DIAPHRAGM THORACIC DIAPHRAGM Dome shaped Musculoaponeurotic structure Separates

DIAPHRAGM

THORACIC DIAPHRAGM • Dome shaped • Musculoaponeurotic structure • Separates thorax from abdomen • Forms roof of abdominal cavity & floor of thoracic cavity

Parts of thoracic diaphragm • Thoracic surface: convex on right & left side but depressed in centre • Summits of the convexities are c/as Cupolae • Right cupola is higher than left due to presence of liver • Abdominal surface : concave • Peripheral part : muscular • Central part : tendinous

THORACIC DIAPHRAGM(contd…. . ) • Sternal heads: 2 fleshy slips from back of xiphoid process • Costal heads : From inner surface of lower 6 ribs & their costal cartilages • Vertebral heads: A pair of crura A pair of medial arcuate ligament A pair of lateral arcuate ligament

THORACIC DIAPHRAGM(contd…. . ) • Right Crus of diaphragm: Right crus is longer & more muscular than left one. Origin is from front of the bodies of L₁ - L₃ & interveining intervertebral discs.

THORACIC DIAPHRAGM(contd…. . ) • Left crus of diaphragm: shorter than right crus origin is from bodies & discs of L₁- L₂ left crus is attached to bare area of stomach by Gastro phrenic ligament both crura are connected to each other by a Median arcuate ligament

THORACIC DIAPHRAGM(contd…. . ) • Medial Arcuate Ligament/ Medial Lumbocostal Arch Bridges in front of psoas major Formed by thickening of psoas fascia Attached med to body of L₁ - L₂ Attached lat to transverse process of L₁ • Lateral Arcuate Ligament/ Lateral Lumbocostal Arch Bridges in front of Quadratus lumborum Formed by thickening of ant. Layer of thoracolumbar fascia Attachments : med… transverse process of L₁ lat…. . Tip of 12 th rib

THORACIC DIAPHRAGM(contd…. . ) Central Tendon • Present in central depressed part • Trefoil leaf shaped with median, right & left leaflets • IVC opening present at junction of median & right leaflet • Left to IVC opening is central point of decussation • Sternal fibers are shortest • Fibers from 9 th costal cartilage are longest

Openings in diaphragm Venecaval opening(T₈) • Quadrilateral in shape • IVC • Branches of Phrenic nerve • Lymphatics from liver Oesophageal Opening (T₁₀) • Elliptical in shape • Oesophagus • Ant. & post. Vagal trunks • Oesophageal branches of left gastric artery • Lymphatics from liver • Phrenoesophageal ligament

Openings in diaphragm Aortic Opening(T₁₂) • Rounded in shape • osseoaponeurotic • Boundaries : median arcuate ligament (ant), body of T₁₂, both crura on sides • Abdominal aorta • Thoracic duct • Azygos vein (when its lumbar azygos vein )

Openings in diaphragm Other Openings • Space of Larrey : Sup. Epigastric vessels & lymphatics • Between costal origin & T. abdominis : lower 5 intercostal nerves & vessels • Between costal origin from 7 th & 8 th costal cartilage : musculophrenic vessels • Behind Lat. Arcuate ligament : subcostal nerve & vessels • Behind medial arcuate ligament : sympathetic trunk & least splanchnic nerve

Openings in diaphragm Other Openings • Each crus is pierced by greater & lesser splanchnic nerves • Left crus is also pierced by hemiazygos vein • Left phrenic nerve pierces left cupola in front of central tendon

Relations of diaphragm • Superior : Pleurae Lungs Pericardium Heart • Inferior : Peritoneum Liver Fundus of stomach Spleen Kidneys Suprarenal glands

Nerve Supply of Diaphragm • Motor supply: Phrenic nerve (C₃‚₄‚₅) Anteromedial Anterolateral Posteromedial Posterolateral • Sensory supply: Central – phrenic nerve Peripheral – lower 6 intercostal nerves • Sympathetic supply: Coeliac plexus via inferior phrenic plexus

Blood supply of diaphragm • Musculophrenic artery • Pericardiophrenic artery • Lower 5 -6 post. Intercostal arteries • Sup. Phrenic artery • Inf. Phrenic artery

Actions of diaphragm • Principal muscle of inspiration • Contraction descent vertical diameter of thorax increases • Upper abdominal viscera displaced below ant. Abdominal wall bulges • Central tendon then becomes fixed lower ribs are elevated increase in AP diameter

Actions of diaphragm • Muscle of Abdominal Straining: Supports expulsive acts like sneezing , coughing , vomiting , crying, defecation , micturation, etc. • Sphincteric action at lower end of esophagus • Thoracoabdominal pump for blood & lymph • Effect of contraction of diaphragm on 3 major openings in diaphragm 1. Venacaval opening ---- dilates 2. Oesophageal opening -------constricts 3. Aortic opening ---- no change

Development of diaphragm • Develops at level of neck & derives its muscular components from cervical myotomes • Septum transversum central tendon • Pleuroperitoneal membrane dorsal paired portion • Lateral thoracic wall circumferential portion of diaphragm • Dorsal mesentery of esophagus dorsal unpaired portion (Crura )

Applied • Hiccups /hiccough occurs due to spamodic contraction of diaphragm 1. Central hiccups due to hiccup centre in medulla (MC cause is uremia ) 2. Peripheral local irritation of diaphragm or its nerve • Shoulder tip pain irritation of diaphragm leads to pain in shoulder because of the common root value of supraclavicular nerve & phrenic nerve. • Unilateral paralysis of diaphragm due to lesion of phrenic nerve. Paralyzed side shows paradoxical movement. • Eventration is congenital defect in the musculature of diaphragm (fibrous membrane present )

Diaphragmatic hernias • Congenital diaphragmatic hernias 1. Morgagni hernia /Retrosternal hernia (anterior right) 2. Bochdalek hernia /posterolateral hernia (posterior left) Occurs through pleuroperitoneal hiatus Fatal condition(lung hypoplasia) S/S: scaphoid abdomen respiratory distress 3. Central hernia 4. Posterior hernia (posterior defect in diaphragm)

Hiatus hernia • Congenital / rolling / paraesophageal hiatus hernia : stomach rolls upwards & lies in post. Mediastinum GE junction is normal • S/S : nausea, dysphagia, pain • Acquired / sliding hiatus hernia : weakness of phrenicoesophageal membrane. • S/S: GERD, heart burn