Respiratory System Handout PDF

Prof. Dr. Sayed Anwar Sayed Handout In Respiratory system By Professor / Sayed Anwar Sayed Faculty of medicine Assiut university 1  Prof. Dr. Sayed Anwar Sayed...

Prof. Dr. Sayed Anwar Sayed Handout In Respiratory system By Professor / Sayed Anwar Sayed Faculty of medicine Assiut university 1  Prof. Dr. Sayed Anwar Sayed Anatomy of the thoracic wall I-The Thoracic Wall It is referred to as the thoracic cage which is formed posteriorly, by the thoracic part of the vertebral column, anteriorly, by the sternum and costal cartilages; laterally, by the ribs and intercostal spaces; superiorly, by the suprapleural membrane; and inferiorly, by the diaphragm which separates the thoracic cavity from the abdominal cavity. The Sternum (Fig.1-2) The sternum is a flat bone that may be divided into three parts: 1-Manubrium sterni, 2- Body of the sternum, and 3- Xiphoid process.  The manubrium: Is broad above and narrows below. Its upper border lies opposite the intervertebral disc between the 2nd and 3rd thoracic vertebrae and shows the jugular (suprasternal) notch in its middle and an oval clavicular notch on either side of the notch for articulation with the clavicle. Its lower border articulates with the body of the sternum by means of fibrocartilagenous joint, (manubriostemal joint) at a projected transverse ridge called the sternal angle (angle of Lowis) that can be felt subcutaneously and it lies opposite the 2nd costal cartilage, that can be help in counting ribs. Its lateral border shows, (1) at its upper end a depression for articulation with the first costal cartilage and (2) at its lower end a small facet for articulation with the upper part of the 2nd costal cartilage. 2  Prof. Dr. Sayed Anwar Sayed  The body: Its lower border articulates with the xiphoid process (xiphisternal joint) that lies opposite the body of the 9th thoracic vertebra. On each lateral border are notches for articulation with the lower part of the 2nd costal cartilage and the 3rd to the 7th costal cartilages. Its anterior surfaces show 3 slight marked transverse ridges that indicate the composite development of the sternum. Its posterior surface is concave and the transverse ridges are less marked.  The xiphoid process: Is the lowest and smallest part of the sternum. It is a plate of hyaline cartilage that becomes ossified at its proximal end in adult life. 3  Prof. Dr. Sayed Anwar Sayed The Thoracic Part of the Vertebral Column It is concave forward and is made tip of twelve vertebrae, together with their intervertebral discs. The thoracic vertebrae (Fig.3) have the following characteristics: (1) The body is medium sized and heart shaped. It shows costal facets on its sides for articulation with the heads of the ribs. (2) The transverse process shows a costal facet near its tip for articulation with the tubercle of the rib (T11 and T12 have no facets on their transverse processes) (3) The spines are long and inclined downward. N.B: The 1st, 10th, 11th and 12th thoracic vertebrae are atypical ones because the followings: -The 1st thoracic vertebra has a complete circular upper costal facet on its body which articulates with the head of the 1st rib, and a semilunar lower facet for the upper facet on the head of the 2nd rib. -The 10th thoracic vertebra has no lower facet on the side of the body as the 11th rib does not articulate with the 10th vertebra. -The 11th thoracic vertebra: Its body is kidney shaped like the lumbar vertebrae and has a single circular facet near the upper border for articulation with the head of the 11th rib. Its transverse process is short with no facet. -The 12th thoracic vertebra: The body has a single circular facet which a space between it and the upper border. The transverse process has no facet and has a mamiliary and accessory processes like the lumbar vertebrae 4  Prof. Dr. Sayed Anwar Sayed The Ribs (Fig.4) Number: They are 12 pairs. There may be an additional rib in the cervical or lumbar region. The number may be reduced one rib. Direction: The 1st rib is almost horizontal. Obliquity of the ribs increases as we go downwards to reach its maximum at the 9th rib, and then diminishes again. Types: 1-True ribs: The upper seven, articulate anteriorly by their costal cartilages with the sternum. 2-False ribs: The 8th, 9th and 10th, each of their costal cartilages joins the one above. 3- Floating ribs: 11th and 12th; have free anterior ends. Identification of side: 1. The posterior end carries a head. 2. The anterior end carries a concavity. 3. The upper border is blunt and rounded. 4.The lower border is sharp due to the presence of a costal groove on its medial surface. 5 The outer surface is convex. Features of the typical rib: I-The posterior or vertebral end has the following parts: 5  Prof. Dr. Sayed Anwar Sayed Head: Shows an articular surface which is divided into 2 facets by a transverse ridge. These facets articulate with the costal facets of 2 contiguous thoracic vertebrae, The transverse ridge is connected to the intervertebral disc by a ligament Neck: Is the flattened part between head and tubercle. Tubercle: Lies anterior to the neck and is divided into: -Articular part, medially, which articulates with transverse process of the corresponding number vertebra. -Non articular part, laterally rough for attachment of the costal cartilage. II -The anterior or sternal end: Concave for attachment of the costal cartilage. III-The shaft: Has an outer convex and inner concave surfaces. Its upper border is rounded and its lower border is sharp. It is twisted anteroposterior. Features of atypical ribs (1st, 2nd, 11th and 12th ribs) a) The first rib It is the shortest rib. It is horizontally placed, So it has the following features: Upper surface marked by rough impressions and two grooves. Lower surface is smooth. Outer border is convex. Inner border is concave. b) The second rib It has no twist in its long axis. So its anterior and posterior ends lie in the same horizontal plane. c) The eleventh rib The head has a single facet. No neck and no tubercle. Anterior end is pointed. d)The twelfth rib The head has a single facet. No neck and no tubercle. No costal groove The costal cartilages: They are bars of hyaline cartilages connecting the upper seven ribs to the lateral edge of the sternum, and the 8th, 9th and 10th ribs to the cartilage immediately above. The cartilages of the 11th and 12th ribs end in the abdominal wall. The thoracic inlet or the superior aperture of the thoracic cage: * Bounded; Posteriorly, by the 1st thoracic vertebra anteriorly by the superior border of the manubrium sterna and on each side by the 1st rib. The thoracic outlet or the inferior aperture of the thoracic cage: * Bounded; Posteriorly, by the 12th thoracic vertebra, anteriorly by the 7th, 8th, 9th and 10th costal cartilages and on each side by the 11th and 12th ribs. It is closed by the diaphragm. The cervical rib: It is due to great development of the costal process of the 7th cervical vertebra. The subclavian artery and the lower trunk of the brachial plexus will be compressed by the rib resulting in vascular and nervous disorders. 