Regional Anatomy II Week 4 SU22 PDF

Week 4 Oral cavity and pharynx Oral Cavity ● ● Vestibule and oral cavity proper Vestibule: ○ ○ ○ ○ Space between lips and cheeks, externally, and teeth and gingiva, internally Oral fissure - space between the lips that communicates with the exterior Labial frenula - two midline mucosal folds con...

Week 4 Oral cavity and pharynx Oral Cavity ● ● Vestibule and oral cavity proper Vestibule: ○ ○ ○ ○ Space between lips and cheeks, externally, and teeth and gingiva, internally Oral fissure - space between the lips that communicates with the exterior Labial frenula - two midline mucosal folds connecting mucosa on inner aspect of lips to gingiva between central incisor teeth Parotid papilla - small elevation of buccal mucosa, opposite 2nd maxillary molar. Marks opening of parotid duct into oral vestibule Oral Cavity ● Boundaries of the oral cavity proper: ○ ○ ○ ○ Anterior and lateral - teeth and gingiva Posterior - oropharyngeal isthmus (communicates between oral cavity and oropharynx), space between right and left palatoglossal arches Superior - palate Inferior - mylohyoid muscles (for a muscular diaphragm that supports the tongue and structures of floor of mouth, this diaphragm is reinforced medially by the geniohyoid muscles) Palate ● Hard palate - anterior ⅔ ○ ○ Formed by palatine processes of maxillae and horizontal plates of palatine bones Covered with mucosa which is tightly bound to underlying bone ● Soft palate - posterior ⅓ ○ ○ ○ ○ ○ ○ Moveable, suspended from posterior border of hard palate Has no bony skeleton When relaxed, extends posterior and inferior into pharynx (separates nasopharynx from oropharynx) Uvula - midline conical projection extending from posterior free border On each side, soft palate becomes continuous with 2 arches (folds) ■ Palatoglossal arch - anterior, extends from soft palate to side of tongue ■ Palatopharyngeal arch - posterior, extends from soft palate to pharyngeal wall Tonsillar sinus (fossa) - triangular interval between palatoglossal and palatopharyngeal arches, occupied by palatine tonsil Muscles of the Soft Palate 1. Levator veli palatini a. b. 2. Tensor veli palatini a. b. 3. Located within palatoglossal arch, extends from soft palate to side of tongue Action - elevates root of tongue, approximates palatoglossal arch to its contralateral mate Palatopharyngeus a. b. 5. Located anterior and slight lateral to levator veli palatini muscle and medial to medial pterygoid muscle. Its tendon curves around pterygoid hamulus Action - tenses soft palate and assists with its elevation. Opens pharyngeal opening of auditory tube Palatoglossus a. b. 4. Located immediately under the mucosa of nasopharynx, just inferior to the pharyngeal opening of the auditory tube Action - elevates soft palate to separate nasopharynx from oropharynx (important during swallowing to prevent passage of food into nasopharynx and nasal cavity) Located within palatopharyngeal arch, extends from soft palate to pharyngeal wall and thyroid cartilage of larynx Action - elevates pharynx and larynx during swallowing, approximates palatopharyngeal arch to its contralateral mate Uvular muscle a. b. Located midline and extends into uvula Action - shortens uvula and pulls it superiorly Nerves and Vessels of the Palate ● ● ● ● Motor innervation - tensor veli palatini is supplied by medial pterygoid nerve (from V3), all other muscles are supplied by the pharyngeal branch of the vagus nerve Sensory innervation - greater and lesser palatine nerves, nasopalatine nerve, tonsillar branches of glossopharyngeal nerve Arteries - greater and lesser palatine arteries (from maxillary artery), ascending palatine artery (from facial artery), palatine branch of ascending pharyngeal artery Veins drain into pterygoid venous plexus and pharyngeal venous plexus. Pharyngeal plexus communicates with pterygoid venous plexus and also drains into the IJV Tongue ● ● Highly muscular organ covered by mucous membrane Functions: ○ ○ ○ ○ ○ ● Speech Manipulation and positioning of food Tasting Swallowing Cleansing of oral cavity Parts: ○ ○ ○ ○ ○ Root - posterior ⅓ lies in oropharynx Body - anterior ⅔ lies in oral cavity proper and ends anteriorly in the apex (tip) of tongue Dorsum - superior roughened surface Inferior (sublingual) surface - faces floor of oral cavity proper. Covered with thin, transparent mucosa Right/left margins - separate dorsum and inferior surface on each side Tongue ● Surface features: ○ ○ ○ Terminal sulcus - V-shaped groove located on dorsum of tongue. Its apex points posteriorly in midline and divides dorsum of tongue into oral or presulcal part (anterior ⅔) and