Oral Cavity Anatomy PDF

ORAL CAVITY   Walls:  Roof  Floor  Lateral walls Opennings  Oral fissure: anterior opening  Oropharyngeal isthmus: Posterior, opens into the oral part of the pharynx ORAL CAVITY    Separated by the upper and lower dental arches into: Oral vestibule: (outer),horseshoeshaped, between...

ORAL CAVITY   Walls:  Roof  Floor  Lateral walls Opennings  Oral fissure: anterior opening  Oropharyngeal isthmus: Posterior, opens into the oral part of the pharynx ORAL CAVITY    Separated by the upper and lower dental arches into: Oral vestibule: (outer),horseshoeshaped, between the dental arches and the deep surfaces of the cheeks and lips Oral cavity proper: (inner), which is enclosed by the dental arches. Walls: the cheeks     Fascia and a layer of skeletal muscle sandwiched between skin externally and oral mucosa internally. Skeletal muscle within the cheeks is the Buccinator muscle Joined to the anterior margin of the superior constrictor muscle by the pterygomandibular raphe, Between the tip of the pterygoid hamulus of the sphenoid bone and a roughened area of bone immediately behind the last molar tooth on the mandible Floor     Formed by three structures: Muscular diaphragm: fills the U-shaped gap between the left and right sides of the body of the mandible composed  Mylohyoid muscles Geniohyoid muscles Tongue, which is superior to the geniohyoid muscles. Mylohyoid     Origin: Mylohyoid line of body of mandible Insertion: Body of hyoid bone NS: Inferior alveolar nerve Action: Elevates floor of mouth and hyoid bone or depresses mandible Geniohyoid     Origin: Inferior mental spine of mandible Insertion: Body of hyoid bone NS: C1 nerve Action: Elevates hyoid bone or depresses mandible The tongue     Muscular structure  Floor of the oral cavity  Anterior wall of the oropharynx Apex: anterior part (triangular), directed anteriorly and sits behind the incisor teeth. Root: attached to the mandible and the hyoid bone Pharyngeal surface: lingual tonsil Tongue Papillae: projections of the lamina propria covered with stratified squamous epithelium. (The dorsal and lateral surfaces of the tongue). 1) Fungiform papillae: mushroom like elevations (red dots)  Dorsum of the tongue, concentrated mainly around the margins and tip of the tongue  most of them contain taste buds  2) Vallate (circumvallate) papillae: About 12 in number  Arranged in an inverted V-shape on the posterior surface of the tongue.  All of them contain taste buds. Tongue 3) Foliate papillae:  On the lateral margins of the tongue, but most of their taste buds degenerate in early childhood. 4) Filiform papillae: pointed, threadlike projections  over the anterior twothirds of the tongue.  have a keratinized surface  lack taste buds, contain receptors for touch and increase friction between the tongue and food. Inferior surface of tongue     Lacks papillae Frenulum of tongue: single median fold continuous with the mucosa covering the floor of the oral cavity, On each side of the frenulum is a lingual vein, and lateral to each vein is a rough fimbriated fold. Ankyloglossia? Tongue     Divided into symmetrical lateral halves by a median septum Two groups of muscles Intrinsic muscles: originate in and insert into connective tissue within the tongue. Include: Superior longitudinal, inferior longitudinal, transvers, and vertical muscles. Extrinsic muscles: originate outside the tongue and insert into connective tissues in the tongue. Include: hyoglossus, genioglossus, and styloglossus muscles Intrinsic muscles of the tongue Superior longitudinal:  Origin: Submucosal connective tissue at the back of the tongue and from the median septum of the tongue  Insertion: submucosal connective tissue and mucosa on margins of tongue  NS: Hypoglossal nerve  Action: Shortens tongue; curls apex and sides of tongue Intrinsic muscles of the tongue Inferior longitudinal:  Origin: Root of tongue  Insertion: Apex of tongue  NS: Hypoglossal nerve  Action: Shortens tongue; uncurls apex and turns it downward Intrinsic muscles of the tongue Transverse:  Origin: Median septum of tongue  Insertion: Submucosal connective tissue on lateral