Afferent
General Somatic Efferent
General Visceral Efferent
General Somatic Afferent
carries sensations from body wall to spinal cord: pain, touch, temp proprioception and pressure
General Visceral Afferent
carries sensations from viscera to spinal cord: mucous membranes glands blood vessels and smooth muscles and cardiac muscles
General Somatic Efferent
motor information from spinal cord to skeletal muscles
General Visceral Efferent
motor information from spinal cord to cardiac muscle, smooth muscles of viscera and glands
ANS branches
includes Sympathetic and Parasympathetic branches - together maintain homeostasis
ANS innervation
vesceral organs, BVs and secretory glands
ANS controlling centers
HT and Brain stem
Differences between PS ANS and S ANS
anatomical, neurotransmitters, physiological effects
Sympathetic Nervous system
acts in sympathy with emotions; fight or flight; more extensive of the ANS branches, ratio of afferent to efferent is 1 to 17;
effects of sympathetic nervous system
increased HR, dilated pupils, constricted arterioles in skin and intestine, dilated muscular arterioles, high BP, pale face, dry mouth, hair stands up, blood rushes to brain heart and skel muscle preferentially, closed alimentary and urinary tract sphincters, bronchi and bronchioles dilated
Sympathetic chain
where pre and post ganglionic neurons interface
Intermediolateral cell column
Lateral Horn from T1-L2, contains cell bodies of preganglionic afferent sympathetic neurons
Preganglionic sympathetic neurons pathway
myelinated neurons with cell bodies in Lateral horn, that leave the spinal cord in ventral root, join the afferent sensory fibers in spinal cord after DRG, pass via white rami communicantes to paravertebral ganglia of sympathetic trunk.
From sympathetic trunk ganglia, efferent sympathetic fibers:
synapse with excitor neuron/postganglionic sympathetic neuron in the ganglion
postganglionic sympathetic neurons
non-myelinated neurons that leave the ganglion and pass to spinal nerves as gray rami communicantes to spinal nerve and distributed to smooth muscles in wall of blood vessles, sweat glands arrector pili,
white and grey rami communicantes
the connections between preganglionic visceral efferent fibers and post ganglionic visceral efferent fibers to and from the spinal cord, white is pre- grey is post-ganglionic.
Splanchnic nerves
formed by efferent preganglionic sympathetic neurons that do not synapse on postganglionic neurons until closer to the effector organ
Greater splanchnic nerve
T5 to T9. pierces the crus of diaphragm and synapses at ganglia of celiac plexus, renal plexus and suprarenal medulla
Lesser Splanchnic nerve
T10 to T11. descends with greater splanchnic nerve synapses on post-ganglionic fibers in lower part of celiac ganglia
Least Splanchnic Nerve
T12. pierces diaphragm and synpases at ganglia of renal plexus
Cervical Ganglion
where T1 to T4 preganglionic sympathetic efferent fibers synapse with post-galglionic sympathetic fibers
cervical postganglionic sympathetic grey fibers
innervate smooth msucels and glands of head neck and upper extremities and heart
Parasympathetic Nervous system outflow
cranial nerves and sacral nerves 2-3-4
Parasympaathetic effect
reverses the change from sympathetic innervation. rest and digest; slower HR, pupils constricted, secretion of saliva and intestinal juices, sphincters relaxes, bladder contracts, glycogen synthesis allowed
Parasympathetic preganglionic cell bodies
located in brain stem and grey matter of sacral segments of spinal cord S2,3,4
Brainstem cells located in the
occulomotor nerve, facial nerve, glossopharyngeal nerve, Vagus nerve
ratio of pre to post ganglionic PARASYMPATHETIC fibers
1 to 3
ratio of pre to post ganglionic SYMPATHETIC fibers
1 to 17
Cardiac plexus
located below the arch of the aorta, formed by sympathetic and parasympathetic nerves
sympathetic innervation of the heart
from upper 5-6 segments of thoracic spinal cord lateral horn
preganglionic neurons innervating the heart end
in the cervical and third and fourth thoracic sympatehtic ganglia
cervical and third and fourth thoracic sympathetic ganglia
where upper 5-6 thoracic spinal segments' sympathetic pregangionic nerves synapse on postganglionic fibers. from here, postganglionic fibers go bilaterally to the heart
Parasympathetic innervation of the heart
vagus nerve
sympathetic innervation of the heart terminates on
SA node, AV node, cardiac muscle cells, coronary arteries
Effects of sympathetic stimulation of the heart
cardiac acceleration, increased force of contraction, dilation of coronary arteries,
adrenergic stimulation of SA node results in
rate of depolarization of pm cells, increase in atrioventricular conduction
Parasympathetic nerves of the heart terminate on
SA node, AV node, Coronary arteries
PS activation effects on heart
HR slows, force of contraction less, constriction of coronary arteries. net saves energy
mechanism of PS post synaptic innervation
acetylcholine binds muscarinic receptors to slow rate of depolarzation of PM cells and atrioventricular conduction and decreases contractility
Cardiac Plexuses
superficial and deep
Superficial Cardiac Plexus
inferior to aortic arh between aortic arch and pulmonary trunk
deep cardiac plexus
between aortic arch and trachial bifurcation
spinal thoracic segments innervating heart
T1 to T5 or T6
SA node function
initiates contraction of the heart
SA node location
subendothelial layer of heart at juntion of SVC and right atrium near superior end of crista terminalis
SA node Heart rate
70 beats per minute
SA node signal sent to
myocardial tissue of both atria
SA node positive and negative innervation by
sympathetic and parasympathetic nervous system
AV node location
internal, inferior aspect of interatrial septum near opening of coronary sinus
AV node receives signal from
SA node
AV node transmits signal
from SA node to AV bundle of His. down through fibrous skeleton of heart along membranous part of interventricular septum
Purkinje fibers
where AV bundle branches split and extend to walls of ventricles
right bundle branch of AV bundle of His stimulates:
muscles of interventricular septum, Anterior papillary muscle, wall of right ventricle
moderator band
carries electrical signal from right bundle of his (interventricular septum muscles) to anterior papillary muscle
Left bundle of His stimulate:
interventricular septum muscles, anterior and posterior papillary msucles and wall of left ventricle
referred pain
pain perceived at different location than its source
zone of referred pain
where somatic sensory neurons that share spinal ganglion with visceral sensory neurons terminate on skin
Cardiac referred pain
pain in upper left limb because of nerves of brachioplexus that shares the spinal cord segments
ganglion shared with cardiac sensory nerves
T1 through T4 or T5
angina pectoris
radiates from substernal and left pectoral regions to left shoulder and medial aspect of left upper limb
part of limb that is stimulated in angina from which nerves?
medial cutaneous nerve of the arm, medial cutaneous nerve of the forearm, ulnar nerves
coronary arteries
T1 through T3 shared by upper limb cutanous nerves