7 Nasal Cavity and Nasopharynx The nose is composed primarily of cartilages except at the “bridge” of the nose where the nasal bone resides. Anteriorly, COLOR the following features of the lateral wall of the nasal the air enters or leaves the nose via the nares, which open cavity, using a different color for each feature: into the nasal vestibule, whereas posteriorly the nasal cavity n 6. Superior concha (turbinate) communicates with the nasopharynx via paired apertures n 7. Middle concha (turbinate) called the choanae. n 8. Inferior concha (turbinate) COLOR the following cartilages contributing to the nose, The innervation of the nasal cavities includes: using a different color for each cartilage: • CN I: olfaction (smell) n 1. Lateral processes of the septal cartilage • CN V1 and V2: sensory via the maxillary division of the trigeminal, except for the anterior part of the nose (V ) n 2. Major alar cartilages 1 • CN VII: secretomotor parasympathetic fibers course from the n 3. Septal cartilage facial nerve to the pterygopalatine ganglion, synapse here, and then course with branches of CN V2 to innervate the nasal The nasal cavity is separated from the cranial cavity by portions mucous glands of the frontal, ethmoid, and sphenoid bones, and from the oral • Postganglionic sympathetics from the superior cervical gan- cavity inferiorly by the hard palate. A nasal septum, usually devi- glion to the blood vessels ated slightly to one side or the other, divides the nasal cavity into right and left chambers. The anterior third of the nasal septum is The blood supply to the nasal cavities is largely by the branches cartilaginous and the posterior two thirds is bony. of the maxillary and facial arteries, with some contributions from the ethmoidal branches of the ophthalmic artery. COLOR the following features of the nasal septum, using a Posteriorly, the nasal cavities communicate via the choanae with different color for each feature: the most superior portion of the pharynx, called the nasophar- n 3. Septal cartilage ynx. In its lateral wall, the opening of the pharyngotympanic (auditory, eustachian) tube is visible and represents a direct n 4. Perpendicular plate of the ethmoid bone conduit to the middle ear cavity. n 5. Vomer The lateral wall of the nasal cavity is characterized by three Clinical Note: shelflike conchae, or turbinates (conchae covered with respi- Acute otitis media, an inflammation of the middle ear, is a com- ratory epithelium also are often referred to as turbinates), that mon disorder in children under the age of 15 years. In part this protrude into the cavity, and along with their covering of nasal disorder is prevalent because of the horizontal nature of the pha- respiratory epithelium, they greatly increase the surface area for ryngotympanic, or auditory, tube in children (the tube is slightly warming, humidifying, and filtering the air. The space beneath more vertical in adults) and the fact that the normal drainage each shelflike concha is called ameatus . At the most superior toward the nasopharynx by gravity is compromised. Infections aspect of the nasal cavity resides the olfactory region, with may be bacterial or viral. its olfactory epithelium and specialized sensory cells for the detection of smells. Plate 7-2 See Netter: Atlas of Human Anatomy, 6th Edition, Plates 35, 36, and 38 Respiratory System Nasal Cavity and Nasopharynx 7 Frontal bone Nasal bones 1 Minor alar cartilage Accessory nasal 3 cartilage Crista galli 2 Cribriform plate Ethmoid bone 4 Nasal septal cartilage Frontal sinus Anterior nasal Sphenoidal sinus spine of maxilla Medial plate of Sphenoid Nasal bone pterygoid process bone Alar fibrofatty tissue 5 3 A. Anterolateral view Basilar part of 2 occipital bone Perpendicular plate Palatine process Palatine of maxilla Horizontal plate bone B. Medial wall of nasal cavity 6 Opening of sphenoidal sinus Superior nasal meatus Hypophysis (pituitary gland) 7 in sella turcica Middle nasal meatus Sphenoidal sinus 8 Basilar part of occipital bone Nasal vestibule Choana Inferior nasal meatus Palatine process of maxilla Opening of pharyngotympanic (auditory) tube Horizontal plate of Soft palate C. Walls of nasal cavity palatine bone Netter’s Anatomy Coloring Book Plate 7-2 7 Paranasal Sinuses There are four pairs of paranasal sinuses, which are open The mucosa of the paranasal sinuses is innervated by sensory chambers within several of the bones surrounding the nose branches from CN V (ophthalmic and maxillary divisions). and orbits. They are lined with respiratory epithelium, assist in warming and humidifying the inspired air, and drain their mucus secretions into the nasal cavities. Sneezing and blowing COLOR the following paranasal sinuses, using a different the nose clears the nasal