Basic Anatomy of the Oral Cavity Marin Vodanović Chapter I Learning outcomes: State and explain the functions of the oral cavity State thea most important Slap nerves in the oral cavity Explain the innervation of the oral cavity State the most important blood vessels in the oral cavity Explain the vascularisation of the oral cavity Distinguish phases in jaw growth and devel- Copyrightopment Describe the characteristics of dental arch- es Specify the parts of the jawbone Explain the Haversian canal system Explain the alveolar bone proper Explain the supporting alveolar bone Explain the trabecular bone Recognise basic structures on radiographic © Nakladimages of the maxilla and mandible Slap Copyright Naklada © 2 Chapter 1 Basic Anatomy of the Oral Cavity he oral cavity (cavum oris) is the initial part it is richly supplied with blood vessels. The Tof the digestive system and has a digestive, colour of the oral mucosa varies from light to phonative, sensory, protective, respiratory, dark pink. It is continuous with the skin of and social function. The digestive function in- the lips and the mucosa of the soft palate and cludes mastication, saliva secretion, preparing pharynx. The palate (palatum) constitutes bolus for deglutition, and deglutition in itself. the roof of the oral cavity and comprises a The phonation includes the creation and ar- hard palate (anterior part) and a soft palate ticulation of sounds in conjunction with other (posterior part). A longitudinal suture runs speech organs. The sensory function of the along the middle of the hard palate connect- oral cavity refers to sensations of taste, smell, ing the left and right parts of the upper jaw touch, pain, and thermal changes. The pro- (maxilla). Shallow transverse palatine folds tective function is primarily linked to the oral (rugae palatinae) can be found on the mucosa mucosa which mechanically protects deeper of the anterior part of the hard palate behind oral tissues, and to saliva which contains cer- the incisors. The soft palate is composed of a tain antimicrobial substances. During strenu- musculotendinous plate which is covered on ous physical work, when there is an increased the underside by the oral mucosa and by the need for air or in case of nasal airway obstruc- nasal mucosa superiorly. The tongue (lingua) tion, the oral cavity assumes a respiratory is a muscular organ which is covered with oral function. The social function of the oral cavity mucosa and is involved in mastication, deglu- is realised not only through speech (phonative function) but also through facial expressions Slap and social contacts such as kissing. The oral cavity is divided into the oral vestibule and the oral cavity proper (cavum oris proprium). The oral cavity proper is also Nasal cavity referred to as the oral cavity in the narrower Hard palate sense. The entrance to the oral cavity is referred Soft palate to as oral fissure (rima oris) and is bounded by Upper lip Vertebral the lips. Posteriorly, the oral cavity terminates column Teeth at the entrance to the pharynx. The cheeks constitute the lateral walls of the oral cavity. Lower lip AnteriorlyCopyright and laterally, the oral cavity proper Pharynx is bounded by the U-shaped maxillary and Tongue mandibular dental arches. While the hard and soft palate constitute the roof of the oral cavity proper, the so-called diaphragma oris formed by both mylohyoid muscles, the anterior bel- ly of the two-bellied (digastric) muscles, and Windpipe Oesophagus (respiratory tract) (digestive tract) the geniohyoid andNaklada genioglossus muscles, together with parts of the tongue, constitute Figure 1.1 Cross-section of the oral cavity and the the floor of the oral cavity. The tongue consti- pharynx (Adapted from: Vodanović, M. Uvod u anato- miju i fiziologiju usne šupljine (Introduction to the Anat- tutes most of the oral cavity proper (Figures omy and Physiology of the Oral Cavity). In: Vodanović, 1.1 and© 1.2). The mucosa of the oral cavity is M. Osnove stomatologije (The Essentials of Dental Medi- relatively thick and consists of a multi-layered cine). Jastrebarsko: Naklada Slap; 2015. 19-32. Printed squamous epithelium and connective tissue; with permission of the publisher.) 