Oral Cavity and Sublingual Region
What is the collective action of the Geniohyoid and Mylohyoid muscles?
Aid in swallowing by acting to move the floor of the mouth and tongue upwards and forwards.
What does the Hypoglossal nerve innervate?
All the muscles of the tongue are supplied by CN XII, the hypoglossal nerve (Fig. 7.59A), except for the palatoglossus (actually a palatine muscle supplied by the pharyngeal plexus, the plexus of nerves that includes motor branches of CN X).
Where does the Mylohyoid muscle attach to the hyoid bone? What is its innervation?
Along with the anterior belly of the digastric muscle, the mylohyoid muscle is innervated by the mylohyoid nerve, a branch of the inferior alveolar nerve, which is a branch of the mandibular division of the trigeminal nerve. The mylohyoid muscle is flat and triangular, and is situated immediately above the anterior belly of the digastric muscle. It forms, with its fellow of the opposite side, a muscular floor for the cavity of the mouth. It arises from the whole length of the mylohyoid line of the mandible, extending from the symphysis in front to the last molar tooth behind. The posterior fibers pass inferomedially to insert into the body of the hyoid bone. It thus belongs to the suprahyoid muscles. The middle and anterior fibers are inserted into a median fibrous raphé extending from the symphysis menti to the hyoid bone, where they joint at an angle with the fibers of the opposite muscle. This median raphé is sometimes absent; the fibers of the two muscles are then continuous
What is the Vermillion border? Why does it appear red?
As the skin of the lips approaches the mouth, it changes color abruptly to red; this red margin of the lips is the vermillion border, a transitional zone between the skin and mucous membrane. The skin of the transitional zone is hairless and so thin that it appears red because of the underlying capillary bed.
What does Chorda Tympani nerve do?
Chorda tympani carries taste fibers from CN VII for the anterior 2/3 of the tongue. Fibers "hitch-hike" on the lingual nerve.
What area of the tongue does the deep lingual artery supply?
Deep lingual artery supplies the anterior part of the tongue; the dorsal and deep arteries communicate with each other near the apex of the tongue
What area of the tongue do the dorsal lingual arteries supply?
Dorsal lingual arteries supply the posterior part, the root of the tongue, and send a tonsillar branch to the palatine tonsil.
What is Geniohyoid's innervation? What is Geniohyoid's relationship to the Mylohyoid muscle and the Genioglossus muscle?
During the first act of deglutition, when the mass of food is being driven from the mouth into the pharynx, the hyoid bone and with it the tongue, is carried upward and forward by the anterior bellies of the Digastrici, the Mylohyoid, and Geniohyoid muscles.
What does the Lingual nerve do?
For general sensation (touch and temperature), the mucosa of the anterior two thirds of the tongue is supplied by the lingual nerve, a branch of CN V3.
List the attachments, innervation, and general action of the palatoglossus muscle.
It arises from the anterior surface of the soft palate, where it is continuous with the muscle of the opposite side, and passing downward, forward, and lateralward in front of the palatine tonsil, is inserted into the side of the tongue, some of its fibers spreading over the dorsum, and others passing deeply into the substance of the organ to intermingle with the Transversus linguæ. Elevates posterior tongue, closes the oropharyngeal isthmus, and aids initiation of swallowing. It is innervated by the pharyngeal branches of the Vagus nerve
What is the relationship of the lingual artery to the hypoglossus muscle?
On entering the tongue, the lingual artery passes deep to the hyoglossus muscle medially.
What does the oral cavity communicate with posteriorly?
Posteriorly, the oral cavity communicates with the oropharynx, the oral part of the pharynx.
What area of the tongue does the sublingual artery supply?
Sublingual artery supplies the sublingual gland and the floor of the mouth.
Identify and describe the surface anatomy features of the oral cavity as listed on pp 249 - 250 of Grant's Dissector.
