Note #1: the doctor skipped some slides in the lecture. Those slides are not included in this sheet and so you will have to review the slides to study them. The reason they were not included is because well, the doctor probably skipped them for a reason. Note #2: I suggest you overview the whole sheet before "memorizing" any of it. After you gain an understanding of the general picture, it will be much easier to grasp. I. Functions of the respiratory system II. External nose i. Cartilaginous part ii. iii. iv. Bony framework Blood supply Nerve supply III. Nasal cavity i. Functions ii. iii. iv. Content Boundaries Mucosa v. Entries of paranasal sinuses vi. vii. Blood supply Nerve supply IV. Paranasal sinuses i. Functions ii. iii. iv. Frontal sinus Ethmoidal sinus Sphenoidal sinus v. Maxillary sinus 1
I. Functions of the respiratory system: 1. Provides for gas exchange 2. Regulates blood ph: we notice that when they measure gas content of the blood with respiratory patients to make sure the ph is normal 3. Filters the inspired air 4. Contains receptors for smell, and produce vocal sounds (phonation): bipolar cells at the roof of the nasal cavity, olfactory nerve and bulb. Also, don't forget that vocal cords are in the larynx, we call them true vocal cords, responsible for production of sound. 5. Excretes small amounts of water and heat: large amount of seromucuous glands in submucosa to moisture and warm entering air Nose is made up of the nasal cavity, and the external nose. II. External Nose: i. Cartilaginous part: 1. Septal cartilage: anterior third of the septum 2. Lateral nasal cartilage: lower and upper lateral nasal cartilages 3. Alar cartilage: the moving parts of the cartilage, contains two muscles, constrictor naris and dilator naris Notes: The Dilator Naris and Contrisctor Naris allow some people to move their ala like rabbits. The ala is also moved in children who have a respiratory tract disease, when they inhale deeply. All these plates of cartilage are hyaline cartilage. ii. Bony framework: 1. The nasal bones: right and left nasal bones with a suture in between 2. Frontal processes of the maxillae 3. Nasal part of the frontal bone (this is the most medial part of the maxillary process of the frontal bone) iii. Blood supply: 1. Ophthalmic artery: arises from the internal carotid artery and enters the orbital vacity with the optic nerve 2. Maxillary artery: when we talk about the upper jaw and the nasal cavity, most of the arteries and nerves arise from the maxillary artery and nerve. In contrast to the lower jaw, where they usually arise from the mandibular. 3. Facial artery supplies the ala and the lower part of the septum 2
iv. Nerve supply: 1. Infratrochlear nerve and External Nasal nerve, branches of the ophthalmic which is a branch of the trigeminal nerve 2. Infraorbital nerve, branch of the maxillary nerve Note that the external nose has blood supply and nerve supply through the ophthalmic and maxillary arteries and nerves. III. Nasal cavity: i. Functions: 1. Respiratory: through the alveoli 2. Olfactory: smell sensation through the olfactory nerve 3. Resonance of voice: through paranasal sinuses which open into the lateral wall of the nasal cavity 4. Drains lacrimal fluid: tears flow from lacrimal gland on the lateral side of the roof of the orbital cavity, some of them flow down over the cheek, while most of them go to the medial side of the orbital cavity to the lacrimal sack in the lacrimal fossa, where they drain through the nasolacrimal duct, which opens at the inferior meatus of the lateral wall of the nasal cavity. This is why when someone cries, they have a running nose. 5. Protective : 3 Sneezing: expels foreign bodies Filtration: through the hair in the vestibule Proteolytic Enzymes: dissolve viruses and bacteria Warming and moistening the air: this is protective to brain cells ii. Content: Here we have a mid-sagittal section (slide #8), note: 1. Vestibule: first part of the nose after the anterior nares, has a stratified squamous keratinized epithelium, with characteristic thick and short hair called vibrissae 2. Anterior Nares (or External Nares): the anterior opening of the nasal cavity. They are always open, helped by the ala of the nose, which has constrictor naris and dilator naris(which widens the nares) 3. Choana (Posterior Nares or Interior Nares): connects the nasal cavity to the nasopharynx. They are surrounded by bone, we have to know the bones that form the boundaries of the choanae. Inferiorly: Horizontal plate of palatine bone Septum: Horizontal plate of palatine bone + vomer Laterally: Medial pterygoid plate of sphenoid Superiorly: Ala of vomer + sphenoidal process of palatine bone + vaginal process of medial pterygoid plate of sphenoid, and an important foramen called the palatovaginal canal
