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Pharynx and Oral Cavity


Atlas References

  • Netter: 65–72, 77, 81–86

  • McMinn: 46, 52

  • Gray's Atlas: 552–557, 572–582

Dissection Steps

  • o

    Identify the borders of the nasopharynx, oropharynx, and laryngopharynx on the cadaver ( Fig. 27.1 ).

    Fig. 27.1, Sagittal view of oral cavity, including nasal and pharyngeal regions, revealing hard palate, nasopharynx region, hard palate mucosa, oral pharynx region, laryngopharynx region, retropharyngeal space, and salpingopharyngeal fold.

  • o

    The tensor veli palatini and the levator veli palatini muscles have been identified during the dissection of the pterygopalatine fossa (see Fig. 27.1 and Chapter 26 ).

  • o

    Identify the torus tubarius, a cartilaginous elevation of the auditory tube (see Figs. 27.4 and 27.1 ), and locate the pharyngeal tonsil superior to it.

  • o

    Extending inferiorly from the torus tubarius is the salpingopharyngeal fold, formed by the underlying salpingopharyngeus muscle (see Fig. 27.3 and Plate 27.1 ).

    Plate 27.1, Muscles of soft palate, sagittal and posterior views.

  • o

    Locate the borders of the tonsillar fossa in the oropharynx and identify the palatine tonsil bounded by two arches. Anteriorly, observe the palatoglossal arch, a mucosal fold formed by the palatoglossus muscle (see Fig. 27.1 ).

  • o

    Posteriorly, a second arch, the palatopharyngeal arch, is formed by a mucosal fold from the underlying palatopharyngeus muscle (see Fig. 27.1 ).

  • o

    In the tonsillar fossa, use your forceps to lift the mucous membrane and pull it off of the underlying musculature ( Fig. 27.2 ).

    Fig. 27.2, Removal of mucous membranes and exposure of underlying musculature.

  • o

    Similarly, remove the mucous membrane and expose the palatopharyngeus muscle (see Fig. 27.2 ).

Dissection Tip

In the laryngopharynx, at the level of the epiglottis, the palatopharyngeus, salpingopharyngeus, and stylopharyngeus muscles give the impression that they blend and fuse with the posterior pharyngeal constrictor muscles (see Fig. 27.2 ). However, the posterior pharyngeal constrictors are separated from these muscles by a thin fascia, the buccopharyngeal fascia. In some specimens, this fascia may appear as a white vertical line.

  • o

    Pull the palatine tonsil forward, and expose the palatopharyngeus muscle ( Fig. 27.3 ).

    Fig. 27.3, Musculature of palatine tonsil reflected anteriorly, exposing the salpingopharyngeus, palatopharyngeus, and posterior pharyngeal wall.

  • o

    Continue the dissection by removing the mucous membranes from the palatoglossal arch, and expose the palatoglossus muscle ( Fig. 27.4 ).

    Fig. 27.4, Musculature of palatine tonsil reflected posteriorly, exposing the palatoglossal fold and palatoglossus muscle.

  • o

    Because this muscle is located deep and lateral to the tongue, pull the tongue forward and the palatine tonsil backward to expose it fully.

  • o

    Divide the palatoglossus muscle, and identify the glossopharyngeal nerve ( Fig. 27.5 ).

    Fig. 27.5, To find the glossopharyngeal nerve, the thumb is placed (dashed area) lateral to the epiglottis between it and the palatine tonsil.

  • o

    At the base of the tongue, identify the lingual tonsil .

Dissection Tip

To find the glossopharyngeal nerve, place your thumb at the lateral border of the epiglottis, between the palatine tonsil and the epiglottis. Split the palatoglossus muscle lateral to your thumb (see Fig. 27.5 ).

  • o

    Identify the space between the epiglottis and the tongue. Look for a membranous ridge, the median glossoepiglottic fold, connecting the posterior surface of the tongue to the epiglottis ( Fig. 27.6 ).

