Photo 2. Superior and middle mediastina with lungs and heart removed

Examine the external features of each lung

Find these structures:

• Right & left lungs

• Apex of lung

• Costal surface of lung

• Mediastinal surface of lung

• Diaphragmatic surface (base) of lung

• Lobes of lungs (Superior [Upper], Middle, Inferior [Lower])

• Cardiac notch of left lung

• Lingula of left lung

• Fissures

  • Oblique [major] fissure

  • Horizontal [minor] fissure of right lung

• Hilum of lung

• Root of lung

2.) Examine the right and left lungs.

Photo 3. Lateral views of the lungs

Photo 4. Lobes of the lungs

Photo 5. Heart and lungs

Note: Structures common to both lungs:

• • Apex: superior portion, which extends into the root of the neck and covered with both visceral pleura and cervical parietal pleura

  • Base of lung: inferior portion, closely associated with diaphragm

  • Borders: three borders (anterior, inferior, and posterior)

  • Fissures: both lungs have an oblique fissure, which separates superior & inferior lobes

  • Lobes: both lungs have a superior & inferior lobe

  • Surfaces: three surfaces (costal, diaphragmatic, and mediastinal)

    • Costal surface: largest and convex

      • Related to costal parietal pleura, which is associated with ribs and costal cartilages, bodies of thoracic vertebrae, and innermost intercostal mm.

    • Diaphragmatic surface: most inferior surface, concave

      • Related to diaphragm and base of lung

    • Mediastinal surface: medial and concave surface

      • Related to middle mediastinum

Note: Structures specific to right lung:

The overall structure of the right lung is heavier and shorter than the left lung due to the close relationship of the more superior extension of the right hemidiaphragm. There are two fissures (oblique and horizontal) and three lobes (superior, middle, and inferior).

Note: Structures specific to left lung:

The anterior border of the left lung has a deep indentation, the cardiac notch, caused by close association of the apex of the heart. Inferior to the cardiac notch is a small extension of the superior lobe, the lingula.

3.) Examine structures comprising the roots of each lung. You may need to (bluntly) remove some parietal pleura and loose connective tissue in order to see the structures of the roots of the lungs.

Photo 6. Medial views of the lungs

4.) On either a prosection, or plastinated specimen, examine the structure and relationships of the bronchial tree.

Find these structures:

■    Tracheobronchial tree

• Main [primary] bronchi (right & left)

• Lobar [secondary] - DEMO

• Superior, middle and inferior (right lung) - DEMO

• Bronchus intermedius - DEMO

• Superior and inferior (left lung) - DEMO

• Lingular bronchus - DEMO

• Segmental [tertiary] - DEMO

• Superior segmental bronchus of right inferior lobe - DEMO

Photo 7. Bronchial tree, right bronchi

Photo 8. Bronchial tree, left bronchi

Photo 9. The bronchial tree of the right lung

Examine the ventilation pathway

Find these structures:

• • Larynx

    • Thyroid cartilage

    • Median cricothyroid membrane

    • Cricoid cartilage

• Trachea

  • Carina of trachea

  • Tracheal bifurcation

• Main [primary] bronchi (right & left)

5.) Examine the ventilation pathway from the larynx to the tracheal bifurcation. You may have to reflect the great vessels superiorly to best visualize parts of the pathway. Using scissors, make a sagittal cut through the arch of the aorta between the brachiocephalic trunk and the L. common carotid a. Be careful to not cut the L. vagus n. and the L. recurrent laryngeal n. Once complete, reflect superolaterally the portions of the arch of the aorta and associated vessels to see the ventilation pathway.

Photo 10. Trachea

Note: Colloquially known as the voicebox, the larynx is a conduit between the pharynx (throat) and the trachea. The laryngeal ‘skeleton’ is anterior to C4-C6 vertebrae, and is composed of two major cartilages (thyroid and cricoid) and several other paired and one unpaired cartilages.

Note: The thyroid cartilage consists of two laminae that meet along the midline to create the laryngeal prominence (aka the ‘Adam’s apple’), a palpable structure of the anterior neck. The laminae do not meet posteriorly. The thyroid cartilage sits atop the cricoid cartilage. The cricoid cartilage is the base of the larynx, and is the only element of the larynx that completely encircles the ventilation pathway.

Note: The conus elasticus is a fibroelastic sheet, that shapes the walls of the larynx as a funnel between the thyroid and cricoid cartilages. The anteromedial aspect of the conus elasticus is the (median) cricothyroid ligament, the connective tissue pierced during a cricothyrotomy. The (median) cricothyroid ligament is located by palpating the laryngeal prominence (superiorly) and the anterior aspect of the cricoid cartilage (inferiorly).

Note: The trachea begins at the level of C6, or the inferior border of the cricoid cartilage.

Photo 11. Larynx

6.) Using scissors, open the anterior portions of the primary bronchi and distal trachea to reveal the interior of the tracheal bifurcation and the carina of the trachea.

Photo 12. Tracheal bifurcation

Locate the diaphragm

Find this structure:

• • Diaphragm

7.) View the diaphragm superiorly.

Photo 13. Diaphragm