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': 'The posterior triangle of the neck is bounded by the following Except \nSelect and explain. \nA. Trapezius, B. Splenius cervicis, C. Sternocleidomastoid, D. Clavicle', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Posterior Triangle\nThe posterior triangle is a space on the side of the neck situated behind the\nsternocleidomastoid muscle.\n\nBoundaries\nAnterior: Posterior border of sternocleidomastoid\n\nPosterior :Anterior border of trapezius\n\nInferior or base: Middle one- third of clavicle\n\nApex lies on the superior nuchal line where the trapezius And sternocleidomastoid meet\n\nRoof : Investing layer\n\nFloor: Formed by a prevertebral layer of deep cervical fascia covering\nthe following muscle: a. splenius capitisb. Levator scapulae; c.\nScalenus medius and occasionally scalenus posterior.', 'role': 'assistant'}]