RA week 3 Flashcards
boundaries of superior mediastinum?
anterior = manubrium posterior = bodies of T1-T4 vertebrae inferior = transverse throacic plane superior = thoracic inlet lateral = parietal pleura
contents of superior mediastinum?
from anterior to posterior
- thymus*
- brachiocephalic veins* + SVC
- arch of aorta*
- trachea*
- oesophagus
- phrenic and vagus nerves
- lymphatics
*= not found in any other part of the adult mediastinum
important venous and arterial structures in superior mediastinum?
veins draining head, neck and upper limb
- right + left brachiocephalic vein (unite to form SVC within superior mediastinum)
- directly posterior to these structures = arch of the aorta
- branches= brachiocephalic trunk, left common carotid artery, left subclavian artery
- brachiocephalic trunk - divides into right subclavian artery + right common carotid artery
- directly posterior to these structures = arch of the aorta
vessels in superior mediastinum
where is vagus nerve found in thorax?
specifically?
passes through superior mediastinum then posterior mediastinum
- right vagus = anterior to right subclavian artery, right recurrent laryngeal nerve loops under right subclavian artery
- left vagus = between left common carotid and left subclavian artery, left recurrent laryngeal nerve loops under arch of aorta (posterior to ligamentum arteriosum)
parasympathetic innervation vagus nerves?
gives branches to:
cardiac plexus deep to arch of aorta
right and left pulmonary plexus on right and left main bronchi
vagus nerves will then continue onto surface of the oesophagus where they form the oesophageal plexus
continue as anterior and posterior vagal trunks (mainly left and right nerves respectively)
phrenic nerve roots?
right phrenic nerve pathway?
anterior rami C3, 4, 5
right phrenic nerve
- runs alongside right brachiocephalic vein, SVC and pericardium on over right atrium
- anterior to root of right lung
- pierces diaphragm near caval opening (IVC)
left phrenic nerve pathway?
- lies between subclavian artery + vein, and to the left of arch of aorta anterior to vagus
- anterior to root of left lung onto surface of pericardium over left atrium + ventricle
- pierces diaphragm to left of pericardium (close to apex of the heart)
note phrenic nerves lie anterior to vagus nerves
vagus nerves disappear as they travel deeper to latch onto surface of oesophagus
trachea begins at what level?
divides? what is this?
what is found on trachea anteriorly?
posteriorly?
trachea begins at C6/7 below the larynx
divides into R + L bronchi at the carina (T4/5)
(carina = V-shaped cartilage at transverse thoracic plane T4/5)
C-shaped cartilages anteriorly
trachealis muscle forms posterior wall of the trachea (allows expansion of the oesophagus - as if trachea had complete rings of cartilage, oesophagus would be trying to expand against rigid structure)
what is the oesophagus?
where does it begin?
pathway?
constrictions?
oeosphagus - fibromuscular tube
begins at C6 (continuation of pharynx)
initially lies to right of aorta then crosses anteriorly before piercing diaphragm at T10
short abdominal course before entering stomach
3 constrictions form:
- arch of aorta
- left bronchus
- diaphragm
oesophagus seen posterior to trachea
boundaries of posterior mediastinum?
structures from superior mediastinum?
superior = transverse thoracic plane
anterior = posterior wall of pericardium + slope of the diaphragm
posterior = bodies of T5-T12 thoracic vertebrae
lateral = parietal pleura
oesophagus + vagus nerves present in posterior mediastinum (travel down from superior mediastinum)
vessels found in posterior mediastinum?
when does it begin? becomes?
branches?
thoracic aorta + its branches
throacic aorta is continuation of arch of aorta, begins at T4/5 (transverse thoracic plane)
becomes abdominal aorta after passing through aortic hiatus of diaphragm
gives branches to:
- oesophagus
- pericardium
- bronchi
- thoracic wall
- diaphragm
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aorta within posterior mediastinum giving off posterior intercostal arteries to supply thoracic wall
veins posterior mediastinum?
azygos venous system
right side of thoracic wall = drained by posterior intercostal veins that drain directly to azygos vein
left side thoracic wall = drains initially to hemiazygos + accessory hemiazygos vein then eventually to azygos vein
azygos venous system?
right hand side
- intercostal spaces 2-11 + subcostal vein all drain directly to azygos vein
- 1st posterior intercostal vein (because of superior location) will drain directly to right brachiocephalic vein
left hand side (3 groups of 4 veins)
- post. intercostal veins 1-4 drain directly to left brachiocephalic vein
- post. intercostal veins 5-8 will drain to accessory hemiazygos vein
- post. intercostal veins 9-11 + subcostal vein will drain to hemiazygos vein
- (hemiazygos + accessory hemiazygos will then drain across into azygos vein which will drain into SVC)
azygos venous system?
