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DiaphragmLearning ObjectivesBe able to describe the anatomy of the diaphragm and the structures are passing through different openings

Be able to discuss the neurovascular supply

Be able to discuss the functional anatomy of it

Be able to discuss different hernias related to it.

Be able to identify radiological anatomy of it

DiaphragmMusculotendinous partition separating the thoracic and abdominal cavities. Convex superior surface faces the thoracic cavityConcave inferior surface faces the abdominal cavity. Curves superiorly into right and left domes. Right dome higher than the left owing to the presence of the right lobe of the liver.

DiaphragmChief muscle of respirationDuring inspiration:Descends during inspiration

Central part moves because periphery attaches to the inferior margin of the thoracic cage and the superior lumbar vertebrae.During expiration:Right dome reaches as high as the 5th ribLeft dome ascends to the 5th intercostal space.

Central Tendon

No bony attachments

Incompletely divided into three leaves.

Caval opening (vena caval foramen): terminal part of the IVC passes to enter the heart, perforates the central tendon.

Pericardium, containing the heart, lies on the central part of the diaphragm.

Muscular part of the diaphragm divided into three parts, based on the peripheral attachments:

Sternal part: attach to the posterior aspect of the xiphoid process.

Costal part: attach to the internal surfaces of the inferior six costal cartilages and their adjoining ribs on each side; the costal parts form the right and left domes.

Lumbar part: arising from the medial and lateral arcuate ligaments, and the three superior lumbar vertebrae.

The crura of the diaphragm: Mussculotendinous bundles that arise from the anterior surfaces of the bodies of the superior three lumbar vertebrae, the anterior longitudinal ligament, and the IV discs.

Right crus: larger and longer than the left crus, arises from the first three or four lumbar vertebrae.

Left crus: arises from the first two or three.

Diaphragm attached on each side to the medial and lateral arcuate ligaments.Medial arcuate ligament: extends from the side of the body of the L2 vertebra to the tip of the transverse process of the L1 vertebra. Lateral arcuate ligament: extends from the tip of the transverse process of the L1 vertebra to the lower border of the 12th rib. Median arcuate ligament: medial borders of the two crura are connected by a median arcuate ligament

Diaphragmatic AperturesThe diaphragmatic apertures (openings, hiatuses) permit vessels, nerves, and lymphatics to pass between the thorax and the abdomen.

Three large apertures for the IVC, esophagus, and aorta and a number of small ones.

Caval OpeningLocated in the central tendon at the level of the T8 vertebrae.

Structure passing:Inferior Vena Cava.

Terminal branches of the right phrenic nerve

Lymphatic vessels on their way from the liver to the middle phrenic and mediastinal lymph nodes.

when the diaphragm contracts during inspiration, it widens the opening and dilates the IVC which facilitate venous return.

Esophageal HiatusPresent in the muscle of the right crus of the diaphragm.

Lies at the level of the T10 vertebra.

Structure passing:EsophagusAnterior and Posterior vagal trunksEsophageal branches of the left gastric vessels, Lymphatic vessels.

The fibers of the right crus of the diaphragm decussate (cross one another) inferior to the hiatus, forming a muscular sphincter for the esophagus that constricts it when the diaphragm contracts.

Aortic HiatusSituated at the level of the inferior border of the T12 vertebra.

Structure passing:AortaThoracic ductAzygos and Hemiazygos veins ( occasionally).

The aorta passes between the crura of the diaphragm posterior to the median arcuate ligament

Movements of the diaphragm do not affect blood flow during respiration.

Small Apertures in the DiaphragmThe sternocostal triangle (foramen), between the sternal and the costal attachments of the diaphragm: Transmits :Lymphatic vessels from the diaphragmatic surface of the liver .Superior epigastric vessels. Sympathetic trunks pass deep to the medial arcuate ligament, accompanied by the least splanchnic nerves.

2. There are two small apertures in each crus of the diaphragm for the greater and lesser splanchnic nerves

Vessels Superior Surface of DiaphragmInferior Surface of DiaphragmArterial supplySuperior phrenic arteries from thoracic aortaMusculophrenic and pericardiophrenic arteries from internal thoracic arteriesInferior phrenic arteries from abdominal aorta

Venous drainageSuperior Surface of Diaphragm

Musculophrenic and Pericardiacophrenic veins drain into Internal thoracic veins Superior phrenic vein (right side) drains into IVCInferior Surface of DiaphragmInferior phrenic veins:Right side drains into IVCLeft side: doubled, drains into IVC and suprarenal vein

Lymphatic drainageSuperior Surface of DiaphragmDiaphragmatic lymph nodes Phrenic nodes Parasternal and Posterior mediastinal nodesInferior Surface of DiaphragmSuperior lumbar lymph nodes

Lymphatic plexuses on superior and inferior surfaces communicate freely

InnervationMotor supply: Phrenic nerves (C3-C5)Sensory supply: Central: Phrenic nerves (C3-C5)Peripheral: Intercostal nerves (T5-T11), and subcostal nerves (T12)

HiccupsInvoluntary, spasmodic contractions of the diaphragm.

