During inspiration diaphragm
Correct Answer: Contract
Description: (A) (Contract) (683, Sembulingam 6th)Diaphragm principal muscle of inspiration* On contraction, the diaphragm descends increasing the vertical diameter of the thorax* During inspiration, due to the contraction, muscle fibers are shortened, but the central tendinous portion is drawn downwards so the diaphragm is flattened. Flattening of diaphragm increases the vertical diameter of the thoracic cageDIAPHRAGM* Motor nerve supply-phrenic nerves ** are the sole motor supply to the diaphragm* Sensory nerve supply- central part- phrenic nerve -peripheral part- Lower six thoracic nerve* Bochdalek hernia occurs through -posterolateral part of diaphragm , more common in left side- Visceral contents herniate and fill the chest cavity stomach and transverse colon are the commonest content of Bochdalek hernia- The abdominal cavity is small and undeveloped and remains scaphoid ** after birth- The herniated viscera as a space occupying lesion and prevent normal lung development- BH can be accurately diagnosed prenately as early as 15th weeks of gestation by USG* Morgagnian Hernia- It is retrosternal hernia ** (occurs through the space between the xiphoid and costal origins of the diaphragm* Level of the diaphragm is highest in the supine position lowest while sitting, and intermediate while standing* The sole motor nerve supply of the diaphragm is phrenic nerve (C4)* Hiccough or hiccup is the result of spasmodic contraction of the diaphragm* Bilateral phrenic nerve paralysis results in adequate ventilation to maintain life* Diaphragmatic ruptures is more common on the LEFT side 9 time more common than right the right diaphragm is protected by two mechanism the liver on the right and the heart in the centre have buffering effect that diffuses the sudden increases in intra-abdominal pressureBochdalek-hernia- Most Bochdalek hernia are on the left side (-80%) and may rarely be bilateral- Compression of the lung results in pulmonary hypoplasia, involving both the lungs( ipsilateral >contralateral- Pulmonary vasculature is also abnormal leading to pulmonary hypertension.- Thus the two main factors that affect morbidity and mortality are pulmonary hypoplasia and pulmonary hypertension.- The most frequent clinical presentation of CDH is respiratory distress due to severe hypoxemia.- The anteroposterior diameter of the chest may be large along with a scaphoid abdomen.- The diagnosis of CDH can be made prenatally by ultrasound.- The postnatal diagnosis is relatively straightforward because a plain chest radiograph demonstrates the gas bubbles or loops of bowel within the chest. There may also be a mediastinal shift away from the hernia.- Historically. The surgical repair of a CDH was considered to be a surgical emergency because it was bell the abdominal viscera within the chest prevented the ability to ventilate. More recently with the recognit role of pulmonary hypertension and pulmonary hypoplasia and the adverse effects of early operative repair; pulmonary function has caused a policy of delayed repair. Thus most pediatric surgeons wait for a variable (24 to 72 hrs) to allow for stabilization of the infant before doing surgical repair.* About contents of the cong. Diaphragmatic hernia.- Most books of surgery write that any abdomen viscera can herniate.- CSDT writes that ''Bowel, spleen & liver sometimes herniate into the chest".* Bag and Mask ventilation is contraindicated in diaphragmatic hernia* Most common prognosis factor in CDH pulmonary hyper tension* Most common site of Morgagni hernia is RIGHT ANTERIOR.* Morgagni hernia is a rare form of cong, diaphragmatic hernia occurring through foramen of Morgagni or space of Larrey i.e, space between the sternal and costal origins of the diaphragm)- It is more common on right side.- Usually it is asymptomatic- Most common viscera to herniate through space of Morgagni is transverse colon (Bailey &Love 24/e,p873)Also know:- Superior epigastric vessels pass through foramen of Morgagni
Category:
Physiology
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