6  Prof. Dr. Sayed Anwar Sayed INTRCOSTAL SPACES The spaces between the ribs are called intercostal spaces. Each space contains three muscles, comparable to those of the anterior abdominal wall, and a neurovascular bundle. INTERCOSTAL MUSCLES 1. The external intercostal muscle; forms the most superficial layer. Its fibers are directed downward and forward from the inferior border of the rib above to the superior border of the rib below. The muscle extends forward from the rib tubercle behind to the costochondral junction in front, where the muscle is replaced by an aponeurosis, the anterior intercostal membrane. 2. The internal intercostal muscle; forms the intermediate layer. Its fibers are directed downward and backward from the subcostal groove of the rib above to the upper border of the rib below. The muscle extends backward from the sternum in front to the angles of the ribs behind, where the muscle is replaced by an aponeurosis, the posterior intercostal membrane. 3. The transversus thoracis muscle; forms the deepest layer and corresponds to the transversus abdominis muscle in the anterior abdominal wall. It may be divided into three portions that are More or less separate from one another: (A) the subcostalis, (B) the intercostalis intimnus, and (C) the sternocostalis. The innermost intercostal muscle; this deeper muscle has all the appearances of the internal intercostal muscle, 7  Prof. Dr. Sayed Anwar Sayed but is seperated from it by the intercostal vessels and nerve. It arises from the inner surface of the rib immediately superior to the costal groove and inserted into the upper margin of the rib below. Its extent is variable, but it usually passes further posteriorly than the internal intercostal and not so far anteriorly as the external. Action of Intercostal Muscles: 1. When the intercostal muscles contract, they all tend to pull the ribs nearer to one another. 2. If the first rib is fixed by the contraction of the muscles in the root of the neck, namely, the scaleni muscles, the intercostal muscles will raise the second to the twelfth ribs toward the first. 3. If on the other hand, the twelfth rib is fixed by the quadrates lumborum muscle and the oblique muscles of the abdomen, the first to the eleventh ribs will be lowered by the contraction of the intercostal muscles. Nerve Supply of Intercostal Muscles The intercostal muscles are supplied by the corresponding intercostal nerves. Intercostal Arteries and Veins Each intercostal space possesses a large single posterior intercostal artery and two small anterior intercostal arteries. The posterior intercostal arteries of the first two spaces are branches from the superior intercostal artery, a branch of the costocervical trunk. The posterior intercostal arteries of the lower nine spaces are branches of the descending thoracic aorta. 8  Prof. Dr. Sayed Anwar Sayed The anterior intercostal arteries of the first six spaces are branches of the internal thoracic artery. The anterior intercostal arteries of the 7th, 8th and 9th spaces are branches of the musculophrenic artery, one of the terminal branches of the internal thoracic artery. Each intercostal artery gives off branches to the muscles, skin, and parietal pleura. In the region of the breast in the female, the branches to the superficial structures are particularly large. 9  Prof. Dr. Sayed Anwar Sayed The corresponding posterior intercostal veins drain backward into the azygos or hemiazygos veins, and the anterior intercostal veins drain forward into the internal thoracic and musculophrenic veins. Intercostal nerves The intercostal nerves are the anterior rami of the first eleven thoracic spinal nerves. The anterior rainus of the twelfth thoracic nerve lies in the abdomen and runs forward in the abdominal wall. Each intercostal nerve enters an intercostal space between the parietal pleura and the internal intercostal muscle. It then runs forward inferiorly to the intercostal vessels in the subcostal groove of the corresponding rib, between the transversus thoracis and internal intercostal muscle. The first six nerves are distributed within their intercostal spaces. The seventh to ninth intercostal nerves leave the anterior ends of their intercostal spaces by passing deep to the costal cartilages, to enter the anterior abdominal wall. In the case of the tenth and eleventh nerves, since the corresponding ribs are floating, these nerves pass directly into the abdominal wall. Branches: The branches of the intercostal nerves are as follows: 1. A collateral branch, which runs forward inferiorly to the main nerve on the upper border of the rib 2. A lateral cutaneous branch, which reaches the skin near the midaxillary line. It divides into an anterior and a posterior branch. 3. An anterior cutaneous branch, which reaches the skin near the midline. It divides into a medial and a lateral branch. 4. Numerous muscular branches, are given off by the main nerve and its collateral branch. 5. Pleural and peritoneal (7-11 intercostal nerves only) sensory branches. 6. Articular branches to the joints of the ribs. The first intercostal nerve is joined to the brachial plexus by a large branch that is equivalent to the lateral cutaneous branch of typical intercostal nerves. The remainder of the first intercostal nerve is small, and there is no anterior cutaneous branch. The second intercostal nerve is joined to the medial cutaneous nerve of the arm by a branch that is equivalent to the lateral cutaneous branch of other nerves. The combined nerves are referred to as the intercostobrachial nerve. The second intercostal nerve therefore supplies the skin of the armpit and the upper medial side of the arm. 10  Prof. Dr. Sayed Anwar Sayed With the exceptions noted, the first six intercostal nerves therefore supply (1) the skin and the parietal pleura covering the outer and inner surfaces of each intercostal space, respectively, and (2) the intercostal muscles of each intercostal space. In addition, the seventh to the eleventh intercostal nerves supply (1) the skin and the parietal peritoneum covering the outer and inner surfaces of the abdominal wall, respectively, and the anterior abdominal below. muscles, which include the external oblique, internal oblique, transversus abdominis, and rectus abdominis muscle. Suprapleural membrane Superiorly, the thorax opens into the root of the neck by a narrow aperture known as the thoracic inlet. It is bounded by the superior border of the manubrium sterni, by the medial border of the first ribs, and by the body of the first thoracic vertebra. The thoracic inlet transmits structures that pass between the thorax and the neck (esophagus, trachea, blood vessels, etc.) and for the most part lie close to the midline. On either side of these structures the inlet is closed by a dense fascial layer called the suprapleural membrane. This tent-shaped fibrous sheet is attached laterally to the medial border of the first rib and costal cartilage. It is attached at its apex to the tip of the transverse process of the seventh cervical vertebra and medially to the fascia investing the structures passing from the thorax into the neck. It protects the underlying cervical pleura and resists the changes in intrathoracic pressure occurring during respiratory movements. Internal Thoracic Artery It is a branch of the first part of the subclavian artery in the neck. It descends vertically on the pleura behind the costal cartilages, a finger breadth lateral to the sternum and ends in the sixth intercostal space by dividing into the superior epigastric and musculophrenic arteries. Branches: The branches of the internal thoracic artery are as follows: 1.Two anterior intercostal arteries for the upper six intercostal spaces. 