    Fig. 27.6, Appreciate the connection between the tongue and epiglottis, the median glossoepiglottic fold, and spaces lateral to it (valleculae).

Anatomy Note

This fold divides the area between the epiglottis and the tongue into two spaces, the valleculae (see Fig. 27.6 ).

Inspection

Anatomy Note

The oral cavity occupies the space between the lips anteriorly and the palatoglossal folds posteriorly. For descriptive purposes, the oral cavity is also divided into the vestibule and the oral cavity proper. The vestibule includes the area between the external surfaces of the teeth and the internal surface of cheeks. The oral cavity proper is the space filled by the tongue.

  • o

    Pull the tongue toward the midline and note the vestibule.

  • o

    Identify the mucous membrane, the frenulum, between the inferior aspect of the tongue and the floor of the mouth ( Fig. 27.7 ).

    Fig. 27.7, Appreciate the lingual frenulum, deep lingual vein, and submandibular duct.

  • o

    Lateral to the frenulum, identify multiple tributaries of the lingual veins and orifices of the submandibular glands, the sublingual papilla (sublingual caruncle ).

  • o

    Continue the inspection of the anterior surface of the tongue, and identify the filiform papillae.

  • o

    Appreciate the much larger and sometimes reddish fungiform papillae.

  • o

    At the posterior surface of the tongue, identify the sulcus terminalis and vallate papillae.

  • o

    At the midpoint of the sulcus terminalis, attempt to visualize the foramen cecum ( Fig. 27.8 and Plate 27.2 ).

    Fig. 27.8, Hard palate reflected posteriorly with view from above revealing filiform, fungiform, and foliate papillae, and at the posterior third of the tongue, the sulcus terminalis (dashed line) and 10 to 12 vallate papillae.

    Plate 27.2, Horizontal section showing superior view of tongue.

  • o

    Pull the tongue medially and make a shallow incision through the mucous membranes lateral to the tongue alongside the mandible ( Fig. 27.9 ).

    Fig. 27.9, Tongue pulled medially with shallow incision (dotted line) through mucous membranes lateral to tongue alongside mandible.

  • o

    Extend the incision toward the palatoglossus but do not sever this muscle ( Fig. 27.10 ).

    Fig. 27.10, Incision extended toward palatoglossus muscle.

  • o

    Lift the mucous membranes of the vestibule and expose the mylohyoid muscle ( Fig. 27.11 ).

    Fig. 27.11, Mucous membranes of vestibule lifted, exposing the mylohyoid muscle.

  • o

    Appreciate neuromuscular structures with the mylohyoid muscle exposed.

  • o

    In the space between the palatoglossus and mylohyoid muscles, identify the lingual nerve descending from the infratemporal fossa into the floor of the mouth ( Figs. 27.12 and 27.13 ). Clean the soft tissues and mucous membranes around the lingual nerve.

    Fig. 27.12, Appreciate the lingual nerve descending from the infratemporal fossa into the floor of the mouth, between palatoglossus and mylohyoid muscles.

    Fig. 27.13, Soft tissues and mucous membranes cleaned around lingual nerve.

Dissection Tip

The dissection of the lingual nerve also continues from the floor of the mouth. Therefore do not attempt to dissect the nerve too deeply.

  • o

    Make an incision through the mucous membrane of the floor of the mouth between the geniohyoid and mylohyoid muscles ( Figs. 27.14 and 27.15 ), and identify the lingual artery ( Fig. 27.16 ).

    Fig. 27.14, Sagittal view of oral cavity, including nasal and pharyngeal regions, revealing hard palate mucosa, upper/lower lips, uvula, and mentalis, genioglossus, geniohyoid, mylohyoid, and salpingopharyngeus muscles.

    Fig. 27.15, Geniohyoid muscle lifted upward to clean soft tissues underneath.

    Fig. 27.16, Sagittal view of oral cavity revealing mucosa of tongue, tongue, genioglossus muscle, lingual artery, mandible, mylohyoid muscle, hyoid bone, and epiglottis.

