Face and oral cavity part 2 Flashcards
Summarise the major, piared salivary glands of the oral cavity
Parotid (mainly serous) IX
parotid duct, opening upper second molar
Submandibular (mainly serous) VII
Sublingual (mainly mucous) VII
Compare serous saliva to mucous saliva
serous- thin saliva
mucous- thicker as it doesn’t have to travel as far- but makes it prone to blockages
Describe the boundaries of the parotid gland
The parotid gland (see pp. 911–912) on each side is entirely outside the boundaries of the oral cavity in a shallow triangular-shaped trench (Fig. 8.260) formed by:
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the sternocleidomastoid muscle behind,
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the ramus of the mandible in front, and
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superiorly, the base of the trench is formed by the external acoustic meatus and the posterior aspect of the zygomatic arch.
What does the parotid gland extend across
The gland normally extends anteriorly over the masseter muscle, and inferiorly over the posterior belly of the digastric muscle.
Describe the passage of the parotid duct
The parotid duct leaves the anterior edge of the parotid gland midway between the zygomatic arch and the corner of the mouth (Fig. 8.59). It crosses the face in a transverse direction and, after crossing the medial border of the masseter muscle, turns deeply into the buccal fat pad and pierces the buccinator muscle.
opens into the oral cavity adjacent to the crown of the second upper molar tooth.
Describe the relationship between the parotid gland and the facial nerve
The facial nerve [VII] exits the skull through the stylomastoid foramen and then passes into the parotid gland, where it usually divides into upper and lower trunks. These pass through the substance of the parotid gland, where there may be further branching and anastomosing of the nerves.
Five terminal groups of branches of the facial nerve [VII]—the temporal, zygomatic, buccal, marginal mandibular, and cervical branches—emerge from the upper, anterior, and lower borders of the parotid gland
Why is the relationship between the parotid gland and the facial nerve important clinically
The intimate relationships between the facial nerve [VII] and the parotid gland mean that surgical removal of the parotid gland is a difficult dissection if all branches of the facial nerve [VII] are to be spared
The commonest tumors of the parotid gland (Fig. 8.60) are benign and typically involve the superficial gland. These include pleomorphic adenoma and adenolymphoma. Their importance is in relation to their anatomical position. The relationship of any tumor to the branches of the facial nerve [VII] must be defined because resection of the tumor may damage the nerve.
Describe the relations of the parotid gland to the external carotid artery
The external carotid artery enters into or passes deep to the inferior border of the parotid gland (Fig. 8.59). As it continues in a superior direction, it gives off the posterior auricular artery before dividing into its two terminal branches (the maxillary and superficial temporal arteries) near the lower border of the ear:
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The maxillary artery passes horizontally, deep to the mandible.
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The superficial temporal artery continues in a superior direction and emerges from the upper border of the gland after giving off the transverse facial artery.
Describe the relations of the parotid gland to the retromadnibular vein
The retromandibular vein is formed in the substance of the parotid gland when the superficial temporal and maxillary veins join together (Fig. 8.59), and passes inferiorly in the substance of the parotid gland. It usually divides into anterior and posterior branches just below the inferior border of the gland.
Describe the relative size of the submandibular glands
The elongate submandibular glands are smaller than the parotid glands but larger than the sublingual glands. Each is hook shaped
Describe the larger arm of the submandibular gland
The larger arm of the hook is directed forward in the horizontal plane below the mylohyoid muscle and is therefore outside the boundaries of the oral cavity—this larger superficial part of the gland is directly against a shallow impression on the medial side of the mandible (submandibular fossa) inferior to the mylohyoid line.
Describe the smaller arm of the submandibular gland
The smaller arm of the hook (or deep part) of the gland loops around the posterior margin of the mylohyoid muscle to enter and lie within the floor of the oral cavity where it is lateral to the root of the tongue on the lateral surface of the hyoglossus muscle.
