NOSE & ASSOCIATED STRUCTURES

LARYNX, TRACHEA, PLEURA LUNGS & DIAPHRAGM

Kaan Yücel M.D., Ph.D. 10.October.2011 Monday

NOSE & ASSOCIATED STRUCTURES

Nose is divisible into two parts as external nose and nasal cavity.

Functions of the nose and the nasal cavities are:o Olfaction (sense of smell)o Respirationo Filtration of the dust in the inspired air o Humidification and warming of the inspired airo Reception of the secretions from the paranasal sinuses and

nasolacrimal ducts

External Nose has five parts:1) Dorsum2) Root3) Apex4) Nares (nostrils, anterior nasal apertures)5) Alae of the noseExternal nose has bony and cartilaginous parts.

Bones contributing to the structure of the external nose: Nasal bones Frontal process of maxilla Nasal part of frontal bone

Cartilages contributing to the structure of the external nose: Lateral cartilages (paired) Alar cartilages (paired) Septal cartilage (single)

Nasal Cavities:

• The two nasal cavities are the uppermost parts of the respiratory tract.

• They contain the olfactory receptors.

The nasal cavities are separated: from each other by a midline nasal septum from the oral cavity below by the hard palate from the cranial cavity above by parts of the frontal, ethmoid, and

sphenoid bones.

Nasal septum is composed of three structures:• Perpendicular plate of the ethmoid bone• Vomer• Septal cartilage

Each nasal cavity is divided into olfactory area (upper 1/3) and respiratory area (lower 2/3).

Posteriorly, each nasal cavity communicates with the nasopharynx through two openings called choana.

Walls of the nasal cavityRoof of the nasal cavity (anterior to posterior) nasal bone frontal bone cribriform plate of the ethmoid bone body of the sphenoid bone

Floor of the nasal cavity is formed by the hard palate (palatine process of maxilla and horizontal plate of the palatine bone).

Lateral wall of the nasal cavity (anterior to posterior) frontal process of maxilla lacrimal bone superior nasal concha (of the ethmoid bone), middle nasal concha (of

the ethmoid bone), inferior nasal concha perpendicular plate of the palatine bone medial lamina of the pterygoid process

Medial wall of the nasal cavity is formed by the nasal septum.

The medial wall has a smooth surface, whereas the lateral wall is uneven due to the existance of the nasal conchae.

The spaces between the nasal conchae and the lateral wall of the nasal cavity are called the meatus.

• Superior nasal meatus• Middle nasal meatus• Inferior nasal meatus

The following sinuses open into the middle nasal meatus Frontal sinus Maxillary sinus Ethmoid air cellsSphenoid sinus opens into the sphenoethmoid recessNasolacrimal duct opens into the inferior nasal meatus

Arterial supply of the noseThe nose has an extensive arterial supply.

The branches of the maxillary, ophthalmic and facial arteries supply the nose.Veins of the noseThere is a rich network of veins deep to the mucosa of the nose.

This venous network is important in warming the air before it enters the trachea and the lungs.

The veins of the nose drain into facial and opthalimic veins.

Nerves of the noseSensory innervation of the nose is mainly from the maxillary nerve and the ophthalmic nerve.Within the epithelium of the olfactory region lies the olfactory cells (neurons).

The peripheral processes of these cells terminate under the mucosa and are sensitive to odour molecules in the air.

The central processes forms the olfactory nerves (CN I). Olfactory nerves pass through the cribriform plate of the ethmoid bone to reach to the olfactory bulb.

Paranasal sinuses

Paranasal sinuses are air filled spaces lying within the bones around the nasal cavity. The paranasal sinuses develop as outgrowths from the nasal cavities and erode into the surrounding bones. All are: lined by respiratory mucosa, which is ciliated and mucus secreting; open into the nasal cavities; and innervated by branches of the trigeminal nerve [V].

Sinuses are named according to the bones they are located in:Frontal sinusesEthmoid sinusesSphenoid sinusesMaxillary sinuses

Frontal sinus The frontal sinuses, one on each side, are variable in size and are the

most superior of the sinuses.

The frontal sinus lies within the inner and outer plates of the frontal bone, posterior to the supercilliary arches and the root of the nose.

The opening of the sinus is called the frontonasal duct.

It drains into the middle nasal meatus.