pharyngeal or post sulcal part (posterior ⅓) Foramen cecum - small pit at apex of terminal sulcus. A remnant of superior end of thyroglossal duct (connects thyroid gland to tongue during development) Median sulcus - shallow midline groove on dorsal surface of oral part of tongue. Divides tongues into right and left halves Tongue ● Sublingual surface features: ○ ○ ○ ○ Lingual frenulum - mucosal fold that connects inferior surface of tongue to floor of oral cavity proper to midline Deep lingual vein - can be observed through mucosa of inferior surface on either side of frenulum Sublingual caruncle (papilla) - small elevation just lateral to base of lingual frenulum; marks opening of submandibular duct Sublingual fold - fold of mucosa of the floor of the oral cavity proper, caused by underlying sublingual gland, directed posterior and lateral from sublingual caruncle. Dorsum of the Tongue ● Oral (presulcal) part ○ ○ ○ ○ ○ ● ● Velvety appearance due to presence of papillae Filiform papillae - most numerous. Project as tapering, threadlike points that impart rough texture to dorsum of tongue. They aid in handling food and contain general sensory nerve endings, but no taste buds Fungiform papillae - scattered among filiform papillae, mushroom-like and reddish Vallate papillae - large papillae, 8 - 12 in number that form a V-shaped row anterior and parallel to the terminal sulcus. Each papilla is surrounded by a circular trough Foliate papillae - found on lateral margins of tongue as short vertical folds (better developed in other mammals) Fungiform, vallate, and foliate papillae contain taste buds Pharyngeal (post sulcal) part ○ ○ No papillae are present Characterized by rounded elevations caused by lymphoid nodules, which collectively form lingual tonsil Muscles of the Tongue ● Extrinsic muscles - originate outside tongue and insert into tongue ○ ○ ○ ○ ● Genioglossus - originates from mental spine of mandible (above origin of geniohyoid). Fibers fan out posterior and superior into tongue. Right and left muscles, acting together, pull tongue forward (protrude) in midline. Hyoglossus - thin, quadrilateral muscle. Originates from greater and lesser horns and body of hyoid bone. Fibers pass superior and anterior to insert into lateral aspect of tongue. Depresses tongue (fibers that originate from lesser horn are sometimes considered a separate muscle [chondroglossus]) Styloglossus - originates from styloid process. Fibers pass anterior and inferior to insert into lateral aspect of tongue. Draws tongue up and backward Palatoglossus - described by some as a tongue muscle Intrinsic muscles - originate and insert within tongue. Superior and inferior longitudinal, transverse, and vertical muscles Unilateral hypoglossal nerve lesion Nerve Supply of the Tongue ● ● Motor nerve supply - Palatoglossus is supplied by the vagus nerve via the pharyngeal branch. All other extrinsic and intrinsic muscles are supplied by hypoglossal nerve. General sensory nerve supply ○ ○ ○ ● Lingual nerve (branch of V3) to the anterior ⅔ Glossopharyngeal nerve to posterior ⅓ Vagus nerve (via internal laryngeal nerve) to small area adjacent to epiglottis Special sensory nerve supply (taste) ○ ○ Facial nerve (via chorda tympani) to anterior ⅔ Glossopharyngeal nerve (via internal laryngeal nerve) to small area adjacent to epiglottis Glossopharyngeal Nerve ● ● ● Contains sensory, motor, and autonomic fibers Arises from medulla of brainstem - exits skull via jugular foramen and has 2 sensory ganglia (superior and inferior glossopharyngeal ganglion). Descends posterior to stylopharyngeus muscle and passes between superior and middle constrictor muscles to enter the pharynx. Passes anterior through tonsillar bed (lateral to palatine tonsil) and ends in posterior ⅓ of tongue Branches ○ Tympanic nerve - forms tympanic plexus, which gives general sensory innervation to mucosa of tympanic cavity. Gives rise to lesser petrosal nerve (carries preganglionic parasympathetic fibers to otic ganglion) Glossopharyngeal Nerve ● Branches (cont.) ○ ○ ○ ○ ○ Carotid branch - descends on internal carotid artery to supply baroreceptors and chemoreceptors of carotid sinus and carotid body Muscular branch - supplies stylopharyngeus muscle Pharyngeal branches - supply sensory innervation to a large part of pharyngeal mucosa Tonsillar branches - supply sensory innervation to mucosa of palatine tonsil and posterior end of soft palate Lingual branches - supply general sensory and special sensory (taste) innervation to mucosa of posterior ⅓ of tongue Lingual Artery ● ● Anterior branch of external carotid artery; passes medial to hyoglossus muscle, which