"pushing them up into the diaphragm which intrudes back into the chest cavity reducing the volume of the air-filled lungs, producing an exhalation. Secondly, its contraction causes ipsilateral rotation and side-bending. It acts with the external oblique muscle of the opposite side to achieve this torsional movement of the trunk. For example, the right internal oblique and the left external oblique contract as the torso flexes and rotates to bring the left shoulder towards the right hip. For this reason, the internal obliques are referred to as ""same-side rotators."" Abdominal internal oblique muscle The internal oblique muscle is a muscle"
"oblique muscle which is attached to the sternum and vertebral ribs anteriorly, and to the pelvis (pubis and ilium in Fig. 17) posteriorly (forming part of the abdominal wall) reverses the inhalatory movement, while compressing the abdominal contents, thus increasing the pressure in all the air sacs. Air is therefore expelled from the respiratory system in the act of exhalation. During inhalation air enters the trachea via the nostrils and mouth, and continues to just beyond the syrinx at which point the trachea branches into two primary bronchi, going to the two lungs (Fig. 16). The primary bronchi enter the"
"of thoraco abdominal cavity; controlled by inspiratory muscles. During expiration, oxygen poor air flows to the anterior air sacs and is expelled by the action of the expiratory muscles. The common ostrich air sacs play a key role in respiration since they are capacious, and increase surface area (as described by the Fick Principle). The oxygen rich air flows unidirectionally across the respiratory surface of the lungs; providing the blood that has a crosscurrent flow with a high concentration of oxygen. To compensate for the large ""dead"" space, the common ostrich trachea lacks valves to allow faster inspiratory air flow."
"Thoracic wall The thoracic wall or chest wall is the boundary of the thoracic cavity. The bony skeletal part of the thoracic wall is the rib cage, and the rest is made up of muscle, skin, and fasciae. The chest wall has 10 layers, namely skin, superficial fascia, deep fascia, serratus anterior, layer for ribs (containing intercostal muscles), and endothoracic fascia from superficial to deep. However, the muscular layers vary according to the region of the chest wall. For example, they may include muscles like pectoralis major or latissimus dorsi. When not breathing for long and dangerous periods of time"
"of the thoracic cavity and separates it from the more inferior abdominopelvic cavity. The abdominopelvic cavity is the largest cavity in the body. Although no membrane physically divides the abdominopelvic cavity, it can be useful to distinguish between the abdominal cavity, the division that houses the digestive organs, and the pelvic cavity, the division that houses the organs of reproduction. The cavities include: At the end of the third week, the neural tube, which is a fold of one of the layers of the trilaminar germ disc, called the ectoderm, appears. This layer elevates and closes dorsally, while the gut"
"and the rectum. Other vital organs inside the abdomen include the liver, the kidneys, the pancreas and the spleen. The abdominal wall is split into the posterior (back), lateral (sides), and anterior (front) walls. The abdominal muscles have different important functions. They assist in the breathing process as accessory muscles of respiration. Moreover, these muscles serve as protection for the inner organs. Furthermore, together with the back muscles they provide postural support and are important in defining the form. When the glottis is closed and the thorax and pelvis are fixed, they are integral in the cough, urination, defecation, childbirth,"
"abdominal cavity, forming a dome convex to the thorax. Contraction of the diaphragm flattens the dome, increasing the volume of the lung cavity. Air enters through the oral and nasal cavities, and travels through the larynx, trachea and [[bronchi]], and expands the [[alveoli]]. Relaxing the diaphragm has the opposite effect, decreasing the volume of the lung cavity, causing air to be pushed out of the lungs. During exercise, the abdominal wall [[Muscle contraction|contracts]], increasing pressure on the diaphragm, which forces air out quicker and more forcefully. The [[rib cage]] is able to expand and contract the chest cavity through the"
"the great arteries, with the 3rd pair of arteries contributing to the common carotids, the right 4th forming the base and middle part of the right subclavian artery and the left 4th being the central part of the aortic arch. The smooth muscle of the great arteries and the population of cells that form the aorticopulmonary septum that separates the aorta and pulmonary artery is derived from cardiac neural crest. This contribution of the neural crest to the great artery smooth muscle is unusual as most smooth muscle is derived from mesoderm. In fact the smooth muscle within the abdominal"
