Thorax

• thoracic cage


  "rib cage"; ribs and costal cartilage; sternum, thoracic vertebrae; floor= respiratory diaphragm
• rib sections


  true ribs: 1-7, have costal cartilage; false ribs: 8-10, indirect attachment to sternum; floating ribs: 11-12, no sternal attachment
• lines of the thorax

  midsternal line; parasternal line (vasculature); midclavicular line (lungs/heart)
• costochondral joint


  Sternal end of rib with lateral end of costal cartilage; Primary cartilaginous (synchondrosis) joint; Strengthened by periosteum surrounding bone and cartilage
• sternocostal joint


  Costal cartilages with sternum; Primary cartilaginous joint (1st rib) Synovial plane joint (ribs 2 -7); Strengthened by radiate sternocostal ligaments
• Costovertebral joint complex (T1-T12)


  each rib articulates with the inferior costal facet of the vertebrae above, and the superior costal facet of the vertebra below; Costovertebral joint - Head of rib with costal facets of vertebrae; Costotransverse joint - Tubercle of rib with the transverse process of vertebrae Plane / gliding joints; Strengthened by radiate ligament
• diaphragm and ribs in different stages of breath

  inspiration shape: dome, expiration shape: flattened; upper ribs (1-6) "pull handle movement", elevates the sternum superiorly and anteriorly; middle 1/3 of ribs (7-10) "bucket handle movement", ribs shaft moves laterally
• diaphragm


  principal muscle of inspiration; openings: caval opening (IVC, phrenic nerve branch), esophageal hiatus (esophagus, vagal trunk), aortic hiatus (descending aorta, thoracic duct); innervated by phrenic nerve (C3-5); origin: costal- inferior border of ribs 7-12, lumbar- vertebral bodies, ALL, arcuate ligament, sternal- posterior surface of xiphoid process; Blood supply: superior and inferior phrenic arteries, musculophrenic artery
• external intercostal muscles


  secondary inspiration muscle; Elevates the ribs during forced inspiration. Provides support for the thoracic cage during respiration. "hands in pockets"
• internal intercostal muscle


  Depress the ribs during forced expiration. Provides support for the thoracic cage during respiration. An interchondral portion of muscle contributes to the elevation of ribs.
• Innermost intercostal muscles


  Depress the ribs during forced expiration (work with internal intercostals). Provides support for the thoracic cage during respiration / Increased muscle tone and rigidity
• serratus posterior (superior and inferior)


  proprioceptive muscles
• subcostal muscle


  Depress the ribs during forced expiration. Provides support for the thoracic cage during respiration
• Transverse thoracis


  Depress the ribs during forced expiration. Provides support for the intercostal spaces and thoracic cage during respiration
• Levatores Costarum


  Elevate the ribs during forced inspiration. Contributes to rotation of the thoracic spine
• intercostal nerve (ventral ramus T1-T6)/ thoracoabdominal nerve (T7-T11)


  supply the thoracic wall. Dorsal (posterior) rami supply joints, back muscles and skin in the thoracic region; Rami communicantes - connect each intercostal nerve to the sympathetic trunk.
• Shingles- Herpes Zoster Infection


  Dermatome distributed skin lesion; Occurs when the VZV, varicella-zoster virus is reactivated
• Pleura

  Visceral Pleura (on lungs), Parietal Pleura (on cage); Pleural space: between visceral and parietal layers, filled with serous fluid
• Lung lobes

  R: 3 lobes; L: (left has less) 2 lobes
• bony thorax


  •Identifying the ribs helps describe soft tissue injuries or lesions • The posterior ribs are easier to identify in a radiograph image •An anteroposterior view makes it difficult to see the trachea and carina but easier to see the boundaries of the heart
• cardiothoracic ratio


  An estimate of heart size using a radiograph image •Normal – the width of the heart less than ½ the width of the chest at the level of the diaphragm

  factors that can influence imaging:

  • Angle of projection

  • Expiration vs inspiration

  • Increased abdominal pressure
• mediastinum


  space between the pleural sacs, includes heart and esophagus

  Regions:

  • Anterior mediastinum – anterior to heart

  • Posterior mediastinum – posterior to heart

  • Superior mediastinum – Superior to the manubriosternal joint
• chronic obstructive pulmonary disorder

  • Elongated lung fields • Narrow mediastinum • Heart appears suspended rather than cradled • Flattened diaphragm
• Collapsed lobe of lung

  • Right upper lobe • Mediastinum shift towards collapsed lobe
• pleural effusion


  • Loss of the costodiaphragmatic recess (costophrenic angle) • Dome shape of diaphragm with a flat density inferior
• superior mediastinum contents


  Trachea and esophagus, Thymus gland, Left common carotid and subclavian arteries, Brachiocephalic trunk, Aortic arch, Brachiocephalic veins, Superior vena cava, Vagus nerves, Recurrent laryngeal nerves, Cardiac nerves, Phrenic nerves, Pericardiacophrenic a and v (Sympathetic trunk)
• 3 branches off the aorta

  brachiocephalic trunk, left common carotid a., left subclavian a.
• anterior mediastinum contents 


  Internal thoracic artery and vein, Thymus gland (also in superior mediastinum)
• posterior mediastinum contents


  Esophagus, Thoracic aorta and branches, Azygos vein, Hemiazygos and Accessory hemiazygos veins, Thoracic duct, Vagus nerve (Sympathetic trunk)
• thoracic duct


  lymphatic; drains to venous angle, between the left subclavian and left internal jugular vein; supplies what side of the body? =Left
• If ETT extends too far past the carina, which bronchus is it most likely to enter?

  Right main bronchi
• Tracheal bifurcation


  T4/T5 (posterior) and manubriosternal junction (anterior)
• Esophagus has 3 parts:

  Cervical (C6-T1) Thoracic (T1-esophageal opening) Abdominal (diaphragm to cardiac orifice); goes through esophageal hiatus; Inn: Sympathetic trunk to esophageal plexus, Vagus nerve to esophageal plexus
• diverticula


  sacs that develop in the weak spots of the mucosal lining; Zenker's diverticulum: most common, found in the cervical region; Parabronchial diverticulum; epiphrenic diverticulum: right above diaphragm
• pericardium


  a serous membrane of the heart

  Layers:

  visceral (epicardium) layer – attached to heart (deepest)

  parietal layer – attached to fibrous pericardium serous fluid in between layers (serous fluid: lubricates heart for pumping)

  Fibrous pericardium – not serous, third layer, purpose is to anchor the heart, anchors inferiorly to the diaphragm, anchors anteriorly to the sternum
• Transverse Pericardial Sinus


  passage within the pericardial cavity; Runs between great vessels; Forms during development; Important landmark for cardiac surgery
• Oblique pericardial Sinus

  posterior aspect; Runs between pulmonary veins, IVC and esophagus
• Atrial Septal Defect

  • Incomplete closure of the oval foramen; Only clinically significant if causes enlargement of the right atrium and ventricle, due to left to right shunt of blood
• Ventricular Septal Defect 


  25% of all forms of congenital heart disease; Left to right shunt of blood through ventricle, increases pulmonary blood flow causing pulmonary hypertension
• Coronary Artery Disease Interventions

  Bypass surgery/ stent