Where does the submandibular duct emerge
The submandibular duct emerges from the medial side of the deep part of the gland in the oral cavity and passes forward to open on the summit of a small sublingual caruncle (papilla) beside the base of the frenulum of the tongue
What is an important relation of the submandibular duct
The lingual nerve loops under the submandibular duct, crossing first the lateral side and then the medial side of the duct, as the nerve descends anteromedially through the floor of the oral cavity and then ascends into the tongue.
Describe the shape of the sublingual glands
The sublingual glands are the smallest of the three major paired salivary glands. Each is almond shaped and is immediately lateral to the submandibular duct and associated lingual nerve in the floor of the oral cavity
Where is the sublingual gland found
Each sublingual gland lies directly against the medial surface of the mandible where it forms a shallow groove (sublingual fossa) superior to the anterior one-third of the mylohyoid line.
Describe the superior margin of the sublingual gland
The superior margin of the sublingual gland raises an elongate fold of mucosa (sublingual fold), which extends from the posterolateral aspect of the floor of the oral cavity to the sublingual papilla beside the base of the frenulum of the tongue at the midline anteriorly
Where do the sublingual ducts drain
The sublingual gland drains into the oral cavity via numerous small ducts (minor sublingual ducts), which open onto the crest of the sublingual fold. Occasionally, the more anterior part of the gland is drained by a duct (major sublingual duct) that opens together with the submandibular duct on the sublingual caruncle.
Describe the arterial supply of the salivary glands
Vessels that supply the parotid gland originate from the external carotid artery and from its branches that are adjacent to the gland. The submandibular and sublingual glands are supplied by branches of the facial and lingual arteries.
Describe the venous drainage of the salivary glands
Veins from the parotid gland drain into the external jugular vein, and those from the submandibular and sublingual glands drain into lingual and facial veins.
Describe the lymphatics of the salivary glands
Lymphatic vessels from the parotid gland drain into nodes that are on or in the gland. These parotid nodes then drain into superficial and deep cervical nodes.
Lymphatics from the submandibular and sublingual glands drain mainly into submandibular nodes and then into deep cervical nodes, particularly the jugulo-omohyoid node.
What are all salivary glands in the oral cavity innervated by
Parasympathetic innervation to all salivary glands in the oral cavity is by branches of the facial nerve [VII], which join branches of the maxillary [V2] and mandibular [V3] nerves to reach their target destinations.
Summarise the innervation of the parotid gland
The parotid gland, which is entirely outside the oral cavity, receives its parasympathetic innervation from fibers that initially traveled in the glossopharyngeal nerve [IX], which eventually joins a branch of the mandibular nerve [V3] in the infratemporal fossa
This branch is the auriculotemporal nerve
Describe the greater petrosal nerve
All salivary glands above the level of the oral fissure, as well as all mucus glands in the nose and the lacrimal gland in the orbit, are innervated by parasympathetic fibers carried in the greater petrosal branch of the facial nerve [VII] (Fig. 8.262). Preganglionic parasympathetic fibers carried in this nerve enter the pterygopalatine fossa and synapse with postganglionic parasympathetic fibers in the pterygopalatine ganglion formed around branches of the maxillary nerve [V2]. Postganglionic parasympathetic fibers join general sensory branches of the maxillary nerve, such as the palatine nerves, destined for the roof of the oral cavity, to reach their target glands.
What does the chorda tympani innervate
All glands below the level of the oral fissure, which include those small glands in the floor of the oral cavity, in the lower lip, and in the tongue, and the larger submandibular and sublingual glands, are innervated by parasympathetic fibers carried in the chorda tympani branch of the facial nerve [VII]
Describe the course of the chorda tympani
The chorda tympani joins the lingual branch of the mandibular nerve [V3] in the infratemporal fossa and passes with it into the oral cavity. On the external surface of the hyoglossus muscle, preganglionic parasympathetic fibers leave the inferior aspect of the lingual nerve to synapse with postganglionic parasympathetic fibers in the submandibular ganglion, which appears to hang off the lingual nerve (Fig. 8.263). Postganglionic parasympathetic fibers leave the ganglion and pass directly to the submandibular and sublingual glands while others hop back onto the lingual nerve and travel with branches of the lingual nerve to target glands.
