Exam 3 - THoracic Cavity : mediastininum and Respiratory Diaphragm

Question 1

What are the subdivisions of the mediastinum?

Answer 1

• Mediastinum = space between lungs
• superior mediastinum
  
  • seperated from inferior by horizontal plane between sternal angle and IV discs T4 - T5
  • Subdivsions
    
    • retrosternal
      
      • begind the sternum
    • prevertebral
      
      • infront of vertebrae
• Inferior mediasinium
  
  • subdivisons
    
    • anterior
    • middle
    • posterior

Question 2

What are the contents of each subdivsions of mediastinum?

Answer 2

• Superior
  
  • retrosternal
    
    • great vessels and branches
    • thymus
  • prevertebral
    
    • Trachea
    • Esophagus
    • Thoracic duct
    • Sympathetic trunks
    • Vagus nerves
• Inferior
  
  • anterior
    
    • Thymus
    • Fat
    • Lymph nodes
  • middle
    
    • Pericardium
    • Phrenic Nerves
    • Pericardiacophrenic artery
    • heart and great vessels
  • posterior
    
    • Esophagus
    • thoracic duct
    • aorta and branches
    • vagus nerves
    • sympathetic trunks
    • azygos system of veins
      
      • (azygos means w/o a twin)

Question 3

What is the blood supply and innervation of the thymus?

Answer 3

• Occupies superior mediastinum on either side of midline
• Located behind manubrium
• Covered by converging Pleura
• Involutes with fat after puberty
• Blood Supply
  
  • Anterior medialstinal arteries from internal thoracic (mammery) art
  • Inferior thyroid arteries from subclavian
• Innervation
  
  • into left brachiocephalic vein
• venous drainage
  
  • Parasympathetic : vagus nerves
  • Sympathetic: Cardiac Sympathetic Plexus

Question 4

What is the overall structure of the pericardium

Answer 4

• Encloses Heart
• Visceral
  
  • serous fused to the fibrous pericardium
    
    • Epicardium
• Fibrous
  
  • fused with central tendon of diaphram
• arterial mesocardium
• venous mesocardium
• Transverse Sinus
  
  • space beween arterial and venous mesocardium
• Oblique Sinus
  
  • Space between right and left pulmonary veins
• ligaments
  
  • pericardiacophrenic Ligament
    
    • fused with sternum
  • Superior and inerior sternopericardial ligaments
• blood supply
  
  • Perocardial arteies
  • Pericaardiacophrenic arteries
  • Musculophrenic Arteries
• nerve supply
  
  • Cn X
  • Phrenic nerve
  • Sympatheic trunk

Question 5

What is the route of the esophagus , its blood supply, musculature, and its innervation

Answer 5

• From base of the neck to:
  
  • Left of the midline
    
    • midline (at level of aortic arch
      
      • left of midline through diaphram
  • behind trachea
  • infront of vertebral column
  • to the right of the thoracic aorta
  • passes through diaphragm at T10 level
• Blood supply
  
  • bronchial artery
  • thoracic aorta
  • Left gastric artery
  • left inferior phrenic artery
• Innervation
  
  • esophageal plexus
    
    • continuation of posterior pulmonary plexus
    • formed by left and right vagus nerves
  • Upper thirds
    
    • voluntary muscle
    • innervation by recurrent laryngeal nerve
  • lower two thirds
    
    • innervated by vagus and sympathetic chain

Question 6

WHat is the pathway of the thoracic aorta (related landmarks and branches)

Answer 6

• pathway
  
  • continuation of aortic arch
  • begins at lower border of T4
    
    • Lies left of midline
  • ends at diaphragm (t12)
    
    • pierces diaphragm
    • continues abdominal aorta
• Branches in thoracic cavity
  
  • pericardial branches to posterior pericardium
  • two bronchial branches to left bronchus
  • small superior (10%) and large inferior (90%) esophageal branches
  • branch to posterior mediastinum
  • nine pairs of intercostal arteries
  • one pair subcostal arteries
  • superior phrenic arteries to superior surface of diaphragm

Question 7

Trace the origin and termination of azygos, hemiazygos, and accessory hemizygos veins and their tributaries

Answer 7

• Azygos vein
  
  • formed below kevek of diaphragm
    
    • by union right ascending lumbarveinand right subcostal vein
  • AScends along right side of thoracic vertebral column
  • arches over root of right lung and enters superior vena cava
  • tributaries
    
    • right intercoastal veins
    • superior intercostal vein
    • hemiazygos vein
    • accessory hemiazygos vein
• Hemiazygos vein
  
  • formed below level of diaphragm
    
    • by union of left ascending lumbar vein and left subcoastal vein
  • pierces diaphragm
  • ascends along left sideof vertebral bodies to level to level of T9
  • Crosses vertebral body and emptiies nito azygos vein
• Accessory Hemiazygos vein
  
  • runs left side of upper thoracic vertebral bodies
  • receives blood from superior intercostal vein and from left intercoastal vein 4 - 8
  • crosses vertebral vody and empties into azygos vein

Question 8

What is the parasternal node?

