Answer Guide for the Maxillary Nerve Distribution, Left Vertebral Triangle, and Larynx - October 21, 2011

Note. The following is a guide to answering the questions and is not the "answer."

Maxillary Nerve Distribution

A 12-year-old girl was struck in the right eye by a baseball. A CT scan reveals fractures of the lateral orbital wall with bone fragments in the pterygopalatine fossa. Sensory disturbances affect the distribution of the maxillary nerve. Discuss the distribution of the maxillary division of the trigeminal nerve. Include foramina, spaces, and functional components. \xA0 Predict the neural deficits that may result from lesions at different locations along the course of the zygomaticotemporal nerve. (12 pts)

General Comment

  • Trigeminal nerve begins in posterior cranial fossa, crosses superior petrosal ridge inferior to superior petrosal sinus, trigeminal ganglion at trigeminal cave and anterior medial slope of petrous temporal bone
  • Maxillary nerve is a branch from trigeminal ganglion, passes anterior within floor of the cavernous sinus along lateral inferior margin of sella turcica, leaves middle cranial fossa by foramen rotundum
  • The maxillary nerve and its branches pass through the pterygopalatine fossa. These branches disperse to the regions of the face, nasal cavity, nasopharynx, maxillary sinus, orbit, and oral cavity.

The Pterygopalatine Fossa

  • Maxillary nerve and branches (GSA)
  • Pterygopalatine ganglion - site of postganglionic parasympathetic cell bodies (GVE)
  • Nerve of the pterygoid canal - conveys GVA, preganglionic parasympathetic GVE, and SVA from the facial nerve and postganglionic GVE sympathetics from the internal carotid plexus
    • Greater superficial petrosal nerve combines with deep petrosal nerve within the cavernous sinus and near the anterior lip of the lacerate foramen to form nerve of the pterygoid canal
  • Arteries/veins named for the foramina that they pass through

Boundaries of the Pterygopalatine Fossa

  • Anterior
    • inferior orbital fissure - between lesser wing of sphenoid and maxilla
      • Maxillary nerve continues as infraorbital nerve
      • Zygomatic nerve (GSA, postganglionic GVE)
  • Posterior
    • Greater wing of the sphenoid
    • Foramen rotundum: PPF to MCF, greater wing of sphenoid
      • Maxillary nerve (GSA)
      • Artery of foramen rotundum (the maxillary nerve)
    • Body of the sphenoid bone
      • pterygoid canal: PPF to MCF (lacerate foramen)
    • Anterior wall of the sphenoid sinus - pterygoid canal along floor
    • Pterygoid canal - floor of sphenoid sinus
    • Palatovaginal canal - vaginal process of sphenoid bone and sphenoid process of palatine bone
  • Superior: body of sphenoid bone
    • Sphenoid sinus
    • Sphenoethmoidal recess
  • Inferior
    • inferior and posterior wall - palatovaginal canal: PPF to nasopharynx, vaginal process of
    • Inferior and posterior - lesser palatine canal: PPF to soft palate
    • Inferior and anterior - greater palatine canal: PPF to hard palate
    • The greater and lesser palatine canals may share common superior opening, palatine bone and maxilla
  • Medial
    • sphenopalatine foramen - perpendicular plate palatine bone and medial pterygoid plate
    • perpendicular plate of palatine bone
    • medial pterygoid plate
  • Lateral
    • pterygomaxillary fissure - posterior aspect of maxilla and anterior border of lateral pterygoid plate