margins of tongue  NS: Hypoglossal nerve  Action: Narrows and elongates tongue Intrinsic muscles of the tongue Vertical:  Origin: Submucosal connective tissue on dorsum of tongue  Insertion: Connective tissue in more ventral regions of tongue  NS: Hypoglossal nerve  Action: Flattens and widens tongue Extrinsic muscles of the tongue Genioglossus:  Origin: Superior mental spines  Insertion: Body of hyoid; entire length of tongue  NS: Hypoglossal nerve  Action: Protrudes tongue; depresses center of tongue Extrinsic muscles of the tongue Hyoglossus:  Origin: Greater horn of hyoid  Insertion: Lateral surface of tongue  NS: Hypoglossal nerve  Action: depresses tongue Extrinsic muscles of the tongue Styloglossus:  Origin: Styloid process  Insertion: Lateral surface of tongue  NS: Hypoglossal nerve  Action: retracts tongue Extrinsic muscles of the tongue Palatoglossus:  Origin: Inferior surface of Palatine aponeurosis  Insertion: Lateral margin of tongue  NS: pharyngeal branch of vagus  Action: Depresses palate; moves palatoglossal arch toward midline; elevates back of the tongue Triangular aperture  Hyoglossus, styloglossus, lingual artery and vein, lingual nerve, hypoglossal nerve, glossopharyngeal nerve Lingual artery   Loops downward and forward to pass deep to the hyoglossus muscle Enters the floor of the oral cavity. travels forward in the plane between the hyoglossus and genioglossus muscles to the apex of the tongue. Deep lingual vein   Separated from the arteries posteriorly by the hyoglossus muscles. Travels with the hypoglossal nerve on the external surface of the hyoglossus muscle Dorsal lingual vein:  follows the lingual artery between the hyoglossus and genioglossus Lingual nerve:  from Posterior trunk of trigeminal     between the tensor veli palatini and lateral pterygoid muscle joined by the chorda tympani nerve lateral surface of the medial pterygoid Between the posterior attachment of the mylohyoid muscle to the mylohyoid line and the attachment of the superior constrictor of the pharynx Lingual nerve:      enters the floor of the oral cavity groove on the medial surface of the mandible immediately inferior to the last molar tooth At risk when operating on the molar teeth Passes into the tongue on the lateral surface of the hyoglossus muscle attached to the submandibular ganglion Lingual nerve    General sensation from the anterior two-thirds of the tongue, oral mucosa on the floor of the oral cavity, and lingual gingivae associated with the lower teeth Taste Anterior 2/3 of tongue Preganglionic parasympathetic fibers to submandibular ganglion The hypoglossal nerve      Motor nerve. emerges on the medulla oblongata Crosses the posterior cranial fossa, and leaves the skull through the hypoglossal canal. Passes downward and forward in the neck and crosses the internal and external carotid arteries to reach the tongue hooking around the occipital artery In the upper part of its course, it is joined by C1 fibers from the cervical plexus. The glossopharyngeal nerve     Motor and sensory nerve, emerges from the medulla oblongata passes laterally in the posterior cranial fossa and leaves the skull by passing through the jugular foramen The superior and inferior sensory ganglia are located on the nerve as it passes through the foramen. Descends through the upper part of the neck to the back of the tongue Roof Hard palate Bones: The palatine processes of the maxillae and horizontal plates of the palatine bones. - Anteriorly and laterally: upper alveolar arch. - Posteriorly: soft palate.  Covered by a tightly bound layer of oral mucosa - Transverse palatine folds (palatine rugae) - palatine raphe: median longitudinal ridge - incisive papilla  Roof Soft palate Continues posteriorly from the hard palate and acts as a valve: - Depressed to help close the oropharyngeal isthmus - Elevated to separate the nasopharynx from the oropharynx.  