Axillary sheath is derived from
-The muscular floor of the posterior triangle is covered by preveebral layer of fascia colli. -It forms the axillary sheath around subclan aery and brachial plexus travelling from the root of neck to the upper limb. -reference: Textbook of anatomy, Head Neck, and brain, Vishram Singh, 2nd edition, page no.80
Preveebral fascia
Pretracheal fascia
Investing layer of deep cervical fascia
Deep fascia of throacic wall
Upper limb