Structure lying at marker C ?
Scalenus anterior muscle Attaches to the scalene tubercle on the inner(medial) border of 1st rib. * It's tendon is sandwiched between subclan vein (passing anterior) and subclan aery (passing posterior). Both vessels cross over the superior surface of 1st rib. Key: A - Area for attachment of scalenus medius B - Groove for subclan aeryC - Scalene tubercle (attachment of anterior scalene) D - Groove for subclan vein
Subclan vein
Subclan aery
Scalenus anterior
Scalenus medius
Thorax: Aerial supply