Muscles: - Tensor veli palatini - Levator veli palatini - Palatoglossus - Palatopharyngeus - Musculus uvulae  Muscles of soft palat Tensor veli palatini:  Origin: Scaphoid fossa of sphenoid bone; fibrous part of pharyngotympani c tube; spine of sphenoid  Insertion: Palatine aponeurosis  NS: Nerve to medial pterygoid muscle  Action: Tenses the soft, opens pharyngotympani c tube Muscles of soft palat Levator veli palatini :  Origin: Petrous part of temporal bone anterior to opening for carotid canal  Insertion: Superior surface of Palatine aponeurosis  NS: pharyngeal branch of vagus  Action: elevate the soft palate above the neutral position Muscles of soft palat Palatopharyngeus  Origin: Superior surface of Palatine aponeurosis  Insertion: Pharyngeal wall  NS: pharyngeal branch of vagus  Action: Depresses soft palate; moves palatopharyngea l arch toward midline; elevates pharynx Muscles of soft palat Palatoglossus:  Origin: Inferior surface of Palatine aponeurosis  Insertion: Lateral margin of tongue  NS: pharyngeal branch of vagus  Action: Depresses palate; moves palatoglossal arch toward midline; elevates back of the tongue Muscles of soft palat Musculus uvulae:  Origin: Posterior nasal spine  Insertion: Connective tissue of uvula  NS: pharyngeal branch of vagus  Action: Elevates and retracts uvula; thickens central region of soft palate Blood supply of palate The ascending palatine artery  Ascends along the external surface of the pharynx. The palatine branch loops medially over the top of the superior constrictor muscle of the pharynx to penetrate the pharyngeal fascia with the levator veli palatini muscle  The palatine branch of the ascending pharyngeal artery: follows the same course as the palatine branch of the ascending palatine artery from the facial artery Blood supply of palate The greater palatine artery   Descends into the palatine canal where it gives origin to a small lesser palatine branch Continues through the greater palatine foramen onto  lesser palatine artery: the inferior surface of the Passes through the lesser palatine foramen just posterior hard palate to the greater palatine foramen, and contributes to the vascular supply of the soft palate Venous drainage of the palate    Drain into the pterygoid plexus of veins in the infratemporal fossa Into a network of veins associated with the palatine tonsil, which drain into the pharyngeal plexus of veins or directly into the facial vein Lymphatic vessels: drain into deep cervical nodes Nerve supply of palate The greater palatine nerve   Descend through the pterygopalatine fossa and palatine canal to reach the palate: Travels through the greater palatine foramen and turns anteriorly to supply the hard palate and gingiva as far as the first premolar The lesser palatine nerve : passes posteromedially to supply the soft palate  The nasopalatine nerve  Nerve supply of Lateral wall of oral cavity  Buccal nerve:  Between the upper and lower heads of lateral pterygoid lateral to the buccinator, supply the adjacent skin and oral mucosa and the buccal gingivae of the lower molars  Blood supply of Lateral wall of oral cavity  Buccal artery Inferior alveolar artery     From the maxillary artery in the infratemporal fossa. Enters the mandibular canal supplying vessels to molars and premolars Divides opposite the first premolar into:  Mental branch: leaves the mental foramen to supply the chin  Incisor branch: continues in bone to supply the anterior teeth and adjacent structures. Posterior superior alveolar artery   from the maxillary artery just after it enters the pterygopalatine fossa leaves the fossa through the pterygomaxillary fissure.  Descends on the posterolateral surface of the maxilla, branches, and enters small canals in the bone to supply the molar and premolar teeth. Anterior superior alveolar artery   from the infraorbital artery, which arises from the maxillary artery in the pterygopalatine fossa. The infra-orbital artery leaves the pterygopalatine fossa through the inferior orbital fissure and enters the inferior orbital groove and canal in the floor of the orbit   The anterior superior alveolar artery originates from the infra-orbital artery in the infra-orbital canal. Passes through bone and branches to supply the incisor and canine teeth Gingival blood supply     Buccal gingiva of the lower teeth: inferior alveolar artery Lingual gingiva: lingual artery of the tongue Buccal gingiva of the upper teeth: anterior and posterior superior alveolar arteries Palatal gingiva: greater palatine Inferior alveolar nerve From mandibular nerve in the infratemporal fossa Enter the mandibular foramen, travel through the bone in the mandibular canal. Branches to the back teeth originate directly from the inferior alveolar nerve.      