Larynx and Pharynx - LO1

CONTENTS:

The pharyngeal regions each contain a number of significant anatomical elements. The highlights of each region are as follows:

• • Nasopharynx:

    • Pharyngeal tonsil (adenoid)

    • Pharyngotympanic (auditory) tubes & associated tubal tonsils

  • Oropharynx:

    • Uvula

    • Fauces (L. throat) - the space bounded by the palatoglossal folds (anteriorly) and palatopharyngeal folds (posteriorly)

      • Palatine tonsillar fossae & associated palatine tonsils

    • Root of the tongue (pharyngeal part of tongue) & associated lingual tonsil

    • Epiglottic valleculae

  • Laryngopharynx:

    • Epiglottis

    • Laryngeal inlet

    • Piriform recesses

    • Opening to esophagus

MUSCLES:

The muscular wall of the pharynx consists of two layers: an outer layer of predominantly circular-oriented constrictors, and an inner layer of longitudinally oriented muscles that shorten and widen the pharynx, and elevate the larynx.

The three pharyngeal constrictor muscles in the external layer of the pharynx surround the pharynx, and meet along a posterior midline pharyngeal raphe. When activated, the pharyngeal constrictor mm. serially constrict the lumen of the pharynx.

The superior pharyngeal constrictor m. consists of four parts, each arising from a distinct location (associated by name), and coalescing posteriorly to the superior portion of the pharyngeal raphe. The four distinct parts (and their anterior attachments) include the:

• • pterygopharyngeal part (pterygoid hamulus & occasionally the posterior aspect of the medial pterygoid plate),

  • buccopharyngeal part (pterygomandibular raphe),

  • mylopharyngeal part (posterior portion of mylohyoid line of the mandible), and the

  • glossopharyngeal part (posterolateral tongue). 

The middle pharyngeal constrictor m. originates on the hyoid bone (greater and lesser horns) and the stylohyoid ligament, and inserts on the pharyngeal raphe.

The inferior pharyngeal constrictor m. consists of two parts. These parts (and their attachments) include the:

• • thyropharyngeal part (thyroid cartilage of the larynx), and the

  • cricopharyngeal part (cricoid cartilage of the larynx).

The pharyngeal constrictor mm. are innervated by the pharyngeal plexus (efferently innervated by branches of the vagus nn.). The cricopharyngeal part of the inferior pharyngeal constrictor receives additional efferent innervation by the external br. of the superior laryngeal n. and the recurrent laryngeal n. (both branches of the vagus n.).

The three longitudinal muscles of the inner layer have a less coordinated anatomical arrangement than the constrictor muscles.

Stylopharyngeus m.

Palatopharyngeus m.

Salpingopharyngeus m.

NEUROVASCULATURE:

The pharyngeal constrictor mm. are innervated by the pharyngeal (neural) plexus, which receives efferent (motor) fibers from the vagus nn. (CN X) and afferent (sensory) fibers from the glossopharyngeal nn. (CN IX). The cricopharyngeal part of the inferior pharyngeal constrictor m. receives dual innervation from the pharyngeal (neural) plexus and the vagus n. (CN X) via the recurrent laryngeal n. and the superior laryngeal n. When activated, the pharyngeal constrictors serially constrict the lumen of the pharynx. Some fibers of the middle pharyngeal constrictor mm. can also act as an elevator of the pharynx. The plexus also receives autonomic fibers from the vagus n. (parasympathetic) and superior cervical ganglion (sympathetic).

The pharyngeal constrictor mm. are primarily supplied by the ascending pharyngeal a., a branch of the external carotid artery. Branches from the inferior thyroid a. also may supply the inferior pharyngeal constrictor m. Both superior and middle pharyngeal constrictor mm. may be partially supplied by tonsillar br. of the facial artery (also a branch of the external carotid a.). The superior pharyngeal constrictor m. may also receive blood from the ascending palatine a. (a br. of the facial a.).

The pharyngeal constrictor muscles are drained of blood by the pharyngeal venous plexus, which drains into the internal jugular vv.

FASCIA:

The pharynx is supported by two associated bodies of fascia: pharyngobasilar fascia and buccopharyngeal fascia. The pharyngobasilar fascia (the deep investing/epimysial layer of the external pharyngeal mm.) suspends the superior pharyngeal constrictor m. from the basilar part of the occipital bone and the adjacent temporal bone. The pharyngobasilar fascia is closely associated with the pharyngeal raphe at the pharyngeal tubercle. The buccopharyngeal fascia (the superficial investing/epimysial layer of the external pharyngeal mm.) consists of a thickened epimysium of the superior pharyngeal constrictor that extends anteriorly from the pharyngeal raphe to the superficial surface of the buccinator m. (of the cheek). A condensed band of the buccopharyngeal fascia that extends from the pterygoid hamulus to the posterior end of the mylohyoid line of the mandible is the pterygomandibular raphe. The pterygomandibular raphe connects the buccinator m. to the superior pharyngeal constrictor m.