Anatomy of the Head and Neck – Oral and Nasal Cavities PDF

Anatomy of the head and neck – Oral and nasal cavities Anatomy of the Head & Neck Oral and nasal cavities [email protected] ANATOMY 0  Lecture outco...

Anatomy of the head and neck – Oral and nasal cavities Anatomy of the Head & Neck Oral and nasal cavities [email protected] ANATOMY 0  Lecture outcomes – to be able to describe the following Ø bony and soft tissue boundaries of the oral cavity Ø innervation, attachments and the action of the muscles of the tongue Ø dorsum of the tongue and describe the sensory nerve supply and the arterial supply and venous drainage Ø anatomy of salivary glands Ø where the ducts of the major salivary glands enter the oral cavity Ø functions of the nose Ø bony and cartilaginous boundaries of the nasal cavity Ø blood supply and innervation of the external nose and the nasal mucosa and the olfactory epithelium ANATOMY 1 Ø position and drainage of the paranasal sinuses  Oral cavity Ø The mouth is the entry point to the alimentary canal Ø (Mouth) where food or drink is tasted, mixed with saliva, masticated and voluntarily swallowed ANATOMY 2  Oral cavity 2 Ø The oral cavity consists of two areas: - vestibule, the space between the teeth and the mucosal inner lining of the cheeks and lips - oral cavity proper, the space contained within the upper and lower dental arches and filled by the tongue © Quizlet.com ANATOMY 3  Oral cavity boundaries Ø Roof: the maxilla and palatine bones Ø Anterior: maxilla and mandible, inc the dental arches Ø Floor and posterior wall: soft tissues. Maxilla Palatine (highlighted Mandible in blue) ANATOMY 4 © Visible Body  Oral cavity – coronal section 1. Oral cavity 2. Buccinator muscle 3. Vestibule 4. Genioglossus (‘chin-tongue’) 5. Geniohyoid (‘chin-hyoid’) 6. Anterior belly of digastric 7. Mylohyoid *Floor mouth* ANATOMY 5  Roof of the mouth Ø Maxilla: separates the oral from the nasal cavity. It makes up for - the anterior boundary of the upper part of Maxilla the oral cavity and - the anterior 2/3 of the roof Ø Palatine: makes up for the remaining 1/3 of the roof. Also the attachment for the soft palate 1. Levator palati 2. Palatopharyngeus 3. Palatoglossus ANATOMY 4. Tensor palati 6 (Posterior aspect of the soft palate)  Floor of the mouth Mandible Ø The floor of the mouth is formed by mucous membrane and muscles: Internal view 1. Mylohyoid 2. Geniohyoid 3. Mylohyoid 4. Anterior belly of digastric Hyoid External view ANATOMY 7  Lips and cheeks Ø Surrounding the oral cavity or mouth are the cheeks and lips, respectively Ø Lips have a multiple role, from acting as a sphincter, grasping food, suckling, speech, etc Ø The lips are described as musculofibrous folds, containing the orbicularis oris (‘orbiting the oral opening’) with accompanying vessels and nerves Ø Blood: upper and lower labial arteries (from facial); Nerves: labial upper from infra-orbital (CN V2) lower from mental (CN V3) ANATOMY 8  Lips and cheeks 2 Ø The cheeks (Buccae) are continuous with the lips and make up the movable walls of the oral cavity Ø Like the lips, the cheeks enclose muscle – principally the buccinators – that are encapsulated by fat. The cheeks are also involved in suckling, facial expression, speech, etc Ø Blood: buccal arteries (branches of the maxillary) Ø Nerves: buccal branches (of the mandibular) ANATOMY 9 © Clinically Oriented Anatomy. 7th Ed. Moore et al  Muscles of the cheeks and lips Orbicularis oris Buccal nerves Buccinator © Visible Body ANATOMY 10  Did you know…? Ø The lips are covered externally by skin and internally by mucous membrane, but… Ø The transitional zone between these is called the vermilion border Ø The vermillion border does not contain glands, which is why we need to lick these regularly to avoid becoming dry Ø The buccinator’s role is to push the cheek towards the teeth, thus preventing food squeezing into the vestibule during chewing Ø The lips do a similar role by stopping food falling of your mouth. (Also preventing disapproving looks if chewing with mouth open) ANATOMY 11 https://goalsplasticsurgery.com/lip-augmentation/  Nerve supply to the muscles of the oral cavity Ø The muscles in the lateral walls are supplied by the facial nerve Ø The floor has a more complex nerve supply: - geniohyoid supplied by fibres from C1 - the mylohyoid & anterior belly of digastric by the mandibular branch of the trigeminal ANATOMY 12  Nerve supply to the mucosa of the oral cavity Ø The mucous membrane of the roof is supplied by branches of the maxillary nerve Ø The lateral walls and floor are supplied by branches of the mandibular division (lingual branch) of the trigeminal ANATOMY 13  Contents of the oral cavity Ø Teeth Ø Tongue Oral cavity Ø Ducts of the salivary glands Oropharynx * Note that, posteriorly, the mouth ANATOMY communicates with the oropharynx 14  The permanent dentition Ø There are 32 permanent teeth Ø These erupt between 6 and 18 years Ø The primary role of teeth is to cut (aka incise) food, to break it down mechanically, mostly through molar action and, to a lesser degree, to assist with speech ANATOMY 15  The permanent dentition 2 Ø Bisected teeth reveal three distinct regions: crown, neck and root (the latter fixed in the tooth socket) Ø Most of the tooth is covered by dentine covered by enamel in the crown region and cement in the root Ø The teeth are supplied by alveolar branches of the maxillary (upper) and the mandibular nerve (lower) ANATOMY 16  The tongue (Latin ‘Lingua’ or Greek ‘Glossa’) Ø The tongue is a special sense organ of, involved primarily with taste but also mastication, deglutition, speech or even oral cleansing Ø Has three main parts: a root, body and apex (tip) Ø The anterior 2/3 of the tongue - the body - rests within the oral cavity while the posterior 1/3 - the root - lies in the oropharynx © Clinically Oriented Anatomy. 