  the neck is the part of the body, on many terrestrial or secondarily aquatic vertebrates, that distinguishes the head from the torso or trunk. the adjective (from latin) signifying "of the neck" is cervical (though in non-technical contexts, this is more frequently used to describe the cervix). ==structure== ===the cervical spine=== the cervical portion of the human spine comprises seven bony segments, typically referred to as c-1 to c-7, with cartilaginous discs between each vertebral body. the neck supports the weight of the head and protects the nerves that carry sensory and motor information from the brain down to the rest of the body. in addition, the neck is highly flexible and allows the head to turn and flex in all directions. from top to bottom the cervical spine is gently curved in convex-forward fashion. it is the least marked of all the curves of the column. ===soft tissue anatomy=== in the middle line below the chin can be felt the body of the hyoid bone, just below which is the prominence of the thyroid cartilage called "adam's apple", better marked in men than in women. still lower the cricoid cartilage is easily felt, while between this and the suprasternal notch the trachea and isthmus of the thyroid gland may be made out. at the side the outline of the sternomastoid muscle is the most striking mark; it divides the anterior triangle of the neck from the posterior. the upper part of the former contains the submaxillary gland also known as the submandibular glands, which lies just below the posterior half of the body of the jaw. the line of the common and the external carotid arteries may be marked by joining the sterno-clavicular articulation to the angle of the jaw. the eleventh or spinal accessory nerve corresponds to a line drawn from a point midway between the angle of the jaw and the mastoid process to the middle of the posterior border of the sterno-mastoid muscle and thence across the posterior triangle to the deep surface of the trapezius. the external jugular vein can usually be
Human_head_and_neck