Attachment of Sibson's fascia is at -

Ans. is 'd' i.e., C7 o The part of thoracic inlet, on either side, is enclosed by a dense fascial sheeth called suprapleural membrane (or Sibson's fascia or diaphragm of superior thoracic aperture),]o ft is tent shaped (triangular in shape).o Its attachments areApex is attached to transverse process of seventh cervical vertebra.Base is attached to inner border of Is'- rib and its costal cartilage.o It superior surface is related to subclavian vessels and its inferior surface is related to cervical pleura, covering the apex of lung.o Morphologically, Sibson's fascia represents the spread out degenerated tendon of scalenus minimus (pleuralis) muscle.