Diaphragm Lecture

The DIAPHRAGM

Dept of Anatomy

ANATOMY • Dome-shaped musculo-tendinous septum which separates the thoracic from the abdominal cavity • Principal muscle of Respiration

ANATOMY • Composed of 2 portions: a. Peripheral part - muscular part b. Central aponeurotic part “CENTRAL TENDON”

DIAPHRAGM: MUSCULAR PART • STERNAL PART - attached to posterior xiphisternal process - anterolateral gap  Sternocostal hiatus (Foramen of Morgagni)

ANATOMY: STERNAL ORIGIN

DIAPHRAGM: MUSCULAR PART • COSTAL PART - arise from inferior 6 ribs and costal cartilages - interdigitate with transversus abdominis m. - forms the right & left hemidiaphragm; moves with respiration - visible in CXR

DIAPHRAGM: MUSCULAR PART •

LUMBAR PART - arise fr. Lumbar vertebra - musculotendinous crura (R & L) - R crus broader & longer - R & L crura joined by median arcuate ligament

DIAPHRAGM: MUSCULAR PART •

LUMBAR PART - thickening of thoracolumbar fascia a) Medial arcuate ligament b) Lateral arcuate ligament  Vertebrocostal triangle- thin muscular membrane that separates left kidney from parietal pleura

DIAPHRAGM: Abdominal Surface

LUMBOCOSTAL TRIANGLE

DIAPHRAGM: CENTRAL TENDON • Convergence of muscle fibers – Aponeurosis • Fused with fibrous pericardiumcardiac silhouette • C-shaped with 3 leaves Right leaf- largest, lateral Middle leaf- intermediate, anterior Left leaf- smallest

The DIAPHRAGM: OVERVIEW STERNAL ORIGIN

COSTAL ORIGIN

LUMBAR ORIGIN

DIAPHRAGM: Thoracic Surface T8-9 INTERVERTEBRAL DISC RIGHT & LEFT LEAF OF CENTRAL TENDON MIDDLE LEAFPERICARDIUM STERNUM

CLINICAL CORRELATION • DIAPHRAGMATIC HERNIA - due to rupture of diaphragm - congenital or traumatic - herniation of abdominal viscera into thoracic cavity - respiratory distress

DIAPHRAGMATIC HERNIA Normal CXR

Abnormal A-P CXR INTESTINAL GAS (LUSCENCY) DIAPHRAGMATIC SHADOW

DIAPHRAGMATIC HERNIA LATERAL CXR Intestinal gas

DIAPHRAGMATIC APERTURES • VENA CAVAL FORAMEN - level of intervertebral disc bet. T8 & T9, right of median plane - Most superior in location - IVC adherent to margins Inspiration Diaphragm contracts  widening of foramen  dilates IVC - R phrenic nerve, R hepatic vein also pass through

DIAPHRAGMATIC APERTURES • ESOPHAGEAL HIATUS - Where esophagus passes obliquely - left of vena caval foramen, R crus, T10 - transmits anterior & posterior Vagal trunks & esophageal br. of L gastric vessels - R crus forms esophageal sphincter w/c prevents gastro-esophageal reflux

DIAPHRAGMATIC APERTURES •

AORTIC HIATUS - Aorta does not pierce the diaphragm because this hiatus is posterior to it - passes posterior to median arcuate ligament, anterior to T12, left of median plane - also transmits Thoracic duct, Azygos veins & 2 Intercostal lymph trunks to cisterna chyli

DIAPHRAGMATIC APERTURES •

STERNOCOSTAL HIATUS - transmits Superior epigastric vessels - also lymph vessels into anterior phrenic lymph nodes

• Other structures that pass thru the Diaphragm - Phrenic nerves, Intercostal nerves, Subcostal nerves, Sympathetic trunks, splanchnic nerve, Hemiazygos vein

DIAPHRAGM: Abdominal Surface VENA CAVAL FORAMEN

ESOPHAGEAL HIATUS AORTIC HIATUS W/ ABDOMINAL AORTA

DIAPHRAGM: Abdominal Surface ESOPHAGEAL HIATUS PHRENIC NERVE CAVAL OPENING LATERAL ARCUATE LIGAMENT L1-L4 VERTERBRA

VESSELS & NERVES • ARTERIAL SUPPLY Superior surface Superior phrenic arteries fr. Thoracic aorta Musculophrenic & Pericardiophrenic arteries fr. Internal thoracic artery Inferior surface Inferior phrenic artery fr. Abdominal aorta

VESSELS & NERVES • VENOUS DRAINAGE Superior surface Musculophrenic & Pericardiophrenic veins to Internal thoracic veins Inferior surface R inferior phrenic vein to IVC L inferior phrenic vein to L suprarenal vein Posterior surface drains into Azygos & Hemiazygos veins

VESSELS & NERVES •

LYMPHATIC DRAINAGE Thoracic Lymph drainage  Phrenic lymph nodes  Mediastinal lymph nodes Abdominal lymph drainage  Superior lumbar lymph nodes

VESSELS & NERVES •

INNERVATION Phrenic nerves- entire motor supply; fr. ventral rami of C3-C5 spinal cord Inferior 6-7 Intercostal & subcostal nervessensory innervation to peripheral diaphragm

DIAPHRAGM: PHRENIC NERVE

PHRENIC NERVE

ACTIONS of the DIAPHRAGM INSPIRATION • Contraction • Dome descent •  vertical diameter • intrathoracic volume • intrathoracic pressure • Air goes in

EXPIRATION • Relaxation • Dome rises • vertical diameter • intrathoracic volume •  intrathoracic pressure • Air is expelled

CHIEF MUSCLE OF INSPIRATION

DIAPHRAGM & RESPIRATION

DIAPHRAGM & BLOOD CIRCULATION CONTRACTION OF DIAPHRAGM

COMPRESSION OF ABDOMINAL VISCERA

BLOOD FORCED TO IVC THRU DILATATION OF VC FORAMEN

BLOOD RETURNS TO HEART

THANK YOU