Summarise the toungue
The tongue is a muscular structure that forms part of the floor of the oral cavity and part of the anterior wall of the oropharynx (Fig. 8.250A). Its anterior part is in the oral cavity and is somewhat triangular in shape with a blunt apex of the tongue. The apex is directed anteriorly and sits immediately behind the incisor teeth. The root of the tongue is attached to the mandible and the hyoid bone.
What plane is the superior surface of the tongue found in
The superior surface of the oral or anterior two-thirds of the tongue is oriented in the horizontal plane.
What plane is the pharyngeal surface of the tongue found in
The pharyngeal surface or posterior one-third of the tongue curves inferiorly and becomes oriented more in the vertical plane.
What are the oral and pharyngeal surfaces of the tongue separated by
The pharyngeal surface or posterior one-third of the tongue curves inferiorly and becomes oriented more in the vertical plane. The oral and pharyngeal surfaces are separated by a V-shaped terminal sulcus of the tongue. This terminal sulcus forms the inferior margin of the oropharyngeal isthmus between the oral and pharyngeal cavities.
What is found at the apex of the V-shaped sulcus
At the apex of the V-shaped sulcus is a small depression (the foramen cecum of the tongue), which marks the site in the embryo where the epithelium invaginated to form the thyroid gland. In some people a thyroglossal duct persists and connects the foramen cecum on the tongue with the thyroid gland in the neck.
What is the superior surface of the tongue covered in
The superior surface of the oral part of the tongue is covered by hundreds of papillae
Firiform
Fungiform
Foliate
Describe the firiform papillae
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Filiform papillae are small cone-shaped projections of the mucosa that end in one or more points.
Describe the fungiform papillae
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Fungiform papillae are rounder in shape and larger than the filiform papillae, and tend to be concentrated along the margins of the tongue.
Describe the vallate papillae
The largest of the papillae are the vallate papillae, which are blunt-ended cylindrical papillae invaginations in the tongue’s surface—there are only about 8 to 12 vallate papillae in a single V-shaped line immediately anterior to the terminal sulcus of the tongue.
Describe the foliate papillae
Foliate papillae are linear folds of mucosa on the sides of the tongue near the terminal sulcus of tongue.
What is the general function of the papillae of the tongue
The papillae in general increase the area of contact between the surface of the tongue and the contents of the oral cavity. All except the filiform papillae have taste buds on their surfaces.
Describe the inferior surface of the tongue
The undersurface of the oral part of the tongue lacks papillae, but does have a number of linear mucosal folds (see Fig. 8.261). A single median fold (the frenulum of the tongue) is continuous with the mucosa covering the floor of the oral cavity, and overlies the lower margin of a midline sagittal septum, which internally separates the right and left sides of the tongue. On each side of the frenulum is a lingual vein, and lateral to each vein is a rough fimbriated fold.
Describe the pharyngeal surface of the tongue
The mucosa covering the pharyngeal surface of the tongue is irregular in contour because of the many small nodules of lymphoid tissue in the submucosa. These nodules are collectively the lingual tonsil.
There are no papillae on the pharyngeal surface.
