IMAGING ANATOMY OF PHARYNX & LARYNX

IMAGING ANATOMY OF PHARYNX & LARYNX is essential to understand subsequent pathology,  The upper aerodigestive tract consists of the pharynx and the larynx. The larynx connects pharynx and trachea.

The pharynx is divided into:

Nasopharynx: extends to inferior portion of  soft palate
Oropharynx: extends from soft palate to hyoid bone
Hypopharynx (laryngeal part of the pharynx): contains pyriform sinuses and posterior pharynx.

The larynx contains:

• The laryngeal surface of epiglottis.                                                                                          • Aryepiglottic folds
• Arytenoid cartilage
• False cords
• True cords (glottis is the space between vocal cords)
• Subglottic larynx

Para-pharyngeal Space    (Fig. 1)

  • it’s Potential space filled with loose connective tissue.
  • A pyramidal Space , with the apex directed toward the lesser cornua of the hyoid bone and the base toward the skull base.
  • It Extends from skull base to mid-oropharynx.
  • BORDERS:
    Lateral: mandible, medial pterygoid muscle
    Medial: superior constrictor muscles of pharynx, tensor and levator veli palatini
    Anterior: buccinator muscle, pterygoid, mandible
    Posterior: carotid sheath.

FIG (1)
  • CONTENTS(Fig. 2)

           • Anterior (prestyloid) compartment : – Internal maxillary artery  – Interior alveolar, lingual, auriculotemporal nerves.

           • Posterior (retrostyloid) compartment:   – ICA, internal jugular vein (IJV) -CNs IX, X, XII -Cervical sympathetic chain lymph nodes.

        • Medial (retropharyngeal) compartment:  Lymph nodes (Rouvière)

FIG (2)
  • Lymphatics (Fig. 3)
    The parapharyngeal space has abundant lymph node groups.
    Lateral pharyngeal node (Rouvière)
    Deep cervical nodes
    Internal jugular chain, including jugulodigastric node
    • Chain of spinal accessory nerve
    • Chain of transverse cervical artery

FIG (3)

Paraganglia (Fig. 4)

Cells of neuroectodermal origin that are sensitive to changes in oxygen and CO2.

Types:

• Carotid body (at carotid bifurcation)
• Vagal bodies
Neoplastic transformation of the jugular bulb ganglion produces the glomus jugulare.

FIG (4)

Fluoroscopic Vocal Cord examination (Fig. 5)

Occasionallyperformedtoevaluatethesubglotticregion (Valsalva maneuver), invisible by laryngoscopy.
• Phonation of “E” during expiration: adducts cords.

• Phonation of “reversed E” during inspiration; distends laryngeal ventricles
• Puffed cheeks (modified Valsalva): distends pyriform
• Valsalva: distends subglottic region
• Inspiration: abducts cords.

FIG (5)

Nodal Stations (Fig. 6)

• IA: between anterior margins of the anterior bellies of the digastric muscles, above the
hyoid bone and below the mylohyoid muscle (submental)
• IB: below mylohyoid muscle, above hyoid bone, posterior to anterior belly of digastric muscle,
and anterior to a line drawn tangential to the posterior surface of the submandibular gland
(submandibular)
Levels II, III, IV: internal jugular nodes       II: (jugulodigastric) from skull base to lower body of the hyoid bone, through posterior edge of the sternocleidomastoid muscle and posterior edge of the submandibular gland.
Note: A node medial to the carotid artery is classified as a retropharyngeal node.
III: hyoid bone to cricoid cartilage
IV: cricoid to clavicle
Level V: skull base to clavicle, between anterior edge of trapezius muscle and posterior edge of
sternocleidomastoid muscle.

• Level VI: visceral nodes; from hyoid bone, top of manubrium, and between common carotid arteries on each side
• Level VII: caudal to top of the manubrium in superior mediastinum (superior mediastinal
nodes).

FIG (6)

Pathologic Adenopathy Size Criteria:

Neck lymphadenopathy by size has poor specificity, and no universal standard exists for determination of adenopathy. Nonetheless, two methods are commonly used:
• Long axis: 15mm in levels I and II, 10mm elsewhere
• Short axis: 11mm in level II, 10mm elsewhere Retropharyngeal nodes should not exceed 8mm
(long) or 5mm (short).

Emerging technologies such as MRI lymph node imaging with iron nanoparticles or PET may prove to be more specific and sensitive.

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THANKS TO PROF.DR. Ralph Weissleder, MD, PhD

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