"during breathing. The intercostals are a set of muscles sandwiched among the ribs. They interconnect ribs, and are therefore the primary respiratory skeletal muscles. They are divided into the ""external"" and the ""internal subscapularis"". The origin and insertion are in the ribs. The intercostals pull the ribs backwards or forwards. The caudofemoralis is a muscle found in the pelvic limb. The Caudofemoralis acts to flex the tail laterally to its respective side when the pelvic limb is bearing weight. When the pelvic limb is lifted off the ground, contraction of the caudofemoralis causes the limb to abduct and the shank"
"rib 12. Along with this change in size, the ribs become progressively oblique (slanted) from ribs 1 through 9, then less slanted through rib 12. The rib cage is separated from the lower abdomen by the thoracic diaphragm which controls breathing. When the diaphragm contracts, the thoracic cavity is expanded, reducing intra-thoracic pressure and drawing air into the lungs. This happens through one of two actions (or a mix of the two): when the lower ribs the diaphragm connects to are stabilized by muscles and the central tendon is mobile, when the muscle contracts the central tendon is drawn down,"
"foster breathing. In early tetrapods, air was driven into the lungs by the pharyngeal muscles via buccal pumping, a mechanism still seen in amphibians. In humans, the main muscle of respiration that drives breathing is the diaphragm. The lungs also provide airflow that makes vocal sounds including human speech possible. Humans have two lungs, a right lung and a left lung. They are situated within the thoracic cavity of the chest. The right lung is bigger than the left, which shares space in the chest with the heart. The lungs together weigh approximately , and the right is heavier. The"
"lungs may collapse, which requires immediate medical attention. Thoracic cavity The thoracic cavity (or chest cavity) is the chamber of the body of vertebrates that is protected by the thoracic wall (rib cage and associated skin, muscle, and fascia). The central compartment of the thoracic cavity is the mediastinum. There are two openings of the thoracic cavity, a superior thoracic aperture known as the thoracic inlet and a lower inferior thoracic aperture known as the thoracic outlet. The thoracic cavity includes the tendons as well as the cardiovascular system which could be damaged from injury to the back, spine or"
"volume of the thoracic cavity. This is achieved by the muscles of respiration, through the contraction of the diaphragm, and the intercostal muscles which pull the rib cage upwards as shown in the diagram. During breathing out the muscles relax, returning the lungs to their resting position. At this point the lungs contain the functional residual capacity (FRC) of air, which, in the adult human, has a volume of about 2.5–3.0 litres. During heavy breathing as in exertion, a large number of accessory muscles in the neck and abdomen are recruited, that during exhalation pull the ribcage down, decreasing the"
"Thorax The thorax or chest (from the Greek θώραξ ""thorax"" ""breastplate, cuirass, corslet"" via ) is a part of the anatomy of humans and various other animals located between the neck and the abdomen. The thorax includes the thoracic cavity and the thoracic wall. It contains organs including the heart, lungs, and thymus gland, as well as muscles and various other internal structures. Many diseases may affect the chest, and one of the most common symptoms is chest pain. In humans and other hominids, the thorax is the chest region of the body between the neck and the abdomen, along"
"the abdominal cavity and pull the diaphragm upward. There are two muscles in the deep or posterior group. Quadratus lumborum arises from the posterior part of the iliac crest and extends to the rib XII and lumbar vertebrae I-IV. It unilaterally bends the trunk to the side and bilaterally pulls the 12th rib down and assists in expiration. The iliopsoas consists of psoas major (and occasionally psoas minor) and iliacus, muscles with separate origins but a common insertion on the lesser trochanter of the femur. Of these, only iliacus is attached to the pelvis (the iliac fossa). However, psoas passes"
"Muscles of respiration The muscles of respiration are those muscles that contribute to inhalation and exhalation, by aiding in the expansion and contraction of the thoracic cavity. The diaphragm and, to a lesser extent, the intercostal muscles drive respiration during quiet breathing. Additional 'accessory muscles of respiration' are typically only used under conditions of high metabolic demand (e.g. exercise) or respiratory dysfunction (e.g. an asthma attack). However, in instances where these accessory muscles become stiff and hard, expansion of the rib cage can be restricted. Maintenance of the elasticity of these muscles is crucial to the health of the respiratory"
