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The cervical plexus is a plexus of the ventral rami of the first four cervical spinal nerves which are located from C1 to C4 cervical segment in the neck. They are located laterally to the transverse processes between prevertebral muscles from the medial side and vertebral (m. scalenus, m. levator scapulae, m. splenius cervicis) from lateral side. There is anastomosis with accessory nerve, hypoglossal nerve and sympathetic trunk. It is located in the neck, deep to sternocleidomastoid. Nerves formed from the cervical plexus innervate the back of the head, as well as some neck muscles. The branches of the cervical plexus emerge from the posterior triangle at the nerve point, a point which lies midway on the posterior border of the sternocleidomastoid. ==Branches== The cervical plexus has two types of branches: cutaneous and muscular. *Cutaneous (4 branches): * *Great auricular nerve - innervates skin near concha auricle (outer ear) and external acoustic meatus (ear canal) (C2&C3) * *Transverse cervical nerve - innervates anterior region of neck (C2&C3) * *Lesser occipital - innervates the skin and the scalp posterosuperior to the auricle (C2&C3) * *Supraclavicular nerves - innervate the skin above and below the clavicle (C3,C4) 〔Clinically Oriented Anatomy by Moore and Dally's 〕 *Muscular * *Ansa cervicalis (loop formed from C1-C3), etc. (geniohyoid (C1 only), thyrohyoid (C1 only), sternothyroid, sternohyoid, omohyoid) * *Phrenic (C3-C5 (primarily C4))-innervates diaphragm and the pericardium * *Segmental branches (C1-C4)- innervates anterior and middle scalenes Additionally there are two branches formed by roots of spinal nerves: *Preauricular nerve (from the posterior roots of C2–C3) *Postauricular nerve (from the posterior roots of C3–C4)〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「cervical plexus」の詳細全文を読む スポンサード リンク
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