Foramina and Functional Components

  • Foramen rotundum
    • maxillary nerve
      • GSA - cell bodies in trigeminal ganglion, distribute to face, orbit, nasopharynx, oral cavity, nasal cavity, nasopharynx, sphenoid and maxillary air sinuses
  • Pterygoid canal
    • Vidian nerve (nerve of the pterygoid canal)
      • Formed within lacerate foramen by union of the greater superficial petrosal nerve and the deep petrosal nerve
      • GVE - Postganglionic sympathetic from internal carotid plexus (cell bodies in superior cervical sympathetic trunk ganglion)
      • GVE - Preganglionic parasympathetic cell bodies in lacrimal nucleus and native to greater superficial petrosal nerve (CNVII)
      • SVA - Taste to the hard and soft palate cell bodies in geniculate ganglion and native to greater superficial petrosal nerve (CNVII)
      • GVA - Touch to the soft palate, cell bodies in geniculate ganglion and native to greater superficial petrosal nerve (CNVII)
  • Inferior orbital fissure
    • Infraorbital nerve GSA - Touch to maxillary sinus and face, cell bodies in trigeminal ganglion
    • Zygomatic nerve GSA GVE - Touch to face, motor to mucosa, postganglionic parasympathetic cell bodies in the pterygopalatine ganglion
      • Zygomatic nerve to zygomaticotemporal nerve to lacrimal nerve to lacrimal gland
  • Pterygomaxillary fissure
    • Posterior superior alveolar nerve GSA GVE - enters posterior wall of maxillary sinus within the infratemporal fossa
  • Sphenopalatine foramen
    • Lateral posterior nasal nerves (superior middle and inferior) GSA GVE - distributes to turbinates of lateral posterior nasal wall
    • Nasopalatine nerve GSA GVE SVA - distributes to nasal septum and anterior hard palate
  • Greater palatine canal
    • Greater palatine nerve GSA GVE SVA - distributes to the hard palate
  • Lesser palatine canal
    • Lesser palatine nerve GSA GVE SVA GVA - distributes to the soft palate
  • Palatovaginal canal (pharyngeal canal)
    • Pharyngeal nerve GSA GVE - distributes to the the nasopharynx

Zygomaticotemporal Nerve

  • Lesion proximal to to the branching of the GVE communicating branch disrupts lacrimation and causes paraesthesia to the anterior temporal region of the face
  • Lesion distal to the branching of the GVE communicating branch does not disrupt tearing, but does cause paraesthesia to the anterior temporal region of the face

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Left Vertebral Triangle

A seventy two year-old male comes to your office with complaints of hoarseness and postnasal drip. You note the distinct smell of tobacco. He has ptosis of the left eye and the left pupil is smaller than the right. There is fullness over the left supraclavicular region. A Pancoast tumor is highly suspected. Discuss the anatomy of the left vertebral triangle. Include boundaries, contents, relationships, fascial specializations, vasculature, innervation, and lymphatic drainage. (12 pts)

General Comments

  • The vertebral triangle shares a lateral border with the anterior border of the interscalene triangle. This common border is provided by the interscalene muscle. The vertebral triangle and its contents account for the predominant features of the root of the neck.

Boundaries

  • Superior - Transverse Process of C6 (carotid tubercle is key relationship)
  • Inferior - First rib from vertebral body T1 to insertion of anterior scalene (first part subclavian artery) -
  • Anterior - Prevertebral Fascia
  • Posterior - Intrinsic posterior cervical muscles at posterior border of transverse process C6 - T1
  • Medial - Vertebral bodies of C6 - T1 and longus colli
  • Lateral - Anterior Scalene Muscle

Contents, Relationships, and Fascial Specializations

  • Intrinsic
    • Vertebral artery (transverse process of C6) - transverse foramen, posterior to common carotid at carotid tubercle, vertebral ganglion
    • Vertebral vein (transverse process of C7) - transverse foramen
    • Subclavian artery - parts of, interscalene triangle, subclavian vein is anterior to anterior scalene
    • Thyrocervical trunk and branches (4)
      • inferior thyroid passes posterior to carotid sheath, ascending cervical on anterior scalene medial to phrenic nerve, transverse cervical and suprascapular arteries cross anterior scalene, phrenic nerve, and fascia
    • Costocervical trunk and branches (2) - posterior margin of subclavian, arguably not in vertebral triangle but the ascending cervical and supreme thoracic branches enter vertebral triangle
    • Dorsal scapular artery (inconsistent) - three possible cites of origin including thyrocervical trunk
    • Internal thoracic artery (definitional) - inferior margin of subclavian artery, lateral to vertebral artery
    • Phrenic nerve - crosses anterior scalene to enter vertebral triangle near first rib
    • Stellate and vertebral sympathetic trunk ganglia - anterior surface of the neck of the first rib
    • Ansa subclavia - communication between stellate and vertebral/middle cervical sympathetic trunk ganglia
    • Thoracic duct - enters between brachiocephalic and internal jugular vein, ascends posterior to subclavian artery
    • Roots of the brachial plexus
  • Extrinsic
    • Prevertebral fascia - superficial to phrenic nerve
    • Carotid sheath and contents -
    • Cervical sympathetic trunk -
    • Recurrent laryngeal nerve -
    • Roots C6 - T1 brachial plexus (arguably intrinsic) -