right hand side
- intercostal spaces 2-11 + subcostal vein all drain directly to azygos vein
- 1st posterior intercostal vein (because of superior location) will drain directly to right brachiocephalic vein
left hand side (3 groups of 4 veins)
- post. intercostal veins 1-4 drain directly to left brachiocephalic vein
- post. intercostal veins 5-8 will drain to accessory hemiazygos vein
- post. intercostal veins 9-11 + subcostal vein will drain to hemiazygos vein
relationship of azygos vein to other structures within posterior mediastinum
pic A = azygos vein can be seen receiving right posterior intercostal veins. Note how azygos vein runs along bodies of thoracic vertebrae next to aorta, travels across to drain into SVC
Pic C = hemiazygous draining into azygos anterior to vertebral bodies
posterior mediastinum lymphatics?
thoracic duct
where does thoracic duct empty?
where is it found?
empties into venous system at junction of left internal jugular and left subclavian veins (left venous angle)
in posterior mediastinum between aorta and azygos vein (on the bodies of the thoracic vertebrae)
in posterior mediastinum
in superior mediastinum
(thoracic duct empties into left venous angle)
nerves posterior mediastinum?
technically sympathetic chain is not part of posterior mediastinum
extends entire length of vertebral column
sympathetic outflow from T1-L2
…
white rami commincantes?
grey?
WRC = myelinated nerves that travel from spinal cord into sympathetic chain
GRC = post-ganglionic, non-myelinated fibres that pass from chain into spinal nerve to be distributed to body wall
…
what arise from sympathetic chain in thoracic region?
function?
splanchnic nerves
- greater splanchnic (T5-T9 ganglia)
- lesser splanchnic (T10, T11 ganglia)
- least splanchnic (T12 ganglion)
supply sympathetic innervation to abdominal viscera (pass thru diaphragm)
least splanchnic nerve is very difficult to see (located behind diaphragm)
what is diaphragm?
features?
sheet of muscle that bulges into thoracic cavity and separates it from the abdominal cavity
- right + left dome, and central tendon
- caval opening (IVC), oesophageal hiatus (oesophagus + vagus nerves), aortic hiatus (aorta, thoracic duct, azygos vein)
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ligaments diaphragm?
median arcuate ligament (most medial)
medial arcuate ligament
lateral arcuate ligament
passage through openings in diaphragm?
T12?
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- T8: IVC → caval opening
- T10: oesophagus + vagal trunks → oesophageal hiatus
- T12: aorta, thoracic duct and azygos vein -→ aortic hiatus
also at T12…
- greater + lesser splanchnic nerves → openings in crura
- least splanchnic nerve + sympathetic trunk → behind medial arcuate ligament
right dome bulges more superiorly due to liver
can also see IVC through caval opening
superior mediastinum
pic A = structures in sup. mediastinum are mostly covered by extension of pericardium around the great vessels - can see left phrenic nerve
pic B = righ phrenic nerve (if lungs present would cross anterior to lung hilum)
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superior mediastinum once pericardium has been removed
- pic A = left and right brachiocephalic veins uniting to form SVC
- pic B = arch of aorta and its branches - brachiocephalic, left common carotid and left subclavian (note that although there are 2 brachiocephalic veins, there is only one brachiocephalic artery)
- pic C = vagus nerve passes through superior mediastinum - on left side the recurrent laryngeal branch wraps under the arch of the aorta
trachea and oesophagus also lie in superior mediastinum
- pic A = division of trachea into left + right main bronchi - the area where trachea divides is called the carina
- pic B = right vagus nerve can be seen lying close to trachea - it has recurrent laryngeal branch but this passes close to the right subclavian artery so is not visible on this photograph
inferior mediastinum (ant, post + middle)
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posterior mediastinum
pic A = structures lying on vertebran bodies - descending (thoracic) aorta is largest structure and passes across the left side of vertebral bodies
pics B + C = thoracic duct lies more medially (not difference in individuals - duct is very dark in B but very pale in C), pic C also shows azygos vein to right of verteral body
posterior mediastinum
descending aorta branches to give posterior intercostal arteries
pic A = arteries on right side (there are equivalent vessels on the left)
pic B = intercostal spaces drained by posterior intercostal veins that drain into azygos/hemi-azygos/accessory hemiazygos veins
right side to draining into azygos vein
posterior mediastinum
pic A = sympathetic chain passing along lateral edge of vertebral bodies on right side - can also see greater splanchnic nerve leaving chain and passing inferiorly towards abdomen
pic B = rami communicantes - also shows intercostal nerve in intercostal space
contents of intercostal spaces can be seen more easily on posterior thoracic wall
pic A = parietal pleura on inner surface of ribs
pic B = intercostal space - intercostal vein sits immediately inferior to the rib, then intercostal artery and finally intercostal nerve
pic A = left and right domes, central tendon covered by pericardium
pic B = can see phrenic nerves piercing surface of diaphragm
quadrants abdominal wall?
