This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Anatomy
[{'content': 'Axillary sheath is derived from? \nSelect and explain. \nA. Preveebral fascia, B. Pretracheal fascid, C. Investing layer of deep cervical fascia, D. Deep fascia of throacic wall', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., Preveebral fascia The deep cervical fascia (fascia colli) has the following 6 layers: Investing layerLies deep to the platysmaForms a pulley to hold tendons of digastrics and omohyoidSplits to enclose the parotid and submandibular glands; the suprasternal and supraclavicular spaces;and the sternocleidomastoid and trapeziusPretracheal layerEncloses larynx, trachea, esophagus and infrahyoid strap musclesForms false capsule of the thyroid and the suspensory ligament of BerryPreveebral fasciaForms axillary sheath around subclan aery and brachial plexusSubclan vein lies outside this sheathCarotid sheathEncloses the internal carotid aery, internal jugular vein and vagus nerve.Buccopharyngeal fasciaLies on the superficial aspect of the buccinators muscle and covers the superior constrictor muscle externallyPharyngobasilar fasciaLies deep to the pharyngeal muscles.", 'role': 'assistant'}]