iii. Boundaries: When we talk about the nasal cavity, we divide it into lateral wall (the part we can hold between our fingers), medial wall (the septum), floor and roof. Floor: Made up of the hard palate (you can touch it with your fingers at the roof of your oral cavity), which consists of two parts: 1. Palatine process of the maxillary bone forming the anterior part 2. Horizontal plate of the palatine bone forming the posterior part Roof: Made up of three parts: 1. Sloping anterior part: the nasal bones 2. Horizontal middle part: cribriform plateof the ethmoid bone, which is perforated to allow the passage of the filaments of the olfactory nerve 3. Sloping posterior part: sphenoid body + ala of the vomer + vaginal process of palatine bone Septum, or Medial Wall: 1. Anteriorly: septal nasal cartilage 2. Posteriorly: vomer inferiorly + perpendicular plate of ethmoid superiorly Note: The ethmoid bone participates in the roof giving cribriform plate, and also in the septum giving perpendicular plate of ethmoid In the lab we'll be able to see the vomer and perpendicular plate of ethmoid, but not the cartilage Lateral wall: you have to link the lateral wall with 3 conchae, 3 meatuses and 1 recess: the superior, middle and inferior conchae and meatuses (the meatuses lie below the conchae), and the sphenoethmoidal recess. Supporting bones for the lateral wall: 1. Perpendicular plate of palatine bone 2. Lacrimal bone 3. Frontal process of maxilla 4. The inferior concha is a separate bone 5. The middle and superior conchae are parts of the ethmoidal bone Parts of the lateral wall: 1. Vestibule: first part of the nose after the anterior nares, has a stratified squamous keratinized epithelium, with characteristic thick and short hair called vibrissae 4
2. Antrum (or Atrium): is a space on the level of the middle meatus but lying anteriorly above the vestibule 3. The 3 conchae meatuses (superior, middle and inferior), and 1 recess (sphenoethmoidal recess) iv. Mucosa: The mucosa of the nasal cavity is lined with respiratory mucous membrane, which is pseudo stratified ciliated columnar, except at two places: 1. Vestibule: lined with stratified squamous keratinized epithelium (which has characteristic thick and short hair called vibrissae, this is very similar to the skin) 2. Roof of the nasal cavity, which has the olfactory region, which in addition to the respiratory mucous membrane, has specialized cells responsible for smell sensation called bipolar cells Functions of the mucous membrane: 1. It has a large plexus of veins which helps warm the inspired air, which protects the brain cells: that's why if you go out late in the winter, you drink water to bring down the temperature, because if the air is too cold and warming doesn't happen correctly the brain cells can be affected causing some disease 2. Trapping of foreign particles and organisms v. Entries of the paranasal sinuses: Chonchae, meatuses, and the recess: A choncha is a process of bone covered by mucosa, with a groove below it called a meatus. It serves to increase the surface area, and divide the inspired air into smaller currents in order to moisture and warm it, which is one of the functions of the nose. The paranasal sinuses open into the lateral wall of the nasal cavity, it is important to know where exactly: 1. The sphenoidal air sinus opens into the sphenoethmoidal recess 2. The posterior ethmoidal sinus opens into the superior meatus 3. The nasolacrimal duct opens into the inferior meatus 4. The middle ethmoidal sinus, the anterior ethmoidal sinus, and the maxillary sinus open into the middle meatus according to the following details. The middle meatus has: 1. A bulge of mucosa, called the bulla ethmoidalis, where the middle ethmoidal sinus opens 2. A groove, or a gutter, below the bulla ethmoidalis, called the hiatus semilunaris, where the maxillary sinus opens posteriorly, and the anterior ethmoidal sinus opens anteriorly 5. The frontal air sinus opens through the frontonasal duct anterior to the middle meatus in an area called the infundibulum. Some books say the frontal sinus opens into the 5
