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Left hemidiaphragm

The left hemidiaphragm forms the left half of the diaphragm, the primary muscle of respiration. It separates the left thoracic cavity (housing the left lung and heart) from the abdominal cavity (containing the stomach, spleen, left kidney, and left adrenal gland). The left dome is slightly lower than the right hemidiaphragm due to the position of the heart. It consists of peripheral muscular fibers inserting into a central tendon, and has three major openings: the aortic hiatus (T12), the esophageal hiatus (T10), and the caval opening (T8), though the caval opening lies more to the right.

Synonyms

  • Left dome of diaphragm

  • Musculus diaphragma (sinister)

  • Respiratory diaphragm (left half)

Function

  • Acts as the main respiratory muscle, descending during inspiration to expand thoracic volume

  • Provides a barrier between thoracic and abdominal cavities

  • Assists in increasing intra-abdominal pressure during coughing, sneezing, vomiting, urination, and defecation

  • Supports adjacent organs such as the heart, stomach, and spleen

Arterial Supply

  • Phrenic arteries (branches of the thoracic aorta and internal thoracic artery)

  • Contributions from musculophrenic and pericardiophrenic arteries

  • Inferiorly, receives branches from the inferior phrenic arteries

Venous Drainage

  • Drains into the pericardiophrenic and musculophrenic veins (which empty into the internal thoracic veins)

  • Inferior drainage via the inferior phrenic veins into the inferior vena cava and left renal vein

Nerve Supply

  • Supplied by the phrenic nerve (C3–C5), providing motor innervation

  • Peripheral parts also receive sensory innervation from the intercostal nerves

MRI Appearance

T1-weighted images:

  • Appears as a thin, low-signal curvilinear structure separating thoracic and abdominal cavities

  • Surrounded by hyperintense fat, enhancing delineation

  • Abnormal thickening may indicate tumor or diaphragmatic disease

T2-weighted images:

  • Left hemidiaphragm remains low signal intensity due to muscle composition

  • Adjacent pleural effusion or ascites appears hyperintense, contrasting with the diaphragm

  • Useful for identifying hernias, defects, or paralysis

STIR (Short Tau Inversion Recovery):

  • Suppresses fat, highlighting diaphragmatic edema, inflammation, or infiltration

  • Normal diaphragm remains low signal, while pathological changes appear hyperintense

T1 Post-Contrast (Gadolinium-enhanced):

  • Normal diaphragm shows mild homogeneous enhancement

  • Abnormal enhancement suggests tumor infiltration, inflammatory changes, or postsurgical scarring

CT Appearance

Non-contrast CT:

  • Appears as a thin, curved soft tissue structure forming the boundary between thorax and abdomen

  • Best seen in coronal and sagittal reconstructions

  • Elevation may be physiological (postprandial, obesity) or pathological (phrenic nerve palsy, subphrenic abscess)

Contrast-enhanced CT (CECT):

  • Enhances slightly, delineating diaphragm more clearly from adjacent viscera

  • Excellent for detecting diaphragmatic hernias, ruptures, eventration, or tumor infiltration

  • Shows relations with adjacent structures (heart, stomach, spleen, lung bases)

MRI images

Left hemidiaphragm MRI axial image -img-00000-00000_00001

MRI images

Left hemidiaphragm MRI coronal image -img-00000-00000

CT image

Left hemidiaphragm anatomy CT axial image -img-00000-00000

CT image

Left hemidiaphragm ct Anatomy, Location and Imaging Appearance CT anatomy image -img-00000-00000

X ray image

Left hemidiaphragm x ray Anatomy, Location and Imaging Appearance CT anatomy image -img-00000-00000