Ethmoid sinusesSeveral ethmoid air cells (3-15) collectively are called the ethmoid sinuses.Ethmoid air cells form three groups:Anterior group ------opens into the middle meatusMiddle group --------opens into the middle meatusPosterior group -----opens into the superior meatus

Sphenoid sinus The sphenoid sinus is situated within the body of the sphenoid

bone. Sinuses of each side is seperated by a bony septum. It drains into the sphenoethmoidal recess.

Maxillary sinus The maxillary sinuses, one on each side, are the largest of the

paranasal sinuses.

They completely fill the bodies of the maxillae.

The maxillary opening drains into the middle nasal meatus through the semilunar hiatus.

Larynx Larnynx is the organ of phonation (vocalization).

It is formed of cartilage, muscles and connective tissue.

Larynx’s inner surface is covered by the respiratory mucosa.

The cavity of the larynx is continuous below with the trachea, and above opens into the pharynx immediately posterior and slightly inferior to the tongue and the posterior opening (oropharyngeal isthmus) of the oral cavity.

Skeleton of larynx is formed of 3 unpaired and 3 paired cartilagesUnpaired cartilages Thyroid cartilage (biggest) Cricoid cartilage Epiglottic cartilagePaired cartilages Arytenoid Corniculate Cuneiform

Thyroid cartilage The thyroid cartilage is the largest cartilage of the larynx.

It is formed of two laminae which fuse anteriorly at the thyroid angle to form laryngeal prominence (Adam’s apple).

Cricoid cartilage The cricoid cartilage is a ring shaped cartilage.

Inferiorly it attaches to the first tracheal ring by the cricotracheal ligament.

Arytenoid cartilagesThe arytenoid cartilages are pyramidal in shape.

An arytenoid cartilage has three processes: Apex (superior) Vocal process (anterior) vocal ligament attaches here Muscular process (lateral)

Epiglottic cartilage (Epiglottis) The epiglottis is a heart shaped cartilage. Its inferior end is attached to the thyroid cartilage by the

thyroepiglottic ligament. Most superior end is free.

Corniculate and cuneiform cartilagesThese are small cartilages lying in the posterior part of the aryepiglottic fold.

Fibroelastic membrane of the larynx It lies under the mucosa of the larynx.

The fibroelastic membrane of the larynx has thickenings at certain regions and forms some of the ligaments between the cartilages.

It is formed of two parts:Quadrangular membraneConus elasticus

Conus elasticus (cricovocal membrane): Its free upper margin thickens to form the vocal ligament, which is covered by mucosa to form the vocal fold.

The opening between the two vocal folds is called rima glottis.

Vocal cord= Vocal fold

The vocal folds are sometimes called 'true vocal folds' to distinguish them from the false vocal folds. These are a pair of thick folds of mucous membrane that protect and sit slightly superior to the more delicate true folds. They have a minimal role in normal phonation, but are often used to produce deep sonorous tones,as well as in musical screaming and the death growl vocal style.

The false folds are also called vestibular folds and ventricular folds.

Each vocal ligament, converges anteriorly and attaches to the anterior part of the inner surface of the thyroid cartilage (thyroid angle).

Posteriorly, they individually attach to the vocal processes of the arytenoid cartilages.

Rima glottis widens during inspiration and two vocal folds are approximated during phonation.

Various changes of the vocal folds determine the color, pitch and the tones of sound.

Pitch increases with tensing, decreases by relaxation.

Intensity of expiration determines the loudness of sound.

Laryngeal Muscles Extrisic muscles These are the suprahyoid and infrahyoid muscles. They either depress or elavate the larynx and hyoid bone.

Intrinsic muscles: There are six intrinsic muscles in the larnyx. They move the laryngeal parts.

INTRINSIC MUSCLESCricothyroid muscle; tenses the vocal folds by pulling the thyroid cartilage anteroinferiorly (to produce high pitch sound).

Posterior cricoarytenoid muscle; is the only muscle widening the rima glottis.

Lateral cricoarytenoid muscle; approximates the vocal processes thus, narrowing the anterior part of rima glottis (contracts alone during whispering). This muscle adducts the arytenoid cartilages to close the rima glottis.

Thyroarytenoid muscle; relaxes the vocal folds by pulling the arytenoid cartilages anteriorly (to produce low pitch sounds).

Arytenoid muscle; approximates the arytenoid cartilages.

Nerves of the larynxLarynx is innervated by the inferior and superior laryngeal nerves. Both the inferior and superior laryngeal nerves are branches of the vagus nerve (CN X).

