The sound becomes low

When normal people pressurize the thyroid cartilage from the front, the sound becomes low. Phenomenon caused by damage to the upper laryngeal nerve, which causes the sound to become low. Lower voice is one of the clinical manifestations of superior laryngeal nerve injury. Symptoms of unilateral superior laryngeal nerve injury: The frequency range of speech is narrowed, and no treble. Symptoms of bilateral superior laryngeal nerve injury: no treble, monotonous sound. The superior laryngeal nerve comes from the nodular ganglia of the vagus nerve. It is located near the jugular foramen and is divided into internal and external branches on the plane of the hyoid bone. The outer branch is often closely associated with the superior thyroid artery on the way down, and is usually located in front of the superior thyroid artery. According to the autopsy of 200 cases of Moosman, 21% of the outer branches were walking in uncertain directions, 15% were located in the thyroid sheath, and 6% were located between the branches of the superior thyroid artery. According to Meng Zhaohui et al.'S (1976) observation of the anatomy of the laryngeal nerve, the superior laryngeal nerve and the superior thyroid artery are closely associated with each other. Among them, the nerve walking behind the superior thyroid artery accounts for 89.3%, the former precedes the artery accounts for 6.7%, and the artery branches The latter accounted for 4%. Secondly, the superior laryngeal nerve is located above the hypopharyngeal contractile muscle on the way downward, and then under the sternum hyoid muscle and thyroid cartilage dominates the cyclothyroid muscle. At the same time, the hypopharyngeal contractile muscle also receives a part of the outer branch of motor fibers. Therefore, the outer branch is covered by the fascia of the pharyngeal constrictor before entering the ciliary thyroid. The outer branch of the superior laryngeal nerve is mainly dominated by motor dominance of the cyclothyroidus, and there are branches to the hypopharyngeal constrictor and thyroid. In addition, before the outer branch enters the ring thyroid muscle, a branch is branched into the throat through the lower edge of the thyroid cartilage, and together with the anterior branch of the recurrent laryngeal nerve, it goes to the formazan and circumflex muscles. 92% of the internal branch of the superior laryngeal nerve passes through the thyroglossal periosteum and is divided into two branches before and after; 8% passes through the anterior branch of the anterior branch located in the soft tissue of the lateral wall of the laryngeal vestibular inside the thyroid cartilage. % Branches communicate with the outer branch of the superior larynx nerve through the thyroid cartilage hole. The posterior branch is distributed in the mucosal layer of epiglottis and epiglottis and sacral cartilage with branches to the iliac muscle (10%) and posterior iliac muscle (5%) . The descending branch of the posterior branch coincides with the posterior branch of the recurrent laryngeal nerve. Siegelman noted that branches of the superior laryngeal nerve dominate the sacral muscle group. Negus has also shown that the inner branches of the superior laryngeal nerve emit motor fibers that dominate the phrenic muscle group. In addition, Katly and Hangen stimulated the inner branch of the superior laryngeal nerve to cause contraction of the phrenic muscle during human laryngectomy. The same results were obtained by stimulating the superior laryngeal nerve.