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2. What are the contents and relationships of the sublingual space?
2. What are the contents and relationships of the sublingual space?
The sublingual (fascial) space is the area between the mucosa of the floor of the oral cavity proper and the mylohyoid m. Posterior to the margin of the mylohyoid m., the sublingual space is continuous with the submandibular fascial space (inferiorly) and lateral pharyngeal fascial space (posteriorly). Infections (mandibular odontogenic, or other) may spread from the sublingual space to adjacent spaces (submandibular, lateral pharyngeal, retropharyngeal, and beyond). Cellulitis (and related edema) in the sublingual, submandibular, and sometimes also the submental spaces may endanger the airway and require immediate intervention. This is known as Ludwig’s angina, and it is life-threatening.
The sublingual space contains:
sublingual glands (& associated ducts),
submandibular ducts,
lingual aa. (& brs.),
lingual vv. (& tributaries),
lingual nn. (& associated submandibular ganglia)
hypoglossal nn. (& vena comitantes)
deep lobe of submandibular gland.
Of the three types of major salivary glands, the sublingual glands are the smallest. They are located superior to the mylohyoid m. and when covered with mucosa, form the sublingual folds. These glands drain via numerous small ducts along the sublingual folds. The deep, smaller part of the submandibular gland is also located in this area and is closely associated with the posterior end of the sublingual gland.
The mylohyoid line of the mandible is formed by the attachment of the mylohyoid m. The two salivary glands in this region are associated with this line: sublingual gland superior, and submandibular gland inferior.
The lingual a. is typically the second branch of the external carotid a. that leaves the external carotid anteriorly. Passing between the hyoglossus m. and the middle pharyngeal constrictor m., the lingual a. supplies the floor of the oral cavity and the tongue. The lingual a. produces several branches, chiefly:
Dorsal lingual brs. - arise medially to the hyoglossus m.; supplies the posterior tongue, soft palate, and palatine tonsil,
Sublingual a. - arise anteriorly to the hyoglossus m.; supplies the sublingual gland, and muscles and tissues of the floor of the oral cavity, and
Deep lingual a. - the terminal br. of the lingual a. - lies along the inferior margin to the tip of the tongue; supplies the anterior tongue.
Nearly all of the lingual a. branches anastomose with their contralateral paired artery along the midline.
Deep to the mucosa in the oral cavity proper, the lingual n. and submandibular duct cross. The lingual n. descends into the oral cavity and loops under (‘cradles’) the submandibular duct to provide general sensory innervation to the anterior 2/3rds of the tongue.
The submandibular (Wharton’s) duct traverses the space between the submandibular gland and sublingual caruncle. The duct is located between the hypoglossal n. and lingual n. in association with the hyoglossus m. The lingual n. passes deep to the duct about midway in the oral cavity.
The lingual n. is an afferent branch of the posterior trunk of V3. It traverses the infratemporal fossa medial to the inferior alveolar n., where it is joined by the chorda tympani (branch of facial n., CN VII). Chorda tympani carries presynaptic parasympathetic fibers to the submandibular ganglion and taste to the body of the tongue (excluding the vallate papillae). The lingual n. enters the oral cavity superior to the mylohyoid m., and enters the tongue to provide sensory innervation to the body of the tongue and the floor of the oral cavity.
The submandibular ganglion is delicately associated with the lingual n. and is superior to the deep portion of the submandibular gland. This ganglion is one of four named peripheral parasympathetic ganglia (ciliary, pterygopalatine, submandibular, and otic). The submandibular ganglion receives preganglionic parasympathetic fibers from the chorda tympani, a branch of the facial n. (CN VII). Postganglionic parasympathetic fibers leave the ganglion to innervate the submandibular and sublingual glands, among other smaller glands (e.g. anterior lingual) by means of the lingual n., a branch of V3.
The vena comitans (accompanying vein) of hypoglossal n. is a tributary of the lingual v. This vein accompanies the hypoglossal n. (CN XII) inferiorly along the hyoglossus m.
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