Mental branch: exits the mandible through the mental foramen and innervates the chin and lower lip Incisor branch: innervates the first premolar, the canine, and the incisor teeth, together with the associated vestibular (buccal) gingiva The posterior superior alveolar nerve       Originates directly from the maxillary nerve in the pterygopalatine fossa Exits the pterygopalatine fossa through the pterygomaxillary fissure Descends on the posterolateral surface of the maxilla. Enters the maxilla through a small foramen Passes through the bone in the wall of the maxillary sinus. Innervates the molar teeth Middle superior alveolar nerve From the infraorbital nerve in the infra-orbital groove,  Passes through the bone in the lateral wall of the maxillary sinus  innervates the premolar teeth Anterior superior alveolar nerve     From the infra-orbital nerve in the infra-orbital canal Passes through the maxilla in the anterior wall of the maxillary sinus, Supplies the canine and incisor teeth.    Palatopharyngeal arches: palatopharyngeus muscles, one on each side, on the oropharyngeal wall. Palatoglossal arches: Palatoglossus muscles define the lateral margins of the oropharyngeal isthmus The palatine tonsil Oral fissure and lips     Fissure: Slit-like opening between the lips that connects the oral vestibule to the outside Lips: composed of soft tissues, lined internally by oral mucosa and covered externally by skin The philtrum: shallow vertical groove on lip external surface sandwiched between two elevated ridges of skin Median labial frenulum: connects the lip to the adjacent gum The oropharyngeal isthmus Opening between the oral cavity and the oropharynx - Formed by:  Laterally: palatoglossal arches;  Superiorly: soft palate  Inferiorly: sulcus terminalis of the tongue that divides the oral surface of the tongue (anterior two-thirds) from the pharyngeal surface (posterior one-third).  Salivary glands (compound tuboalveolar glands)   minor salivary glands – within mucosa  Secrete saliva all the time to keep mouth moist Major salivary glands  Paired (2 each)    Saliva: mixture of water, ions, mucus, enzymes keep mouth moist dissolves food so can be tasted moistens food starts enzymatic digestion buffers acid antibacterial    Parotid Submandibular Sublingual External to mouth Ducts to mouth Secrete saliva only right before or during eating Parotid gland    Largest (Serous) Relations:  Superior: external acoustic meatus zygomatic arch  Anterior: ramus of mandible  Posterior: sternocleidomastoid muscle behind  Inferior: posterior belly of digastric Facial nerve pass through it and divide it into:  Superficial lobe  Deep lobe Parotid gland    Largest (Serous) Relations:  Superior: external acoustic meatus zygomatic arch  Anterior: ramus of mandible  Posterior: sternocleidomastoid muscle behind  Inferior: posterior belly of digastric Facial nerve pass through it and divide it into:  Superficial lobe  Deep lobe Parotid gland   Parotid duct: (Stensen duct)  Passes anteriorly  Lateral surface of the masseter muscle  penetrate the buccinator muscle  Open into the oral cavity opposite to second upper molar Contains:  External carotid artery and terminal branches  Retromandibular vein  Facial nerve Nerve supply of Parotid gland    Sensory: auriculotemporal nerve Parasympathetic glossopharyngeal nerve.  