2. Perforating arteries, which accompany the terminal branches of the corresponding intercostal nerves. 3.The pericardiacophrenic artery, which accompanies the phren nerve and supplies the pericardium. 4. Mediastinal arteries to the contents of the anterior mediastinum, e.g the thymus gland. 5. The superior epigastric artery, which enters the rectus sheath an supplies the rectus muscle as far as to umbilicus. 11  Prof. Dr. Sayed Anwar Sayed 6. The musculophrenic artery, which runs around the costal margin c the diaphragm and supplies the lower five intercostal spaces and the diaphragm. Internal Thoracic Vein The internal thoracic vein begins as venae comitantes of the interns themcic artery. The venae eventually join to form a single vessel, which drains into the brachiocephalic vein on each side. Blood supply of thoracic wall Each intercostal space possesses a large single posterior intercostal artery and two small anterior intercostal arteries. The posterior intercostal arteries of the first two spaces are branches from the superior intercostal artery, a branch of the costocervical trunk. The posterior intercostal arteries of the lower nine spaces are branches of the descending thoracic aorta. The anterior intercostal arteries of the first six spaces are branches of the internal thoracic artery. The anterior intercostal arteries of the 7th, 8th and 9th spaces are branches of the musculophrenic artery, one of the terminal branches of the internal thoracic artery. Each intercostal artery gives off branches to the muscles, skin, and parietal pleura. In the region of the breast in the female, the branches to the superficial structures are particularly large. The azygos vein: The azygos vein is inconstant in origin, it may arise from the posterior aspect of the inferior vena cava, at or below the level of the renal veins such a vein (Lumbar azygos) is frequently present and ascends in front of the upper lumbar vertebrae. The azygos vein may pass behind the lateral border of the right crus of the diaphrogm or it may pierce the crus. Occasionally it may be pass through the aortic opening of the diaphragm on the right side of the cisterna chyli. In front of the body of the 12th thoracic vertebra, it is joined by a large vessel which formed by the union of the right ascending lumbar vein with the right subcostal vein. This common trunk may, in absence of a lumbar azygos vein, form the azygos itself. Whatever its mode of origin, the azygos vein ascends in the posterior mediastinum to the level of the 4th thoracic vertebra, where it arches forward above the root of the right lung and ends in the superior vena cava just before piercing the pericardium. In 12  Prof. Dr. Sayed Anwar Sayed its course it lies in front of the bodies of the lower eight thoracic vertebrae, the anterior longitudinal ligament and the right posterior intercostal arteries. On its right side are the right greater splanchnic nerve, lung and pleura, on its left throughout the greater part of its course, are the thoracic duct and aorta and higher up, where it arches forward above the root of the right lung, the oesophagus, trachea and right vagus. Tributaries: The azygos vein collects from the posterior intercostal veins of the right side, with the exception of the first, the veins from the second, third and fourth intercostal spaces usually open by a common stem, called the right superior intercostal vein. It receives also the hemiazygos and accessory hemiazygos veins, several oesophageal, mediastinal, and pericardial veins. When it begins as a lumbar azygos vein, the common trunk formed by the union of the right ascending lumbar and subcostal veins is the largest tributary. The hemiazygos vein: The hemiazygos vein starts on the left like the azygos vein on the right side. Ascending on the front of the vertebral column as high as the eighth thoracic vertebra, it passes across the column, behind the aorta, oesophagus and thoracic duct, to end in the azygos. Its tributaries are the lower three posterior intercostal veins and the common trunk formed by the union of the ascending lumbar and subcostal veins of the left side, and some oesophageal and mediastinal veins. Its lower end often communicates with the left renal vein. The accessory hemiazygos vein: The accessory hemiazygos vein descends on the left side of the vertebral column. It receives the veins from the fourth or (fifth) to the eighth intercostal spaces inclusive of the left side, and sometimes the left bronchial veins. It crosses the body of the seventh thoracic vertebra and joins the azygos vein. The accessory hemiazygos vein sometimes joins the hemiazygos, and the common trunk thus formed opens into the azygos vein. The posterior intercostal veins: The posterior intercostal veins run with the posterior intercostal arteries and are eleven in number on each side. As they approach the vertebral column each vein receives a tributary which accompanies the posterior branch of the corresponding artery returning blood from the muscles and skin of the back and from the vertebral venous plexuses. On both sides of the thorax the first posterior intercostal vein 13  Prof. Dr. Sayed Anwar Sayed ascends in front of the neck of the first rib. It arches forwards above the pleura to end in the corresponding brachiocephalic vein. On the right the 2nd, 3rd and often, the 4th posterior intercostal veins unite to form the right superior intercostal vein, which joins the terminal part of the azygos vein. The veins from the intercostal space under the 4th open separately into the versa azygos. On the left side the 2nd, 3rd and sometimes the 4th posterior intercostal veins unite to form the left caper for intercostal vein. The veins from the 4th or (5th) to the 8th intercostal spaces end in the accessory hemiazygos vein, and the veins from the lower three spaces in hemiazygos vein. The bronchial veins: The bronchial veins usually two on each side, return blood from the larger bronchi and from the structures at the roots of the lungs. The bronchial veins of the right side, open into the terminal part of the azygos vein, those