All are true about Sibson's fascia EXCEPT
Sibson's fascia is a modification of the endothoracic fascia in the supraclavicular region, covering the thoracic inlet. It is a degenerated tendon of scalenus minimus. Attachment : Transverse process of C7 veebra and inner border of 1st rib. It separates the subclan aery and vein ( running on the posterio superior surface of the first rib) from the cervical pleura.