tympanic branch, then lesser petrosal nerve, the otic ganglion then auriculotempor al nerve Sympathatic: periarterial nerve plexuses around the external carotid artery,  Parasympathetic: increase saliva secretion  Sympathatic: decrease saliva secretion mainly vasoconstriction Submandibular gland     Mixed, Hook shaped, two parts Superficial part: (Large) in submandibular fossa inferior to the mylohyoid line Deep part:  Loops around the posterior margin of the mylohyoid muscle  Within the floor of the oral cavity  Superior to the mylohyoid muscle  Lateral surface of the hyoglossus muscle Submandibular duct (Wharton duct ): emerges from the medial side of the deep part  Lingual nerve loops under the submandibular duct  Opens into: sublingual caruncle (papilla) beside the base of frenulum of the tongue Sublingual gland       Smallest, Almond shaped, mainly mucus Location: Medial surface of the mandible (sublingual fossa) Superior to the anterior one-third of mylohyoid muscle Superior margin of the sublingual gland raises an elongate fold of mucosa (sublingual fold) pass anteriorly to reach sublingual caruncle (papilla) beside the base of frenulum of the tongue Ducts:  Minor sublingual ducts: open onto the crest of the sublingual fold  Major sublingual duct: opens together with the submandibular duct on the sublingual caruncle Nerve supply of Submandibular and Sublingual glands      Sensory: lingual nerve Parasympathetic Facial nerve via chorda tympani nerve Sympathatic: periarterial nerve plexuses around the external carotid artery Following distribution of facial and lingual arteries  Parasympathetic: increase saliva secretion  Sympathatic: decrease saliva secretion mainly by vasoconstriction Maxillary anesthesia Local infiltration  Able to be performed in the maxilla due to the thin cortical nature of the bone  Involves injecting to tissue immediately around surgical site Field block  Local anesthetic deposited near a larger terminal branch of a nerve (Periapical injections) Nerve block  Local anesthetic deposited near main nerve trunk and is usually distant from operative site (Infraorbital, Greater palatine, Nasopalatine)    Mandibular anesthesia   Local infiltration do not work in the adult mandible due to the dense cortical bone Provides anesthesia to the pulpal, alveolar, lingual and buccal gingival tissue, and skin of lower lip and medial aspect of chin on side injected Inferior alveolar nerve block        Anesthetizes 2 nerves: Inferior alveolar nerve Lingual nerve Method Orient the needle from the contralateral premolars and advance it along the occlusal plane of the mandible Use the non-dominant hand to retract the buccal soft tissue (thumb in coronoid notch of mandible; index finger on posterior border of extraoral mandible) lateral to the pterygomandibular raphe Inferior alveolar nerve block        Method Pterygomandibular space Mandibular foramen Lateral to sphenomandibular ligament Needle contacts the mandible after entering 20 to 25mm Perform aspiration to determine whether the needle is in a blood vessel Slowly inject the anesthetic Inferior alveolar nerve block   Areas anesthetized:  All mandibular teeth (inferior alveolar nerve)  Epithelium of the anterior 2/3rds of the tongue (lingual nerve)  All lingual gingiva and lingual mucosa (lingual nerve)  All buccal gingiva and mucosa from the premolars to the midline (mental nerve)  Skin of the lower lip (mental nerve) A transient, dental-induced Bell’s palsy can result if the needle is placed too far posteriorly in the parotid bed and anesthetic is introduced close to the facial nerve Akinosi block           A closed-mouth approach Anesthetizes 2 nerves: Inferior alveolar nerve Lingual nerve Provides same areas of anesthesia as the IAN nerve block Useful technique in: Patients with trismus Fractured mandibles Mentally handicapped individuals Children Akinosi block      Method Insert the needle into the mucosa between the medial border of the mandibular ramus and the maxillary tuberosity at the level of the cervical margin of the maxillary molars Advance the needle parallel to the maxillary occlusal plane approximately 23 to 25mm(note: no bone will be contacted) After a negative result on aspiration, slowly inject the anesthetic Mental/incisive nerves block      Method Area of injection mucobuccal fold at or anterior to the mental foramen. This lies between the mandibular premolars Depth of injection ~5-6mm Inject 0.5-1.0cc of local anesthesia Message local anesthesia into tissue to manipulate into mental foramen to anesthetize the incisive branch