of the left side, into the left superior intercostal vein or the hemiazygos vein. The brachiocephalic veins The right brachiocephalic vein is formed at the root of the neck by the union of the right subclavian and the right internal jugular veins. The left brachiocephalic vein has a similar origin. It passes obliquely downward and to the right behind the manubrium sterni and infront of the large branches of the aortic arch. It joins the right brachiocephalic vein to form the superior vena cava. Azygos system of veins 14  Prof. Dr. Sayed Anwar Sayed The Nose The nose consists of the external nose and the nasal cavity, both of which are divided by a septum into right and left halves. External Nose The external nose has two elliptical orifices called the nostrils, which are separated from each other by the nasal septum. The lateral margin, the ala nasi, is rounded and mobile. The framework of the external nose is made up above by the nasal bones, the frontal processes of the maxillae, and the nasal part of the frontal bone. Below, the framework is formed of plates of hyaline cartilage. Blood Supply of the External Nose The skin of the external nose is supplied by branches of the ophthalmic and the maxillary arteries. The skin of the ala and the lower part of the septum are supplied by branches from the facial artery. Nerve Supply of the External Nose The infratrochlear and external nasal branches of the ophthalmic nerve (CN V) and the infraorbital branch of the maxillary nerve (CN V). Nasal Cavity The nasal cavity extends from the nostrils in front to the posterior nasal apertures or choanae behind, where the nose opens into the nasopharynx. The nasal vestibule is the area of the nasal cavity lying just inside the nostril. The nasal cavity is divided into right and left halves by the nasal septum. The septum is made up of the septal cartilage, the vertical plate of the ethmoid, and the vomer. 15  Prof. Dr. Sayed Anwar Sayed Lateral wall of the nasal cavity Nasal septum Walls of the Nasal Cavity Each half of the nasal cavity has a floor, a roof, a lateral wall, and a medial or septal wall. Floor The palatine process of the maxilla and the horizontal plate of the palatine bone. Roof The roof is narrow and is formed anteriorly beneath the bridge of the nose by the nasal and frontal bones, in the middle by the cribriform plate of the ethmoid, located beneath the anterior cranial fossa, and posteriorly by the downward sloping body of the sphenoid. Lateral Wall The lateral wall has three projections of bone called the superior, middle, and inferior nasal conchae. The space below each concha is called a meatus. 1-Sphenoethmoidal Recess The sphenoethmoidal recess is a small area above the superior concha. It receives the opening of the sphenoid air sinus. 2-Superior Meatus The superior meatus lies below the superior concha. It receives the openings of the posterior ethmoid sinuses. 3-Middle Meatus The middle meatus lies below the middle concha. It has a rounded swelling called the bulla ethmoidalis that is formed by the middle ethmoidal air sinuses, which open on its upper border. A curved opening, the hiatus semilunaris, lies just below the bulla. The anterior end of the hiatus leads into a funnel-shaped channel called the 16  Prof. Dr. Sayed Anwar Sayed infundibulum, which is continuous with the frontal sinus. The maxillary sinus opens into the middle meatus through the hiatus semilunaris. 4-Inferior Meatus The inferior meatus lies below the inferior concha and receives the opening of the lower end of the nasolacrimal duct, which is guarded by a fold of mucous membrane. Medial Wall The medial wall is formed by the nasal septum. The upper part is formed by the vertical plate of the ethmoid and the vomer. The anterior part is formed by the septal cartilage. The septum rarely lies in the midline, thus increasing the size of one half of the nasal cavity and decreasing the size of the other. Lateral wall of the nasal cavity Mucous Membrane of the Nasal Cavity The vestibule is lined with modified skin and has coarse hairs. The area above the superior concha is lined with olfactory mucous membrane and contains nerve endings sensitive to the reception of smell. The lower part of the nasal cavity is lined with respiratory mucous membrane. A large plexus of veins in the submucous connective tissue is present in the respiratory region. 17  Prof. Dr. Sayed Anwar Sayed Lateral wall of the nasal cavity Nerve Supply of the Nasal Cavity The olfactory nerves from the olfactory mucous membrane ascend through the cribriform plate of the ethmoid bone to the olfactory bulbs. The nerves of ordinary sensation are branches of the ophthalmic division (V1) and the maxillary division (V2) of the trigeminal nerve. Blood Supply to the Nasal Cavity Branches of the ophthalmic, maxillary and facial arteries supply different territories within the walls, floor and roof of the nose. They ramify to form anastomotic plexuses within and deep to the nasal mucosa. Anastomoses also occur between some larger arterial branches. The anterior and posterior ethmoidal branches of the ophthalmic artery supply the roof of the nose (including the septum). The sphenopalatine branch of the maxillary artery supplies the mucosa of the conchae, meati and posteroinferior part of the nasal septum, i.e. it is the principal vessel supplying the nasal mucosa. Its terminal part ascends through the incisive canal to anastomose on the septum with branches of the sphenopalatine and anterior ethmoidal arteries and with the septal branch of the superior labial artery. This septal region (Little's area) is a common site of bleeding from the nose. Lymph Drainage of the Nasal Cavity The lymph vessels draining the vestibule end in the submandibular nodes. The remainder of the nasal cavity is drained by vessels that pass to the upper deep cervical nodes. 18  Prof. Dr. Sayed Anwar Sayed Innervation of the nasal cavities. Arterial supply of the nasal cavities. The Paranasal Sinuses The paranasal sinuses are cavities found in the interior of the maxilla, frontal, sphenoid, and ethmoid bones. They are lined with mucoperiosteum and filled with air; they communicate with the nasal cavity through relatively small apertures. The maxillary and sphenoidal sinuses are present in a rudimentary form at birth; they enlarge appreciably after the eighth year and become fully formed in adolescence. Drainage of Mucus and Function of Paranasal Sinuses The mucus produced by the mucous membrane is moved into the nose by ciliary action of the columnar cells. The function of the sinuses is to act as resonators to the 19  Prof. Dr. Sayed Anwar Sayed voice; they also reduce the weight of the skull. When the apertures of the sinuses are blocked or they become filled with fluid, the quality of the voice is markedly changed. Maxillary Sinus The maxillary sinus is pyramidal in shape and located within the body of the maxilla behind the skin of the cheek. The roof is formed by the floor of the