"arteries are branches that originate throughout the length of the posterior aspect of the descending thoracic aorta. Descending thoracic aorta The descending thoracic aorta is a part of the aorta located in the thorax. It is a continuation of the descending aorta and contained in the posterior mediastinal cavity. The descending thoracic aorta begins at the lower border of the fourth thoracic vertebra where it is continuous with the aortic arch, and ends in front of the lower border of the twelfth thoracic vertebra, at the aortic hiatus in the diaphragm where it becomes the abdominal aorta. At its commencement,"
"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"
"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"
"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,"
"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"
"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"
"the medial tract, the multifidi originates on the sacrum. The muscles of the abdominal wall are subdivided into a superficial and a deep group. The superficial group is subdivided into a lateral and a medial group. In the medial superficial group, on both sides of the centre of the abdominal wall (the ""linea alba""), the rectus abdominis stretches from the cartilages of ribs V-VII and the sternum down to the pubic crest. At the lower end of the rectus abdominis, the pyramidalis tenses the ""linea alba"". The lateral superficial muscles, the transversus and external and internal oblique muscles, originate on"
"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,"
"Rectus abdominis muscle The rectus abdominis muscle, also known as the ""abdominal muscle"" or ""abs"", is a paired muscle running vertically on each side of the anterior wall of the human abdomen, as well as that of some other mammals. There are two parallel muscles, separated by a midline band of connective tissue called the linea alba. It extends from the pubic symphysis, pubic crest and pubic tubercle inferiorly, to the xiphoid process and costal cartilages of ribs V to VII superiorly. The proximal attachments are the pubic crest and the pubic symphysis. It attaches distally at the costal cartilages"
"are separated by tough connective tissue membranes (or septa). Each of these compartments has its own blood and nerve supply, and contains a different group of muscles. Anterior compartment muscles of the thigh include sartorius, and the four muscles that comprise the quadriceps muscles- rectus femoris, vastus medialis, vastus intermedius and vastus lateralis. Posterior compartment muscles of the thigh are the hamstring muscles, which include semimembranosus, semitendinosus, and biceps femoris. Medial compartment muscles are pectineus,adductor magnus, adductor longus and adductor brevis, and also gracilis. Because the major muscles of the thigh are the largest muscles of the body, resistance exercises"
"muscle. The anterior compartment is separated from the posterior compartment by the lateral intermuscular septum and from the medial compartment by the medial intermuscular septum. The nerve of the anterior compartment of thigh is the femoral nerve. Innervation for the quadriceps muscles come from the posterior division of the femoral nerve, while the anterior division (which contains cutaneous as well as muscular components) gives a lateral and a medial branch, the second being responsible for the innervation of the sartorius muscle. The iliacus and the psoas major and psoas minor muscles, sometimes considered part of the anterior compartment, do not"
"Transverse abdominal muscle The transverse abdominal muscle (TVA), also known as the transverse abdominis, transversalis muscle and transversus abdominis muscle, is a muscle layer of the anterior and lateral (front and side) abdominal wall which is deep to (layered below) the internal oblique muscle. It is thought by most fitness instructors to be a significant component of the core. The transverse abdominal, so called for the direction of its fibers, is the innermost of the flat muscles of the abdomen, being placed immediately beneath the internal oblique muscle. The transverse abdominal arises as fleshy fibers, from the lateral third of"
"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"
"without treatment, but they may take several months to resolve. The rectus abdominis is similar in most vertebrates. The most obvious difference between animal and human abdominal musculature is that in animals, there are a different number of tendinous intersections. Rectus abdominis muscle The rectus abdominis muscle, also known as the ""abdominal muscle"" or ""abs"", is a paired muscle running vertically on each side of the anterior wall of the human abdomen, as well as that of some other mammals. There are two parallel muscles, separated by a midline band of connective tissue called the linea alba. It extends from"
"such as coughing or during exercise and not in relaxed breathing. The external intercostal muscles, and the intercartilaginous part of the internal intercostal muscles, (the part of the muscle that lies between the cartilage portion of the superior and inferior ribs), are used in inspiration, by aiding in elevating the ribs and expanding the thoracic cavity. Internal intercostal muscles The internal intercostal muscles (intercostales interni) are a group of skeletal muscles located between the ribs. They are eleven in number on either side. They commence anteriorly at the sternum, in the intercostal spaces between the cartilages of the true ribs,"