Result from irritation of afferent or efferent nerve endings or of medullary centers in the brainstem that control the muscles of respiration, particularly the diaphragm.

Causes, such as indigestion, diaphragm irritation, alcoholism, cerebral lesions, and thoracic and abdominal lesions, all which disturb the phrenic nerves.Section of a Phrenic Nerve:Complete paralysis and atrophy of the muscular part of the corresponding half of the diaphragm, (except in persons who have an accessory phrenic nerve).

Hemidiaphragm can be recognized radiographically by its permanent elevation and paradoxical movement.

Instead of descending on inspiration, it is forced superiorly by the increased intra-abdominal pressure.

Secondary to descent of the opposite unparalyzed hemidiaphragm.

Fig. 6. Right-sided diaphragm rupture. Admissionchest radiograph shows elevated right hemidiaphragmapex (arrowhead) to left of point midway betweenlateral chest wall and right mediastinal margin.Source: http://www.sassit.co.za/Journals/Trauma/AbdominalREF: Imaging of Diaphragm Injuries Page No. 203Referred Pain from the Diaphragm

Irritation of the diaphragmatic pleura or the diaphragmatic peritoneum is referred to the shoulder region because the area of skin supplied by the C3-C5 segments of the spinal cord because same segments also contribute anterior rami to the phrenic nerves.

Irritation of peripheral regions of the diaphragm:

Innervated by the inferior intercostal nerves, is being referred to the skin over the costal margins of the anterolateral abdominal wall.Rupture of the Diaphragm and Herniation of VisceraResult from a sudden large increase in either the intra thoracic or intra-abdominal pressure.

Most diaphragmatic ruptures are on the left side (95%) because the right side of the diaphragm receives reinforcement from its close association with the liver.

The stomach, small intestine and mesentery, transverse colon, and spleen may herniate through this area into the thorax. The Chest X-ray showed rupture of the LEFT Hemi-diaphragm with

LTRTHiatal or Hiatus hernia:Protrusion of part of the stomach into the thorax through the esophageal hiatus.

Structures that pass through the esophageal hiatus:Vagal trunks Left inferior phrenic vesselsEsophageal branches of the left gastric vessels

These structures may be injured in surgical procedures on the esophageal hiatus(e.g. repair of a hiatus hernia).

Causes of a Hiatal HerniaLarger-than-normal esophageal hiatus, as a result , part of the stomach "slips" into the chest. Other potentially contributing factors include: A permanent shortening of the esophagus which pulls the stomach up.

An abnormally loose attachment of the esophagus to the diaphragm which allows the esophagus and stomach to slip upwards.Hiatal hernias: categorized as Sliding or Para-esophageal. Sliding hiatal hernia:Part of the stomach protrude into the chest.

Gastro-oesophageal junction may reside permanently in the chest

Often the gastro-oesophageal junction just appear into the chest only during a swallow.

In each swallow the muscle of the esophagus contracts causing the esophagus to shorten and to pull up the stomach.

At the end of the swallow the herniated part of the stomach falls back into the abdomen.

Para-esophageal hernia:Gastro- esophageal junction: normal in position

Part of the stomach passes or bulges into the chest beside the esophagus.

Herniated organ remains in the chest at all times.

Not affected by swallows.

Stomach may become "strangled," or have its blood supply shut off.

Plain X-rayBarium meal x-rayPara-esophageal hernia:Gastro- esophageal junction is normal in position

Part of the stomach passes or bulges into the chest beside the esophagus.

Herniated organ remains in the chest at all times and are not affected by swallows.

Sliding hiatus herniaIn individuals with hiatal hernias, the opening of the esophageal hiatus (hiatal opening) is larger than normal, and a portion of the upper stomach slips up or passes (herniates) through the hiatus and into the chest. Paraesophageal hernia:Cardia or fundus of the stomach prolapses through the diaphragmatic hiatus leaving the gastroesophageal junction in normal position.

Sliding hiatal hernia:Stomach immediately below the gastroesophageal junction prolapse through the diaphragmatic hiatus into the chest.

A plain chest radiograph showing a well-defined, rounded, soft-tissue mass in the retrocardiac region consistent with a sliding hiatal hernia.

A frontal chest radiograph in a patient with a large hiatal hernia demonstrating a retrocardiac opacity with radiolucent gas, which shifts the mediastinum to the right.Many people with hiatal hernia have no symptoms, but others may have heartburn related to gastroesophageal reflux disease( GERD).

People with heartburn may experience chest pain that can easily be confused with the pain of a heart attack. Congenital Diaphragmatic HerniaPosterolateral defect of the diaphragm is the only relatively common congenital anomaly of the diaphragm.

Occurs on the left owing to the presence of the liver on the right.

Occurs approximately once in 2200 newborn infants.

Life-threatening breathing difficulties may be associated with this anomaly because of the compromised space available for the development and inflation of lungs.

Schematic drawing showing a severe left-sided congenital diaphragmatic hernia with liver and bowel herniation in to the fetal chest

LeftRT.

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