7th Ed. ANATOMY Moore et al17  The tongue 2 Ø The tongue can be described as a collection of muscles that together make a mobile muscular organ, covered by mucous membrane Ø The figure below shows how this collection of muscles is split into two main subgroups: intrinsic and extrinsic Ø Intrinsic muscles change the shape of the tongue while the extrinsic change its position Extrinsic muscles 1. Palatoglossus 2. Styloglossus 3. Hyoglossus 4. Genioglossus ANATOMY 18  Nerve supply to the tongue Ø Innervation of the tongue is rather complex as it needs to consider both its roles in taste and mastication (muscle movement) Ø All muscles of the tongue except palatoglossus are innervated by the hypoglossal nerve Ø The palatoglossus is innervated by the pharyngeal plexus 1. Styloglossus 2. Genioglossus ANATOMY 3. Hyoglossus 19  Nerve supply to the tongue - sensation and taste Ø The anterior 2/3: - general sensation (touch and temperature) of the anterior 2/3 is via the lingual nerve, a branch of CN V3 - taste is via the chorda tympani (from CN VII) Ø The posterior 1/3 and the vallate pappilae is supplied by the lingual branch of CN IX Sensory 1. X 2. IX 3. V mandibular division - lingual n 4. VII – chorda tympani ANATOMY 5. IX 20 6. X  Blood supply to the tongue Ø The tongue receives blood primarily via the lingual artery, a branch of the external carotid artery Ø The artery runs deep to the hypoglossus muscle © Visible Body ANATOMY Lingual artery 21  Venous drainage of the tongue (2 routes) Ø The dorsum and sides of the tongue are drained by the posterior lingual veins, that leads to the lingual vein. The lingual vein drains to the internal jugular vein Ø The remainder is drained by the deep lingual and sublingual veins, that join and lead to the lingual vein ANATOMY 22  Lymphatic drainage of the tongue Ø The lymphatic drainage of the tongue is done in regions, each taking a different route Ø However, lymph drains ultimately towards the deep cervical nodes, that pass it into the general circulation at the venous angles (jugular and subclavian) ANATOMY 23  Salivary glands Ø Salivary glands are responsible for keeping the mouth moist Ø Salivation comes through numerous small glands, however, there are three pairs of large salivary glands: Submandibular, sublingual and Parotid Ø These large glands respond (i.e. excrete) primarily when food is in the mouth 1. Parotid gland 2. Parotid Duct 3. Openings of sublingual glands 4. Opening of submandibular gland 5. Sublingual gland 6. Submandibular gland ANATOMY 24  Salivary glands 2 Ø The duct of the parotid salivary gland enters the mouth near the upper 2nd molar tooth. The secretion is serous Ø The duct of the submandibular gland enter the floor of the mouth. It is a mixed gland having both serous and mucous secretions Ø The sublingual gland has between 16 and 20 short duct which open into the floor of the mouth. It is mucus secreting Ø These major glands moisten the food dissolving the chemicals which stimulate the taste bud. The moisture in the saliva helps turn the food into a bolus to aid swallowing. Saliva also contains enzymes which begin the process of digestion The minor glands, in turn, are very important in maintaining oral hygiene as the continual background level of secretion flushes the ANATOMY oral surfaces and helps to control the level of bacteria 25  The nose and nasal cavity Ø Both have the main role of enabling the sense of smell …But also: Ø Form the upper portion of the respiratory tract Ø Moistens and warms the inspired air Ø Filters the air to remove foreign particles Ø Acts as a resonating chamber for speech ANATOMY 26  The nose Ø The external nose is the portion that protrudes from the face Ø Its frame is of cartilage covered by skin Ø The nose can vary considerably in size. However, all have a thick skin covering the cartilage and extending into the nasal opening – nares – where thick hairs help to filter the incoming air ANATOMY 27  The nasal cavity Ø The nasal cavity is an irregular shaped cavity bordered by - Floor: the palatine bone that separates it with the oral cavity - Roof: the cribiform plate (ethmoid) separating it from the cranial cavity Ø The cavity is high, deep but narrow and divided into left and right by the nasal septum Ø It communicates anteriorly with the (external) nose and posteriorly with the nasal part of the pharynx Ø The wall is lined by a mucosal layer that makes a sticky sheet. This covers the surface and traps dust, bacteria etc. Cillia then propel it towards the nasopharynx ANATOMY 28  The nasal cavity 2 ANATOMY 29  The nasal cavity 3 Ø The lateral wall of the nasal cavity shows three circular tube-like protrusions called conchae Ø The conchae force incoming air to swirl around, which slows it down sufficiently to be warmed and also propel the dust, bacteria etc towards the mucus layer ANATOMY 30  The nasal cavity 4 Ø Another feature of the nasal cavity are the paranasal sinuses Ø Although empty (hence the term ‘sinuses’) the wall of the sinuses are composed of mucus excreting epithelium Ø These are emptied into the nasal cavity and act to help moisten the surface of the nasal cavity and of the incoming air ANATOMY 31  Surface projection of the paranasal air sinuses ANATOMY 32  ’VAN’ of the nasal cavity Ø V (Veins): a plexus leading to the ophtalmic, sphenopalatine and facial Ø A (Arteries): ophthalmic, maxillary and facial Ø N (Nerves): ophthalmic (anterosuperior) and maxillary (postero-inferior) ANATOMY 33  Questions? Email: [email protected] ANATOMY 34