orbit, and the floor is related to the roots of the premolars and molar teeth. The maxillary sinus opens into the middle meatus of the nose through the hiatus semilunaris. Frontal Sinuses The two frontal sinuses are contained within the frontal bone. They are separated from each other by a bony septum. Each sinus is roughly triangular, extending upward above the medial end of the eyebrow and backward into the medial part of the roof of the orbit. Each frontal sinus opens into the middle meatus of the nose through the infundibulum. Sphenoidal Sinuses The two sphenoidal sinuses lie within the body of the sphenoid bone. Each sinus opens into the sphenoethmoidal recess above the superior concha. Ethmoid Sinuses The ethmoidal sinuses are anterior, middle, and posterior and they are contained within the ethmoid bone, between the nose and the orbit. They are separated from the latter by a thin plate of bone so that infection can readily spread from the sinuses into the orbit. The anterior sinuses open into the infundibulum; the middle sinuses open into the middle meatus, on or above the bulla ethmoidalis; and the posterior sinuses open into the superior meatus. Sinus Site of Drainage Maxillary sinus Middle meatus through hiatus semilunaris Frontal sinuses Middle meatus via infundibulum Sphenoidal Sphenoethmoidal recess sinuses Ethmoidal sinuses Anterior group Infundibulum and into middle meatus Middle group Middle meatus on or above bulla ethmoidalis Posterior group Superior meatus 20  Prof. Dr. Sayed Anwar Sayed Paranasal air sinuses The Pharynx  The pharynx is a fibromuscular chamber, 12 cm long.  It is attached above to the base of the skull.  It is continuous below with the esophagus.  Communicating with it from front are the nasal, oral, and laryngeal cavities.  It is divided into three parts; nasopharynx, oropharynx and laryngopharynx. 1-Nasopharynx: - It lies behind the nasal cavities. -The pharyngeal end of the auditory tube opens in its lateral well. -At the junction of the roof and its posterior wall, there is a collection of lymphoid follicles forming the pharyngeal tonsils. In children it may be enlarged to form adenoids. 2-Oropharynx: It lies behind the mouth and tongue. Its side wall presents the palatine tonsil on each side. 3-Laryngo-pharynx: It lies behind the larynx. It is continuous with oesophagus opposite the lower border of the cricoid cartilage (level of the sixth cervical vertebra). 21  Prof. Dr. Sayed Anwar Sayed The Larynx The larynx is an organ that provides a protective sphincter at the inlet of the air passages and is responsible for voice production. It is situated below the tongue and hyoid bone and between the great blood vessels of the neck and lies at the level of the fourth, fifth, and sixth cervical vertebrae. It opens above into the laryngeal part of the pharynx, and below is continuous with the trachea. The larynx is covered in front by the infrahyoid strap muscles and at the sides by the thyroid gland. The framework of the larynx is formed of cartilages that are held together by ligaments and membranes, moved by muscles, and lined by mucous membrane. Cartilages of the Larynx  Thyroid cartilage: This is the largest cartilage of the larynx and consists of two laminae of hyaline cartilage that meet in the midline in the prominent V angle (the so-called Adam's apple). The posterior border extends upward into a superior cornu and downward into an inferior cornu. On the outer surface of each lamina is an oblique line for the attachment of muscles.  Cricoid cartilage: This cartilage is formed of hyaline cartilage and shaped like a signet ring, having a broad plate behind and a shallow arch in front. The cricoid cartilage lies below the thyroid cartilage, and on each side of the lateral surface is a facet for articulation with the inferior cornu of the thyroid cartilage. Posteriorly, the lamina has on its upper border on each side a facet for articulation with the arytenoid cartilage. All these joints are synovial.  Arytenoid cartilages: There are two arytenoid cartilages, which are small and pyramid shaped and located at the back of the larynx. They articulate with the 22  Prof. Dr. Sayed Anwar Sayed upper border of the lamina of the cricoid cartilage. Each cartilage has an apex above that articulates with the small corniculate cartilage, a base below that articulates with the lamina of the cricoid cartilage, and a vocal process that projects forward and gives attachment to the vocal ligament. A muscular process that projects laterally gives attachment to the posterior and lateral cricoarytenoid muscles.  Corniculate cartilages: Two small conical-shaped cartilages articulate with the arytenoid cartilages. They give attachment to the aryepiglottic folds.  Cuneiform cartilages: These two small rod-shaped cartilages are found in the aryepiglottic folds and serve to strengthen them.  Epiglottis: This leaf-shaped lamina of elastic cartilage lies behind the root of the tongue. Its stalk is attached to the back of the thyroid cartilage. The sides of the epiglottis are attached to the arytenoid cartilages by the aryepiglottic folds of mucous membrane. The upper edge of the epiglottis is free. The covering of mucous membrane passes forward onto the posterior surface of the tongue as the median glossoepiglottic fold; the depression on each side of the fold is called the vallecula. Laterally the mucous membrane passes onto the wall of the pharynx as the lateral glossoepiglottic fold. Cartilages of the larynx Membranes and Ligaments of the Larynx  Thyrohyoid membrane: This connects the upper margin of the thyroid cartilage to the hyoid bone. In the midline it is thickened to form the median 23  Prof. Dr. Sayed Anwar Sayed thyrohyoid ligament. The membrane is pierced on each side by the superior laryngeal vessels and the internal laryngeal nerve, a branch of the superior laryngeal nerve.  Cricotracheal ligament: This connects the cricoid cartilage to the first ring of the trachea.  Quadrangular membrane: This extends between the epiglottis and the arytenoid cartilages. Its thickened inferior margin forms the vestibular ligament, and the vestibular ligaments form the interior of the vestibular folds.  Cricothyroid ligament: The lower margin is attached to the upper border of the cricoid cartilage. The superior margin of the ligament, instead of being attached to the thyroid cartilage, ascends on the medial surface of the thyroid cartilage. Its upper free margin, composed almost entirely of elastic tissue, forms the important vocal ligament on each side. The vocal ligaments form the interior of the vocal folds (vocal cords). The anterior end of each vocal ligament is attached to the thyroid cartilage, and the posterior end is attached to the vocal process of the arytenoid cartilage. Inlet of the Larynx The inlet of the larynx looks backward and upward into the laryngeal part of the pharynx. The opening is wider in front than behind and is bounded in front by the epiglottis, laterally by the aryepiglottic fold of mucous membrane, and posteriorly by the arytenoid cartilages with the corniculate cartilages. The cuneiform cartilage lies within and strengthens the aryepiglottic fold and produces a small elevation on the upper border. 