The Respiratory SystemThe Respiratory SystemLectured by Bien Nillos, MDLectured by Bien Nillos, MDReference: Gray’s AnatomyReference: Gray’s Anatomy

The LarynxThe Larynx• placed at the upper part of the air passageplaced at the upper part of the air passage

• situated between the trachea and the root situated between the trachea and the root of the tongue, at the upper and forepart of of the tongue, at the upper and forepart of the neck, where it presents a considerable the neck, where it presents a considerable projection in the middle lineprojection in the middle line

• forms the lower part of the anterior wall of forms the lower part of the anterior wall of the pharynx, and is covered behind by the the pharynx, and is covered behind by the mucous lining of that cavitymucous lining of that cavity

The LarynxThe Larynx• Until puberty the larynx of the male differs little in Until puberty the larynx of the male differs little in

size from that of the female. In the female its size from that of the female. In the female its increase after puberty is only slight; increase after puberty is only slight;

• in the male it undergoes considerable increase; in the male it undergoes considerable increase; all the cartilages are enlarged and the thyroid all the cartilages are enlarged and the thyroid cartilage becomes prominent in the middle line cartilage becomes prominent in the middle line of the neck, while the length of the rima glottidis of the neck, while the length of the rima glottidis is nearly doubled.is nearly doubled.

The LarynxThe Larynx

The LarynxThe Larynx• The Cartilages of the Larynx are nine in number, The Cartilages of the Larynx are nine in number,

three single and three pairedthree single and three paired• Thyroid, cricoid, epiglottis, two arytenoids, two Thyroid, cricoid, epiglottis, two arytenoids, two

corniculates, two cuneiformscorniculates, two cuneiforms• The Thyroid Cartilage (cartilago thyreoidea) is The Thyroid Cartilage (cartilago thyreoidea) is

the largest cartilage of the larynx. It consists of the largest cartilage of the larynx. It consists of two laminæ the anterior borders of which are two laminæ the anterior borders of which are fused with each other at an acute angle in the fused with each other at an acute angle in the middle line of the neck, and form a middle line of the neck, and form a subcutaneous projection named the laryngeal subcutaneous projection named the laryngeal prominence (pomum Adami)prominence (pomum Adami)

The LarynxThe Larynx

The LarynxThe Larynx• The Cricoid Cartilage (cartilago cricoidea) The Cricoid Cartilage (cartilago cricoidea)

is smaller, but thicker and stronger than is smaller, but thicker and stronger than the thyroid, and forms the lower and the thyroid, and forms the lower and posterior parts of the wall of the larynx.posterior parts of the wall of the larynx.

• It consists of two parts: a posterior It consists of two parts: a posterior quadrate lamina, and a narrow anterior quadrate lamina, and a narrow anterior arch, one-fourth or one-fifth of the depth of arch, one-fourth or one-fifth of the depth of the lamina.the lamina.

The LarynxThe Larynx

The LarynxThe Larynx• The Arytenoid Cartilages (cartilagines arytænoideæ) are The Arytenoid Cartilages (cartilagines arytænoideæ) are

two in number, and situated at the upper border of the two in number, and situated at the upper border of the lamina of the cricoid cartilage, at the back of the larynx. lamina of the cricoid cartilage, at the back of the larynx. Each is pyramidal in form, and has three surfaces, a Each is pyramidal in form, and has three surfaces, a base, and an apex.base, and an apex.

• The Corniculate Cartilages (cartilagines corniculatæ; The Corniculate Cartilages (cartilagines corniculatæ; cartilages of Santorini) are two small conical nodules cartilages of Santorini) are two small conical nodules consisting of yellow elastic cartilage, which articulate with consisting of yellow elastic cartilage, which articulate with the summits of the arytenoid cartilages and serve to the summits of the arytenoid cartilages and serve to prolong them backward and medialward. They are prolong them backward and medialward. They are situated in the posterior parts of the aryepiglottic folds of situated in the posterior parts of the aryepiglottic folds of mucous membrane, and are sometimes fused with the mucous membrane, and are sometimes fused with the arytenoid cartilages.arytenoid cartilages.

The LarynxThe Larynx• The Cuneiform Cartilages (cartilages of The Cuneiform Cartilages (cartilages of

Wrisberg) are two small, elongated pieces Wrisberg) are two small, elongated pieces of yellow elastic cartilage, placed one on of yellow elastic cartilage, placed one on either side, in the aryepiglottic fold, where either side, in the aryepiglottic fold, where they give rise to small whitish elevations they give rise to small whitish elevations on the surface of the mucous membrane, on the surface of the mucous membrane, just in front of the arytenoid cartilages.just in front of the arytenoid cartilages.