Answer 8

• Lies behind sternum along course of internal thoracic artery
• Source
  
  • Recieve lymph from thoraccic wall, upper anterior abdominal wall, and idaphragm
  • Also recieve significant amount of lymph from mammary galnd
• dump into parasternal lmph channel

Question 9

what is teh posterior intercoastal nodes?

Answer 9

• Lies in the posterior intercoastal space between heads of ribs
• source
  
  • recieves lymph from thoracic wall and paravertebral regions
• Drain
  
  • into the thoracic duct
    
    • from left and lower right
  • into right lymphatic duct
    
    • from upper right

Question 10

What is the diaphragamatic nodes?

Answer 10

• Lie on upper surface of diaphragm
• Source
  
  • Recieves lymph from diaphragm, pericardium, upper surface of liver
• drain
  
  • to parasternal and posterior mediastinal nodes
    *

Question 11

What is the posterior mediastinal nodes?

Answer 11

Lie along esophagus and descending thoracic aorta

Question 12

What is the brachiocephalic nodes?

Answer 12

Lie along brachiocephalic veins

Question 13

What is source of bronchiomediastinal lymph trunk?

Answer 13

• Recieves from
  
  • posterior mediastinal nodes
  • brachiocephalic nodes
  • tracheobronchial nodes
  • parasternal nodes

Question 14

What is the source and drainage of the left thoracic duct?

Answer 14

• Recieves most lymph from body below diaphragm
  
  • left side of thoracic cavity and part of right plus left internal jugular and left subclavian lymph trunks
• Empties into venous system at junction of left internal jugular vein and left subclavian vein

Question 15

What pathway does the left thoracic duct take?

Answer 15

• Arises form cisterna chyli
  
  • at union of right and left lumbar trunks
• begins on front of vertebral body t-12 or l1
• runs up through the thorax along the fornt of the vertebral column
• at first it lies to the right of midline
• it moves over to the left side when it reaches level T-5

Question 16

What is the source of right thoracic duct?

Answer 16

• Drains upper right thoracic cavity , right upper extremity, and right side of head and neck
• emppties into venous system at junction of
  
  • right internal jugular vein
  • right vein sibclavian vein

Question 17

WHat are thoracic nerves with regard to origin and fiber types composition

Answer 17

• Thoracic sympapthetic chain
  
  • lie against neck of ribs and costovertebral junctions
  • 12 ganglia pairs
    
    • first one fused with inferior cervical (stellate) ganglion
  • cervical ganglia
    
    • superior
    • middle
    • inferior
  • Preganglionic sympathetic supply to the thoracic viscera are from t1 to t5
  • post ganglionic are from
    
    • superior,middle,inferior cervical ganglia
    • t1 - t5 paravertebral ganglia
  • they exit the chain as direct fibers and travel downwards to enter the thorax
    
    • as cardiopulmonary splanchnic nerves

Question 18

how do the thoracic and abdominal splanchnic nerves terminate?

Question 19

What major parasympathetic sypplies to the contents of the thoracic cavity?

Question 20

how does the vagus nerves run?

Answer 20

• cranial nerve x
• major parasympathetic supply to thoracic abdominal viscera
• route
  
  • parallel to esophagus
  • innervates esophagis
  • passes posterior to root of lung on each side
  • pierces diaphragm with esiohagus
  • becomes gastric nerve
  • supplies viscera in thoracic cavity
  • right vagus nerve -> posterior vagus trunk
  • left vagus nerve -> anterior vagus trunk

Question 21

What is the origin and route of the phrenic nerves and list structures supplied?

Answer 21

• Arises in neck form
  
  • ventral rami of c3 c-5
• passes anterior to pulmonary root on each side (only nerve to do so)
• sole motor innervation diaphragm
• sensory fibers to pericardium, mediastinal pleura, and pleural and peritoneal covernigs of diaphragm
• Pain via phrenic nerves usally reffered to base of neck and tip of shoulder
• accompanied by pericardiacophrenic arties
  
  • branches of internal thoracic arteries

Question 22

What are splanchnic nerves with regard to origin and fiber types composition

Answer 22

• Composed of preganglionic fibers and visceral sensory fibers
• supply abdominal viscera
• synapse in prevertebral ganglia
• greater:
  
  • T5 - T9
  • synapse in celaic ganglion
• lesser
  
  • t10 - t11
  • synapses in the superior
• least
  
  • t12 synapses in the aorticorenal ganglion

Question 23

What are the branches of the vagus nerve?

Answer 23

• Branches
  
  • cardiac bracnhes to cardiac plexus
  • pulmonary branches to pulmonary plexus
  • esophageal bracnhes to esophageal plexus
  • left recurrent larynheal nerve from left vagus
    
    • hooks around arc of aorta to left of ligamentum arteriosum
  • right recurrent larngeal nerve from right vagus
    
    • hooks around subclavian artery
    • therefire: arises in neckm not thorax