Carefully cut the sternomastoid muscle at its attachment to the sternum and reflect
it superiorly to the mastoid process to better expose the contents of the carotid sheath as
shown. If you cannot
feel the mastoid process deep to the muscle, you have not reflected it far enough.
Avoid using your scalpel in this area as there are a number of important nerves and arteries deep to
the sternomastoid.
NOTE: This muscle is a very important landmark for important deeper structures so be sure
to visualize the relationships by replacing the muscle over the carotid sheath.
Now clean the thyrocervical trunk and
its branches, the vertebral artery, internal
thoracic artery as well as the costocervical trunk and its branches. NOTE: The branches of the thyrocervical trunk are related anteriorly to the anterior
scalene muscle. The costocervical trunk is usually found posterior to the anterior
scalene muscle.
Find the phrenic nerve on the
anterior scalene m. and the vagus nerve descending deep and between the common
carotid a. and internal
jugular v. Look for the ansa subclavius, which
extends from the sympathetic chain and loops around the subclavian artery.
Review the relationships of the
thyroid gland, trachea and esophagus. Look for the recurrent laryngeal nerve
ascending the groove between the esophagus and trachea.