  • o

    As the mucous membranes are reflected laterally from the midline, identify the submandibular duct (Wharton's duct) and the sublingual gland.

  • o

    Expose the submandibular duct posteriorly to its origin from the submandibular gland, around the posterior edge of the mylohyoid muscle ( Fig. 27.17 ).

    Fig. 27.17, Submandibular duct exposed posteriorly from origin at submandibular gland around posterior edge of the mylohyoid muscle.

  • o

    Distal to the tortuous lingual artery, identify the lingual nerve.

Anatomy Note

The lingual nerve passes medially toward the tongue as it crosses over the submandibular duct ( Fig. 27.18 ).

Fig. 27.18, Appreciate lingual nerve distal to tortuous lingual artery, passing medially toward tongue and crossing over submandibular duct, and hypoglossal nerve posteriorly.

  • o

    Posterior to the tongue, expose the hypoglossal nerve.

  • o

    Pull the tongue posteriorly and expose the mylohyoid muscle ( Fig. 27.19 ).

    Fig. 27.19, Tongue pulled posteriorly, exposing mylohyoid muscle.

  • o

    Trace the lingual nerve as it descends from the infratemporal fossa between the palatoglossus and mylohyoid muscles. Note the submandibular duct crossing the lingual nerve ( Fig. 27.20 ).

    Fig. 27.20, Appreciate lingual nerve descending from infratemporal fossa and submandibular duct crossing over it.

  • o

    With the tongue pulled posteriorly, dissect between the lingual nerve and submandibular gland, and expose the submandibular ganglion (see Fig. 27.20 ).

Dissection Tip

The following landmarks help to identify the different structures in the floor of the mouth ( Figs. 27.21 and 27.22 ):

  • The lingual artery passes deep to the hyoglossus muscle and is often tortuous.

  • The hypoglossal nerve passes superficial to the hyoglossus muscle and is seen at the posterior part of the tongue.

  • Seen from the midline with the tongue in situ, the lingual nerve passes medially toward the tongue as it crosses over the submandibular duct (see Fig. 27.18 ).

  • With the tongue reflected posteriorly, note the submandibular duct crossing over the lingual nerve (see Figs. 27.19 and 27.20 and Plate 27.3 ).

    Plate 27.3, Arteries, veins, and nerves of the tongue.

Fig. 27.21, Sagittal view of oral cavity, including nasal and pharyngeal regions, revealing vestibule, lingual artery, hypoglossal nerve, lingual nerve, mylohyoid muscle, uvula, and hyoid bone.

Fig. 27.22, Sagittal view of the oral cavity, highlighting hard palate and mucosa, tongue, hypoglossal nerve, lingual artery and nerve, mylohyoid muscle, and posterior pharyngeal wall.

  • o

    If time permits, separate and expose the hyoglossus, genioglossus, geniohyoid, styloglossus, and mylohyoid muscles.

Dissection Tip

To identify the following muscles, note their course:

  • The genioglossus muscle runs from the mandible to the tongue.

  • The geniohyoid runs from the mandible to the hyoid bone.

  • The hyoglossus runs from the tongue to the hyoid bone.

  • The styloglossus arises from the styloid process and enters the tongue posteriorly and passes under the palatoglossus to fuse with the hyoglossus muscle.

  • o

    After you identify these muscles, make a small vertical cut near the tip of the tongue, and expose the vertical muscle fibers and intrinsic transverse muscle fibers.

  • o

    Make another incision in the superficial tissue from the dorsum of the tongue, and expose the intrinsic longitudinal fibers ( Fig. 27.23 ).

    Fig. 27.23, Midsagittal section of cadaveric head reveals intrinsic muscle of tongue.

Anatomy Note

In some cadavers, you may find some bony outgrowths in the oral cavity the torus palatinus and torus mandibularis. The torus palatinus and torus mandibularis are variant benign excrescences of the hard palate and mandible, respectively ( Fig. 27.24 ).

Fig. 27.24, Torus mandibularis is a benign, bony outgrowth of the mandible.

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