Transversus thoracis muscle

Last revised by Assoc Prof Craig Hacking on 12 May 2021

The transversus thoracis muscle is the innermost muscle of the anterior thoracic wall (deep to external intercostal and internal intercostal muscles).  

Gross anatomy

The transversus thoracis is a thin band of muscle and tendon arising from the lower posterior surface of the sternum, posterior edge of the xiphisternum and the costal cartilage of the lowest 3-4 ribs at their sternal end. It diverges supero-laterally to attach by slips to the underside of the 2nd to 6th costal cartilages 1. The transversus thoracis muscle is morphologically identical to the transversus abdominis muscle 2

Blood supply
Nerve supply
Action

The transversus thoracis muscle is an accessory muscle of respiration. It depresses the ribs which supports expiration. 

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Cases and figures

  • Figure 1: deep anterior chest wall muscles (Gray's illustration)
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  • Figure 2: intercostal space
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