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Written Examination Part IV. - Essay

Note: This is an outline of topics to be covered. It is not the "answer key." It is an answer guide.

Cavernous Sinus

A 48 year old male presents to the emergency department with complaints of a severe headache. He recently underwent root canal therapy for a periapical abscess on his left maxillary canine. He awoke today with a severe left sided headache, 10/10 in intensity, and he states it feels like it is "sitting behind my eye." On exam, you note mild proptosis and fixed adduction of the left eye. Discuss the anatomy of the cavernous sinus. Include boundaries, contents, relationships and functional components of nerves. What symptoms are caused by damage to each structure within the cavernous sinus? (12 pts).
  • General Comments
    • The cavernous is a venous blood sinus (not an air sinus) created by divergent layers of periosteal 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 sphenoid -
    • Apex of the petrous temporal bone
  • 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 -
    • Oculomotor nerve (and branches) -
    • Trochlear nerve -
    • Ophthalmic nerve (V1) and branches -
    • Maxillary nerve (V2) -
    • Abducens nerve -
  • 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

Vertebral Triangle

A 72 y.o.m. comes to your office with complaints of hoarseness. He has noticed it for three weeks. He thinks he has “allergies” causing some post nasal drip that has resulted in his hoarseness. His only other complaint is some blurred vision. On exam, you note the distinct smell of tobacco. He has lid lag of the left eye and the exam of the pupil is unequal – the left being smaller than the right. Discuss the anatomy of the vertebral triangle. Include boundaries, contents, relationships, fascial specializations, vascularization, innervation, lymphatic drainage, and significance. (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.
  • Bones, Spaces, and Borders
    • Superior - Transverse Process of C6 (carotid tubercle is key relationship)
    • Inferior - First rib from verterbal 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 and Relationships
    • Intrinsic
      • Vertebral artery (transverse process of C6)-
      • Vertebral vein (transverse process of C7) -
      • Subclavian artery -
      • Thyrocervical trunk and branches (4) -
      • Costocervical trunk and branches (2) -
      • Dorsal scapular artery (inconsistent) -
      • Internal thoracic artery (definitional) -
      • Phrenic nerve -
      • Stellate and vertebral sympathetic trunk ganglia -
      • Ansa subclavia -
      • Thoracic duct -
    • Extrinsic
      • 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 -
  • Compression of the common carotid artery
    • Carotid tubercle -

Cervical Fasciae

A 45 y.o. female comes to your office because she is concerned that she has a “tumor in her jaw.” She began to note swelling on the buccal and labial aspects of her left mandible approximately 2 weeks ago. It initially was painful but over the last few days that has resolved. However, she now has a very “sour” taste in her mouth. On examination, the patient has an obvious facial swelling in the mid aspect of the body of her left mandible. She also has associated enlargement and tenderness of her submandibular lymph nodes. Intraoral exam displays a very poor dentition with gingival erythema, loss of contour, multiple dental caries and a fetid odor. Lectures by Drs. Fornadley, Bollard, Goldenberg, Kanekar and Fedok highlighted that cervical infections may become widely dispersed. Discuss the spaces defined by the cervical fasciae. Include boundaries, contents, relationships, and significance. (12 pts)
  • Cervical Investing Fascia Attachments and Specialization
    • from posterior cervical spines (nuchal ligament)
    • envelopes trapezius and sternocleidomastoid muscles
    • envelopes strap muscles
    • envelopes parotid gland (parotid fascia) and submandibular gland
    • superior limits - mandible anterior, scalp posterior
    • inferior limits - sternum, clavical, acromion, vertebra prominens
    • creates a continuous collar (carpet)
  • Pretracheal Visceral Fascia Attachments and Specialization
    • surrounds the cervical viscera - thyroid gland, trachea, esophagus, recurrent laryngeal nerves
    • posterior: buccopharyngeal fascia (named part of pretrachael visceral fascia)
    • superior limit - thyroid cartilage
    • inferior limit - superior/anterior mediastinum
  • Prevertebral Fascia Attachments and Specialization
    • surrounds the intrinsical musculature of the cervical vertebral column
    • attached to the spinous processes of the cervical vertebrae
    • partly covers splenius captius, levator scapula, scalene muscles, longus colli, longus capitus, anterior vertebral bodies
    • superior limit - base of skull near pharyngeal tubercle
    • inferior limit - continuous throughout thorax
    • alar layer of prevertebral fascia - second layer of prevertebral fascia attached to transverse processes, border for "danger space"
    • diverticulum of prevertebral fascia at interscalene triangle forms the axillary sheath
      • space defined by axillary sheath is continuous with space defined by prevertebral fascia
      • anesthesia of brachial plexus could block phrenic nerve - watch out for bilateral effects!
  • Spaces Defined by Cervical Fascias
    • pretracheal space - defined by the collar of pretracheal fascia
      • from thyroid cartilage to superior mediastinum
    • retropharyngeal space - defined by pretracheal visceral fascia (buccopharyngeal fascia part) and prevertebral fascia
      • extends from the pharyngeal tubercle to the posterior mediastinum (where alar fascia blends with visceral fascia)
      • especially important for considerations of spread infection
      • infections can enter this space through compromise of the buccopharyngeal fascia (the "throat")
    • danger space (prevertebral space) - between alar layer of prevertebral fascia and prevertebral fascia
      • from base of skull (pharyngeal tubercle) and extending inferiorly throughout the thorax

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-- LorenEvey - 20 Nov 2007

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