24  Prof. Dr. Sayed Anwar Sayed The Piriform Fossa The piriform fossa is a recess on either side of the fold and inlet. It is bounded medially by the aryepiglottic fold and laterally by the thyroid cartilage and the thyrohyoid membrane. Laryngeal Folds Vestibular Fold The vestibular fold is a fixed fold on each side of the larynx. It is formed by mucous membrane covering the vestibular ligament and is vascular and pink in color. Vocal Fold (Vocal Cord) The vocal fold is a mobile fold on each side of the larynx and is concerned with voice production. It is formed by mucous membrane covering the vocal ligament and is avascular and white in color. The vocal fold moves with respiration and its white color is easily seen when viewed with a laryngoscope. The gap between the vocal folds is called the rima glottidis or glottis. The glottis is bounded in front by the vocal folds and behind by the medial surface of the arytenoid cartilages. The glottis is the narrowest part of the larynx and measures about 2.5 cm from front to back in the male adult and less in the female. In children the lower part of the larynx within the cricoid cartilage is the narrowest part. Laryngeal cavity. A. Posterolateral view. B. Posterior view (cutaway). C. Superior view through the laryngeal inlet Cavity of the Larynx The cavity of the larynx extends from the inlet to the lower border of the cricoid cartilage, where it is continuous with the cavity of the trachea. It is divided into three regions:  The vestibule, which is situated between the inlet and the vestibular folds. 25  Prof. Dr. Sayed Anwar Sayed  The middle region, which is situated between the vestibular folds above and the vocal folds below.  The lower region, which is situated between the vocal folds above and the lower border of the cricoid cartilage below. Sinus of the Larynx The sinus of the larynx is a small recess on each side of the larynx situated between the vestibular and vocal folds. It is lined with mucous membrane. Muscles of the Larynx The muscles of the larynx may be divided into two groups: extrinsic and intrinsic. a) Extrinsic Muscles These muscles move the larynx up and down during swallowing. Note that many of these muscles are attached to the hyoid bone, which is attached to the thyroid cartilage by the thyrohyoid membrane. It follows that movements of the hyoid bone are accompanied by movements of the larynx.  Elevation: The digastric, the stylohyoid, the mylohyoid, the geniohyoid, the stylopharyngeus, the salpingopharyngeus, and the palatopharyngeus muscles  Depression: The sternothyroid, the sternohyoid, and the omohyoid muscles b) Intrinsic Muscles Two muscles modify the laryngeal inlet:  Narrowing the inlet: The oblique arytenoid muscle  Widening the inlet: The thyroepiglottic muscle Five muscles move the vocal folds (cords):  Tensing the vocal cords: The cricothyroid muscle.  Relaxing the vocal cords: The thyroarytenoid (vocalis) muscle.  Adducting the vocal cords: The lateral cricoarytenoid muscle.  Abducting the vocal cords: The posterior cricoarytenoid muscle.  Approximates the arytenoid cartilages: The transverse arytenoid muscle. 26  Prof. Dr. Sayed Anwar Sayed Thyro-arytenoid muscle Mucous Membrane of the Larynx The mucous membrane of the larynx lines the cavity and is covered with ciliated columnar epithelium. On the vocal cords, however, where the mucous membrane is subject to repeated trauma during phonation, the mucous membrane is covered with stratified squamous epithelium. Nerve Supply of the Larynx Sensory Nerves 27  Prof. Dr. Sayed Anwar Sayed  Above the vocal cords: The internal laryngeal branch of the superior laryngeal branch of the vagus.  Below the level of the vocal cords: The recurrent laryngeal nerve. Motor Nerves All the intrinsic muscles of the larynx except the cricothyroid muscle are supplied by the recurrent laryngeal nerve. The cricothyroid muscle is supplied by the external laryngeal branch of the superior laryngeal branch of the vagus. Blood Supply of the Larynx  Upper half of the larynx: The superior laryngeal branch of the superior thyroid artery.  Lower half of the larynx: The inferior laryngeal branch of the inferior thyroid artery. Lymph Drainage of the Larynx The lymph vessels drain into the deep cervical group of nodes. Arterial supply of the larynx, left lateral view 28  Prof. Dr. Sayed Anwar Sayed Venous drainage of the larynx, anterior view Innervation of the larynx 29  Prof. Dr. Sayed Anwar Sayed The Trachea The trachea is a mobile cartilaginous and membranous tube. It begins in the neck as a continuation of the larynx at the lower border of the cricoid cartilage at the level of the sixth cervical vertebra. It descends in the midline of the neck. In the thorax the trachea ends below at the carina by dividing into right and left principal (main) bronchi at the level of the sternal angle (opposite the disc between the fourth and fifth thoracic vertebrae). During expiration the bifurcation rises by about one vertebral level, and during deep inspiration may be lowered as far as the sixth thoracic vertebra. In adults the trachea is about 4‫ ½آ‬in. (11.25 cm) long and 1 in. (2.5 cm) in diameter. The fibroelastic tube is kept patent by the presence of U-shaped bars (rings) of hyaline cartilage embedded in its wall. The posterior free ends of the cartilage are connected by smooth muscle, the trachealis muscle. Relations of the Trachea in the Neck:  Anteriorly: Skin, fascia, isthmus of the thyroid gland (in front of the second, third, and fourth rings), inferior thyroid vein, jugular arch, thyroidea ima artery (if present), and the left brachiocephalic vein in children, overlapped by the sternothyroid and sternohyoid muscles.  Posteriorly: Right and left recurrent laryngeal nerves and the esophagus.  Laterally: Lobes of the thyroid gland and the carotid sheath and contents. The relations of the trachea in the superior mediastinum of the thorax are as follows:  Anteriorly: The sternum, the thymus, the left brachiocephalic vein, the origins of the brachiocephalic and left common carotid arteries, and the arch of the aorta.  Posteriorly: The esophagus and the left recurrent laryngeal nerve.  Right side: The azygos vein, the right vagus nerve, and the pleura.  