9 Head and Neck Anatomy & Embryology with Radiology Correlates Flashcards
Where is the abnormality and potential tract of the 2nd branchial cleft sinus?
Second branchial cleft anomalies typically present below the angle of the mandible and at the anterior border of the sternocleidomastoid muscle. The potential tract for this sinus passes:
- Deep to the external carotid artery, stylohyoid, and digastric muscle
- Superficial to the internal carotid artery opening in the tonsillar fossa.
What is the most common branchial cleft anomaly?
Second branchial cleft anomalies are the most common, representing approximately 95% of all anomalies. First branchial cleft anomalies are the second most common. Third and fourth branchial cleft anomalies are rare.
What are the boundaries and subsites of the oral cavity?
- Anterior: Vermillion border of the lip
- Superior: Hard-soft palate junction
- Lateral: Tonsillar pillars***
- Posterior/inferior: Circumvallate papillae of the tongue
- Subsites: Lip, oral tongue (anterior two thirds), buccal mucosa, floor of mouth, hard palate, upper and lower gingiva (alveolar ridges), and retromolar trigone
What are the boundaries of the nasopharynx?
- Anterior: Posterior nasal cavity
- Superior: Sphenoid sinus
- Posterior: First and second vertebrae
- Inferior: Soft palate
- Lateral: Eustachian tube, torus tubarius, and the fossa of Rosenmuller (most common site of origin for nasopharyngeal carcinoma)
What are the boundaries and subsites of the oropharynx?
- Anterior: Oral cavity
- Superior: Soft palate
- Posterior: Posterior pharyngeal wall
- Inferior: Hyoid
- Subsites: Base of tongue (posterior third), palatine tonsil/lateral pharyngeal wall, soft palate, and posterior pharyngeal wall
Where is HPV-associated squamous cell carcinoma (SCCA) most commonly located?
The oropharynx, specifically the tonsils and base of tongue, is the most common location for HPV SCCA.
What are the boundaries and subsites of the hypopharynx?
- Anterior: Larynx
- Superior: Hyoid bone and pharyngoepiglottic folds
- Posterior: Retropharyngeal space
- Inferior: Esophageal introitus at the cricopharyngeus muscle
- Subsites: The piriform sinuses, the postcricoid region, and the posterior pharyngeal wall
Describe the subsites of the hypopharynx.
The piriform sinuses are an inverted pyramid with the base at the level of the pharyngoepiglottic fold and the apex extending to just below the cricoid cartilage.
The second subsite, the postcricoid region, is the anterior wall of the hypopharynx. It extends from the just inferior to the posterior aspect of the arytenoid cartilages to the esophageal introitus.
The third region of the hypopharynx, the posterior pharyngeal wall, extends from the hyoid bones to the superior aspect of the cricopharyngeus muscle.
Describe the different layers of the deep cervical fascia.
Deep fascia is divided into three layers: the external, middle, and internal layers. The external layer is underneath the platysma layer and invests the superficial neck structures. The middle layer encloses the visceral structures including the trachea and esophagus. The most internal layer surrounds the deep muscles of the neck and cervical vertebrae.
Where are the retropharyngeal space, danger space, and prevertebral space?
- Retropharyngeal Space Boundaries
- Superior: Skull base
- Inferior: Mediastinum at the tracheal bifurcation
- Anterior: Buccopharyngeal (visceral) fascia that lines the posterior pharynx and esophagus
- Posterior: Alar fascia over the danger space
- Lateral: Carotid sheath
- Danger Space Boundaries
- Superior: Skull base
- Inferior: Diaphragm
- Anterior: Alar fascia and retropharyngeal space
- Posterior: Prevertebral fascia and prevertebral space
- Lateral: Transverse process of the vertebrae
- Prevertebral Space Boundaries
- Superior: Clivus of the skull base
- Inferior: Coccyx
- Anterior: Prevertebral fascia and danger space
- Posterior: Vertebral bodies
- Lateral: Transverse process of the vertebrae
Describe the lymphatics of the retropharyngeal space.
There are two groups of retropharyngeal lymph nodes, lateral and medial. The lateral retropharyngeal lymph nodes (RPLNs) are also known as the Rouvière nodes and are subdivided into the lateral nasopharyngeal and lateral oropharyngeal lymph nodes. The number of lateral RPLNs ranges from 1 to 3 and they are normally 2 to 5 mm in size.
The medial RPLNs are inferior to the lateral nodes and are subclassified into upper and lower lymph nodes. Retropharyngeal lymph nodes typically become smaller in adults and medial retropharyngeal lymph nodes are rarely present in adults
Nasopharyngeal cancer is the most common primary tumor that metastasizes to the retropharyngeal lymph nodes.
Describe the cervical triangles of the neck.
The sternocleidomastoid muscles divide each side of the neck into two major triangles, anterior and posterior. The anterior triangle of the neck is further divided by the strap muscles into the superior and inferior carotid triangles. The posterior triangle is formed by the sternocleidomastoid anteriorly, the clavicle inferiorly, and the anterior border of the trapezius posteriorly. The omohyoid divides the posterior triangle into a small inferior subclavian triangle and a larger posterior occipital triangle.