Innervation

  • Cervical and brachial plexuses -
  • Sympathetic trunk and derivatives -

Lymphatic drainage

  • Deep cervical nodes -
  • Thoracic duct

Compression of the common carotid artery

  • Carotid tubercle -

Significance

  • A surgical nightmare of critical structures

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Larynx

A 57-year-old male underwent a left hemithyroidectomy for a benign adenoma.\xA0 The patient complains of persistent hoarseness. He also notes occasional coughing, a sense of shortness of breath, and vocal fatigue. Operative damage to the left recurrent laryngeal nerve is indicated. Review the anatomy of the larynx. Include bones, cartilages, spaces, boundaries, ligaments, muscles, movements and limitations of movement, vasculature, innervation and functional components, relationships to surrounding structures, lymphatic drainage, and function. (12 pts)

General Comment

  • The larynx functions in breathing, swallowing, and phonation
  • Alimentary canal pathway crosses airway pathway

Relationships

  • Superior - oropharynx, nasopharynx, oral cavity, epiglottis
  • Inferior - cricopharyngeus muscle (upper esophageal sphincter), esophagus
  • Anterior - pretracheal fascia, pretracheal space, strap musculature, isthmus of thyroid
  • Posterior - pharynx, vertebral bodies, buccopharyngeal fascia, prevertebral space, carotid sheath and contents, inferior thyroid artery
  • Lateral (left/right) - piriform recesses, hypopharynx, vagal nerve branches, thyroid gland,

Bones and Cartilages

  • Comment - Rigidity of cartilage framework allows for airway patency and muscular attachments
  • Hyoid bone
    • Free floating and from the 2nd and 3rd branchial arches
    • Attachment for the supra- and infrahyoid musculature, tongue musculature
    • Lesser and greater cornu
  • Thyroid cartilage
    • Large shield-like cartilage making up anterior and lateral walls larynx
    • Laryngeal prominence
    • Thyrohyoid membrane
    • Synovial articulation with cricoid cartilage, cricothyroid membrane (anteriorly)
    • Anterior site of attachment for true and false vocal cords
    • Prominence - posterior and superior
    • superior cornu and inferior cornu
  • Cricoid cartilage
    • Complete cartilaginous ring shaped like a signet ring with widest part facing posterior, 2-3 cm in height posteriorly
    • Cricothyroid joint - synovial
    • Continuous with trachea
  • Epiglottis
    • Anterior and superior of larynx
    • Hyoepiglottic ligament and thyroepiglottic ligaments
    • Vallecula on either side of median glossoepiglottic fold and lateral glossoepiglottic folds
    • Elevates during swallowing
  • Arytenoid cartilage
    • Articulates with posterior/superior margin of cricoid cartilage
    • Vocal processes - vocal ligament, vocalis muscle, and thyroarytenoid muscle
    • Muscular process - lateral and posterior cricothyroid muscles, interarytenoid muscle
  • Corniculate cartilage
    • Small cartilages resting on the superior aspect of the arytenoid cartilages
    • Rudimentary in humans, with possible role in esophageal opening in animals
  • Cuneiform cartilage
    • Small isolated cartilage within the aryepiglottic folds
    • No clear function
  • Elastic membranes
    • Quadrangular membrane - superior is aryepiglottic fold and inferior is false vocal fold
    • Conus elasticus - thyroid to cricoid cartilages, superior margin is the true vocal fold