Left side: The arch of the aorta, the left common carotid and left subclavian arteries, the left vagus and left phrenic nerves, and the pleura. Blood Supply of the Trachea The upper two thirds are supplied by the inferior thyroid arteries and the lower third is supplied by the bronchial arteries. Lymph Drainage of the Trachea 30  Prof. Dr. Sayed Anwar Sayed The lymph drains into the pretracheal and paratracheal lymph nodes and the deep cervical nodes. Nerve Supply of the Trachea The sensory nerve supply is from the vagi and the recurrent laryngeal nerves. Sympathetic nerves supply the trachealis muscle. The Bronchi The trachea bifurcates behind the arch of the aorta into the right and left principal (primary, or main) bronchi. The bronchi divide dichotomously, giving rise to several million terminal bronchioles that terminate in one or more respiratory bronchioles. Each respiratory bronchiole divides into 2 to 11 alveolar ducts that enter the alveolar sacs. The alveoli arise from the walls of the sacs as diverticula. Principal Bronchi The right principal (main) bronchus is wider, shorter, and more vertical than the left and is about 1 in. (2.5 cm) long. Before entering the hilum of the right lung, the principal bronchus gives off the superior lobar bronchus. On entering the hilum, it divides into a middle and an inferior lobar bronchus. Lungs Each lung is conical in shape and is covered by visceral pleura. It is suspended in its own pleural cavity, being attached to the mediastinum by its root. Each lung has a blunt apex, which projects upward into the root of the neck for about 1 inch above the medial one-third of the clavicle; a concave base, which overlies the dome of the diaphragm, an extensive convex costal surface, which is related to the inner surfaces 31  Prof. Dr. Sayed Anwar Sayed of the ribs and costal cartilages and intercostal spaces and a concave mediastinal surface, which is molded to the mediastinal structures Lobes of the lungs: The right lung is slightly larger than the left and is divided by the oblique and horizontal fissures into three lobes, the upper, middle, and lower lobes. The left lung is divided by the oblique fissure into two lobes, the upper and lower lobe Bronchopulmonary segments: The lobes of the lungs are subdivided into a number of bronchopulmonary segments, each of which receives a segmental bronchus, an artery, and a vein. Each segment is pyramidal in shape, having its apex toward the root of the lung and its base toward the lung surface. 32  Prof. Dr. Sayed Anwar Sayed Major structures related to the right lung Major structures related to the left lung. 33  Prof. Dr. Sayed Anwar Sayed Root of the lung: The root of the lung is formed of structures that are entering or leaving the lung. It is made up of the bronchi, pulmonary artery and veins, lymph vessels, bronchial vessels, and nerves. It is surrounded by a tubular sheath of pleura which joins the mediastinal parietal pleura to the visceral pleura covering the lungs. Blood Supply of Lungs: The bronchi and their branches receive their blood from the bronchial arteries, which are branches of the aorta. These 4rteries also supply the connective tissue of the lung and the visceral pleura. The bronchial veins drain into the azygos and hemiazygos vein The alveoli receive deoxygenated blood from the terminal branches of the pulmonary arteries. The oxygenated blood leaving the alveolar capillaries drains into the tributaries of the pulmonary veins, which follow the intersegmental connective tissue septa to the lung root. Two pulmonary veins leave each lung root The bronchial veins: The bronchial veins usually two on each side, return blood from the larger bronchi and from the structures at the roots of the lungs. The bronchial veins of the right side open into the terminal part of the azygos vein, those of the left side, into the left superior intercostal vein or the hemiazygos vein Lymph Drainage of Lungs: The lymph vessels travel along the bronchi and pulmonary arteries from the periphery towards file hilus, or root of the lung. The lymph vessels are extensively interrupted by lymph nodes, many of which lie in the angles of the branching bronchi. There are numerous nodes in the lung root and alongside the trachea, which together are referred to as the tracheobronchial nodes. Emerging from the upper end of these nodes is the bronchornediastinal trunk. The two trunks ascend on either side of the trachea and drain into the brachiocephalic vein or the thoracic or right lymphatic ducts. Nerve Supply of Lungs: At the root of each lung is a pulmonary plexus composed of efferent and afferent autonomic nerve fibers. The plexus is formed from branches of the sympathetic trunk and receives parasympathetic fibers from the vagus nerve. The sympathetic efferent fibers produce bronchodilatation and vasoconstriction. The parasympathetic efferent fibers produce bronchoconstriction, vasodilatation, and increased glandular secretion. Afferent impulses derived from the bronchial mucous membrane and from stretch receptors in the alveolar walls pass to the central nervous system in both sympathetic and parasympathetic nerves. Pleurae 34  Prof. Dr. Sayed Anwar Sayed Each pleura has two parts: (1) a parietal layer, which lines the thoracic wall, covers the thoracic surface of the diaphragm and the lateral aspect of the mediastinum, and extends into the root of the neck to line the undersurface of the suprapleural membrane at the thoracic inlet, and (2) a visceral layer, which completely covers the outer surfaces of the lungs and extends into the depths of the interlobar fissures.(Fig.12-13) The two layers become continuous with one another by means of a cuff of pleura that surrounds the structures entering and leaving the lung at the lung root. To allow for movement of the lung root during respiration, the pleural cuff hangs down as a loose fold called The pulmonary ligament. The parietal and visceral layers of pleura are separated from one another by a slit like space, the pleural cavity. This normally contains a small amount of tissue fluid, the pleural fluid, which covers the surfaces of the pleura as a thin film and permits the two layers to move on each other with the minimum of friction. For purposes of description, it is customary to divide the parietal pleura according to the region in which it lies or the surface that it covers. The cervical pleura extends up into the neck, lining the undersurface of the suprapleural membrane. It reaches a level about 1 to 1 1/2 inches (2.5- 4 cm) above the medial third of the clavicle. The costal pleura lines the inner surfaces of the ribs, the costal cartilages, the intercostal spaces, the sides of the vertebral bodies, and the back of the sternum. The diaphragmatic pleura covers the thoracic surface of the diaphragm. In quiet respiration the costal and diaphragmatic pleurae are in apposition to each other below the lower border of the lung. In deep inspiration the margins of the base of the lung descend, and the costal and diaphragmatic pleurae separate. This lower area of the pleural cavity into which the lung expands on inspiration is referred to as the costodiaphragmatic recess. The recess is 2 inches (5 cm) deep in the scapular line posteriorly; 3 to 3 1/2inches (8-9 cm) in the midaxillary line and 1 to 11/2 inches (2.5- 4 cm)in the midclavicular line. 35  Prof. Dr. Sayed Anwar Sayed The pleura The mediastinal pleura covers and forms the lateral boundary of the mediastinum. At the root of the lung it