regions abdominal wall?
e.g. iiver?
abdominal wall can be further divided into regions via imaginary mid-clavicular, sub-costal and trans-tubercular lines
9 regions: right + left hypochondrium, epigastric, right + left lumbar, umbilical, right + left inguinal, suprapubic
liver is in right upper quadrant but more specifically liver fills the right hypochondrium (and is so large that it passes into epigastric and right lumbar regions)
layers of abdominal wall?
superficial fascia layer?
skin → superficial fascia (fatty layer that contains small cutaneous nerves and vessels) → muscle layers and deep fascia → extraperitoneal fascia (contains retroperitoneal structures such as the kidneys) → parietal peritoneum (deepest layer)
superficial fascia changes structure on lower part of abdominal wall
- above umbilicus = similar to that found everywhere else in the body
- below umbilicus splits into 2 layers:
- superficial (fatty) = Camper’s fascia
- deep (membranous) = Scarpa’s fascia
Scarpa’s fascia? attachments?
found?
males?
females?
thin, membranous layer with little fat that attaches to pubic symphysis and linea alba in the midline
below inguinal ligament it fuses with fascia of thigh to form fascia lata
also attaches to poserior part of perineal membrane to become Colle’s fascia (superficial perineal membrane)
males = fascia of penis, dartos fascia of scrotum, fundiform ligament of penis
females = contributes to labia majora
function of muscle layers of anterolateral abdominal wall?
supports abdominal viscera
allows movement
function of muscle layers of anterolateral abdominal wall?
supports abdominal viscera
allows movement
external oblique fibre direction + attachment?
feature of external oblique? where does this attach? function?
what structure does it form? attachments?
function of external oblique?
innervation?
infero-medial (hands in pockets) from ribs 5-12 to iliac crest and linea alba
has tough sheet of connective tissue aponeurosis - meet in midline to form linea alba, ataches from xiphoid process to pubic symphysis
forms anterior wall of rectus sheath (hides rectus abdominus from view)
lower border of aponeurosis forms inguinal ligament - between ASIS and pubic tubercle
function = flex trunk using both, turn to same side using one
innervation = anterior rami T7-T12 (i.e. lower 6 intercostal nerves - T12 also called “subcostal nerve”)
internal oblique fibre direction + attachment?
feature of internal oblique? attachments? function?
function of internal oblique?
innervation?
(deep to, smaller and thinner than external)
fibres supero-medial (hands on chest) from thoracolumnar fascia, inguinal ligament + iliac crest to ribs 9-12
has aponeurosis that meets in midline at linea alba, attaches to pectineal line, pubic crest
contributes to rectus sheath (discussed later)
function = both sides flex trunk, one side bends trunk
innervation = anterior rami T7-T12 and L1
transversus abdominus found?
fibre direction? function?
feature? function?
attachments?
innervation?
deep to internal oblique
transverse direction - only act to provide some support to body wall
also has an aponeurosis that contributes to posterior wall of rectus sheath
from thoracolumbar fascia, iliac crest, inguinal ligamanet and costal cartilages ribs 7-12 to → linea alba, pubic crest and pectineal line
innervation = anterior rami T7-L1 (like internal oblique)
rectus abdominus attachments?
function? used during?
feature?
innervation?
from pubic tubercle, crest and symphysis to → xiphoid process and costal cartilages of ribs 5-7 (fibres run upwards)
flexion of trunk, support/compression of abdominal wall (used during sit ups)
does not have aponeurosis like the other muscles but is instead contained within the rectus sheath
innervation = anteior rami T7-T12 (like external oblique)
pyramidalis muscle?
attachments?
function?
innervation?
often absent - small, triangular muscle anterior to rectus abdominis
from pubis to linea alba
tenses linea alba
innervation = anterior ramus T12
rectus sheath made up of?
above costal margin?
above umbilicus vs below umbilicus (halfway between umbilicus and pubic bones)
- above umbilicus = anterior wall made up of aponeuroses of external + internal oblique, posterior wall made up of aponeuroses of internal oblique + transversus abdominis. Internal oblique aponeurosis froms 2 layers that pass around rectus abdominis.
