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 pericardium- cardiac silhouette

• C-shaped with 3 leavesRight leaf- largest, lateral

Middle leaf- intermediate, anterior

Left leaf- smallest

The DIAPHRAGM: OVERVIEW

STERNAL ORIGIN

COSTAL ORIGIN

LUMBAR ORIGIN

DIAPHRAGM: Thoracic Surface

RIGHT & LEFT LEAF OF CENTRAL

TENDON

T8-9 INTERVERTEBRAL

DISC

MIDDLE LEAF-PERICARDIUM

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

L1-L4 VERTERBRA

LATERAL ARCUATE LIGAMENT

VESSELS & NERVES

• ARTERIAL SUPPLY

Superior surface Superior phrenic arteries fr. Thoracic aorta

Musculophrenic & Pericardiophrenic arteries fr. Internal thoracic artery

Inferior surfaceInferior phrenic artery fr. Abdominal aorta

VESSELS & NERVES• VENOUS DRAINAGE

Superior surface Musculophrenic & Pericardiophrenic

veins to Internal thoracic veins

Inferior surfaceR inferior phrenic vein to IVCL 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 nerves- sensory innervation to peripheral

diaphragm

DIAPHRAGM: PHRENIC NERVE

PHRENIC NERVE

ACTIONS of the DIAPHRAGM

CHIEF MUSCLE OF INSPIRATION

INSPIRATION• Contraction• Dome descent• vertical diameter• intra-thoracic volume• intra-thoracic pressure• Air goes in

EXPIRATION• Relaxation• Dome rises• vertical diameter• intra-thoracic volume• intra-thoracic pressure• Air is expelled

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

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