is reflected as a cuff around the vessels and bronchi and here becomes continuous with the visceral pleura. Nerve Supply of the Pleura: The parietal pleura is supplied as follows: The costal pleura is segmentally supplied by the intercostal nerves; the mediastinal pleura is supplied by the phrenic nerve; and the diaphragmatic pleura is supplied over the domes by the phrenic nerve and around the periphery by the lower five intercostal nerves. The visceral pleura covering the lungs receives an autonomic vasomotor supply, but is insensitive to common sensation such as pain and touch. Surface Markings of Lungs and Pleura Lung The apex of the lung projects into the neck. It can be mapped out on the anterior surface of the body by drawing a curved line, convex upward, from the sternoclavicular joint to a point 1 inch (2.5 cm) above the junction of the medial and intermediate thirds of the clavicle. The anterior border of the right lung begins behind the sternoclavicular joint and runs downward almost reaching the midline behind the sternal angle. It then continues downward until it reaches the xiphisternal joint. The anterior border of the left lung has a similar course, but at the level of the fourth costal cartilage it deviates laterally and extends for a variable distance beyond 36  Prof. Dr. Sayed Anwar Sayed the lateral margin of the sternum to form the cardiac notch. This notch is produced by the heart displacing the lung to the left. The anterior border then turns sharply downward to the level of the xiphisternal joint. The lower border of the lung in mid inspiration follows a curving line, which crosses the sixth rib in the midclavicuiar line and the eighth rib in the midaxillary line, and reaches the tenth rib adjacent to the vertebral column posteriorly. The posterior border of the lung extends downward from the spinous process of the seventh cervical vertebra to the level of the tenth thoracic vertebra, and lies about 1 1/2 inches (4 cm) from the midline. The oblique fissure of the lung can be indicated on the surface by a line drawn from the root of the spine of the scapula obliquely downward, laterally and anteriorly, following the course of the sixth rib to the sixth costochondral junction. In the left lung the upper lobe lies above and anterior to this line, the lower lobe lies below and posterior to it. In the right lung there is an additional fissure, the horizontal fissure, which may be represented by a line drawn horizontally along the fourth costal cartilage, to meet the oblique fissure in the midaxillary line. Above the horizontal fissure lies the upper lobe and below it, the middle lobe below and posterior to the oblique fissure lies the lower lobe. Pleura The boundaries of the pleural sac can be marked out as lines on the surface of the body. The lines, which will indicate the limits of the parietal pleura where it lies close to the body surface, are referred to as the lines of pleural reflection. The cervical pleura bulges upward into the neck and has a surface marking identical to that of the apex of the lung. A curved line may be drawn, convex upward, from the sternoclavicular joint to a point 1 inch (2.5 cm) above the junction of the medial and intermediate thirds of the clavicle. The anterior border of the right pleura runs down behind the sternoclavicular joint almost reaching the midline behind the sternal angle. It then continues downward until it reaches the xiphisternal joint. The anterior border of the left pleura has a similar course but at the level of the fourth costal cartilage it deviates laterally and extends to the lateral margin of the sternum to form the cardiac notch (Note that the pleural cardiac notch is not as large as the cardiac notch of the lung). It then rums sharply downward to the xiphisternal joint. The lower border of the pleura on both sides follows a curved line laterally ,downwards and backwards which crosses the eighth rib in midclavicular line and the tenth rib in the midaxillary line and reaches the twelfth rib adjacent to the 37  Prof. Dr. Sayed Anwar Sayed vertebral column, i.e., at the lateral border of the erector spinae muscle, Note that the lower margins of the lungs cross the sixth, eighth, and tenth ribs at the midclavicular lines, the midaxillary lines and the sides of the vertebral column, respectively, and lower margins of the pleurae cross, at the same points respectively the eighth, the tenth and the twelfth ribs. The distance between the two borders corresponds to the costodiaphragmatic recess. Surface Markings of Lungs and Pleu The diphragm This is a fibromuscular partition between the thoracic and abdominal cavities. Origin(Fig.69): Sternal origin consists of two slips from the back of the xiphoid process. Costal origin: is by wide obliquely placed slips from the lower six costal cartilages. Vertebral origin: is by the crura and the arcuate ligaments. Crura: These are thick, fleshy bundles attached to the anterior surfaces of the upper (left) or three(right)lumbar vertebral bodies and the intervertebral dies Arcuate ligaments : 1)the median arcuate ligament A tendinuous band, that joins the medial side of the upper parts of the two crura over the anterior surface of the aorta. 2)The medial arcuate ligament 38  Prof. Dr. Sayed Anwar Sayed A tendious thickening of the fascia over psoas major that connects the lateral side of each crus to the transverse process of the first or second lumbar vertebra. 3) The lateral arcuate ligament; a linear thickening of the anterior layer of the thoracolumbar fascia, passes from the medial arcuate ligament over the anterior surface of quadrates lumborum to the twelfth rib Insertion : All the muscle fibres of the diaphragm converge on the strong C.shaped central tendon Nerve Supply : The motor supply to the diaphragm is from the phrenic nerves. The sensory supply: Comes via the phrenic and lower intercostal nerves Action: It is an important muscle of respiration. It increases the vertical extent of the thoracic cavity by partially flattening its dome and compressing the abdominal contents when it contracts. Foramina in Diaphragm (Fig.68): There are three main openings: 1-Aortic opening lies between the upper ends of the two crura, posterior to the median arcuate ligament, and anterior to the twelfth thoracic vertebra. In addition to the aorta, it transmits the thoracic duct, the azygos vein, and lymph vessels. 2-The oesophageal opening: Is an oval hiatus in the muscular part of the diaphragm one inch to the left of the median plane and posterior to the central tendon,at the level of the tenth thoracic vertebra. In addition to the oesophagus, it transmits the anterior and posterior vagal trunks, oesophageal branches of the left gastric artery and communications between gastric and oesophageal veins. 3-The inferior vena cava opening lies in the central tendon of the diaphragm one inch to the right of the median plane at the level of the eighth thoracic vertebra. Fig.68:Openings in the diaphragm 39