The celiac artery (celiac trunk) branches from the descending aorta near the opening in the diaphragm. It is a short thick branch of artery about an inch in length and divides into three branches, the gastric, hepatic, and splenic. It supplies the intestines, spleen, and liver. Research Celiac Artery
In man and the higher vertebrates, the chest is the cavity formed by the breast-bone in front and the ribs and backbone at the sides and behind, shut off from the abdomen below by the diaphragm or midriff. It contains the heart, lungs, etc, and the gullet passes through it. Research Chest
A cough is a sudden and forcible expiration immediately preceded by closure of the glottis or narrowed portion of the box of the windpipe. The force for the action is obtained by a deep breath, then follows the closure of the glottis, succeeded by the expiratory effort forcing open the glottis. The action is performed by the expiratory muscles, that is the abdominal muscles, by whose contraction the diaphragm is forced up, and the muscles of the chest, by which the ribs are pulled down. The cavity of the chest being thus diminished air is driven out of the lungs.
The object of the cough is usually to expel any foreign material in the lungs or air-tubes. The offending material may be there present as the result of inflammation, catarrh, etc. It may also have gained entrance from without. Thus the irritating material may be merely some food or drink which has slipped into the larynx, or it may be dust, etc, in the air inhaled, and the cough is the means of expelling the intruder. But a cough may also be produced when there is no irritating material present. The larnyx or windpipe may be in an inflamed and irritable condition, in which state even the entrance of cold air will excite coughing. Moreover, cough may be produced by irritation of nerves, distant from the lungs and air-passages, by what is called reflex action. Thus irritation of the stomach, irritation connected with the ear, irritation of certain nerves by pressure of growths, etc, may produce a cough, when the respiratory organs are not directly affected at all. Irritation at the back of the throat, as of the tickling of a long uvula, and so on, also produces it. Research Cough
The diaphragm is the primary muscle responsible for respiration. Connected to the abdominal wall, the lumbar vertebra, the lower ribs, the sternum, and the pericardium of the heart by tendinous tissue, the thin diaphragm creates a partition between the thoracic and abdominal cavity. The
diaphragm forms a domed structure, and when the diaphragm muscle contracts, it lowers to a more flattened arrangement. This flattening causes a vacuum in the thoracic cavity and pressure in the abdominal cavity. The vacuum is filled by the expanding lung tissue and inhaled air. The pressure on the lower viscera are helpful in childbirth and in pushing fecal matter through the lower intestinal tract for expulsion. When the diaphragm relaxes to its domed structure, the air is exhaled and the lungs contract. Though the intercostal and abdominal muscles are also used in respiration, during sleep, it is primarily due to contractions of the diaphragm. The diaphragm is supplied by the inferior and superior phrenic arteries and the musculophrenic artery. It is innervated phrenic nerve. Research Diaphragm
The liver is the largest gland in the human body. It lies under the short ribs on the right side of the upper part of the abdomen below the diaphragm; it is convex on the upper surface and concave below, and is composed of four lobes. The liver has three functions: it secretes bile, stores glycogen and converts waste products into urea and uric acid for excretion. Research Liver
The lungs are organs used for respiration. Lungs are found as a pair in air-breathing vertebrates within the chest cavity and are responsible for aerating the blood - bringing fresh air to the blood and removing carbon dioxide from the blood. The lungs consist of air tubes which divide into very small tubes within the lung tissue. The heart pumps blood to the veins of the lungs, these veins divide into very small branches where the blood is brought into contact with the air in the air cells at the ends of the smallest divisions of the air tubes, the bronchi. Air is drawn into and expelled from the lungs through the trachea by means of the contraction and relaxation of the diaphragm and intercostalmuscles. Research Lungs
The oesophagus is the region of the alimentary canal following the pharynx. The walls of the
oesophagus are muscular and force food along by contractions. The oesophagus is composed of a thick muscle wall which is voluntary (striped) muscle in the upper part, and involuntary (smooth) muscle in the lower part. The oesophagus ends byjoining the cardiac orifice of the stomach a little less than four cm below the diaphragm. It therefore has three parts. The cervical portion in the lower part of the neck lies immediately behind the trachea with lobes of the thyroid on either side. The thoracic portion lies, in the upper part, close to the back of the trachea in front of the vertebral column. In the lower part the oesophagus passes a little to the left and is crossed by the left bronchus, later .lying immediately behind the pericardium until it pierces the diaphragm.
Except during the passage of food, the oesophagus is flattened like a muscle strap but can distend to 25 mm in diameter. With the exception of the pylorus it is the narrowest portion of the alimentarytract and the oesophagus itself has three constrictions where it becomes narrower than in the rest of its course. The first is at the upper end behind the cricoid cartilage; the second is at the level of the bifurcation of the trachea into right and left bronchus; while the third narrow point is where the oesophagus passes through the diaphragm. Unlike the abdominal parts of the alimentarytract, there is no peritoneal coat on the thoracic and cervical
oesophagus. Research Oesophagus
The pleura of the thorax are the serous membranes which enclose the upper chest cavity. The pleura enclose the lungs and protect them from friction against the wall of the thorax. It is formed of two layers - the visceral and parietal pleura - between which is lubricated by serous fluid. The parietal pleura is the exterior layer of this pulmonary pleural sac, which connects to the thorax wall, the mediastinal membrane, and the diaphragm muscle. Research Parietal Pleura
The pericardium is the outer membrane which surrounds the heart muscle. It is in contact with the pulmonary pleura and is connected to the diaphragm muscle by tendinous fibres. Research Pericardium
The phrenic nerve originates in the upper half of the spinal cord, between the third and fifth cervical vertebrae, and extends to innervate the diaphragm muscle. It is responsible for transmitting the nerve impulses to the diaphragm which cause it to contract and expand, facilitating breathing. Research Phrenic Nerve
The Probert Encyclopaedia was designed, edited and programed by
Matt and Leela Probert
Abbreviations
Research Celiac Artery
