Nasal & Oral Cavities and Infratemporal Fossa

Nasal & Oral Cavities and Infratemporal Fossa

• Study notes on the medical gross anatomy involving the nasal and oral cavities as well as the infratemporal fossa

Learning Objectives

• Distinguishing osteological features of the nasal, oral, and infratemporal regions, including paranasal sinus drainage, the relationship between the palate, mandible, and TMJ, and the role of the lateral spaces (ITF, pterygopalatine fossa, paralingual space) as conduits for the neurovasculature is essential
• Associating the actions of the tongue muscles and muscles of mastication in facilitating chewing and swallowing tasks is important
• Integrating the cranial nerve pathways involved in special senses (olfaction and taste), sensation via trigeminal branches to the nasal/oral mucosa and teeth is one of the objectives
• Understanding motor innervation (palate vs tongue muscles - vagus vs hypoglossal), and autonomics to the glands of the head is important
• Describing the blood supply to the nasal and oral cavities is a key objective, including the primary arteries (carotids), their branches (maxillary and lingual), and the vascular pathways/anastomoses that support these regions
• Discussing clinical correlates related to these regions and supported by medical imaging techniques is an objective

Region & Function

• The nasal and oral cavities are part of the respiratory tract and contain the peripheral organ of smell
• The airway allows for respiration and ventilation, including air conditioning to humidify and warm
• Reception and elimination of secretions occurs via sinuses and ducts, along with immune defense from tonsils and mucociliary system
• Aiding in digestion, through the process of indigestion, mastication and deglutition, as well as the elimination of secretions
• Communication is enabled by phonation extension of resonance chamber for voice & articulation as well as external nose contribution to identity & expression
• As interpretting and responding to smell via CN1 Olfactory and interpreting taste via CN VII Facial, X Vagus, IX Glossopharyngeal
• From the nasal vestibule, the nasal cavity is partitioned bilaterally by the nasal septum; the inferior 2/3rds of the nasal mucosa serve for respiration while the superior 1/3rd houses CN1 composed of special sensory fibers conveying olfaction (smell)
• The oral cavity begins with the digestive tract: Vestibule is the external junction between teeth & gingivae and Oral Cavity Proper is internal to teeth to the entrance of oropharynx
• Although literature suggest smell affects perception of taste: there are not taste buds in nasal cavity, but association/convergence of two senses in the brain

Superficial Anatomy

• The external nose is the visible cartilaginous portion; primarily structured with lateral cartilages and alar cartilages
• Dorsum extends from the root to the apex pierced by two piriform nares (nostrils)
• The superior bony part of the nose, including its root, is covered by thin skin whereas the cartilaginous part is covered with thicker skin as the skin extends into the vestibule of the nose, where dust is filtered

Osteology - Nasal Cavity

• The lateral and medial wall are appreciated by opening the cranial cavities off the midline
• The bones serve as the superstructure of nasal cavity walls and form the external nose
• Nerves & arteries course through foramina & pockets/hollows (sinuses)
• The sphenopalatine foramen allows the sphenopalatine artery, nasopalatine nerves, and posterior superior lateral nasal nerve to pass through and communication between the nasal cavity and the pterygopalatine fossa

Paranasal Sinuses

• Taking a midline look shows the septum and bony structures underlying conchae
• In a radiograph the pockets/hollows forming the paranasal sinuses beside the nasal cavity are visible with minimal radiation
• The consequence of these sinuses includes lightening the skull, improving nasal function, immune defense, etc
• A T-rex skull exhibiting sinuses shows an evolutionary reduction in skull mass
• Bilateral air-filled cavities/extensions in the frontal, ethmoid, sphenoid, & maxilla bones
• Frontal sinuses are between the outer & inner tables of the frontal bone posterior to superciliary arches & root of nose
• Ethmoidal cells (sinuses) are small invaginations of the mucous membrane & ethmoid bone between the nasal cavity & the orbit
• The sphenoidal sinuses are located in the body of the sphenoid & may extend into the wings of the bone, being unevenly divided and separated by a bony septum, having thin plates of bone that separate the sinuses from the optic nerves and optic chiasm, the pituitary gland, the internal carotid arteries, and the cavernous sinuses
• Maxillary sinuses are the largest of the paranasal sinuses and occupy bodies of the maxillae
• Apex extends toward aften into zygomatic bone, base forms inf part of the lateral wall, roof is ormed by the floor of the orbit and floor is formed by alveolar part

Boundaries of the Nasal Cavity

• The nasal mucosa is bound tightly to the periosteum & perichondrium of the supporting bones & cartilages of the nose, lining the communicating chambers
• The nasal cavity is bounded superiorly by regions, inferiorly by the hard palate and laterally by nasal conchae/turbinates superiorly and medially by the nasal septum
• Superior concha covers underlying olfactory bulb & nerve endings
• Middle concha projecting out over openings of maxillary sinus between the mid and inf concha
• Inferior concha plays the most important role in determining direction of air flow across the lateral wall
• Air flow across the concha results in humidification, filtration and changes in air temperature
• A consequence of the concha includes flow of inhaled air across a surface area covered in mucosa that traps inhaled particles, as is constantly cleaned through the respiratory epithelium also a rich underlying arterial surface warms inhaled air which cools due dilation

Sinus Drainage

• In the nasal cavity, a recess or nasal meatus underlies each bony nasal concha (lateral walls) that aids in reception and elimination of secretions which divides it into four passages