Again: 6 anterior part of the hiatus semilunaris, and other say it opens through the frontonasal duct into the infundibulum. 1. Sphenoidal sinus: sphenoethmoidal recess 2. Maxillary sinus: posterior part of the hiatus semilunaris of the middle meatus 3. Frontal sinus: frontonasal duct into the infundibulum, which lies anterior to the middle meatus 4. Ethmoidal sinus: a. Anterior ethmoidal sinus: anterior part of hiatus semilunaris of middle meatus b. Middle ethmoidal sinus: bulga ethmoidalis of middle meatus c. Posterior ethmoidal sinus: superior meatus vi. Blood supply: The doctor advises the use of the picture (slide #26) to avoid memorizing and "grasping" the blood supply of the nasal cavity. Generally, the blood supply comes from the ophthalmic and maxillary arteries 1. Sphenopalatine artery: a. branches from the maxillary artery in the pterygopalatine fossa b. divides into long and short sphenopalatine c. short sphenopalatine feeds the upper posterior quadrant of the lateral wall (feeds posterior aspect = short is enough) d. long sphenopalatine feeds the septum (feeds septum = needs to be long) i. is also called the nasopalatine artery, similar to the nerve to the septum ii. is the main blood supply of the septum iii. also called the septal branch of the sphenopalatine artery e. notice its position in relevance to its name 2. Anterior and posterior ethmoidal arteries: a. branch from the ophthalmic artery, which branches from the internal carotid b. anterior ethmoidal artery feeds the anterior superior quadrant of the lateral wall i. it gives a branch called the external nasal artery, which supplies the external nose c. posterior ethmoidal artery is a relatively weak feed to the upper posterior quadrant of the lateral wall (main feed is short sphenopalatine) i. it passes into the nasal cavity through the cribriform plate d. notice their positions in relevance to their names (hint: they pass through the ethmoid bone) e. both the anterior and posterior ethmoidal arteries give off septal branches to the septum which are not as important as the long sphenopalatine (or nasopalatine) artery
3. Branches from the facial artery: the facial artery gives the superior labial artery to the upper lip, which then continues to the nose a. supply the anterior inferior quadrant of the lateral wall 4. Greater and lesser palatine arteries: a. branch from the maxillary artery in the pterygopalatine fossa b. lesser palatine goes to the soft palate c. greater palatine goes to the hard palate, then to the roof of the oral cavity, then through the incisor foramen to the nose d. greater palatine supplies the two inferior quadrants of the lateral wall Epistaxis: in nose bleeding, a common mistake is to make people lay on their back, which makes them swallow blood. Instead, you're supposed to apply some pressure for two minutes which should stop the bleeding. Kiesselbach's area lies between the anterior one third and the upper two thirds, is where the long sphenopalatine artery and facial artery anastomose, and is usually the site of bleeding in the epistaxis. Note, though, that bleeding usually occurs through the facial artery and not the sphenopalatine artery. Venous drainage: 1. Posterior part: drains into the pterygoid plexus around the lateral pterygoid muscle, which then drains into the maxillary vein 2. Anterior part: drains into the facial vein 3. Upper most part: can drain into the cavernous sinus through emissary veins, which makes this area a dangerous site for infection cause it can reach the cavernous sinus Lymphatics: 1. Anterior part: drains into the submandibular lymph node 2. Posterior part: drains into the deep cervical lymph node vii. Nerve supply: 1. Olfactory nerve: sensory for smell. It starts at the bipolar cells at the