What is the most common part of the duct that is involved in a stone? SpoilerMiddle 1/3 Why is this site most affected? SpoilerDue to looping of lingual nerve around duct, and thick mucus secretion and have to pour secretion in floor of mouth against gravity What are digastric triangle boundaries and their nerve supply? SpoilerSuperior: Inferior border of the mandible Anterior: Anterior belly of the di gastric muscle Posterior: Posterior belly of the digastric muscle Nerve supply SpoilerThe anterior belly of the digastric muscle is innervated by the mylohyoid nerve, which is a branch of the mandibular nerve The posterior belly of the digastric muscle is innervated by the digastric branch of the facial nerve. Names & actions of extrinsic muscles of the tongue SpoilerGenioglossus: protrusion of the tongue & depression of the tongue tip Hyoglossus: retraction of the tongue & depression of the lateral margins of the tongue Styloglossus: retraction of the tongue & elevation of the sides of the tongue Palatoglossus: Elevation of the posterior part of the tongue If you have injury of Hypoglossal, lingual or marginal mandibular what will the patient have? Marginal mandibular SpoilerDrippling of saliva from corner of affected side Poor speech articulation (slurred speech) Asymmetry on smiling or crying Hypoglossal SpoilerParalysis and atrophy in ipsilateral side Deviation to ipsilateral side on protrusion Poor speech articulation Lingual SpoilerLoss of general sensation from ant 2/3 of tongue and floor of mouth Loss of taste sensation from tongue only Boundaries of Posterior Triangle SpoilerBoundary Description Apex Sternocleidomastoid and the Trapezius muscles at the Occipital bone Anterior Posterior border of the Sternocleidomastoid Posterior Anterior border of the Trapezius Base Middle third of the clavicle [image: 1773944974415-596e7a43-c73e-42b3-bc28-fcbd5be83066-image.jpeg] Origin & Insertion of Omohyoid SpoilerOrigin - Insertion Inferior belly superior border of scapula near suprascapular notch - intermediate tendon Superior belly intermediate tendon - body of hyoid bone Study Notes Hypoglossal nerve SpoilerBecause the genioglossus muscle on the healthy side "pushes" the tongue, it will deviate toward the side of the injury when the patient sticks it out. Why lingual nerve injury causes loss of taste, even though it primarily carries general sensation? SpoilerWhile the Lingual nerve is a branch of the Mandibular nerve and carries general sensation (touch, pain, temperature), it also acts as a "highway" for taste fibers.The Chorda Tympani Connection. The reason a lingual nerve injury (specifically if it occurs after the two nerves join) causes loss of taste is due to the Chorda Tympani, a branch of the Facial nerve (CN VII). The Join: High up in the infratemporal fossa, the Chorda Tympani "hitches a ride" with the Lingual nerve. The Shared Path: From that point forward, they travel together as one physical cord. Omohyoid, remember that its two bellies are held together by an intermediate tendon. This tendon is actually tethered to the clavicle by a deep layer of fascia. This is why when the muscle contracts, it doesn't just pull the hyoid down; it also helps maintain the patency of the internal jugular vein!