Supraclavicular nerve

The supraclavicular nerves (descending branches) arise from the third and fourth cervical nerves; they emerge beneath the posterior border of the sternocleidomastoideus (sternocleidomastoid muscle), and descend in the posterior triangle of the neck beneath the platysma and deep cervical fascia.Dermatome distribution of the trigeminal nerveCutaneous nerves of right upper extremity.Diagram of segmental distribution of the cutaneous nerves of the right upper extremity.Side of neck, showing chief surface markings. The supraclavicular nerves (descending branches) arise from the third and fourth cervical nerves; they emerge beneath the posterior border of the sternocleidomastoideus (sternocleidomastoid muscle), and descend in the posterior triangle of the neck beneath the platysma and deep cervical fascia.