3 BIOLOGY AND MORPHOLOGY OF HUMAN TEETH Anterior palatine arch Maxillary dental arch Palatine tonsils Posterior palatine arch Hard palate Longitudinal palatine Tongue suture Mandibular dental arch Soft palate Uvula Pharynx Figure 1.2 The oral cavity tition, drinking, speech, and the perception vary glands exist in pairs. The minor salivary of taste. Anatomically, the tongue is divided glands are found in the cheeks, lips, tongue, into three parts, namely, the root, the dorsum, palate, tonsils, and pharynx. and the apex. It is composed of seven muscles Slap which extend perpendicular to its surface and are transverse and parallel to its longitudinal Innervation of the oral axis. cavity The mucosa of the dorsum of the tongue is permeated by numerous visible protrusions, The oral cavity and the organs contained referred to as lingual papillae; they play a role therein are innervated by several cranial in mechanical, tactile, or gustatory recogni- nerves with their sensory and motor fibres, tion, which is important for mixing food. The which are the following: nervus trigeminus lips (labia oris) are composed of muscles and (fifth cranial nerve), nervus facialis (seventh connective tissue. They are richly supplied cranial nerve), nervus glossopharyngeus with Copyrightblood vessels and nerves. The red part of (ninth cranial nerve), and nervus vagus (tenth the lip is covered by mucosa which constitutes cranial nerve). the transition between the skin of the face The trigeminal nerve (nervus trigeminus) and oral mucosa. The salivary glands in the is a nerve of the first pharyngeal arch which oral cavity are divided into major and minor consists of a sensory and a motor part and salivary glands. The labial mucosa contains innervates the masticatory muscles and some minor salivary glands the size of pin heads. pharyngeal and supralingual muscles. It Nakladatransmits general sensory information from The largest part of the total saliva volume is secreted by the major salivary glands. The the face and a large part of the forehead, teeth, parotid gland (glandula parotis), the subman- lips, and the nasal cavity. The main branches dibular gland (glandula submandibularis), of the trigeminal nerve are the ophthalmic and© the sublingual gland (glandula sublingua- nerve (nervus ophtalmicus), the maxillary lis) are the major salivary glands. As opposed nerve (nervus maxillaris), and the mandibular to the minor salivary glands, the major sali- nerve (nervus mandibularis). 4 Chapter 1 Basic Anatomy of the Oral Cavity The ophthalmic nerve innervates the eye- the lesser palatine nerve (nervus palatinus balls, sockets, frontal sinuses, nose, forehead, minor), which innervates the soft palate and the vertex. It is the first and smallest the nasopalatine nerve (nervus nasopalati- branch of the trigeminal nerve and contains nus), which innervates the nose and the only sensory nerve fibres. The branches of the palatine gingiva of maxillary anterior teeth ophthalmic nerve are as follows: the middle superior alveolar nerve (nervus the lacrimal nerve (nervus lacrimalis), alveolaris superior medius), which inner- which innervates the sockets and the skin vates the maxillary sinuses and the maxil- of the upper eyelids and receives anasto- lary premolars moses from the post-ganglionic fibres of the anterior superior alveolar nerve (ner- the pterygopalatine ganglion via the zygo- vus alveolaris superior anterior), which in- matic nerve nervates the maxillary anterior teeth the frontal nerve (nervus frontalis), which the infraorbital nerve (nervus infraorbital- innervates the forehead and vertex is), which innervates the skin on the front the nasociliary nerve (nervus nasociliaris), part of the cheeks, the lower eyelids, the which innervates the eyeballs, the ethmoi- lateral nasal surfaces, the upper lip, and dal chambers, the nose, and the skin of the the upper labial mucosa nasal bridge and the tip The mandibular nerve is the third and the The maxillary nerve is the second branch largest branch of the trigeminal nerve. It pro- of the trigeminal nerve, which has purely sen- vides sensory innervationSlap to the mandibular sory fibres which innervate the cheeks, lower teeth and gingiva, the skin of the temples, a eyelids, the lateral sides of the nose, the upper part of the ear, the lower lip, the lower part of lip, teeth, the maxillary mucosa, the inlet of the face, the anterior two-thirds of the tongue, the sphenoid bone, the maxillary sinuses, the and the mucosa of the oral cavity floor. It pro- posterior ethmoidal chambers, the superior vides motor innervation to the masticatory and middle nasal conchae, the palate and pal- muscles and the other muscles which develop atine tonsils, the roof of the pharynx, and the from the first pharyngeal arch. The branches dura mater of the middle cranial fossa. The of the mandibular nerve are as follows: branches of the maxillary nerve are as follows: the buccal nerve (nervus buccalis), which the posteriorCopyright superior alveolar nerve (ner- innervates the mucosa and skin of the vus alveolaris superior posterior), which cheeks innervates the maxillary molars and the the lingual nerve (nervus lingualis), which maxillary sinuses innervates the floor of the oral cavity and the zygomatic nerve (nervus zygomaticus), the anterior two-thirds