cavity and sinuses of excess color for each sinus: secretions. The paranasal sinuses and their features are n 1. Frontal sinus summarized in the following table. n 2. Ethmoid air cells (sinuses) n 3. Sphenoid sinus 4. Maxillary sinus SINUS DESCRIPTION n Frontal Paired sinuses, lying anteriorly in frontal bone and draining into semilunar hiatus of middle meatus Clinical Note: Ethmoid Paired anterior, middle, and posterior sinuses in ethmoid bone; anterior and middle draining into Rhinosinusitis is an inflammation of the paranasal sinuses, most middle meatus (hiatus semilunaris and ethmoid commonly the ethmoid and maxillary sinuses and nasal cavity. bulla, respectively), and posterior, into superior Usually, this condition begins as a viral infection followed by a nasal meatus secondary bacterial infection that obstructs the discharge of Sphenoidal Paired sinuses, in sphenoid bone, draining into normal sinus mucus secretions and compromises the sterility of spheno-ethmoidal recess the sinuses. Maxillary Paired sinuses, in maxilla, draining into middle meatus (semilunar hiatus); largest sinus (20-30 ml) Plate 7-3 See Netter: Atlas of Human Anatomy, 6th Edition, Plates 43 and 44 Respiratory System Paranasal Sinuses 7 1 2 Opening of frontonasal Opening of duct sphenoidal sinus Semilunar 3 hiatus Middle nasal concha (cut away) 1 Opening of maxillary sinus Inferior Orbit nasal concha A. Sagittal section Opening into middle nasal meatus Roots of teeth 4 Crista galli Nasal cavities B. Lateral dissection 2 Orbit Opening of 4 maxillary sinus Inferior nasal concha Vomer Oral cavity C. Coronal section Netter’s Anatomy Coloring Book Plate 7-3 7 Oropharynx, Laryngopharynx, and Larynx The pharynx (throat) is subdivided into three regions: • Ventricle: the recesses that extend laterally between the • Nasopharynx: lies posterior to the nasal cavities and above vestibular and vocal folds the soft palate (already discussed) • Infraglottic cavity: the space below the vocal folds to the • Oropharynx: extends from the soft palate to the superior tip of level of the cricoid cartilage; below the cricoid cartilage the the epiglottis, and lies posterior to the oral cavity infraglottic cavity becomes the proximal trachea • Laryngopharynx: extends from the tip of the epiglottis to the inferior aspect of the cricoid cartilage (often referred to by The vestibular (false) folds are protective in nature but the clinicians as the “hypopharynx”), lying posterior to the larynx vocal (true) folds control phonation much like a reed instrument. Vibrations of the folds produce sounds as air passes through The oropharynx and laryngopharynx provide a passageway the rima glottidis; the pitch produced by these vibrations is for both air and food (solid and liquids) and are essentially dependent upon the diameter, length, thickness, and tension fibromuscular tubes lined with stratified squamous epithelium of the vocal folds. The size of the rima glottidis and tension to protect the lining from abrasion. The muscular walls of the on the folds is determined by the laryngeal muscles, but the pharynx are formed largely by the three pharyngeal constrictors amplification, resonance, and quality of the sound is a product discussed previously (see Plate 3-5). Waldeyer’s lymphatic of the shape and size of the pharynx, oral cavity, nasal and ring, composed of the tubal tonsils, nasopharyngeal tonsils, paranasal cavities, and movements of the tongue, lips, cheeks, lingual tonsils, and the palatine tonsils, “guard” the openings into and soft palate. the pharynx and provide an important lymphatic immunologic defense mechanism, especially in children and adolescents (see Plate 6-6). COLOR the following features of the larynx, using a different color for each feature: The larynx lies anterior to the laryngopharynx and proximal n 1. Epiglottis esophagus, at about the level of the C3-C6 vertebrae and n 2. Thyroid cartilage superior to the trachea. Structurally, the larynx consists of nine cartilages joined by ligaments and membranes. n 3. Infraglottic cavity n 4. Cricoid cartilage n 5. Trachea CARTILAGE DESCRIPTION n 6. Vestibular folds Thyroid Two hyaline laminae and the laryngeal prominence n 7. Vocal folds (Adam’s apple) 8. Laryngeal vestibule Cricoid Signet ring–shaped hyaline cartilage just inferior to n thyroid n 9. Ventricle Epiglottis Spoon-shaped elastic cartilage plate attached to thyroid Arytenoid Paired pyramidal cartilages that rotate on cricoid cartilage Clinical Note: Corniculate Paired cartilages that lie on apex of arytenoid Hoarseness can be due to any condition that results in improper cartilages vibration or coaptation of the vocal folds. Acute laryngitis is an Cuneiform Paired cartilages in ary-epiglottic folds that have no inflammation of the vocal folds