separates lingual artery from hypoglossal nerve at anterior border of hyoglossus muscle. It turns upward and forward to reach tip of tongue (this distal part is known as the deep lingual artery) Supplies tongue, palatine tonsil, sublingual gland, mylohyoid, and geniohyoid muscles, and mucosa of floor of mouth Submandibular Gland ● ● One of the major salivary glands, together with the parotid and sublingual glands Wraps around posterior body of mylohyoid muscle and has superficial and deep parts ○ ○ ● Superficial part (larger) located in submandibular (digastric) triangle of neck Deep part (smaller) located above mylohyoid muscle, between mandible (lateral to gland) and hyoglossus muscle (medial to gland), gives rise to submandibular duct Submandibular duct - passes forward, medial to sublingual gland, opens into floor of oral cavity proper at tip of sublingual caruncle (papilla). Lingual nerve passes inferior to submandibular duct, crossing it from lateral to medial before entering the tongue. Sublingual Gland ● ● ● Smallest of the major salivary glands Rests of floor of mouth between mandible (lateral to gland) and genioglossus muscle (medial to gland) covered superiorly by mucosa of floor of mouth (forms sublingual fold) About 12 small ducts originate from superior border of gland and open separately along sublingual fold of floor of mouth. A few of the more anterior ducts may drain into submandibular duct Teeth ● Children have 20 deciduous teeth; in each half of the maxillary and mandibular dental arches there are 5 teeth ○ ○ ○ ● 2 incisors 1 canine 2 molars Adults have 32 permanent teeth; in each half of the maxillary and mandibular dental arches there are 8 teeth ○ ○ ○ ○ 2 incisors 1 canine 2 premolars 3 molars Teeth ● Parts ○ ○ ○ ● ● ● Crown - projects from gingiva Root - fixed in alveolus by periodontal ligament (number of roots varies depending on type of tooth) Neck - slightly constricted area between crown and root Most of the tooth is composed of dentin, which is covered by enamel over the crown, and cement over root Pulp cavity contains nerves, connective tissue, blood, and lymph vessels Root canal transmits nerves and vessels to and from pulp cavity through apical foramen Pharynx Pharynx ● ● ● Fibromuscular, funnel-shaped organ that has a common chamber for the digestive and respiratory systems Extends from base of skull to inferior border of cricoid cartilage, where it becomes continuous with esophagus It has lateral and posterior walls, but the anterior wall is incomplete due to its communication anteriorly with the nasal cavity, oral cavity, and larynx Pharynx Parts: 1. 2. 3. Nasopharynx Oropharynx Laryngopharynx (hypopharynx) Separated posteriorly from vertebral column and anterior vertebral muscles and prevertebral fascia by loose connective tissue of retropharyngeal space Nasopharynx ● ● ● ● ● ● It is entirely respiratory in function Expands from base of skull to soft palate Communicates anteriorly with nasal cavity via choanae (posterior nasal apertures) Pharyngeal tonsil - collection of lymphoid tissue located in roof of nasopharynx (adenoids) Pharyngeal opening of auditory tube is located in lateral wall of nasopharynx Medial end of the auditory tube cartilage elevates the mucosa (torus tubarius) Nasopharynx ● ● The salpingopharyngeal fold is a mucosal fold that extends downward from posterior limb of torus tubarius and covers salpingopharyngeal muscle Tubal tonsil is a collection of lymphoid tissue around pharyngeal opening of auditory tube Clinical Considerations ● Congenital choanal atresia ○ Congenital narrowing of back of nasal cavity. In approximately 1/7,000; more common in females than males Oropharynx ● ● ● ● Extends from soft palate to superior border of epiglottis Communicates anteriorly with oral cavity via oropharyngeal isthmus Palatine tonsil is located in its lateral wall between palatoglossal and palatopharyngeal arches (in tonsillar fossa/sinus) Anterior surface of epiglottis is connected to root of tongue by 3 glossoepiglottic folds (1 median and 2 lateral) Pharyngeal lymphoid ring (Waldeyer’s ring) is a collection of lymphoid tissue at the entrance of the pharynx from the nasal and oral cavities. It includes 1. Pharyngeal 2. Tubal 3. Lungual 4. Palatine tonsils Clinical Considerations Tonsilloliths - aka tonsil stones. Benign accumulations of soft, sometimes painful bits of food particles, mucus, bacteria, and debris that get stuck in the crypts of your tonsils. Laryngopharynx ● ● ● Also known as the hypopharynx, extends from superior border of epiglottis to inferior border of cricoid cartilage where pharynx becomes continuous with esophagus Communicates with laryngeal cavity via laryngeal inlet Piriform fossa (recess) - depression located inferior lateral to laryngeal inlet and medial to laminal of thyroid cartilage. The internal laryngeal nerve is located under the mucosa of the piriform fossa Clinical Consideration of Piriform Fossa Coin swallowed by a child Fish bone Muscles of the Pharynx Constrictor muscles - form an external muscle layer. Fibers are mostly circularly arranged like a stack of 3 glasses with the superior constrictor partly overlapped by the middle constrictor, and the middle constrictor partly overlapped by the inferior constrictor 1. 