The LarynxThe Larynx• The Epiglottis (cartilago epiglottica) is a The Epiglottis (cartilago epiglottica) is a

thin lamella of fibrocartilage of a yellowish thin lamella of fibrocartilage of a yellowish color, shaped like a leaf, and projecting color, shaped like a leaf, and projecting obliquely upward behind the root of the obliquely upward behind the root of the tongue, in front of the entrance to the tongue, in front of the entrance to the larynx.larynx.

• The depressions between the epiglottis and the root of the tongue, on either side of the median fold, are named the valleculæ.

The LarynxThe Larynx• The corniculate and cuneiform cartilages,

the epiglottis, and the apices of the arytenoids at first consist of hyaline cartilage, but later elastic fibers are deposited in the matrix, converting them into yellow fibrocartilage, which shows little tendency to calcification

The LarynxThe Larynx

The LarynxThe Larynx• The entrance of the larynx is a triangular

opening, wide in front, narrow behind, and sloping obliquely downward and backward.

• bounded, in front, by the epiglottis; behind, by the apices of the arytenoid cartilages, the corniculate cartilages, and the interarytenoid notch; and on either side, by a fold of mucous membrane, enclosing ligamentous and muscular fibers, stretched between the side of the epiglottis and the apex of the arytenoid cartilage

The LarynxThe Larynx• The Ventricular Folds (plicœ ventriculares;

superior or false vocal cords) are two thick folds of mucous membrane, each enclosing a narrow band of fibrous tissue, the ventricular ligament which is attached in front to the angle of the thyroid cartilage immediately below the attachment of the epiglottis, and behind to the antero-lateral surface of the arytenoid cartilage, a short distance above the vocal process.

The LarynxThe Larynx• The Vocal Folds (plicœ vocales; inferior or

true vocal cords) are concerned in the production of sound, and enclose two strong bands, named the vocal ligaments (ligamenta vocales; inferior thyroarytenoid)

The LarynxThe Larynx

The LarynxThe Larynx

• The Ventricle of the Larynx (ventriculus laryngis [Morgagnii]; laryngeal sinus) is a fusiform fossa, situated between the ventricular and vocal folds on either side, and extending nearly their entire length.

The Intrinsic Muscles of the LarynxThe Intrinsic Muscles of the Larynx• The Cricothyreoideus (Cricothyroid),

triangular in form, arises from the front and lateral part of the cricoid cartilage; its fibers diverge, and are arranged in two groups.

• The lower fibers - pars obliqua

• The anterior fibers - pars recta

The Intrinsic Muscles of the LarynxThe Intrinsic Muscles of the Larynx• The Cricoarytænoideus posterior (posterior

cricoarytenoid) arises from the broad depression on the corresponding half of the posterior surface of the lamina of the cricoid cartilage;

• its fibers run upward and lateralward, and converge to be inserted into the back of the muscular process of the arytenoid cartilage.

• The uppermost fibers are nearly horizontal, the middle oblique, and the lowest almost vertical.

The Intrinsic Muscles of the LarynxThe Intrinsic Muscles of the Larynx• The Cricoarytænoideus lateralis (lateral

cricoarytenoid) is smaller than the preceding, and of an oblong form. It arises from the upper border of the arch of the cricoid cartilage, and, passing obliquely upward and backward, is inserted into the front of the muscular process of the arytenoid cartilage.

The LarynxThe Larynx

The Intrinsic Muscles of the LarynxThe Intrinsic Muscles of the Larynx• The Arytænoideus is a single muscle,

filling up the posterior concave surfaces of the arytenoid cartilages. It arises from the posterior surface and lateral border of one arytenoid cartilage, and is inserted into the corresponding parts of the opposite cartilage. It consists of oblique and transverse parts.

The Intrinsic Muscles of the LarynxThe Intrinsic Muscles of the Larynx• The Thyreoarytænoideus (Thyroarytenoid)

is a broad, thin, muscle which lies parallel with and lateral to the vocal fold, and supports the wall of the ventricle and its appendix. It arises in front from the lower half of the angle of the thyroid cartilage, and from the middle cricothyroid ligament. Its fibers pass backward and lateralward, to be inserted into the base and anterior surface of the arytenoid cartilage.