Describe the contents of the posterior cervical triangle.
- Cutaneous branches of the cervical plexus
- Spinal accessory nerve
- Suprascapular and transverse cervical vessels
What are the boundaries of the lymphatic levels of the neck?
- Level Ia (Submental Triangle)
- Anterior: Mandible
- Lateral: Anterior belly of the digastric
- Posterior: Hyoid
- Superior: Mylohyoid
- Level Ib (Submandibular Triangle)
- Superior: Mandible
- Posterior/Inferior: Posterior belly of the digastric
- Anterior/Inferior: Anterior belly of the digastric
- Level II (Upper Jugular Region)
- Superior: Skull base
- Inferior: Hyoid bone
- Lateral: Posterior border of the sternocleidomastoid muscle
- Medial: Lateral border of the sternohyoid and stylohyoid muscles
- IIa: Region anterior to the spinal accessory nerve
- IIb: Region postero-superior to the nerve
- Level III (Middle Jugular Region)
- Superior: Hyoid bone
- Inferior: Junction of the omohyoid and internal jugular vein
- Lateral: Posterior border of the sternocleidomastoid muscle
- Medial: Lateral border of the sternohyoid muscle
- Level IV (Lower Jugular Region)
- Superior: Omohyoid
- Inferior: Clavicle
- Lateral: Posterior border of the sternocleidomastoid muscle
- Medial: Lateral border of the sternohyoid muscle
- Level V (The Posterior Triangle)
- Medial: Posterior border of the sternocleidomastoid muscle
- Lateral: Anterior border of the trapezius muscle
- Inferior: Clavicle
- Va: Region superior to the inferior border of the cricoid cartilage
- Vb: Region inferior to the inferior border of the cricoid cartilage
- Level VI (The Anterior Compartment)
- Superior: Hyoid
- Inferior: Suprasternal notch
- Lateral: Medial border of the carotid sheaths
Name the cranial nerves and skull base foramina where they exit.
- Cranial Nerve I: Olfactory Nerve—Cribriform plate of the ethmoid bone
- Cranial Nerve II: Optic Nerve—Optic canal
- Cranial Nerve III: Oculomotor Nerve—Superior orbital fissure
- Cranial Nerve IV: Trochlear Nerve—Superior orbital fissure
- Cranial Nerve V: Trigeminal Nerve
- V1: Ophthalmic Nerve—Superior orbital fissure
- V2: Maxillary Nerve—Foramen rotundum
- V3: Mandibular Nerve—Foramen ovale
- Cranial Nerve VI: Abducens Nerve—Superior orbital fissure
- Cranial Nerve VII: Facial Nerve—Enters at internal acoustic meatus
- Motor Root—Exits through stylomastoid foramen
- Nervus Intermedius:
- Chorda Tympani—Exits through petrotympanic fissure
- Greater Superficial Petrosal Nerve—Exits through the pterygoid canal
- Cranial Nerve VIII: Vestibulocochlear Nerve—Internal acoustic meatus
- Cranial Nerve IX: Glossopharyngeal Nerve—Jugular foramen
- Cranial Nerve X: Vagus Nerve—Jugular foramen
- Cranial Nerve XI: Accessory Nerve—Jugular foramen
- Cranial Nerve XII: Hypoglossal Nerve—Hypoglossal canal
Describe the pterygopalatine fossa.
- Boundaries of the Pterygopalatine Fossa
- Anterior: Maxilla
- Superior: Medial half of the inferior orbital fissure
- Posterior: Pterygoid plates of the sphenoid bone
- Inferior: Upper end of the palatine canal
- Lateral: Pterygomaxillary fissure
- Medial: Sphenopalatine foramen and perpendicular plate of the palatine bone
- Communications of the Pterygopalatine Fossa
- Anterior: Maxillary sinus (no direct communication)
- Superior: Orbital cavity through the inferior orbital fissure
- Posterior: Middle cranial fossa through foramen rotundum and the pterygoid canal
- Inferior: Oral cavity through the palatine canal
- Lateral: Infratemporal fossa through the pterygomaxillary fissure
- Medial: Nasal cavity through the sphenopalatine foramen
- Contents of the Pterygopalatine Fossa
- Fat
- Maxillary artery
- Maxillary division of the trigeminal nerve
- Pterygopalatine ganglion: Parasympathetic ganglion where post-parasympathetic nerves innervate the lacrimal gland and nasal mucosa.
Figure:
Boundaries of the pterygopalatine fossa. A, lateral view; B, superior view. TG, trigeminal ganglion; FR, foramen rotundum; FO, foramen ovale; SPF, sphenopalatine foramen; GW, greater wing of sphenoid; LRM, lateral rectus muscle; MA, maxillary artery; ION, infraorbital nerve; IOA, infraorbital artery; PPG, pterygopalatine ganglion.
