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Topic

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Left lumbar part of diaphragm

The left lumbar part of the diaphragm is one of the muscular portions of the diaphragm, forming part of its posterior aspect. It arises from the upper lumbar vertebrae and contributes to the formation of the left crus. Together with the right lumbar part, it anchors the diaphragm to the vertebral column and surrounds the openings for major vessels. The lumbar parts are critical for diaphragmatic stability and respiration, as well as important anatomical landmarks in cross-sectional imaging.

Synonyms

  • Left crus of the diaphragm

  • Lumbar origin of diaphragm (left side)

  • Vertebral part of diaphragm (left)

Origin, Course, and Attachments

  • Origin: Arises from the bodies of the first and second lumbar vertebrae (L1–L2) and their associated intervertebral discs on the left side

  • Course: Fibers ascend vertically and medially, forming the left crus of the diaphragm

  • Attachments: Blend superiorly with the central tendon of the diaphragm and interdigitate with fibers from the sternal and costal parts

Relations

  • Anteriorly: Left adrenal gland, stomach, pancreas, and celiac plexus

  • Posteriorly: Left psoas major muscle, vertebral bodies of L1–L2

  • Medially: Right crus of diaphragm, median arcuate ligament, aortic hiatus

  • Laterally: Costal part of diaphragm and 12th rib

Function

  • Provides structural anchoring of the diaphragm to the lumbar vertebrae

  • Plays a vital role in respiration by contracting and descending during inspiration

  • Contributes to formation of the aortic hiatus and the esophageal hiatus margin

  • Assists in intra-abdominal pressure regulation during coughing, sneezing, and straining

Clinical Significance

  • Hernias: Weakness or defects may cause diaphragmatic hernias (e.g., Bochdalek hernia near posterior diaphragm)

  • Tumor involvement: May be infiltrated by retroperitoneal, adrenal, or gastric tumors

  • Imaging landmark: Helps identify the level of the aortic hiatus and celiac trunk origin

  • Trauma: Diaphragmatic rupture can involve the lumbar portion, leading to herniation of abdominal contents into thorax

MRI Appearance

T1-weighted images:

  • Left lumbar diaphragm appears as a thin, low-to-intermediate signal muscular band

  • Surrounded by bright retroperitoneal and mediastinal fat, which provides contrast

T2-weighted images:

  • Muscle shows low-to-intermediate signal intensity

  • Surrounded by bright CSF (spinal canal) and abdominal fluid if present

  • Pathological edema or inflammation appears with brighter signal intensity

T1 Fat-Sat Post-Contrast:

  • Normal muscle shows mild or no enhancement

  • Pathology (inflammation, tumor infiltration, metastasis) shows focal or diffuse enhancement

3D T2 SPACE / CISS:

  • Left lumbar diaphragm shows intermediate signal intensity compared to muscle

  • Surrounded by bright fat and adjacent fluid spaces, giving excellent contrast

  • Useful for detecting subtle tears, hernias, or tumor invasion at diaphragmatic crura

CT Appearance

Non-Contrast CT:

  • Appears as a soft tissue density muscular band arising from L1–L2 vertebral bodies

  • Clear margins against surrounding fat enhance visibility

  • Hernias, calcifications, or focal thickening may be identified

Post-Contrast CT:

  • Shows mild uniform enhancement in normal muscle

  • Pathologic infiltration (tumor, inflammation, abscess) shows irregular or heterogeneous enhancement

  • Diaphragmatic rupture appears as discontinuity with herniation of abdominal contents

MRI image

left lumbar part of diaphragm mri coronal anatomy image-img-00000-00000

MRI image

Left lumbar part of diaphragm