All of the intrinsic muscles are innervated by the inferior (recurrent) laryngeal nerve except the cricothyroid muscle, which is innervated by the external laryngeal nerve (branch of the superior laryngeal nerve).

Trachea

The trachea extends from the inferior end of larynx to the level of T5-T6 vertebra.

It terminates by dividing into right and left main bronchi.

Trachea is formed of tracheal rings which are incomplete posteriorly.

Posterior parts of the tracheal rings are closed by smooth muscle called the trachealis muscle.

Trachea is enclosed with a fibroelastic membrane.

This membrane thickens between the tracheal rings to form anular ligaments (tracheal ligaments) between the adjacent rings.

Pleaura & the Lungs PleuraEach pulmonary cavity (right and left) is lined by a pleural membrane (pleura) that also reflects onto and covers the external surface of the lungs occupying the cavities.

Each lung is invested by and enclosed in a serous pleural sac that consists of two continuous membranes:

Visceral pleura (invests all surfaces of the lungs)

Parietal pleura (lines the pulmonary cavities and the inner surface of the thorax)

The pleural cavity—the potential space between the layers of pleura—contains a capillary layer of serous pleural fluid, which lubricates the pleural surfaces and allows the layers of pleura to slide smoothly over each other during respiration.

Lungs The two lungs are organs of respiration and lie on either side of the

mediastinum surrounded by the right and left pleural cavities.

Air enters and leaves the lungs via main bronchi, which are branches of the trachea.

Their main function is to oxygenate the blood by bringing the inspired air into close relation with the venous blood in the pulmonary capillaries.

The pulmonary arteries deliver deoxygenated blood to the lungs from the right ventricle of the heart.

Oxygenated blood returns to the left atrium via the pulmonary veins.

Each lung bears the following features:1. Apex (upper pole)2. Three surfaces (costal, mediastinal and diaphragmatic).3. Root of the lung is formed by the structures entering and

leaving the lung through its hilum.4. There are two lobes in the left lung seperated by the oblique

fissure.5. There are three lobes in the right lung seperated by

horizontal and oblique fissures.

Tracheobronchial Tree Beginning at the larynx, the walls of the airway are

supported by horseshoe- or C-shaped rings of hyaline cartilage.

The sublaryngeal airway constitutes the tracheobronchial tree.

The trachea, located within the superior mediastinum, constitutes the trunk of the tree.

It bifurcates at the level of the transverse thoracic plane (or sternal angle) into main bronchi, one to each lung, passing inferolaterally to enter the lungs at the hila (singular = hilum).

Within the lungs, the bronchi branch in a constant fashion to form the branches of the tracheobronchial tree.

Each main (primary) bronchus divides into secondary lobar bronchi, two on the left and three on the right, each of which supplies a lobe of the lung.

Each lobar bronchus divides into several tertiary segmental bronchi that supply the bronchopulmonary segments.

The bronchopulmonary segments are: The largest subdivisions of a lobe. Pyramidal-shaped segments of the lung, with their apices

facing the lung root and their bases at the pleural surface. Separated from adjacent segments by connective tissue

septa. Supplied independently by a segmental bronchus and a

tertiary branch of the pulmonary artery. Named according to the segmental bronchi supplying them. Usually 18-20 in number Surgically resectable.

Beyond the tertiary segmental bronchi, there are generations of branching conducting bronchioles that eventually end as terminal bronchioles, the smallest conducting bronchioles.

Conducting bronchioles transport air but lack glands or alveoli.

Each terminal bronchiole gives rise to several generations of respiratory bronchioles, characterized by scattered, thin-walled outpocketings (alveoli) that extend from their lumens.

The pulmonary alveolus is the basic structural unit of gas exchange in the lung.

Auscultation of the lungsListening to the sound of air as it passes the tracheobronchial tree is called the auscultation and carried by a stethescope

Bronchial arteries The bronchial arterties supply blood to the tissues of the lung. Left bronchial arteries are paired and the right bronchial artery is one single artery

Bronchial veinsRight bronchial vein drains into the azygos vein, whereas left bronchial vein drains into the accessory hemiazygos vein.On each side a superior pulmonary vein and an inferior pulmonary vein carry oxygenated blood from the lungs back to the heart. The veins begin at the hilum of the lung, pass through the root of the lung, and immediately drain into the left atrium.

Nerves of the lungs and pleuraLungs are innervated by pulmonary plexuses, which contains both sympathetic and parasympathetic nerves.

The vagus nerve supplies parasympathetic innervation. (bronchoconstrictor, vasodilator to the lung vessels, secretomotor to the glands).

