With regard to the recurrent laryngeal nerve (RLN), which of the following is true?
A The left RLN loops around the subclavian vein and ascends medially into the neck.
B The right RLN loops around the inferior thyroid artery, ascends laterally to medially, and enters the cricothyroid membrane.
C The laryngeal nerve is nonrecurrent in 0.5% of patients.
D The RLNs innervate the true vocal cords and the cricothyroid muscles.
E The medial branch of the RLN is primarily sensory.
Explanation-
The recurrent laryngeal nerve arises from the vagus nerve after it has already passed into the mediastinum. The left RLN loops around the aortic arch and then travels medially in the neck within the tracheoesophageal groove. The right RLN loops around the subclavian artery, passes posterior to the artery, and travels laterally to medially toward the tracheoesophageal groove. Once in the central aspect of the neck, the RLN nerve can branch into medial and lateral components. The medial branch typically carries the motor fibers and is at risk for injury along its course toward the cricothyroid membrane if not identified as a separate structure relative to the lateral sensory branch. The laryngeal nerves can be nonrecurrent in approximately 0.5% of patients. In this case the nerve originates from the cervical position of the vagus nerve. The risk for injury during cervical procedures is higher when the nerve is nonrecurrent because instead of running parallel to the tracheoesophageal groove, it travels perpendicular. It is more common on the right and is most often associated with the presence of aberrant cervical vascular anatomy such as a retroesophageal subclavian artery. The RLN innervates all the intrinsic muscles of the larynx except the cricothyroid muscles.
Answer C
A The left RLN loops around the subclavian vein and ascends medially into the neck.
B The right RLN loops around the inferior thyroid artery, ascends laterally to medially, and enters the cricothyroid membrane.
C The laryngeal nerve is nonrecurrent in 0.5% of patients.
D The RLNs innervate the true vocal cords and the cricothyroid muscles.
E The medial branch of the RLN is primarily sensory.
Explanation-
The recurrent laryngeal nerve arises from the vagus nerve after it has already passed into the mediastinum. The left RLN loops around the aortic arch and then travels medially in the neck within the tracheoesophageal groove. The right RLN loops around the subclavian artery, passes posterior to the artery, and travels laterally to medially toward the tracheoesophageal groove. Once in the central aspect of the neck, the RLN nerve can branch into medial and lateral components. The medial branch typically carries the motor fibers and is at risk for injury along its course toward the cricothyroid membrane if not identified as a separate structure relative to the lateral sensory branch. The laryngeal nerves can be nonrecurrent in approximately 0.5% of patients. In this case the nerve originates from the cervical position of the vagus nerve. The risk for injury during cervical procedures is higher when the nerve is nonrecurrent because instead of running parallel to the tracheoesophageal groove, it travels perpendicular. It is more common on the right and is most often associated with the presence of aberrant cervical vascular anatomy such as a retroesophageal subclavian artery. The RLN innervates all the intrinsic muscles of the larynx except the cricothyroid muscles.
Answer C
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