The Intrinsic Muscles of the LarynxThe Intrinsic Muscles of the Larynx• The Thyreoarytænoideus (Thyroarytenoid)

is a broad, thin, muscle which lies parallel with and lateral to the vocal fold, and supports the wall of the ventricle and its appendix. It arises in front from the lower half of the angle of the thyroid cartilage, and from the middle cricothyroid ligament. Its fibers pass backward and lateralward, to be inserted into the base and anterior surface of the arytenoid cartilage.

The Intrinsic Muscles of the LarynxThe Intrinsic Muscles of the Larynx• The Cricoarytœnoidei posteriores

separate the vocal folds, and, consequently, open the glottis, by rotating the arytenoid cartilages outward around a vertical axis passing through the cricoarytenoid joints; so that their vocal processes and the vocal folds attached to them become widely separated.

The Intrinsic Muscles of the LarynxThe Intrinsic Muscles of the Larynx• The Cricoarytœnoidei laterales close the

glottis by rotating the arytenoid cartilages inward, so as to approximate their vocal processes.

• The Arytœnoideus approximates the arytenoid cartilages, and thus closes the opening of the glottis, especially at its back part.

The Intrinsic Muscles of the LarynxThe Intrinsic Muscles of the Larynx• The Cricothyreoidei produce tension and

elongation of the vocal folds by drawing up the arch of the cricoid cartilage and tilting back the upper border of its lamina; the distance between the vocal processes and the angle of the thyroid is thus increased, and the folds are consequently elongated.

The Intrinsic Muscles of the LarynxThe Intrinsic Muscles of the Larynx• The Thyreoarytœnoidei, consisting of two

parts having different attachments and different directions, are rather complicated as regards their action. Their main use is to draw the arytenoid cartilages forward toward the thyroid, and thus shorten and relax the vocal folds

The LarynxThe Larynx• The mucous membrane of the larynx is

furnished with numerous mucous secreting glands, the orifices of which are found in nearly every part; they are very plentiful upon the epiglottis, being lodged in little pits in its substance; they are also found in large numbers along the margin of the aryepiglottic fold, in front of the arytenoid cartilages, where they are termed the arytenoid glands. They exist also in large numbers in the ventricular appendages. None are found on the free edges of the vocal folds

The Vessels of the LarynxThe Vessels of the Larynx• The chief arteries of the larynx are the

laryngeal branches derived from the superior and inferior thyroid. The veins accompany the arteries; those accompanying the superior laryngeal artery join the superior thyroid vein which opens into the internal jugular vein; while those accompanying the inferior laryngeal artery join the inferior thyroid vein which opens into the innominate vein

The Nerves of the LarynxThe Nerves of the Larynx• The nerves are derived from the internal

and external branches of the superior laryngeal nerve, from the recurrent nerve, and from the sympathetic. The internal laryngeal branch is almost entirely sensory, but some motor filaments are said to be carried by it to the Arytænoideus

The TracheaThe Trachea• The trachea or windpipe (Fig. 961) is a

cartilaginous and membranous tube, extending from the lower part of the larynx, on a level with the sixth cervical vertebra, to the upper border of the fifth thoracic vertebra, where it divides into the two bronchi, one for each lung.

• The trachea is nearly but not quite cylindrical, being flattened posteriorly; it measures about 11 cm. in length; its diameter, from side to side, is from 2 to 2.5 cm., being always greater in the male than in the female. In the child the trachea is smaller, more deeply placed, and more movable than in the adult.

The TracheaThe Trachea• The trachea or windpipe (Fig. 961) is a

cartilaginous and membranous tube, extending from the lower part of the larynx, on a level with the sixth cervical vertebra, to the upper border of the fifth thoracic vertebra, where it divides into the two bronchi, one for each lung.

• The trachea is nearly but not quite cylindrical, being flattened posteriorly; it measures about 11 cm. in length; its diameter, from side to side, is from 2 to 2.5 cm., being always greater in the male than in the female. In the child the trachea is smaller, more deeply placed, and more movable than in the adult.

The TracheaThe Trachea• The Right Bronchus (bronchus dexter),

wider, shorter, and more vertical in direction than the left, is about 2.5 cm. long, and enters the right lung nearly opposite the fifth thoracic vertebra. The azygos vein arches over it from behind; and the right pulmonary artery lies at first below and then in front of it. About 2 cm. from its commencement it gives off a branch to the upper lobe of the right lung.