The sympathetic innervation comes from the sympathetic trunk (bronchodilator, vasoconstrictor to the lung vessels, inhibitor to the glands).

Lymph nodesSuperficial, or subpleural, and deep lymphatics of the lung drain into lymph nodes called tracheobronchial nodes around the roots of lobar and main bronchi and along the sides of the trachea.

DIAPHRAGM A very thin, a double-domed muscle, is the only structure (apart

from the pleura and peritoneum) that separates the chest from the abdominal viscera

Its mainly convex superior surface faces the thoracic cavity, and its concave inferior surface faces the abdominal cavity.

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The diaphragm is the chief muscle of inspiration (actually, of respiration altogether, because expiration is largely passive).

It descends during inspiration; however, only its central part moves.

The central tendon of the diaphragm is a thin but strong aponeurosis situated near the center of the vault formed by the muscle.

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During expiration, the right dome reaches as high as the 5th rib and the left dome ascends to the 5th intercostal space. The level of the domes of the diaphragm varies according to the:

Phase of respiration (inspiration or expiration)

Posture (e.g., supine or standing)

Size and degree of distension of the abdominal viscera.

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It is divided into three parts, based on the peripheral attachments:Sternal partCostal partLumbar part

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The crura of the diaphragm are musculotendinous bands that arise from the anterior surfaces of the bodies of the superior 3 lumbar vertebrae, the anterior longitudinal ligament, and the IV discs.

Right crus

Left crus

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The right and left crura and the fibrous median arcuate ligament, which unites them as it arches over the anterior aspect of the aorta, form the aortic hiatus. The diaphragm is also attached on each side to the medial and lateral arcuate ligaments.

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ArteriesThe arteries supplying the the diaphragm are the branches of the internal thoracic artery, the thoracic aorta and the abdominal aorta.

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VeinsThe veins empty into the internal thoracic veins and the inferior phrenic veins. Lympathic drainage of diaphragmLymph from the nodes of the diaphragm drains into the parasternal, posterior mediastinal, phrenic, anterior diaphragmatic, and superior lumbar (caval/aortic) lymph nodes. InnvervationThe entire motor supply to the diaphragm is from the right and left phrenic nerves.

Phrenic nerve

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Diaphragmatic AperturesThe diaphragmatic apertures (openings, hiatus) permit structures (vessels, nerves, and lymphatics) to pass between the thorax and abdomen. There are three large apertures for: 1. Inferior vena cava (IVC)2. Esophagus3. Aortaand a number of small ones.

I’m Eating Apples.

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The most superior of the three large diaphragmatic apertures

An aperture in the central tendon primarily for the IVC

Also passing through the caval opening : terminal branches of the right phrenic nerve and a few lymphatic vessels.

CAVAL OPENING

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ESOPHAGEAL HIATUS

An oval opening for the esophagus in the muscle of the right crus of the diaphragm at the level of the T10 vertebra.

Also transmits the anterior and posterior vagal trunks, esophageal branches of the left gastric vessels, and a few lymphatic vessels.

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AORTIC HIATUS

The opening posterior in the diaphragm for the aorta.

The aortic hiatus also transmits the thoracic duct and sometimes the azygos and hemiazygos veins.

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SMALL OPENINGS IN DIAPHRAGMIn addition to the three main apertures, there is a small opening, the sternocostal triangle (foramen), between the sternal and costal attachments of the diaphragm. This triangle transmits lymphatic vessels from the diaphragmatic surface of the liver and the superior epigastric vessels.

There are two small apertures in each crus of the diaphragm; one transmits the greater splanchnic nerve and the other the lesser splanchnic nerve.

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Actions of Diaphragm

When the diaphragm contracts, its domes are pulled inferiorly so that the convexity of the diaphragm is somewhat flattened.

As the diaphragm descends, it pushes the abdominal viscera inferiorly. This increases the volume of the thoracic cavity and decreases the intrathoracic pressure, resulting in air being taken into the lungs.

In addition, the volume of the abdominal cavity decreases slightly and intra-abdominal pressure increases somewhat.

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Movements of the diaphragm are also important in circulation because the increased intra-abdominal pressure and decreased intrathoracic pressure help return venous blood to the heart.

When the diaphragm contracts, compressing the abdominal viscera, blood in the IVC is forced superiorly into the heart.

http://www.johngull.co.uk/Anatomy%20of%20the%20voice.htm