2. 3. Superior Middle inferior Muscles of the Pharynx Longitudinal muscles - forms mostly an internal muscle layer 1. 2. 3. Stylopharyngeus Palatopharyngeus Salpingopharyngeus Superior Constrictor ● ● Origin - posterior border of medial pterygoid plate with the hamulus, pterygomandibular raphe, posterior part of mylohyoid line of mandible, and lateral aspect of the root of the tongue Insertion - fibers pass posterior and medial to meet fibers of opposite muscle in posterior midline (pharyngeal raphe) and uppermost fibers insert into pharyngeal tubercle of occipital bone Medial Constrictor ● ● Origin - greater and lesser horns of hyoid and stylohyoid ligament (ligament that extends from styloid process to lesser horn of hyoid) Insertion - pharyngeal raphe Inferior Constrictor ● ● Origin - oblique line of thyroid cartilage, lateral aspect of cricoid cartilage and tendinous arch between thyroid and cricoid cartilages. The tendinous arch passes over the cricothyroid muscle Insertion - pharyngeal raphe Longitudinal muscles - forms mostly an internal muscle layer 1. 2. 3. Stylopharyngeus Palatopharyngeus Salpingopharyngeus Stylopharyngeus ● ● Origin - styloid process Insertion - passes inferior and medial to enter the pharyngeal wall by passing between superior and middle constrictors. Some fibers insert into posterior border of thyroid cartilage and the rest of the fibers terminate in the pharyngeal wall with fibers of the palatopharyngeus Salpingopharyngeus ● ● Origin - cartilage of auditory tube near tube’s pharyngeal opening Insertion - fibers descend and blend with those of palatopharyngeus Palatopharyngeus, salpingopharyngeus, and stylopharyngeus from a posterior view Gaps Between Overlapping of constrictor muscles leaves 4 gaps in the musculature for structures to enter or leave the pharynx. Structures passing through the gap between superior constrictor and base of the skull 1. 2. 3. Pharyngotympanic (auditory/eustachian) tube Levator veli palatini muscle Ascending palatine artery (branch of facial artery) Structures passing through the gap between superior and middle constrictors 1. 2. Stylopharyngeus muscle Glossopharyngeal nerve Structures passing through the gap between middle and inferior constrictors 1. 2. Internal laryngeal nerve Superior laryngeal artery (branch of superior thyroid artery) and vein Structures passing through the gap inferior to the inferior constrictor 1. 2. Recurrent laryngeal nerve Inferior laryngeal artery (branch of inferior thyroid artery) and vein Innervation of the Pharynx Pharyngeal plexus - formed by pharyngeal branches of glossopharyngeal nerve, vagus nerve, and superior cervical ganglion. The glossopharyngeal fibers are sensory, most vagal fibers are motor, and sympathetic fibers are vasomotor Innervation of the Pharynx Sensory nerve supply ● ● ● Maxillary nerve (V2) supplies mucosa of upper part of nasopharynx (via the pharyngeal branch of the pterygopalatine ganglion) and the upper part of the tonsillar fossa and palatine tonsil (via lesser palatine branch of pterygopalatine ganglion) Glossopharyngeal nerve is the main source of sensory nerve supply to the pharyngeal mucosa Vagus nerve supplies mucosa around the laryngeal inlet (via internal laryngeal nerve) Innervation of the Pharynx Motor nerve supply ● Almost all muscle are supplied by the vagus nerve via the pharyngeal branch Exceptions: ● ● Stylopharyngeus (supplied by the glossopharyngeal nerve) Inferior constrictor receives some innervation from the external laryngeal nerve Blood Supply of the Pharynx Arteries - external carotid artery branches ● ● ● ● ● Ascending pharyngeal artery (pharyngeal branches) Facial artery (ascending palatine artery and tonsillar branches) Maxillary artery (descending palatine and pharyngeal branches) Lingual artery (dorsal lingual branches) Superior thyroid artery (muscular branches) Blood Supply of the Pharynx Veins - form plexus on outer surface of pharynx that drains above into pterygoid venous plexus and below into facial vein and directly into IJV