Surface Anatomy of the Oral Cavity Proper Borders: Lateral and anterior - the teeth and gums Superior - the hard palate Inferior - the mucosa covering the tongue and sublingual area Posterior - the palatoglossal folds (right and left) Structures: Tongue Body Apex Median sulcus Sublingual area Frenulum of the tongue (sublingual frenulum) Sublingual fold (plica sublingualis) Sublingual caruncle Opening of submandibular duct - on the sublingual caruncle Deep lingual veins - seen on either side of the frenulum of the tongue
What does the Glosspharyngeal nerve do on the tongue
The Glossopharyngeal nerve (CN IX) provides general sensory AND taste to the posterior 1/3 of the tongue.
Locate and trace the hypoglossal nerve. How does its position and course compare with that of the lingual nerve?
The Hypoglossal nerve passes deep to the posterior belly of the digastric muscle, it passes to the submandibular region to enter the tongue.
What two extrinsic tongue muscles contribue to the sublingual region?
The Hypoglossus and Genioglossus muscle contribue to the sublingual region. The Hypoglossus muscle forms the posterior portion of the medial wall of the floor of the oral cavity. This Genioglossus muscle arises from the superior mental spine and extends superiorly to form the anterior portion of the medial wall of the floor of theoral cavity before its posterior fibers pass medial and deep to the Hyoglossus muscle.
Identify and trace the lingual nerve as it enters and passes through the floor of the mouth. What is its relationship to the submandibular duct and to the muscles of the lateral and medial walls of the floor of the oral cavity?
The Lingual nerve passes between the Hyoglossus and deep part of the submandibular gland; it finally runs from laterally to medially inferiorly crossing beneath the duct of the submandibular gland, and along the tongue to its tip becoming the sublingual nerve, lying immediately beneath the mucous membrane.
What features help to demarcate between the sensory areas of the lingual nerve and of the glossopharyngeal nerve?
The Terminal Sulcus and the Vallate papillae serves as landmark between the areas supplied by the lingual nerve (anterior 2/3) and glosspharyngeal nerve (posterior 2/3) of the tongue.
List the attachments, innervation, and general action of the genioglossus muscle.
The anterior attachment of the genioglossus muscle is the superior mental spine of the mandible and its posterior attachments are the hyoid bone and the tongue. The genioglossus muscle protrudes the tongue. The genioglossus muscle is innervated by the hypoglossal nerve (XII).
Locate the sublingual artery and vein.
The arterial supply of the sublingual glands is from the sublingual and submental arteries—branches of the lingual and facial arteries, respectively
What muscle makes up the cheek? Where are its attacments and what is it innervated by?
The buccinator muscle is the major muscle of the cheek. It attaches to the orbicularis oris anteriorly, the pterygomandibular raphe posteriorly, and to the alveolar processes of the maxilla superiorly and mandible inferiorly, respectively. The mucosa of the cheek is innervated by the buccal nerve of V3.
What are the extrinsic mucsles of the tongue?
The extrinsic muscles of the tongue 1. genioglossus 2. hyoglossus 3. styloglossus 4. palatoglossus* originate outside the tongue and attach to it.
Describe the suglingual region.
The floor of the mouth, or sublingual region, is covered by a mucous membrane. The base of the floor is composed of several muscles (see cross-section in Table 7.11). The Mylohyoid muscle attaches laterally to the mylohyoid line on both sides of the mandible and medially to the hyoid bone and a central raphe. The mylohyoid m. forms the inferolateral portion of the floor of the mouth. There is also a central mass of muscle that contains tongue muscles and the geniohyoid muscle. The geniohyoid m. attaches to the hyoid bone and the inferior mental spine. The tongue and central muscles, therefore, divide the oral cavity portion of the lower jaw into a "U-shaped" cavity with the central muscle mass located inside the "U." The anterior digastric muscles lie superficial to the mylohyoid muscle.
