What is ENT -What is the location of the mental foramen?
At about the second premolar, the mental nerve leaves the mandible through the mental foramen.
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What is ENT - Describe the pterygopalatine fossa.
The pterygopalatine fossa is the space below the apex of the orbit. Boundaries of the Pterygopalatine Fossa • Anterior: Maxilla • Posterior: Pterygoid plates of the sphenoid bone • Superior: Medial half of the inferior orbital fissure • 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 postganglionic nerves innervate the lacrimal gland and nasal mucosa. What is ENT - Explain the parapharyngeal space and list what each compartment contains.
The larger cornu of the hyoid bone serves as the apex of the inverted pyramid-shaped parapharyngeal region, which has its base at the base of the skull. Boundaries of the Parapharyngeal Space • Anterior: Pterygomandibular raphe and pterygoid muscles • Posterior: Vertebral fascia • Superior: Skull base • Inferior: Hyoid bone • Lateral: Mandible, deep parotid gland • Medial: Pharynx (superior constrictor muscle, buccopharyngeal fascia) Compartments and their contents • Pre-styloid compartment: Internal maxillary artery, pterygoid venous plexus, minor salivary gland tissue, and fat • Post-styloid compartment: Neurovascular bundle including carotid artery, internal jugular vein, sympathetic chain, and cranial nerves IX, X, XI. What is ENT - 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 • Motor division—Stylomastoid foramen • Chorda tympani—Petrotympanic fissure • 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 What is ENT - Where do the lymphatic levels of the neck begin and end?
The borders of lymph node levels can be determined physically during surgical dissection or by using radiographic correlates. Different radiological and surgical landmarks are used to identify specific neck level limits. In brackets, the radiographic landmarks are listed: Level I Level Ia – Submental • Superior: Mandible • Inferior: Hyoid bone • Lateral: Ipsilateral anterior belly of the digastric muscle • Medial: Midline of the neck from the mandible to the hyoid Level Ib – Submandibular • Superior: Mandible • Inferior: Digastric attachment to hyoid (inferior edge of hyoid) • Lateral/posterior: Posterior belly of the digastric muscle • Medial: Anterior belly of the digastric muscle Level II Level IIa – Upper Jugular Region • Superior: Skull base • Inferior: Carotid bifurcation (hyoid bone) • Lateral/posterior: Spinal accessory nerve (posterior border of internal jugular vein) • Medial: Lateral border of the sternohyoid and stylohyoid muscles Level IIb – Submuscular recess • Superior: Skull base • Inferior: Carotid bifurcation (hyoid bone) • Lateral/posterior: Lateral border of the SCM • Medial: Spinal accessory nerve (medial border of internal carotid artery) Level III – Mid-Jugular • Superior: Carotid bifurcation (hyoid bone) • Inferior: Omohyoid muscle (inferior border of cricoid cartilage) • Lateral/posterior: Sensory branches of cervical plexus (lateral border of the SCM) • Medial: Lateral border of the sternohyoid muscle (medial border of common carotid artery) Level IV – Lower Jugular • Superior: Omohyoid muscle (inferior border of cricoid cartilage) • Inferior: Clavicle • Lateral/posterior: Sensory branches of cervical plexus (lateral border of the SCM) • Medial: Lateral border of the sternohyoid muscle (medial border of common carotid artery) Level V – Posterior Triangle Level Va • Superior: Convergence of SCM and trapezius muscles • Inferior: Inferior border of cricoid cartilage • Lateral: Anterior border of the trapezius muscle • Medial: Sensory branches of cervical plexus (lateral border of the SCM) Level Vb • Superior: Inferior border of cricoid cartilage • Inferior: Clavicle • Lateral: Anterior border of the trapezius muscle • Medial: Sensory branches of cervical plexus (lateral border of the SCM) Level VI – Anterior Compartment • Superior: Hyoid • Inferior: Suprasternal notch • Lateral: Common carotid arteries Level VII – Superior Mediastinal • Superior: Superior border of the sternum • Inferior: Innominate artery • Lateral: Innominate artery and left common carotid artery What is ENT - Describe the cervical triangles of the neck
• The SCMs divide each side of the neck into two major triangles: anterior and posterior. • The anterior triangle is further divided into the submandibular, carotid, and muscular triangles. • The submandibular triangle is bordered by the mandible and the posterior and anterior bellies of the digastric muscle. • The carotid triangle is bordered by the posterior belly of the digastric, the SCM, and the omohyoid. • The muscular triangle is bordered by the midline of the neck, the SCM, and the omohyoid. • The posterior triangle is formed by the SCM 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 What is ENT - Describe the retropharyngeal space's lymphatics.
Retropharyngeal lymph nodes (RPLNs) are divided into lateral and medial groups. The lateral nasopharyngeal and lateral oropharyngeal lymph nodes are subsets of the lateral RPLNs, commonly referred to as Rouvière nodes. What is ENT - Where are the retropharyngeal space, danger space, and prevertebral space?
• Retropharyngeal Space Boundaries • Superior: Skull base • Inferior: Mediastinum at the tracheal bifurcation • Anterior: Buccopharyngeal fascia lining 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 What is ENT - What does the carotid sheath contain and what layers of deep cervical tissue make up the sheath?
All three layers of deep cervical fascia make up the carotid sheath. The carotid artery, internal jugular vein, vagus nerve, and sympathetic chain are all contained within the carotid sheath. What is ENT - Describe the deep cervical fascia's many layers.
The superficial (investing), middle (pre-tracheal or visceral), and deep layers of deep fascia are the three divisions (prevertebral). The superficial layer covers the superficial neck structures and lies below the platysma. The trachea and esophagus are included in the visceral structures that are enclosed in the middle layer. The cervical vertebrae and deep neck muscles are encircled by the deep layer. |
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