The TracheaThe Trachea• The Left Bronchus (bronchus sinister) is

smaller in caliber but longer than the right, being nearly 5 cm. long. It enters the root of the left lung opposite the sixth thoracic vertebra. It passes beneath the aortic arch, crosses in front of the esophagus, the thoracic duct, and the descending aorta, and has the left pulmonary artery lying at first above, and then in front of it.

The TracheaThe Trachea

The TracheaThe Trachea• The cartilages of the trachea vary from

sixteen to twenty in number: each forms an imperfect ring, which occupies the anterior two-thirds or so of the circumference of the trachea, being deficient behind, where the tube is completed by fibrous tissue and unstriped muscular fibers. The cartilages are placed horizontally above each other, separated by narrow intervals.

The TracheaThe Trachea• The first cartilage is broader than the rest, and

often divided at one end; it is connected by the cricotracheal ligament with the lower border of the cricoid cartilage, with which, or with the succeeding cartilage, it is sometimes blended.

• The last cartilage is thick and broad in the middle, in consequence of its lower border being prolonged into a triangular hook-shaped process, which curves downward and backward between the two bronchi.

The TracheaThe Trachea• The trachea is supplied with blood by the

inferior thyroid arteries. The veins end in the thyroid venous plexus. The nerves are derived from the vagus and the recurrent nerves, and from the sympathetic; they are distributed to the Trachealis muscles and between the epithelial cells.

Thorax Surface Thorax Surface AnatomyAnatomy

The LungsThe Lungs• Each lung is invested by an exceedingly delicate

serous membrane, the pleura, which is arranged in the form of a closed invaginated sac.

• A portion of the serous membrane covers the surface of the lung and dips into the fissures between its lobes; it is called the pulmonary (visceral) pleura.

• The rest of the membrane lines the inner surface of the chest wall, covers the diaphragm, and is reflected over the structures occupying the middle of the thorax; this portion is termed the parietal pleura.

The LungsThe Lungs• The two layers are continuous with one

another around and below the root of the lung; in health they are in actual contact with one another, but the potential space between them is known as the pleural cavity (space)

The LungsThe Lungs

The Pleura of the LungsThe Pleura of the Lungs• Like other serous membranes, the pleura is

covered by a single layer of flattened, nucleated cells, united at their edges by cement substance. These cells are modified connective-tissue corpuscles, and rest on a basement membrane. Beneath the basement membrane there are net-works of yellow elastic and white fibers, imbedded in ground substance which also contains connective-tissue cells. Bloodvessels, lymphatics, and nerves are distributed in the substance of the pleura.

The Pleura of the LungsThe Pleura of the Lungs• The arteries of the pleura are derived from

the intercostal, internal mammary, musculophrenic, thymic, pericardiac, and bronchial vessels. The veins correspond to the arteries.

• The nerves are derived from the phrenic and sympathetic (Luschka)

The LungsThe Lungs• The right lung usually weighs about 625

gm., the left 567 gm., but much variation is met with according to the amount of blood or serous fluid they may contain.

• The lungs are heavier in the male than in the female, their proportion to the body being, in the former, as 1:37, in the latter as 1:43.

The LungsThe Lungs• The lungs are the essential organs of

respiration; they are two in number, placed one on either side within the thorax, and separated from each other by the heart and other contents of the mediastinum

• The substance of the lung is of a light, porous, spongy texture; it floats in water, and crepitates when handled, owing to the presence of air in the alveoli; it is also highly elastic; hence the retracted state of these organs when they are removed from the closed cavity of the thorax.

The LungsThe Lungs• The apex (apex pulmonis) is rounded, and

extends into the root of the neck, reaching from 2.5 to 4 cm. above the level of the sternal end of the first rib. A sulcus produced by the subclavian artery as it curves in front of the pleura runs upward and lateralward immediately below the apex.

The LungsThe Lungs• The base (basis pulmonis) is broad,

concave, and rests upon the convex surface of the diaphragm, which separates the right lung from the right lobe of the liver, and the left lung from the left lobe of the liver, the stomach, and the spleen.

The LungsThe Lungs• The costal surface (facies costalis;

external or thoracic surface) is smooth, convex, of considerable extent, and corresponds to the form of the cavity of the chest, being deeper behind than in front. It is in contact with the costal pleura, and presents, in specimens which have been hardened in situ, slight grooves corresponding with the overlying ribs.