Briefly summarize the innervation of the gingvae of the lower and upper jaws.
The gingivae (gums) are composed of fibrous tissue covered with mucous membrane, which is firmly attached to the alveolar processes of the mandible and maxilla and the necks of the teeth. The buccal gingivae of the mandibular molar teeth (Fig. 7.48) are supplied by the buccal nerve, a branch of the mandibular nerve (Fig. 7.52C). The lingual gingivae of all mandibular teeth are supplied by the lingual nerve. The palatine gingivae of the maxillary premolar and molar teeth are supplied by the greater palatine nerve; and the palatine gingivae of the incisors, by the nasopalatine nerve. The labial and buccal aspects of the maxillary gingivae are supplied by the anterior, middle, and posterior superior alveolar nerves (Fig. 7.52A).
List the attachments, innervation, and general action of the hyoglossus muscle.
The hyoglossus muscle, which is deep to the mylohyoid muscle (Fig. 7.89). The inferior attachments of the hyoglossus muscle are the body and greater horn of the hyoid bone and its superior attachment is the lateral side of the tongue. The hyoglossus muscle depresses and retracts the tongue. It is innervated by the hypoglossal nerve (CN XII).
What is the lingual septum?
The lingual septum is the fibrous band, which provides anchoring for the tongue muscles, lies deep to the median sulcus, and helps to separate the tongue into left and right halves. The four intrinsic and four extrinsic muscles in each half of the tongue are separated by the fibrous lingual septum, which extends vertically from the midline groove of the tongue (Fig. 7.58C). This is an important consideration in surgery on the tongue, particularly cancer surgeries.
Identify the muscles of the upper and lower lips, and their innervation and blood supply.
The lips, the mobile, fleshy muscular folds surrounding the mouth, contain the orbicularis oris and superior and inferior labial muscles, vessels, and nerves. The upper lip is supplied by superior labial branches of the facial and infra-orbital arteries. The lower lip is supplied by inferior labial branches of the facial and mental arteries. The upper lip is supplied by the superior labial branches of the infra-orbital nerves (CN V2), and the lower lip is supplied by the inferior labial branches of the mental nerves (CN V3) (Fig. 7.52A).
Distinguish between filliform, fungiform and vallate papillae.
The mucous membrane on the anterior part of the tongue is rough because of the presence of numerous lingual papillae (Fig. 7.56B): 1. Vallate papillae are large and flat-topped; they lie directly anterior to the terminal sulcus and are surrounded by deep moat-like trenches, the walls of which are studded by taste buds; the ducts of serous lingual glands (of von Ebner) open into these trenches. 2. Foliate papillae are small lateral folds of lingual mucosa; they are poorly developed in humans. 3. Filiform papillae are long, numerous, thread-like, and scaly; they contain afferent nerve endings that are sensitive to touch. 4. Fungiform papillae are mushroom-shaped and appear as pink or red spots; they are scattered among the filiform papillae but are most numerous at the apex and sides (margins) of the tongue. The vallate, foliate, and most of the fungiform papillae contain taste receptors in the taste buds. A few taste buds are also in the epithelium covering the oral surface of the soft palate, the posterior wall of the oropharynx, and the epiglottis.
Locate and define the Oral Cavity Proper.
The oral cavity (mouth) consists of two parts: the oral vestibule and the oral cavity proper (Fig. 7.48). The oral vestibule communicates with the exterior through the mouth. The size of the oral fissure (opening) is controlled by muscles such as the orbicularis oris (the sphincter of the oral fissure). The oral cavity proper is the space posterior and medial to the upper and lower dental arches. It is limited laterally and anteriorly by the maxillary and mandibular alveolar arches housing the teeth.
Locate and define the Vestibule.
The oral vestibule is the slit-like space between the lips and cheeks superficially and the teeth and gingivae deeply.
What duct pierces the buccinator?
