S3 Dissection Summary

S3 Dissection Summary


Part 1 - Exposing the Pharynx & Esophagus

    • Locate the intervertebral disc between C7-T1, and work from this level superiorly
        • Remove any remaining musculature in the way
    • Lift the esophagus, pharynx, other viscera, and neurovasculature anteriorly to separate from the anterior vertebral column
    • Chisel through the C7-T1 intervertebral disc
    • Disarticulate the superior articular facets of C1 from the occipital condyles
    • Using an autopsy (Stryker) saw, complete a mid-sagittal section of the vertebral bodies of C1-C7
    • Expose the posterior pharynx and esophagus


Part 2 - Muscles of the Pharynx

    • Clean the stylopharyngeus mm.
    • Locate the glossopharyngeal nn. (CN IX)
    • Clean and distinguish the pharyngeal constrictor muscles


Part 3 - Cervical Ganglia

    • Locate and clean the superior cervical ganglion at the C1/C2 level
    • Follow the cervical sympathetic trunk and locate:
        • middle cervical ganglion ( C5/C6 level)
        • inferior cervical ganglion (C7/T1 level)


Part 4 - Carotid Sheath

    • Position (but do NOT remove) the superior cervical ganglion and sympathetic trunk laterally
    • Remove the posterior carotid sheath, and locate the:
    • Locate the branches of the vagus n. (CN X) in this region
    • Locate the carotid bifurcation.
    • Follow the external carotid a. superiorly, and locate the
        • superior thyroid a.
          • superior laryngeal a.
    • Locate the thyrocervical trunk and identify:
        • inferior thyroid a.
          • inferior laryngeal a.


Part 5 - Divisions of the Pharynx

    • Make a sagittal section along the posterior aspect of esophagus and pharynx
    • Locate the:
        • nasopharynx
        • oropharynx
        • laryngopharynx


Part 6 - Larynx

    • Looking at the posterior larynx, locate the:
        • laryngeal inlet
        • ary-epiglottic folds
        • interarytenoid notch
    • Remove the mucosal layer of the laryngopharynx to expose the posterior aspect of the larynx
    • Identify the muscles of the posterior larynx
    • Reflect the inferior pharyngeal constrictor mm. laterally from the thyroid cartilages
    • Locate the cricothyroid m.
    • Remove the pharyngeal mucosa of the ary-epiglottic folds superior to the oblique and transverse arytenoid mm. to reveal the arytenoid cartilages and lateral crico-arytenoid mm.
    • Turn the donor supine, and locate the:
        • thyrohyoid membrane
        • cricothyroid m.
    • Reflect the cricothyroid muscle unilaterally, and locate the cricothyroid joint
    • Mid-sagittally section the thyroid cartilage
    • With the donor prone, disarticulate (cut) a single cricothyroid joint and reflect the posterior edge of the ipsilateral thyroid lamina anteriorly to reveal a closer view of the lateral crico-arytenoid m.
    • Make a midsagittal cut from the posterior laryngeal inlet inferiorly through the cricoid cartilage to open the larynx and visualize internal structures
    • Locate the laryngeal cartilages from an internal view
    • Locate the:
        • laryngeal vestibule
        • vestibular folds
        • rima vestibuli
        • laryngeal ventricle
        • vocal folds
        • rima glottidis
        • infraglottic cavity
    • On one side, remove the mucosal lining of the larynx to expose the contents of the vocal folds and the remainder of the conus elasticus
        • vocalis m.
        • vocal ligament
        • thyro-arytenoid m.
    • Uncover the quadrangular membrane, and its vestibular ligament
    • With the donor supine, investigate the relationships of the larynx to the hyoid bone and the trachea
    • Just proximal to the tracheal bifurcation, excise a section of the trachea, and examine its features