Summarise the muscles of the tongue
Muscles: styloglossus hyoglossus genioglossus intrinsic muscles CN XII
Describe the anatomy, function and innervation of the genioglossus muscle
origin- superior mental spines
insertion- body of hyoid; entire length of tongue
innervation- hypoglossal nerve
function- protrudes tongue; depresses centre of tongue
Describe the AFI of the hypoglossus muscle
origin- greater horn and adjacent part of body of hyoid bone
insertion- lateral surface of tongue
innervation- hypoglossal nerve
function- depresses the tongue
Describe the AFI of the styloglossus muscle
origin- anterolateral surface of styloid process
insertion - lateral surface of tongue
innervation- hypoglossal nerve
function- elevates and retracts tongue
Describe the AFI of the palatoglossus muscle
origin- inferior surface of palatine aponeurosis
insertion- lateral margin of tongue
innervation- Vagus nerve [X] (via pharyngeal branch to pharyngeal plexus)
function- depresses palate, moves palatoglossal fold toward midline, elevates back of tongue
How is the tongue divided
The tongue is completely divided into left and right halves by a median sagittal septum composed of connective tissue. This means that all muscles of the tongue are paired. There are intrinsic and extrinsic lingual muscles.
What are the intrinsic muscles of the tongue
The intrinsic muscles of the tongue (Fig. 8.251) originate and insert within the substance of the tongue. They are divided into superior longitudinal, inferior longitudinal, transverse, and vertical muscles,
Describe the AFI of the superior longitudinal muscle (found just deep to the inferior surface of the tongue)
origin- surface of tongue)
Submucosal connective tissue at the back of the tongue and from the median septum of the tongue
insertion- Muscle fibers pass forward and obliquely to submucosal connective tissue and mucosa on margins of tongue
innervation- hypoglossal nerve
function- shortens tongue, curls apex and sides of tongue
Describe the AFI of the inferior longitudinal muscle ( found between the genioglossus and hyoglossus muscles)
origin- route of tongue (some fibres from hyoid)
insertion- apex of tongue
innervation- hypglossal nerve
function- shortens tongue, uncurls apex and turns it downwards
Describe the AFI of the transverse intrinsic muscle
origin- median septum of tongue
insertion- submucosal connective tissue on lateral margins of tongue
innervation- hypoglossal nerve
function- narrows and elongates tongue
Describe the AFI of the vertical intrinsic muscle
origin- submucosal connective tissue on dorsum of tongue
insertion- connective tissue in more vertical regions of tongue
innervation- hypoglossal nerve
function- flattens and widens tongue
Summarise the innervation of the tongue
Except for the palatoglossus, which is innervated by the vagus nerve [X], all muscles of the tongue are innervated by the hypoglossal nerve [XII].
How can we test the function of the hypoglossal nerve
Asking a patient to “stick your tongue out” can be used as a test for the hypoglossal nerves [XII]. If the nerves are functioning normally, the tongue should protrude evenly in the midline. If the nerve on one side is not fully functional, the tip of the tongue will point to that side.
What is the hyoglossus muscle an important landmark for
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The lingual artery from the external carotid artery in the neck enters the tongue deep to the hyoglossus, between the hyoglossus and genioglossus.
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The hypoglossal nerve [XII] and lingual nerve (branch of the mandibular nerve [V3]), from the neck and infratemporal fossa of the head, respectively, enter the tongue on the external surface of the hyoglossus.
Which nerve is responsible for taste and general sensation of the pharyngeal part (posterior 1/3rd of tongue)
Taste (SA) and general sensation from the pharyngeal part of the tongue are carried by the glossopharyngeal nerve [IX].
Describe the passage of the glossopharyngeal nerve
The glossopharyngeal nerve [IX] leaves the skull through the jugular foramen and descends along the posterior surface of the stylopharyngeus muscle. It passes around the lateral surface of the stylopharyngeus and then slips through the posterior aspect of the gap (oropharyngeal triangle) between the superior constrictor, middle constrictor, and mylohyoid muscles. The nerve then passes forward on the oropharyngeal wall just below the inferior pole of the palatine tonsil and enters the pharyngeal part of the tongue deep to the styloglossus and hyoglossus muscles. In addition to taste and general sensation on the posterior one-third of the tongue, branches creep anterior to the terminal sulcus of the tongue to carry taste (SA) and general sensation from the vallate papillae.