The parotid duct pierces the buccinator and mucosa to open at a papilla opposite the second upper molar.
What forms the roof of the oral cavity?
The roof of the oral cavity proper is formed by the palate.
Locate the lingual tonsils. What are lingual tonsils?
The root of the tongue lies within the oropharynx, posterior to the terminal sulcus and the palatoglossal arches (Fig. 7.56B). Its mucous membrane is thick and freely movable. It has no lingual papillae, but the underlying lymphoid nodules, known collectively as the lingual tonsil, give this part of the tongue its cobblestone appearance. The lingual tonsils are rounded masses of lymphatic tissue that cover the posterior region of the tongue.
List the attachments, innervation, and general action of the styloglossus muscle.
The styloglossus muscle (Fig. 7.89). The proximal attachment of the styloglossus muscle is the styloid process and its distal attachment is the lateral side of the tongue. The styloglossus muscle retracts the tongue and draws it superiorly. It is innervated by the hypoglossal nerve (CN XII).
Locate the sublingual glands. List their relationships in the floor of the mouth. How do the ducts from the sublingual glands compare with that of the submandibular gland?
The sublingual glands are the smallest and most deeply situated (Fig. 7.61A). Each almond-shaped gland lies in the floor of the mouth between the mandible and the genioglossus muscle. The glands from each side unite to form a horseshoe-shaped mass around the lingual frenulum. The sublingual gland has about 12 short ducts that drain along the summit of the sublingual fold.
Locate the submandibular gland. Where is it located in relation to the mylohyoid and hyoglossus muscles? What is the course of the submandibular duct, in particular the duct's relationship to the lingual nerve? Locate the sublingualcaruncles on each side of the lingual frenulum.
The submandibular glands lie along the body of the mandible, partly superior and partly inferior to the posterior half of the mandible and partly superficial and partly deep to the mylohyoid muscle (Fig. 7.61A). The submandibular duct arises from the part of the gland that lies between the mylohyoid and the hyoglossus. Passing from lateral to medial, the lingual nerve loops under the submandibular duct as it runs anteriorly to open via one to three orifices on a small, fleshy sublingual papilla on each side of the lingual frenulum (Figs. 7.57 and 7.61A). The orifices of the submandibular ducts are visible, and saliva often sprays from it when the tongue is elevated and retracted.
Briefly summarize the innervation of the teeth of the lower and upper jaws.
The superior and inferior alveolar nerves, branches of CN V2 and CN V3, respectively, form superior and inferior dental plexuses that supply the maxillary and mandibular teeth (Fig. 7.52A).
What is the number of deciduous and permanent teeth found in children and adults, respectively?
The teeth are hard conical structures set in the dental alveoli (tooth sockets) of the upper and lower jaws and are used in mastication (chewing) and assisting in articulation. Children have 20 deciduous (primary) teeth. The first tooth usually erupts at 6 to 8 months of age and the last tooth by 20 to 24 months of age. Eruption of the permanent (secondary) teeth, normally 16 in each jaw (3 molars, 2 premolars, 1 canine, and 2 incisors on each side), usually is complete by the midteens (Fig. 7.50), except for the third molars ("wisdom teeth"), which usually erupt during the late teens or early 20s.
Distinguish between the dorsal lingual and deep lingual veins. Where do the veins drain?
The veins of the tongue are the: -Dorsal lingual veins, which accompany the lingual artery. -Deep lingual veins (Fig. 7.57), which begin at the apex of the tongue and run posteriorly beside the lingual frenulum to join the sublingual vein. All lingual veins terminate, directly or indirectly, in the IJV.
Describe the intrinsic muscles of the tongue.
These muscle fibers are completely contained within the mass of the tongue. The fibers are oriented along the longitudinal, vertical and transverse planes of the tongue. Their action is to alter the shape of the tongue (rather than alter its position) and are, therefore, important in speech. They are innervated by CN XII, the hypoglossal nerve.