The LungsThe Lungs• The mediastinal surface (facies mediastinalis; inner

surface) is in contact with the mediastinal pleura. It presents a deep concavity, the cardiac impression, which accommodates the pericardium; this is larger and deeper on the left than on the right lung, on account of the heart projecting farther to the left than to the right side of the median plane.

• Above and behind this concavity is a triangular depression named the hilum, where the structures which form the root of the lung enter and leave the viscus. These structures are invested by pleura, which, below the hilus and behind the pericardial impression, forms the pulmonary ligament

The LungsThe Lungs

The LungsThe Lungs• The posterior border (margo posterior) is broad and

rounded, and is received into the deep concavity on either side of the vertebral column. It is much longer than the anterior border, and projects, below, into the phrenicocostal sinus.

• The anterior border (margo anterior) is thin and sharp, and overlaps the front of the pericardium. The anterior border of the right lung is almost vertical, and projects into the costomediastinal sinus; that of the left presents, below, an angular notch, the cardiac notch, in which the pericardium is exposed. Opposite this notch the anterior margin of the left lung is situated some little distance lateral to the line of reflection of the corresponding part of the pleura.

The LungsThe Lungs• The left lung is divided into two lobes, an upper and a

lower, by an interlobular fissure, which extends from the costal to the mediastinal surface of the lung both above and below the hilus.

• As seen on the surface, this fissure begins on the mediastinal surface of the lung at the upper and posterior part of the hilus, and runs backward and upward to the posterior border, which it crosses at a point about 6 cm. below the apex.

• It then extends downward and forward over the costal surface, and reaches the lower border a little behind its anterior extremity, and its further course can be followed upward and backward across the mediastinal surface as far as the lower part of the hilus.

The LungsThe Lungs• The right lung is divided into three lobes, superior,

middle, and inferior, by two interlobular fissures. One of these separates the inferior from the middle and superior lobes, and corresponds closely with the fissure in the left lung. Its direction is, however, more vertical, and it cuts the lower border about 7.5 cm. behind its anterior extremity.

• The other fissure separates the superior from the middle lobe. It begins in the previous fissure near the posterior border of the lung, and, running horizontally forward, cuts the anterior border on a level with the sternal end of the fourth costal cartilage; on the mediastinal surface it may be traced backward to the hilus.

The LungsThe Lungs• A little above the middle of the mediastinal

surface of each lung, and nearer its posterior than its anterior border, is its root, by which the lung is connected to the heart and the trachea. The root is formed by the bronchus, the pulmonary artery, the pulmonary veins, the bronchial arteries and veins, the pulmonary plexuses of nerves, lymphatic vessels, bronchial lymph glands, and areolar tissue, all of which are enclosed by a reflection of the pleura.

The BronchiThe Bronchi• The right bronchus gives off, about 2.5 cm. from

the bifurcation of the trachea, a branch for the superior lobe. This branch arises above the level of the pulmonary artery

• The left bronchus passes below the level of the pulmonary artery before it divides, and hence all its branches are hyparterial; it may therefore be looked upon as equivalent to that portion of the right bronchus which lies on the distal side of its eparterial branch

The LungsThe Lungs• The lungs are composed of an external

serous coat, a subserous areolar tissue and the pulmonary substance or parenchyma.

The LungsThe Lungs• The pulmonary artery conveys the venous blood

to the lungs; it divides into branches which accompany the bronchial tubes and end in a dense capillary net-work in the walls of the alveoli. In the lung the branches of the pulmonary artery are usually above and in front of a bronchial tube, the vein below.

The LungsThe Lungs

The LungsThe Lungs• The lungs are supplied from the anterior and

posterior pulmonary plexuses, formed chiefly by branches from the sympathetic and vagus. The filaments from these plexuses accompany the bronchial tubes, supplying efferent fibers to the bronchial muscle and afferent fibers to the bronchial mucous membrane and probably to the alveoli of the lung. Small ganglia are found upon these nerves.

The LungsThe Lungs• The lungs are supplied from the anterior and

posterior pulmonary plexuses, formed chiefly by branches from the sympathetic and vagus. The filaments from these plexuses accompany the bronchial tubes, supplying efferent fibers to the bronchial muscle and afferent fibers to the bronchial mucous membrane and probably to the alveoli of the lung. Small ganglia are found upon these nerves.

““Now I see the secret of making the best Now I see the secret of making the best person: it is to grow in the open air and to eat person: it is to grow in the open air and to eat

and sleep with the earth.” and sleep with the earth.” Walt WhitmanWalt Whitman