Which nerve provides general sensory information to the anterior 2/3rds of the tongue
General sensory innervation from the anterior two-thirds or oral part of the tongue is carried by the lingual nerve, which is a major branch of the mandibular nerve [V3].
Describe the passage of the lingual nerve
It originates in the infratemporal fossa and passes anteriorly into the floor of the oral cavity by passing through the gap (oropharyngeal triangle) between the mylohyoid, superior constrictor, and middle constrictor muscles (Fig. 8.258). As it travels through the gap, it passes immediately inferior to the attachment of the superior constrictor to the mandible and continues forward on the medial surface of the mandible adjacent to the last molar tooth and deep to the gingiva. In this position, the nerve can be palpated against the bone by placing a finger into the oral cavity.
The lingual nerve then continues anteromedially across the floor of the oral cavity, loops under the submandibular duct, and ascends into the tongue on the external and superior surface of the hyoglossus muscle.
What else does the lingual nerve innervate
In addition to general sensation from the oral part of the tongue, the lingual nerve also carries general sensation from the mucosa on the floor of the oral cavity and gingiva associated with the lower teeth. The lingual nerve also carries parasympathetic and taste fibers from the oral part of the tongue that are part of the facial nerve [VII].
mixed cranial nerve components- touch sensation and nerve fibres involved in taste.
Which nerve provides taste sensation to the oral part of the tongue
The facial nerve
Describe the passage of the facial nerve
Taste (SA) from the oral part of the tongue is carried into the central nervous system by the facial nerve [VII]. Special sensory (SA) fibers of the facial nerve [VII] leave the tongue and oral cavity as part of the lingual nerve. The fibers then enter the chorda tympani nerve, which is a branch of the facial nerve [VII] that joins the lingual nerve in the infratemporal fossa
Describe the passage of the hypoglossal nerve
The hypoglossal nerve [XII] leaves the skull through the hypoglossal canal and descends almost vertically in the neck to a level just below the angle of the mandible (Fig. 8.259). Here it angles sharply forward around the sternocleidomastoid branch of the occipital artery, crosses the external carotid artery, and continues forward, crossing the loop of the lingual artery, to reach the external surface of the lower one-third of the hyoglossus muscle.
The hypoglossal nerve [XII] follows the hyoglossus muscle through the gap (oropharyngeal triangle) between the superior constrictor, middle constrictor, and mylohyoid muscles to reach the tongue.
What happens in the upper neck
In the upper neck, a branch from the anterior ramus of C1 joins the hypoglossal nerve [XII]. Most of these C1 fibers leave the hypoglossal nerve [XII] as the superior root of the ansa cervicalis (Fig. 8.259). Near the posterior border of the hyoglossus muscle, the remaining fibers leave the hypoglossal nerve [XII] and form two nerves:
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the thyrohyoid branch, which remains in the neck to innervate the thyrohyoid muscle, and
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the branch to the geniohyoid, which passes into the floor of the oral cavity to innervate the geniohyoid.
Summarise the blood supply of the tongue
The tongue is drained by dorsal lingual and deep lingual veins
The major artery of the tongue is the lingual artery
Summarise the lymphatics of the tongue
All lymphatic vessels from the tongue ultimately drain into the deep cervical chain of nodes along the internal jugular vein:
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The pharyngeal part of the tongue drains through the pharyngeal wall directly into mainly the jugulodigastric node of the deep cervical chain.
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The oral part of the tongue drains both directly into the deep cervical nodes, and indirectly into these nodes by passing first through the mylohyoid muscle and into submental and submandibular nodes.
Describe the submental nodes
The submental nodes are inferior to the mylohyoid muscles and between the digastric muscles, while the submandibular nodes are below the floor of the oral cavity along the inner aspect of the inferior margins of the mandible.
The tip of the tongue drains through the mylohyoid muscle into the submental nodes and then into mainly the jugulo-omohyoid node of the deep cervical chain.
