Proximal Attachment
The tenth intercostal intimus muscle lies deep to the tenth intercostal internus in the middle two-quarters of the intercostal space.  It is a more substantial muscle than those of the upper intercostal spaces and it arises from the internal aspect of the tenth rib.

Distal Attachment
Anteriorly the fibers pass infero-laterally, while laterally they pass infero-medially to insert onto the internal aspect of the eleventh rib.

Nerve Supply
The tenth intercostal intimus muscle is supplied by the tenth intercostal nerve.

Action
The tenth intercostal intimus muscle is most active during expiration, but its primary role is with the tenth intercostal externus to stiffen the chest wall during respiration.