"wall and have a function in inhalation, are also intercostal muscles, just not one of the three principal layers. Intercostal muscle Intercostal muscles are several groups of muscles that run between the ribs, and help form and move the chest wall. The intercostal muscles are mainly involved in the mechanical aspect of breathing. These muscles help expand and shrink the size of the chest cavity to facilitate breathing. There are three principal layers; Both the external and internal muscles are innervated by the intercostal nerves (the ventral rami of thoracic spinal nerves), are supplied by the intercostal arteries, and are"
"the only muscle capable of separating the vocal cords for normal breathing is the posterior cricoarytenoid. If this muscle is incapacitated on both sides, the inability to pull the vocal folds apart (abduct) will cause difficulty breathing. Bilateral injury to the recurrent laryngeal nerve would cause this condition. It is also worth noting that all muscles are innervated by the recurrent laryngeal branch of the vagus except the cricothyroid muscle, which is innervated by the external laryngeal branch of the superior laryngeal nerve (a branch of the vagus). Additionally, intrinsic laryngeal muscles present a constitutive Ca-buffering profile that predicts their"
"continue directly through to become mesobronchi. Ten different air sacs attach to the lungs to form areas for respiration. The most posterior air sacs (abdominal and post-thoracic) differ in that the right abdominal air sac is relatively small, lying to the right of the mesentery, and dorsally to the liver. While the left abdominal air sac is large and lies to the left of the mesentery. The connection from the main mesobronchi to the more anterior air sacs including the interclavicular, lateral clavicular, and pre-thoracic sacs known as the ventrobronchi region. While the caudal end of the mesobronchus branches into"
"Thoracic cavity The thoracic cavity (or chest cavity) is the chamber of the body of vertebrates that is protected by the thoracic wall (rib cage and associated skin, muscle, and fascia). The central compartment of the thoracic cavity is the mediastinum. There are two openings of the thoracic cavity, a superior thoracic aperture known as the thoracic inlet and a lower inferior thoracic aperture known as the thoracic outlet. The thoracic cavity includes the tendons as well as the cardiovascular system which could be damaged from injury to the back, spine or the neck. Structures within the thoracic cavity include:"
"food from moving into the airway. From the larynx, air moves into the trachea and down to the intersection that branches to form the right and left primary (main) bronchi. Each of these bronchi branch into secondary (lobar) bronchi that branch into tertiary (segmental) bronchi that branch into smaller airways called bronchioles that eventually connect with tiny specialized structures called alveoli that function in gas exchange. The lungs which are located in the thoracic cavity, are protected from physical damage by the rib cage. At the base of the lungs is a sheet of skeletal muscle called the diaphragm. The"
"cases the sclerites are fused to various degrees. Thorax The thorax or chest (from the Greek θώραξ ""thorax"" ""breastplate, cuirass, corslet"" via ) is a part of the anatomy of humans and various other animals located between the neck and the abdomen. The thorax includes the thoracic cavity and the thoracic wall. It contains organs including the heart, lungs, and thymus gland, as well as muscles and various other internal structures. Many diseases may affect the chest, and one of the most common symptoms is chest pain. In humans and other hominids, the thorax is the chest region of the"
"angled obliquely downward and backward from rib to rib. These muscles can therefore assist in lowering the rib cage, adding force to exhalation. Muscles of respiration The muscles of respiration are those muscles that contribute to inhalation and exhalation, by aiding in the expansion and contraction of the thoracic cavity. The diaphragm and, to a lesser extent, the intercostal muscles drive respiration during quiet breathing. Additional 'accessory muscles of respiration' are typically only used under conditions of high metabolic demand (e.g. exercise) or respiratory dysfunction (e.g. an asthma attack). However, in instances where these accessory muscles become stiff and hard,"
"abdominal muscles and internal intercostal muscles generate abdominal and thoracic pressure, which forces air out of the lungs. Exhaled air is rich in carbon dioxide, a waste product of cellular respiration during the production of energy, which is stored as ATP. Exhalation has a complementary relationship to inhalation which together make up the respiratory cycle of a breath. The main reason for exhalation is to rid the body of carbon dioxide, which is the waste product of gas exchange in humans. Air is brought in the body through inhalation. During this process air is taken in through the lungs. Diffusion"
"in non-respiratory functions, helping to expel vomit, faeces, and urine from the body by increasing intra-abdominal pressure, and preventing acid reflux by exerting pressure on the esophagus as it passes through the esophageal hiatus. Along with the diaphragm, the intercostal muscles are one of the most important groups of respiratory muscles. These muscles are attached between the ribs and are important in manipulating the width of the rib cage. There are three layers of intercostal muscles. The external intercostal muscles are most important in respiration. These have fibres that are angled obliquely downward and forward from rib to rib. The"