roof, then filaments go through the cribriform plate, to the olfactory bulb, the olfactory tract, and then to the center in the brain which gives the meaning of the nerve impulse (smell) 2. Branches of the ophthalmic and maxillary branches of the trigeminal nerve provide general sensation 3. Parasympathetic fibers from the facial nerve provide secretomotor innervation Ophthalmic branches: Anterior ethmoidal nerve: very similar to the course of the anterior ethmoidal artery, also gives off a branch to the external nose, called the external nasal nerve Posterior ethmoidal nerve: supplies mucosa of the ethmoidal and sphenoidal sinuses, does not extend into the nasal cavity itself Note: both are branches of the nasociliary nerve, which is branch of the ophthalmic nerve 7
Maxillary branches: 1. Posterior superior lateral nasal nerves: supply the posterior superior quadrant of the lateral wall 2. Posterior inferior nasal nerves: originate from greater palatine nerve and supply posterior inferior quadrant of lateral wall 3. Anterior superior alveolar: branch of the infraorbital nerve, supplies the lateral wall near the anterior end of the inferior concha 4. Nasopalatine nerve: a. largest of the maxillary nerves b. also called the sphenopalatine nerve c. goes to the septum and innervates it d. then passes through the incisive canal to the hard palate, supplying the oral mucosa posterior to the incisor teeth 5. Posterior superior medial nasal nerves: cross the roof to the nasal septum and supply both these regions The summary below is copied directly from the slides: 1. Postero-superior quadrant: posterior-superior lateral nerve and vessels (short sphenopalatine) 2. Postero-inferior quadrant: greater palatine nerve and vessels 3. Antero-superior quadrant : Ant. Ethmoidal nerve (internal and external nerve) and artery 4. Antero-inferior quadrant : Ant. Superior alveolar nerve and branches from the facial and greater palatine artery 5. Nasal septum: a. Lower posterior part by the long sphenopalatine nerve b. Upper anterior part by the septal branch of the anterior ethmoidal nerve c. Blood supply by the long sphenopalatine artery IV. Paranasal sinuses: A cavity within some bones of the skull filled with air, lined with mucosa that is attached to the periosteum. They are rudimental at birth, but they grow with the growing of the bone, and they participate in formation of the face. i. Function: 1. Resonance of the voice 2. Decrease weight of the skull 3. Protection: they moisten and warm the inhaled air protecting brain cells ii. Frontal sinus: innervated by branches of supraorbital nerve, which is a branch of the ophthalmic nerve 8
iii. Ethmoidal (anterior, middle, and posterior): innervated by anterior and posterior ethmoidal branches of the nasociliary nerve, which is a branch of the ophthalmic nerve iv. Sphenoidal: 1. one cavity in body of sphenoid with septum in middle, so two cavities 2. It is above the pituitary gland, so in case of a pituitary tumor, they can x-ray the sphenoid air sinus and see its size, and accordingly judge the mass of the tumor. (How does the tumor affect the sinus size even though it has a wall? The bony wall is very thin and is susceptible to the pressure caused by the mass of the tumor) v. Maxillary sinus is the most important sinus clinically: 1. In cases of infection: a. in all the former sinuses, the opening lies on a low level which allows easy downwards drainage in case of an infection b. to drain the maxillary sinus through its normal opening, you'd have to put your head between your legs, which isn't practical at all c. consequently, sometimes an opening is made through the face into the maxillary sinus to allow its drainage in case of infection (and later; abscess formation) 2. Due to its anatomic position above the molars, it can form a fistula with the molars, forming a pathway of puss from the sinus to the molars, leading to puss appearing there, especially in old patients with extracted molars Note also that it is pyramidal in shape, and has important relations above to the orbit, below to the roots of the upper molar and premolar teeth, behind to the infratemporal fossa, medially to the lower part of the nasal cavity. Good luck and study hard. 9