Laryngeal musculature

  • Intrinsic muscles
    • Cricothyroid muscle - acts at cricothyroid joint, rocks thyroid cartilage anterior, external laryngeal nerve, tenses true vocal cord, raises pitch
    • Thyroarytenoid muscle - origin at inner surface of thyroid cartilage and insertion at vocal process of arytenoid cartilage, recurrent laryngeal nerve, includes vocalis muscle at superior edge, adducts, shortens, and tenses vocal folds
    • Posterior cricoarytenoid muscle - posterior cricoid cartilage to muscular process of arytenoid cartilage, abducts true folds
    • Lateral cricoarytenoid muscle - lateral cricoid cartilage to muscular process of arytenoid cartilage, adducts vocal folds
    • Interarytenoid muscle - connects arytenoid cartilages, adducts vocal folds
    • Cricoarytenoid joint - adduction/abduction, rocking
    • Cricothyroid joint - rocking (pivot) of thyroid cartilage on the cricoid cartilage, lengthens and tenses true vocal cord
  • Extrinsic muscles
    • infrahyoid muscles, depressors of larynx, ansa cervicalis, omohyoid, sternohyoid, sternothyroid
    • Suprahyoid muscles, elevators of larynx, thyrohyoid (cervical plexus), stylohyoid (VII SVE), digastric (V, VII, SVE), mylohyoid (V SVE), stylopharyngeus (IX SVE), palatopharyngeus (X SVE), salpingopharyngeus (X SVE)
    • Pharyngeal musculature
      • Superior constrictor - hamulus of medial pterygoid, pterygomandibular raphe, mylohyoid line, and the pharyngeal tubercle, pharyngeal raphe
      • Middle constrictor- greater and lesser cornu of hyoid bone, stylohyoid ligament, pharyngeal raphe
      • inferior constrictor - lateral surface thyroid cartilage, cricoid cartilage, pharyngeal raphe
      • cricopharyngeus - inferior portion of inferior constrictor, upper esophageal sphincter

Mucosal anatomy

  • True vocal fold - superior free edge of conus elasticus
  • False vocal fold - inferior free edge of quadrangular membrane
  • Ventricle: diverticulum between true and false folds
  • Saccule: anterior located extension of ventricle having glandular tissue
  • Epiglottis, aryepiglottic folds
  • Piriform sinuses of laryngopharynx funnel toward esophagus

Voice Production

  • Power source: exhalation
  • Sound source: Vibration of the true vocal fold, subglottic pressure exceeds glottic closing pressure
  • Abduction/adduction and tension of vocal folds
  • Post-production modifier, supraglottic space, oropharynx, nasopharynx, air sinuses
  • Cycle creates fundamental vibration frequency of 80-200 Hz in men, 150-350 Hz in women

Swallowing

  • Closure of true and false vocal folds
  • Larynx raised by extrinsic muscles and epiglottis folds over the aditus (aryepiglottic muscle assists)
  • Bolus passes from vallecula into piriform recess by crossing the lateral glossoepiglottic folds
  • Relaxation of cricopharyngeus allows passage into the esophagus

Innervation

  • Recurrent laryngeal nerve
    • Vagus nerve (CN X) for larynx proper
    • Recurrent laryngeal nerve provides SVE to intrinsic muscles except for cricothyroideus (external branch superior laryngeal nerve), GVA to mucosa inferior to ventricle (infraglottic)
    • Right recurrent laryngeal nerve recurs at subclavian artery, ascends posterior to subclavian artery in tracheoesophageal groove
    • Left recurrent laryngeal nerve recurs at aortic arch, ascends medial to arch in the tracheoesophageal groove.
    • Right and left recurrent laryngeal nerves ascend posterior to the thyroid gland and to the cricothyroid joint to become the inferior laryngeal nerves
  • Internal branch of superior laryngeal nerve (GVE GVA)
    • Superior laryngeal nerve branches for the vagus nerve immediately inferior to the nodose ganglion
    • Internal laryngeal nerve passes through thyrohyoid membrane superior to superior laryngeal artery to provide GVA to the vestibule
    • Mediates afferent limb of cough reflex (GVA)
  • External branch of superior laryngeal nerve (SVE)
    • SVE to cricothyroideus muscle and possibly cricopharyngeus muscle (upper esophageal sphincter), raises pitch

Vascular Supply

  • Paired branches from the external carotid system
  • Superior laryngeal artery arises from the superior thyroid artery, passes through thyrohyoid membrane inferior to the internal branch of the superior laryngeal nerve
    • runs across floor of piriform sinus, supplies mucosa and musculature of larynx mostly superior to false vocal fold
  • Inferior laryngeal artery from inferior thyroid artery
    • runs deep to inferior pharyngeal constrictor along with the recurrent laryngeal nerve, supplies mucosa and musculature of larynx mostly inferior to true vocal fold
  • Superior and inferior thyroid arteries anastomose in the vicinity of the ventricle.

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Topic revision: r2 - 09 Nov 2019, LorenEvey
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