"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"
"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"
"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"
"(brachial plexus) going to the arm. In several ethnic groups, most significantly the Japanese, the tenth rib is sometimes a floating rib, as it lacks a cartilaginous connection to the seventh rib. The human rib cage is a component of the human respiratory system. It encloses the thoracic cavity, which contains the lungs. An inhalation is accomplished when the muscular diaphragm, at the floor of the thoracic cavity, contracts and flattens, while the contraction of intercostal muscles lift the rib cage up and out. Expansion of the thoracic cavity is driven in three planes; the vertical, the anteroposterior and the"
"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"
"to what it covers (e.g., transversalis, psoas fascia). In medical vernacular, the term 'abdominal wall' most commonly refers to the layers composing the anterior abdominal wall which, in addition to the layers mentioned above, includes the three layers of muscle: the transversus abdominis (transverse abdominal muscle), the internal (obliquus internus) and the external oblique (obliquus externus). In human anatomy, the layers of the abdominal wall are (from superficial to deep): The surface contains several ligaments separated by fossae: Abdominal wall In anatomy, the abdominal wall represents the boundaries of the abdominal cavity. The abdominal wall is split into the posterior"
"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:"
"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"
"parallel to the inferior vena cava, which is located just to the right of the abdominal aorta, and becomes smaller in diameter as it gives off branches. This is thought to be due to the large size of its principal branches. At the 11th rib, the diameter is 122mm long and 55mm wide and this is because of the constant pressure. The abdominal aorta is clinically divided into 2 segments: The abdominal aorta supplies blood to much of the abdominal cavity. It begins at T12 and ends at L4 with its bifurcation into the common iliac arteries, and usually has"
"Abdominal internal oblique muscle The internal oblique muscle is a muscle in the abdominal wall that lies below the external oblique and just above the transverse abdominal muscles. Its fibers run perpendicular to the external oblique muscle, beginning in the thoracolumbar fascia of the lower back, the anterior 2/3 of the iliac crest (upper part of hip bone) and the lateral half of the inguinal ligament. The muscle fibers run from these points superiomedially (up and towards midline) to the muscle's insertions on the inferior borders of the 10th through 12th ribs and the linea alba. In males, the cremaster"
"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"
"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"
"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"
"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"
"different innervation – namely, the femoral nerve.) Medial compartment of thigh The medial compartment of thigh is one of the fascial compartments of the thigh and contains the hip adductor muscles and the gracilis muscle. The obturator nerve is the primary nerve supplying this compartment. The muscles in the compartment are: The obturator externus muscle is sometimes considered part of this group, and sometimes excluded. (Spatially, it is in this location, but functionally, it is more similar to the other lateral rotator group muscles). The pectineus is sometimes included in this group, and sometimes excluded. (It has the same function"
"The anterior compartment is one of the two anatomic compartments of the upper arm, the other being the posterior compartment. The anterior compartment contains three muscles; the biceps brachii, the brachialis and the coracobrachialis. These muscles are all innervated by the musculocutaneous nerve which arises from the fifth, sixth and seventh cervical spinal nerves. The blood supply is from the brachial artery. The posterior compartment of the arm is also known as the ""extensor compartment"", as its main action is extension. The muscles of this compartment are the triceps brachii and anconeus muscle and these are innervated by the radial"
"muscles, the rib cage makes up the thoracic wall and provides attachments for the muscles of the neck, thorax, upper abdomen, and back. The rib cage has a major function in the respiratory system. Ribs are described based on their location and connection with the sternum. All ribs are attached behind to the thoracic vertebrae and are numbered accordingly one to twelve. Ribs that articulate directly with the sternum are called ""true ribs"", whereas those that connect indirectly via cartilage are termed ""false ribs"". Floating ribs (eleven and twelve) are not attached to the sternum at all. The terms ""true"
"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"