"Abdomen The abdomen (less formally called the belly, stomach, tummy or midriff) constitutes the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. The region occupied by the abdomen is termed the abdominal cavity. In arthropods it is the posterior tagma of the body; it follows the thorax or cephalothorax. The abdomen stretches from the thorax at the thoracic diaphragm to the pelvis at the pelvic brim. The pelvic brim stretches from the lumbosacral joint (the intervertebral disc between L5 and S1) to the pubic symphysis and is the edge of the pelvic"
"separates the thoracic cage from the parietal pleura. It depresses the ribs. Contraction of this muscle aids in exertional expiration by decreasing the transverse diameter of the thoracic cage. Transversus thoracis muscle The transversus thoracis muscle () lies internal to the thoracic cage, anteriorly. It is a thin plane of muscular and tendinous fibers, situated upon the inner surface of the front wall of the chest. It is in the same layer as the subcostal muscles and the innermost intercostal muscles. It arises on either side from the lower third of the posterior surface of the body of the sternum,"
"air inhaled. The trachea is the tube which carries air from the oral cavity and into the lungs, and is about 75–80 cm in length in the adult. It is held permanently open by 50-60 ""C""-shaped rings of cartilage, 5–6 cm in diameter. At the bifurcation of the trachea, there are two bronchi, the right of which is slightly larger in size. The bronchi then branch into smaller bronchioles, which in turn branch off into smaller bronchioles until they reach the alveoli (which absorb oxygen from the air and releases the carbon dioxide waste). The bronchi and bronchioles are all"
"baseline level of stiffness and size. The diaphragm is the primary muscle that allows for lung expansion and contraction. Smaller muscles between the ribs, the external intercostals, assist with this process. The epithelial lining of the upper respiratory tract is interspersed with goblet cells that secrete a protective mucus. This helps to filter waste, which is eventually either swallowed into the highly acidic stomach environment or expelled via spitting. The epithelium lining the respiratory tract is covered in small hairs called cilia. These beat rhythmically out from the lungs, moving secreted mucus foreign particles toward the laryngopharynx upwards and outwards,"
"mammals, the thorax is the region of the body formed by the sternum, the thoracic vertebrae, and the ribs. It extends from the neck to the diaphragm, and does not include the upper limbs. The heart and the lungs reside in the thoracic cavity, as well as many blood vessels. The inner organs are protected by the rib cage and the sternum. Thoracic vertebrae are also distinguished in birds, but not in reptiles. In insects, crustaceans, and the extinct trilobites, the thorax is one of the three main divisions (or tagmata) of the creature's body, each of which is in"
"body section posterior to that bearing the legs and head (the prosoma or cephalothorax). Abdomen The abdomen (less formally called the belly, stomach, tummy or midriff) constitutes the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. The region occupied by the abdomen is termed the abdominal cavity. In arthropods it is the posterior tagma of the body; it follows the thorax or cephalothorax. The abdomen stretches from the thorax at the thoracic diaphragm to the pelvis at the pelvic brim. The pelvic brim stretches from the lumbosacral joint (the intervertebral disc between"
"Intercostal muscle Intercostal muscles are several groups of muscles that run between the ribs, and help form and move the chest wall. The intercostal muscles are mainly involved in the mechanical aspect of breathing. These muscles help expand and shrink the size of the chest cavity to facilitate breathing. There are three principal layers; Both the external and internal muscles are innervated by the intercostal nerves (the ventral rami of thoracic spinal nerves), are supplied by the intercostal arteries, and are drained by the intercostal veins. Their fibers run in opposite directions. The scalene muscles, which also move the chest"
"that ""when both sets of muscles (diaphragm and abdominals) tense, the epigastrium pushes forward"". Therefore, the epigastric region is not a muscle nor is it an organ, but it is a zone of activity where the actions of the rectus abdominis and the diaphragm produce an outward bulging of the upper abdominal wall. It is also the spot where the Heimlich Maneuver is able to produce a rapid and forceful exhalation of breath. Epigastrium In anatomy, the epigastrium (or epigastric region) is the upper central region of the abdomen. It is located between the costal margins and the subcostal plane."