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Diaphragm

Objectives Discuss the origin and insertion of diaphragm. Enlist the openings (with their contents) in the diaphragm. Give the motor and sensory nerve supply of the diaphragm.

Diaphragm The diaphragm is a thin musculo-tendinous septum that separates thorax & abdominal cavities. It is pierced by the structures that pass between the chest and the abdomen. The diaphragm is the most important muscle of respiration. It is dome shaped and consists of a peripheral muscular part, which arises from the margins of the thoracic opening, and a centrally placed tendon.

Origin of diaphragm The origin of the diaphragm can be divided into three parts: 1- Sternal origin: Back of xiphoid process of sternum. 2- Costal origin: Inner aspect of lower 6 ribs & C.Cs. Forms the rt & lt domes 3- Vertebral origin: Two crura: Right crus arises from the ventral aspect of the upper three lumbar vertebrae. Left crus arises from the upper two lumbar vertebrae.

Origin of diaphragm

Origin of diaphragm b. Arcuate ligaments: * Median arcuate ligament: A median tendinous arch connecting the right and left crura. * Medial arcuate ligament: On each side, connecting each crus with the tip of transverse process of L1. * Lateral arcuate ligament: On each side, connecting the tip of transverse process of L1 with the last rib.

Origin of diaphragm

Insertion of diaphragm Into the central tendon of diaphragm which is formed of three lobes: 1- Right lobe. 2- Left lobe. 3- Median lobe. * The central tendon is depressed and the lateral parts are elevated forming the right and left copula = dome.

Insertion of Diaphragm- Central Tendon The diaphragm is inserted into a central tendon. The superior surface of the tendon is partially fused with the inferior surface of the fibrous pericardium. Some of the muscle fibers of the right crus pass up to the left and surround the esophageal orifice in a slinglike loop. These fibers appear to act as a sphincter and possibly assist in the prevention of regurgitation of the stomach contents into the thoracic part of the esophagus.

Insertion of Diaphragm-Central Tendon

Nerve Supply of the Diaphragm Motor nerve supply: The right and left phrenic nerves (C3, 4, 5) Sensory nerve supply: The parietal pleura and peritoneum covering the central surfaces of the diaphragm are supplied by the phrenic nerve The periphery of the diaphragm is supplied by the lower six intercostal nerves.

Nerve supply of diaphragm

Actions of the diaphragm Action: 1- Muscle of inspiration: On contraction the diaphragm pulls its central tendon down and increases the vertical diameter of the thorax. The diaphragm is the most important muscle used in inspiration 2- Increase the intra abdominal pressure in forced actions: Assists the contraction of the muscles of the anterior abdominal wall in raising the intra-abdominal pressure for micturition, defecation, and parturition 3- Right crus acts as a sphincter to the lower end of esophagus.

4- Thoracoaabdominal pump: The descent of the diaphragm decreases the intrathoracic pressure & increases the intra-abdominal pressure. This compresses the blood in the inferior vena cava and forces it upward into the right atrium of the heart. Within the abdominal lymph vessels is also compressed, and its passage upward within the thoracic duct is aided by the negative intrathoracic pressure. The presence of valves within the thoracic duct prevents backflow.

Actions of diaphragm

Major openings in the diaphragm 8 10 12

Major openings in the diaphragm 1- IVC opening: a.Site: In the central tendon of diaphragm between right and median lobe. b.Level: T8 c.Structures passing through: 1)Inferior vena cava. 2)Right phrenic nerve. 3)Lymphatics.

Major openings in the diaphragm 2- Aortic opening: a.Site: Posterior to median arcuate ligament. b.Level: T12 c.Structures passing through: 1)Aorta. 2)Azygos vein. 3)Thoracic duct.

Major openings in the diaphragm 3- Oesophageal opening: a.Site:Right crus. b.Level: T10 c.Structures passing through: 1)Oesophagus. 2)Vagi. 3)Anastomotic branches between left gastric and aortic oesophageal arteries.

Other structures passing through diaphragm 1-Splanchnic nerves which pierce the crura. 2-Inferior hemiazygos vein which pierce the left crus. 3- Psoas major M. 4-Sympathetic trunk (pass deep to the medial arcuate ligament). 5-Quadratus lumborum. 6- Subcostal N, Vs (Pass deep to the lateral arcuate ligament).

Other structures passing through the diaphragm 7-Lower five intercostal Nerves and vessels. 8-Superior epigastric vessels. 9-Musculophrenic vessels. 10- Lt phrenic nerve

Blood supply The phrenic artery. The musculophrenic. Branches of the mammary artery. The intercostals.

Clinical notes Hiccup Hiccup is the involuntary spasmodic contraction of the diaphragm accompanied by the approximation of the vocal folds and closure of the glottis of the larynx. It is a common condition in normal individuals and occurs after eating or drinking as a result of gastric irritation of the vagus nerve endings. It may, however, be a symptom of disease such as pleurisy, peritonitis, pericarditis, or uremia. Paralysis of the Diaphragm A single dome of the diaphragm may be paralyzed by crushing or sectioning of the phrenic nerve in the neck. Occasionally, the contribution from the fifth cervical spinal nerve joins the phrenic nerve late as a branch from the nerve to the subclavius muscle. This is known as the accessory phrenic nerve. To obtain complete paralysis under these circumstances, the nerve to the subclavius muscle must also be sectioned. Penetrating Injuries of the Diaphragm Any penetrating wound to the chest below the level of the nipples should be suspected of causing damage to the diaphragm until proved otherwise. The arching domes of the diaphragm can reach the level of the fifth rib (the right dome can reach a higher level).

Prof.: Dr. Wafaa Abdel-Rahman Thank You Prof.: Dr. Wafaa Abdel-Rahman Dr. Rania Gabr