1. Superior meatus receives the opening of the sphenoidal sinus as the sphenoethmoidal recess
2. In the middle meatus: the frontal sinus, anterior ethmoidal cells, middle ethmoidal cells, and maxillary sinus
3. Inferior meatus serves as the opening of the nasolacrimal duct
4. Common nasal meatus is the medial part of the nasal cavity between the conchae & the nasal septum, which the lateral recesses and meatus open to

Arterial Supply

• The rich arterial supply warms the air by major arterial contributions: maxillary, ophthalmic, & facial
• Branches for blood are sphenopalatine, greater palatine, anterior & posterior ethmoid (terminal branches), nasal septal branch (superior labial branch)
• In the anterior nasal septum the kiesselbach area is the site of anastomotic arterial plexus involving all arteries supplying the septum

Olfactory Nerve

• As Special Sensory the olfaction of specialized visceral afferent is the sensation of odor that results for substances aerosolized in the environment
• Olfactory nerves arise from olfactory epithelium in the superior part and pass throught the cribriform plate
• Axons project to higher centers in the brain where the neurons are stimulated by molecules and synapse with mitral cells

Somatic Sensory

• Branches of V1 (opthalmic): lacrimal, nasociliary, supraorbital, supra trochlear, infratrochlear and the Ant & Post Ethmoidal from nasociliary contribute
• The V2 (maxillary) nerve passes into the orbital region posterior to the lateral nasal wall
• The nerve supply of the anterosuperior portion is from the ophthalmic nerve by way of the anterior and posterior ethmoidal nerves, branches of the nasociliary nerve while the nerve supply of the posteroinferior portion of the nasal mucosa is from maxillary nerve by way of the nasopalatine nerve to the nasal septum

Clinical Correlates

• Shearing forces that damage CN I and or lacerate the meninges is Cribriform Plate Fracture where as a result Cerebrospinal fluid leaks into the nose
• 2ndary consequence of rupture which goes untreated is bacterial infection which may develop into meningitis
• Halo sign is clear drainage which is a seperation from bloody drainage
• Nasal fractures can deviate the septum and cause air way blockage

Oral Cavity

• It is subdivided into the Vestibule--external junction between the teeth and gingivae and Oral Cavity Proper--internal to teeth
• Bounded by: Roof of hard and soft palate. Posterior by oropharynx. Lateral is cheek and retromolar regions and the floor is tongue and mylohyoid mm

Osteology- Oral Cavity

• In the oral aspect there are 3 orifaces: inciisve and the Greater and Lesser Palatine orifaces
• The nasopalatine nerves go through the Incisive fossa and the Greater Palatine Vesseles and nerves emerge from the palatine bony border

Ostology - Fossae

• Shallow bone depressions (neurovasculature passage) for sensory function to the lower face.
• Shaared with: maxillary A; pteryogopalatine ganglion; trigoeminal brances; parapsympathetic ganglis;
• The pteryomaxillary fissure- the oening the connects to the pterygo palatine fossa
• Found in the infraTemporal Fossa: tempralis m, maxillary a, pterogoid venous plexus, mandibular, chorda tympani
• Found in the pterogopalatine Fossa: Maxillary, pteryogopalatine ganglion, maxillary a (part 3)

Mastication

• Muscles of Mastication: temporalis, masseter, lateral pterygoid, and medial pterygoid. The lateral pteryfoid aids
• Big picture -insert on mandible EXCEPT the Masseter m

Tongue

• Dorsal tongue: epiglottis; palatine tonsil; lingual tonsil; foramen cecum; vallate.
• The inferior surface is covered with a mucous membrane thru which the deep veins are visible.

Tongue Musles

• The four intrinsic and four extrinsic muscles are separated bu the fibrous lingual septum. Genioglossus, Hyoglossus and Styloglossus (CN XII hypoglossal)
• The muscles do not act separate- they are are all inter related
• The position is altered by the extrinsic and the shape by the intricic musles

Special Motor/Sensory

• V3 Mandibular (lower teeth, ant 2/3rd tongue, mastication, + highway for parasymp)
• Auriculotemporal loops middle meningeal a. External ear and parotid via Otic gangl
• Lingual N (taste and para from chorda tympani CN VII, is the Ant 2/3 tongue
• In Mandibular: Sensation:inf alveolar; motor to mylohyoid with the Mental N
• Cheeek : bucal N
• salivary gland: Otic and submandibular ganglis.

Tongue Inner Vation

• The Hypoglossel is a Motor. (palate muscles)
• Vahus is sensory (root of tongue epiglottis/ special epiglottis)
• Glossophrayngeal (gen and special Posterios)
• Lingual (CN V5) and Chorda Tampini and lingual

Arterial Suply

• Arterial sup lies come fro Lingula-from the carotid. The branches are-Dorsal=lingual arteries that sup ply postertio.
• The Sup and Inf alveolar supplies maxillary. These have vains.
• Just need to know maxillary & middle meningeal & branches in nasal cavity

Salivary Glands

• All encapsulated with secretory docts in the oral cavitye
• They also secrete saliva (digestive enzymes + antimicrobial agents) that fcalilitate and swatllowing
• 3 parotid lands and subamanidbular and sulingula: largest w/ branchinf facial n, duct open and molar
• Sulbimdibular: thuck beneath, ducts cross of the lingual n; Sulbingula : duct open near freinulam
• Prarotit gland ( CN IV) and Sulmandibular and Sulbinula- CN VII via facial N via ganglis

Autonomics

• Trigeminal ride fibers from others as well
• Autonomic innervations are FULL pathway

Cliincal Correlates

• Nerve block anesthesis
• Superior: CN V2( molars to anterior and cainings maxillary)
• CNv2 inferior: skin and lower lip. Isplateral Mandivular teeth and gums.skin of chin