nerves of the thorax Flashcards
somatic nerves
supply skeletal muscles only
11 pairs of intercostal nerves and 1 pair phrenic nerves
somatic sensory nerves
sensation from the skin muscles and bones and parietal pleura of peicardium
much non-cutaneous sensation is proprioceptive - feedback on function in muscles, tendons, and joints
autonomic
supply sm, cardiac muscle, exocrine glands (heart muscles, bv, bronchi, bronchila glands, sweat gland)
autonomic sensory fibres
carry sensory info from viscera
sympathetic nerves
motor to sm and cardiac muscle, exocrine glands and carry pain sensation from viscera
chest wall sympathetic innevation
from spinal nerves T1-11
thoracic viscera innevation
from spinal nerves T3-T6
parasympathetic nerves
motor- sm, cardiac pacemaker sstem, exocrine glands and carry sensory information providing functional feedback (enteroception) from the viscera
only to viscera
parasympathetic supply to thoracic viscera
from brainstem in vagus nerves - 10th pair of cranial nerves
intercostal nerves
T1-11
segmental nerves - each pair supplies single body segment containing single vertebrae and associated muscles and skin
forms roots from spinal cord
ventral - motor
dorsal - sensory
cell bodies of sensory in ganglion on posteror root just before spinal nerve
cell bodies of motor - in anterior horn in spinal cord
ganglion and junction of roots is in intervertebral foremen
spinal nerve divide into rami
smaller rami is posterior - imnervates posterior muscles and skin
anterior is larger - runs between internal and innermost IC muscles suppluing muscles to midline and branches that innervate skin (2 branches from each nerve - one lateral and 1 anterior)
intercostal nerves
nerves from the anterior rami
dermatome
area of skin supplied by spinal nerve
myotome
muscles supplied by a particular spinal nerve
what is the overlap between dermatomes
50%
phrenic nerves
from anterior rami of 3 adjoining cervical spinal nerves C3, 4, 5
C4 main contributor
effect of damage to motor tracts above C4
disconnects diaphragm
breathing cant occur
asphyxia
plexi
areas of shared distribution of several pairs of spinal nerves - cervical plexus is from C2 - 5
path of phrenic nerve
down neck on muscles from cervical transverse process
pass through diaphragm, either side of the mediastinum
R - follow path of great veins (R brachiocephalic - SVC - fibrous pericardium covering sinus venous and inferior vena cava
L crosses arch of aorta and then runs across fibrous pericardium overlaying the L ventricle
what does each phrenic nerve supply
the muscles on its side of the diaphragm
difference between the autonomic and somatic motor nerve
somatic - axons of lower motor neurons extend from spinal cord to their end plates
autonomic - preganglionic in brain and spinal cord, post ganglionic go to target tissue - reduces cell bodies in CNS, but also reduces precision
SNS
preganglionic T1 - L2
simple segmntal spinal nerves
to body wall travel with somatic but have ganglia
preganglionic leave the spinal cord - synapse in sympathetic chain
postganglionic then return to the spinal nerves
rami communicantes
bundles of nerves joining the sympathetic ganglia to spinal nerves
SNS preganglionic fibres ramus communican
wrapped in white coloured myelin sheath - form white ramus communican
SNS postganglionic fibres ramus communican
not myelinated - grey
sympathetic chain
formed from the ganglia joined by bundles of nerves
extend beyond T1-L2 from mid cervical to pelvis
purpose of the sympathetic chain
allow preganglionic fibres to run up/down for one or more segments before synapsing
therefore provide innervation to the whole body
Visceral SNS
pass to white rami but don’t synapse
instead they synapse closer to the target organ
SNS supplies to heart and lungs
reach cardiac and pulmonary plexi and synapse here
where do teh thoracic visceral supplies arise from
T3-6
where does the sympathetic supply to the heart arise
T2 - 4
PNS
have preganglionic neurons
supply ganglia containing larger number of postganglionic cells
difference with PNS and SNS
no somatic supply in PNS
the entire supply is from the vagus
vagus nerves
also affect head and neck
leave the skull with the internal jugular veins through jugular foramina and run down whole length of neck with internal jugular veins and internal carotid and common carotid arteries - take through the thoracic inlet into superior mediastinum - L and R vagi have different relations
path of the R vagus nerve
posterior to SVC, root of R lung
break into plexus surrounding oesophagus
abdomen
path of L vagus nerve
cross aortic arch
posterior to lung root - join R vagus
form oesophagael plexus
abdomen
what does the oesophagael plexus supply
oesophagus
vagi and heart/lungs
vagi contribute branches to pul and cardiac plexi - synapse in small ganglia before reaching their targets
sensory visceral fibres in the vagus
more numerous than motor fibres
sensory info about CVS, respiratory and alimentary system to vital centres in the brainstem
features of the heart
anterior, sternocostal face (RA)
inferior/diaphragmatic surface from RV
posterior surface - LA
apex - LA
when does the IVC enter teh RA
just after entry into the thorax
lower region
what is teh coronary sinus
