Thorax Anatomy

Thorax Anatomy

1. Pleural Cavities

   • Parietal Pleura
     • Aspects: --> Cervical --> Costal --> Mediastinal --> Diaphragmatic
     • = lines the chest wall, secretes pleural fluid to reduce friction
   • = potential space between parietal and visceral layers
     • Pneumothorax causes it to become real space - air enters and lung collapses due to breakage of surface tension
     • Lungs grow INTO pleural sac during development (budding week 4, splitting into 2 week 6)
   • Visceral Pleura
     • = firmly attached to the lungs, continuous with mediastinal pleura
   • Pleural Recesses
     • Parts of pleural cavity NOT filled during QUIET inspiration
     • Costo-diaphragmatic
     • Costo-mediastinal

2. Lungs

   • Surfaces: --> Costal --> Vertebral --> Diaphragmatic --> Cardiac
   • Hilum (Root)
     • Bronchi (posterior)
       • Cartilagenous 
     • Pulmonary arteries (superior)
     • Pulmonary veins (inferior)
     • Bronchial lymph nodes?
       • may appear black due to pollution
     • Pulmonary ligament (inferior to hilum)
       • Just a fold of pleural membrane - attaches lung to mediastinum
   • Fissures
     • Oblique (on both)
     • Horizontal (RIGHT only)
   • Cardiac notch (LEFT)
     • where heart sits
   • Lingula (LEFT)
     • Angle between diagphragmatic surface and cardiac notch
   • Impressions
     • LEFT
       • Aortic arch
       • LEFT common carotid (vertically)
       • LEFT subclavian artery
     • RIGHT
       • SVC
       • Azygous arch
   • Tracheobronchial lymph nodes
     • Tracheal
       • either side of trachea
     • Bronchial
       • around bifurcation
     • Bronchiopulmonary
       • hilum of lungs
     • Pulmonary
       • within lungs

3. Positions of viscera

   • Standing up
     • Aortic arch = thoracic plane (T4/5)
     • Trachea bifurcation BELOW plane
     • Diaphragm central tendon = mid-xiphoid process (T9/10)
   • Lying down
     • Aortic arch ABOVE thoracic plane
     • Trachea bifurcation = plane
     • Diaphragm central tendon = xiphisternal junction (T9)

4. Pericardium

   • Fibrous sac
   • Sinuses
     • Transverse pericardial
       • separates aorta and pulmonary trunk
     • Oblique pericardial
       • posterior; behind left atrium
   • Pericarditis
     • Inflammation of the pericardium
     • Can causes capillaries to become leaky = pericardial effusion
       • Fibrous sac cannot expand so limits expansion of heart = lowered CO
     • Chest pain
   • Heart
     • RIGHT atrium
       • Inputs = SVC, IVC, coronary sinus
       • Smooth part
         • Crista terminalis
       • Fibrous muscle
         • Musculi pectinati
       • Fossa ovalis
         • Should be closed - foramen ovale in embryo
       • Tricuspud valve
         • 3 cusps
           • Anterior, posterior, septal
         • Connected to chordae tendinae
     • RIGHT ventricle
       • Papillary muscles
         • innervated by Purkinje fibres
       • Irreg. muscle fibres
         • = Trabeculae carnae
       • Moderator band
         • nerve tissue connecting anterior papillary muscle to septum
       • Infundibulum
         • Smooth wall leading to pulmonary valve
         • Pulmonary valve
           • 3 semilunar cusps
           • Pulmonary trunk
             • LUNGS
     • LEFT atrium
       • Input: pulmonary veins
       • Auricle has musculi pectinati, but smooth inside
       • Fossa ovalis depression
       • Mitral valve
     • LEFT ventricle
       • Mitral valve
         • Bicuspid - anterior and posterior
       • Irreg. muscle fibres
         • trabeculae carnae
       • Chordae tendinae + paillary muscles
       • Aortic valve
         • Semilunar
         • Aorta
           • BODY
     • Coronary vessels
       • RIGHT coronary artery
         • in atrio-ventricular groove
         • RIGHT marginal
           • Small Cardiac Vein
         • Posterior Inter-ventricular
           • (Right posterior descending)
           • Middle cardiac vein
       • LEFT coronary artery
         • Circumflex
         • LAD
           • Great Cardiac Vein

5. Thoracic Duct

   • Arises from the cisterna chyli
     • root of the mesentery of the small intestine
   • Drains lymph fluid
     • Abdomen
     • Pelvis
     • LEFT thorax
     • Head and neck
     • Upper and lower limbs
   • Empties into vein at junction of IJV and left subclavian

6. Trachea

   • C shaped
     • Because oesophagus is behind it
   • Rings of cartilage
     • hold trachea open
   • Bifurcates at T4/5
     • (transverse thoracic plane)
     • "Carina"
       • mucus membrane here responsible for cough reflex
   • Lined with pseudostratified ciliated columnar epithelium
     • glands to secrete mucus