- below umbilicus = aponeoroses of external oblique, internal oblique + transversus abdominis all lie anterior to rectus abdominis. Posterior wall is formed from transversalis fascia
(see pic)
rectus abdominis attaches to rib cage and at this level it lies directly on the surface of the costal cartilages - aponeurisus of external oblique lies superior to rectus abdominis forming anterior wall of rectus sheath
lower ⅓rd rectus sheath?
therefore…
transition marked by?
lower ⅓rd rectus sheath (halfway between umbilicus + pubic bones) - all aponeuroses lie above rectus muscle
therefore rectus abdominis lies directly on transversalis fascia
transition point from strong aponeurosis to delicate transversalis fascia is called arcuate line (curved line between shiny white aponeurosis + yellow fascia)
posterior surface of anterior abdominal wall?
vessels?
there are 3 “folds”
- median umbilical ligament - urachus remnant (only 1)
- medial umbilical ligament - unbilical artery remnant (1 each side)
- lateral umbilical fold - contains inferior epigastric artery and vein (1 each side)
inferior epigastric artery and vein lie directly inferior to rectus abdominis and supply blood to/drain blood from anterior wall
superficial vessels and nerves abdominal wall?
run in superficial fascia and supply this layer and skin
veins drain towards axilla or femoral vein
arteries arise from femoral artery or internal thoracic artery
nerves are anterior and lateral branches of the intercostal nerves
iliohypogastric nerve from L1 also supplies the wall in the inguinal region
deep vessels and nerves abdominal wall?
Deeper vessels supply the muscles of the walls e.g. lumbar and intercostal arteries
upper part of rectus abdominis supplied by terminal branch of the internal thoracic artery – the superior epigastric artery
rest of rectus abdominis supplied by the inferior epigastric artery (a branch of the external iliac artery)
ilioinguinal + iliohypogastric nerves are from L1 roots in the lumbar plexus
they are sensory nerves to pubic region and medial thigh
supply motor innervation to internal oblique and transversus abdominis
lymphatic drainage abdominal wall?
lymph nodes found?
Lymphatic drainage divided into superficial + deep
Superficial (skin and fascia) – above the umbilicus is to nodes in the axilla, below the umbilicus is to nodes in the inguinal region
Deep – upper region is to parasternal nodes, middle areas to lumbar nodes + lower areas to external iliac nodes.
deep lymph nodes lie near arteries:
- parasternal nodes lie near internal thoracic artery
- lumbar nodes lie either side of the abdominal aorta
- external iliac nodes surround the external iliac artery
nerve supply to anterolateral abdominal wall?
T7-T11 intercostal nerves (+subcostal T12) are main supply to anterolateral abdominal wall (some supply from L1)
pic A = superficial muscles of the thoracic wall. muscles of abdominal wall also attach to the ribcage - most superior parts of rectus abdominis and external oblique can be seen in this photo
pic B = can see external oblique attaching to ribs + attachment points of serratus anterior
pic B = layer of superficial fascia under the skin that is continuous with the fascia of the thorax, lower limb + pelvis
pic C = umbilicus fascia forms 2 layers. Fatty layer called camper’s fascia + membranous layer called Scarpa’s fascia
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pic A = difficult to see any muscle fibres because of aponeurosis of external oblique. This forms the anterior layer of the rectus sheath.
pic B = muscle fibres of external oblique and its aponeurosis passing medially towards linea alba
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pic A = external oblique
pic B = internal oblique deep to external
pic C = deep to internal oblique is transversus abdominis. note fibres of transversus abdominus run horizontally across body wall
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pic A = anterior wall of the abdomen with anterior layer of rectus sheath reflected to show rectus abdominis. not emuscle fibres run in vertical orientation and have several fibrous intersections - “6-pack” appearance
pic B = posterior surface of rectus sheath. ⅔rds way between umbilicus and pubic bones this sheath alters. prior to this point the aponeuroses of external oblique and ½ of internal oblique passed superior to rectus abdominis and the other ½ of internal oblique + aponeurosis of transversus abdominis passed inferior to rectus abdominis
Pic C = transition point where all of the aponeuroses pass over the anterior surface of rectus abdominis. This leaves rectus abdominis lying on the transversalis fascia. This can be seen as an area where the shiny aponeurosis of the posterior wall of the rectus sheath ends and the more yellow membranous layer of the transversalis fascia can be seen instead. This is called the arcuate line and has been highlighted by a dotted line in photograph C
