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

A 38 year-old male presents to the E.D. with a swollen left eye. He denies any trauma to the eye. He does report, initially, having a headache \x93on the top of my head.\x94 He now has a generalized headache, fevers, pain behind his eye, and if you open his eyelid he reports double vision. On exam, the patient appears ill with obvious ptosis, proptosis, and inability to track with his left eye during extra-ocular muscle testing. He has hyperesthesia on the skin of his left face, from the forehead to just above the mandible. His fundoscopic exam displays papilledema. Discuss the anatomy of the cavernous sinus. Include boundaries, contents, and relationships. What symptoms are caused by damage to the structures and cranial nerve functional components within the cavernous sinus? (12 pts)

General Comments

• The cavernous is a venous blood sinus (not an air sinus) created by divergent layers of endosteal and meningeal dura. It is located in the middle cranial fossa adjacent to the sella turcica. Immediately medial to the thin lateral border of the sella turcica is the sphenoid air sinus. This relationship puts the cavernous sinus at risk during transsphenoidal surgery of the hypophysis. Five of the 12 cranial nerves have components at risk during pathology of the cavernous sinus.

Bones

• Sella turcica -
• Greater wing of the sphenoid bone -
• Lesser wind of the sphenoid bone -
• Apex of the petrous temporal bone
• Anterior and posterior clinoid processes -

Boundaries and external relationships

• Superior -
• Inferior -
• Anterior -
• Posterior -
• Medial -
• Lateral -

Contents, internal relationships, functional components, and expected clinical symptoms

• Internal carotid artery -
• Internal carotid plexus -
• Sympathetic root of the ciliary ganglion -
• Deep petrosal nerve -
• Greater superficial petrosal nerve -
• Nerve of the pterygoid canal (Vidian nerve) -
• Oculomotor nerve (and branches) -
• Trochlear nerve -
• Ophthalmic nerve (V1) and branches -
• Maxillary nerve (V2) -
• Abducens nerve -
• Inferior hypophyseal artery

Vascularization

• Hypophyseal arteries -
• Ophthalmic vein -
• Sphenoparietal sinus -
• Superior petrosal sinus -
• Inferior petrosal sinus -
• Emissary vein to pterygoid venous plexus -
• Intercavernous sinus sinus -

Innervation

• Meningeal branches of maxillary and mandibular nerves -

Routes of Infection

• Face and Orbit -
• Scalp -
• Infratemporal fossa -
• Ischiorectal fossa and internel vertebral venous plexus -
• Base of skull and external vertebral venous plexus -
• Intercavernous sinus -

A 27 year-old male medical student presents with complaints of left sided headache. He has been studying for an upcoming neuroanatomy exam and is now convinced that he has a \x93brain tumor.\x94 He states it is \x93worse in the morning\x94 and thinks it might be affecting his hearing because he has noted some pain in his left ear. On exam, the patient has some difficulty opening his mouth and it appears that his mandible deviates to the left side. His left external ear canal and tympanic membrane are normal in appearance and he has no hearing deficits on gross testing. When you palpate anterior to the tragus of the left ear it is tender and there is a \x93clicking\x94 appreciated with jaw opening. Review the anatomy of the temporomandibular joint and infratemporal fossa. Include bones, boundaries, contents, bony communications, ligaments, muscles, movements and limitations of movement, vasculature and venous communications, innervation and functional components, relationships to surrounding structures, lymphatic drainage, and significance. (12 pts)

Bones of the Temporomandibular Joint

• Postglenoid tubercle - posterior margin of mandibular fossa of the temporal bone zygomatic process
• Mandibular fossa - receives the head of the mandible
• Articular eminence of the zygomatic process of the temporal bone - anterior margin of the mandibular fossa
• Coronoid process of the mandible - insertion for temporalis muscle
• Neck of the mandible - insertion for the lateral pterygoid muscle (inferior)
• Lingula - attachment of the sphenomandibular ligament
• Angle of the mandible lateral side - insertion for the masseter muscle
• Angle of the mandible medial side - insertion for the medial pterygoid
• Temporal fossa and superior/inferior temporal lines - origin of the temporalis muscle and fascia
• Lateral and medial surfaces of the the lateral pterygoid plate - origins of the lateral and medial pterygoid muscles
• Infratemporal crest - origin of the superior head of the lateral pterygoid
• Zygomatic arch - origin of the masseter muscle

Articulations of the Temporomandibular Joint

• Mandibular fossa
• Articular disk
• Condyle of the mandible
• Superior and inferior synovial joint cavities
• Posterior, lateral, and anterior joint capsule and ligaments

Muscles and movements

• Masseter - elevation and ipsilateral deviation
• Medial pterygoid - elevation and contralateral deviation
• Superior head lateral pterygoid - depression, protraction, and contralateral deviation
• Inferior head lateral pterygoid - elevation, protraction, and contralateral deviation
• Posterior temporalis - elevation, retraction, and ipsilateral deviation
• Anterior temporatlis - elevation
• Infrahyoid muscles - depression of the mandible

Innervation

• Muscles of mastication - mandibular division of trigeminal
• Strap muscles - ansa cervicalis
• Nerve to mylohyoid, thyrohyoid, and geniohyoid
• Hilton's law for the joint capsule plus the auriculotemporal nerve

Relationships of the Temporomandibular Joint

• Medial - petrotympanic fissure and chorda tympani nerve, styloid process and infratemporal fossa
• Lateral - parotid region, parotid gland, facial nerve,
• Superior - mandibular fossa, temporal fossa
• Inferior - lingula, digastric triangle, maxillary artery
• Anterior - articular tubercle
• Posterior - external auditory meatus, auriculotemporal nerve, parasympathetic communicating branch,

Boundaries of the Infratemporal Fossa

• anterior - posterior aspect of maxilla
• posterior - styloid process
• superior - infratemporal crest
• inferior - body of mandible
• medial - pterygoid plate (pterygo maxillary fissure)
• lateral - ramus of mandible

Bony communications

• Foramen ovale - middle cranial fossa to infratemporal fossa, mandibular nerve (GSA, SVE) and lesser superficial nerve (Preganglionic GVE)
• Foramen spinosum - middle cranial fossa to infratemporal fossa, middle meningeal artery
• Petrotympanic fissure - middle ear to infratemporal fossa, chorda tympani nerve (SVA, preganglionic GVE)
• Inferior orbital fissure - maxillary artery becomes infraorbital artery
• Pterygomaxillary fissure - terminal branches of maxillary artery, posterior superior alveolar nerve (GSA and postganglionic GVE)
• Mandibular foramen - inferior alveolar nerve (GSA) and artery

Contents - ligaments, muscles, movements and limitations of movement

• Temporomandibular joint
• Sphenomandibular ligament
• Pterygomandibular raphe
• Lateral and medial pterygoid muscles - protraction and elevation plus secondary actions

Vasculature and venous communications

• Maxillary artery and branches
• Pterygoid venous plexus - communicates with orbit and face, with retromandibular vein to neck and face, foramen ovale to cavernous sinus

Innervation and functional components

• Mandibular branch of trigeminal nerve - GSA SVE
• Chorda tympani - SVA GVE
• Lesser superficial petrosal nerve - GVE

Lymphatic drainage and significance

• Pathways to deep and superfical cervical nodes
• Muscles of mastication
• Spread of infection to intracranial locations
• Gateway to the pterygopalatine fossa and route for injection to treat trigeminal neuralgia