7. Oesophagus

   • Pierces diaphragm at T10
     • through muscular part to help prevent reflux
   • 3 constrictions
     • Upper/ Pharyngeal
       • level of cricoid cartilage
     • Middle/ aortic
       • at bifurcation of trachea
     • Inferior/ diaphragmatic
       • at piercing of diaphragm (lower oesophageal sphincter)
     • = Likely place for obstructions
   • Oesophageal plexus
     • Vagus fibres
     • From sympathetic trunk
   • Thick, stratified epithelium
     • to resist damage/abrasion as food travels down throat
   • Muscular, flat
     • except when food is passing down it

8. Thoracic vertebrae

   • Body
   • Lamina
     • between transverse and spinous processes
   • Pedicles
     • between body and transverse processes
   • Articulations
     • Superior/ Inferior articular facets
       • articulate with inferiort/superior articular facets of vertebra above/below
     • Transverse costal facets
       • articulate with tubercles of ribs
     • Superior/inferior demifacets
       • on vertebral body - articulate with head of rib at that level and one below

9. Superior thoracic aperture

   • Rib 1, manubrium, T1

10. Inferior thoracic aperture

    • Xiphoid process, inf. margin of costal cartilages, ribs 11+12, T12

11. Ribs

    • Typical (2-10)
      • Head
      • Neck
      • Tubercle
      • Angle
        • most likely to break (not in infants)
      • Body
      • Costal groove
        • protects neurovascular bundle
    • Rib 1
      • Head
      • Neck
      • Tubercle
      • Angle
      • Body
    • Ribs 11+12
      • Head
      • Angle
      • Body
    • Infants - horizontal
    • Age - cartilage ossifies
      • becomes harder to move ribcage to breathe

12. Sternum

    • Manubrium
      • Jugular notch
      • Articular sites for clavicle and rib 1
        • primary cartilagenous joints = no movement
      • Superior demifacet for rib 2
    • Body
      • Inferior demifacet for rib 2
      • Articular facets for ribs 3 - 6
      • Superior demifacet for rib 7
    • Xiphoid process
      • Inferior demifacet for rib 7

13. Breast

    • Fat lobules
    • Suspensory ligaments
    • Secretory lobules
      • produce milk
    • Lactiferous ducts
    • Lactiferous sinuses
    • Simple mammary gland
      • All lobules supplying one duct
    • Complex mammary gland
      • All glands serving one nipple
    • Nipple
    • Blood supply
      • Medial + Lateral mammary artieries
        • from internal thoracic
      • Drains to axillary vein
    • Innervated by anterior + lateral cutaneous branches of intercostal nerves 4 - 6
    • Lymph drains to axillary nodes
      • Anterior Posterior Infraclavicular Central Apical Lateral
      • Some to parasternal or other breast

14. Blood Vessels

    • Posterior intercostals
      • 11 pairs: Upper 2 from costocervical trunk of subclavian Lower 9 from thoracic aorta
    • Anterior intercostals
      • 9 pairs: Upper 6 from internal thoracic artery  Lower 3 from musculophrenic artery
    • Internal thoracic artery
      • Musculophrenic
      • Superior epigastric

15. Nerves

    • Intercostal nerves
      • in costal grooves of ribs
    • Long thoracic
      • supplies serratus anterior
    • Medial + Lateral Pectoral
      • Medial = both Pec major and minor Lateral = ONLY Pec major

16. Muscles

    • Pectoralis Major
      • Origins: medial half of clavicle, sternum, costal cartilages 1-7 Insertions: Proximal part of humerus Innervation: Medial and Lateral Pectoral nerves
    • Pectoralis Minor
      • Origins: Surface of ribs 3-5 Insertions: Coracoid process Innervation: Medial pectoral nerves
    • Diaphragm
      • Phrenic nerve (C3,4,5)
        • Central tendon developed at C2, then picked up myotomes from C3,4,5 during development
      • Attachments
        • Sternum
        • Ribs
        • Lumbar vertebrae
          • L and R crurae
        • Lateral arcuate ligaments
          • over quadratus lumborum muscle
        • Medial arcuate ligaments
          • Over psoas major
        • Median arcuate ligaments
          • over aorta
      • Hiatuses
        • Vena Cava
          • T8
        • Oesophagus
          • T10
        • Aorta
          • T12
    • Serratus anterior
      • Origins: Anterior surface of ribs 1-8/9 Insertion: Anterior surface of medial border of scapula Innervation: Long thoracic nerve (C5-C7)
    • Latissimus dorsi
      • Origins: spinous processes of T6-L5+sacrum, iliac crest, ribs 10-12 Insertions: intertubercular sulcus of humerus Innervation: C6-C8
    • Intercostals
      • External
        • \\// used in inspiration
      • Internal
        • //\\ in forced expiration
        • Neurovascular bundle between
      • Innermost
        • //\\ in forced expiration
        • Neurovascular bundle between