a vein that drains the heart - entering the RA close to IVC
what is the R auricle
ear like extension of the RA
overlaps teh root of pul trunk on R side
what is the line of demarcation between RA and RV
atrioventricular groove
R coronary artery lies here
where does the pul trunk leave the heart
RV
passes superiorly adn then L
divide into R and L pul arteries beneath the arch of the aorta
where is teh anterior interventricular groove
obliquely inferiorly to L from root of pul trunk
separates the surfaces of the ventricles
there is also a coronary artery
where does the aorta leave
superior aspect of LV
under cover of pul trunk - emerges on its R
what is the outward bulge in the aortic wall
3 aortic sinuses
accomodate cusps of aortic valve in systole
where do the R and L coronary arteries originate from
2 of the cusps of the aortic valve
path of the R coronary artery
in atrioventricular groove
to diaphragmatic border
descends as posterior interventricular artery
marginal artery is a branch of the R coronary artery - along inferior region of the heart
path of the L coronary artery
atrioventricular groove to division of 2 branches
anterior intrventricular branch - in groove to apex and then to diaphragmatic surface
circumflex branch t L margin and to diaphragmatic surface
cardiac veins
accompany arteries
tributaries of coronary sinus
great cardiac vein accompanies the anterior interventricular artery
middle cardiac vein running
with the posterior interventricular artery
small cardiac vein accompanies the marginal artery
angina pectoris
chest pain caused by transient ischaemia from narrowing arteries
MI - occlusion of arteries and necrosis of myocardium
what are the fossa ovalis
the remnant of foramen ovale
why does the RV look different to the L
thick muscular projections - papillary muscles which the chordae tendineae are attached
describe the cusps in the pul valve
nodular thickening at medial edge of each cusp
allow it to close properly on diastole
how many pulmonary veins are there
4
what leads into the aorta
smooth walled outflow tract
why do teh 4 valves lie in a plane
they are in the fibrous plaque that separates the atria from the ventricles
where is the aortic arch
in the superior mediastinum
landmarks of the aortic arch
begin and end at 2nd CC
top is midway between jugular notch and sternal angle
landmarks of the brachiocephalic trunk
from aortic arch superolaterally to R sternoclaviacular joint
here it splits int R subclavian and R common carotid
landmarks of the R subclavian artery
laterally from R sternoclavicular joint
arch over 1st rib
R common carotid artery
ascends into neck on R side of trachea under sternocleidomastoid
line from R sternoclavicualr joint to lobe of ear
left common carotid artery
from aortic arch posterior and L of BC trunk line to L sternocavicular joint L of trachea L of SCM muscle to L ear lobe
left subclavian artery
from L sternoclavicular joint arching over 1st rib
internal jugular veins
lateral to common carotid to reach sternoclavcular joints
subclavian veins
parallel to SC arteries behind sternoclavicualr joints
R BC vein
from R sternoclavicular joint to inferior border of 1st CC
L BC vein
L sternoclavicular joint to inferior border of 1st CC
SVC
R 1st CC to R 3rd CC
behind the r side of the manubrium and sternum to join R atrium
what plane are the valves in
the atrioventricular plane
from medial end of L 3rd CC to medial 4th ICS
landmarks for the valves
3rd CC pul
3rd ICS aortic
4th CC mitral
4th ICS tricuspid
how do you hear soun from 1 valve
stethoscope downstream of given valve
auscultation of tricuspid
L 5th ICS - sternum
lub
(bell then diaphragm)
auscultation of mitral
L 5th ICS at mid clavicular line
lub
auscultation of pul valve
L 2nd ICS - sternum
dub
auscultation of aortic
R 2nd ICS near sternum
dub
info from palpation of arterial pulse
1) pulse rate
2) rhythm
3) character
4) volume
5) any delays between major arteries (e.g. radiofemoral delay)
how do you plapate
pulps of forefinger and middle finger
palpation in the common carotid artery
in the neck, between the lateral side of thyroid
cartilage and medial border of sternocleidomastoid muscle).
palpation in the superficial temporal artery
in front of the tragus of the ear. This vessel is a
terminal branch of the external carotid artery).
palpation in the subclavian artery
in the supraclavicular region, at the angle between
clavicle and sternocleido mastoid muscle.
palpation in the axillary artery
the medial side of humerus,
posterior to the tendon of short head of biceps
palpation of the brachial artery mid arm
along middle third of humerus , in the medial
bicipital groove behind the medial border of biceps
palpation of teh brachial artery pulse in cubital fossa
on the medial side of tendon of biceps on a fully
extended elbow)
palpation of radial artery
at the wrist over the distal end of radius)
palpation of teh femoral artery
the midinguinal point,
palpation of teh popliteal artery
inferior part of the popliteal fossa, against the
posterior surface of tibia
palpation of the posterior tibial artery
behind medial malleolus-bony prominence on the medial side of
ankle joint
palpation of the dorsalis pedis artery
dorsum of the foot, lateral to extensor hallucis longus
tendon -tendon of the big toe
