Cervical plexus

Levator scapulae Spinal accessory nerve Lesser occipital nerve Greater auricular nerve Branch to infrahyoid musculature Ansa cervicalis Transverse cervical nerve Supraclavicular nerve Phrenic nerve NERVE ROOTS: Supplied by the ventral rami of C1-C4. SENSORY INNERVATION: Four major sensory nerves of the cervical plexus. From C2, C3: lesser occipital nerve - covers the superior pole of the pinna and postero lateral head; greater auricular nerve - covers the inferior pole of the pinna and the angle of the mandible; transverse cervical nerve (aka the anterior cutaneous nerve of the neck) - covers the anterolateral neck.  From C3 and C4: supraclavicular nerve - covers the posterolateral neck, upper chest, and shoulder. MOTOR INNERVATION: Phrenic nerve innervates the diaphragm (C3, C4, C5); C1 innervates both the geniohyoid and thyrohyoid muscles and forms the superior (or descending) root of the ansa cervicalis, which innervates the superior belly of the omohyoid muscle; inferior root of the ansa cervicalis (C2 and C3) innervates sternohyoid, sternothyroid, and the inferior belly of omohyoid. SUPRA- VS. INFRAHYOID: Sternohyoid, sternothyroid, omohyoid, and thyrohyoid are all infrahyoid muscles (meaning they lie below the hyoid bone) and they are collectively referred to as strap muscles. On the contrary, geniohyoid is a suprahyoid muscle (meaning it lies above the hyoid bone); the other suprahyoid muscles are mylohyoid, stylohyoid, and the digastric. CRANIAL NERVE 11 (the spinal accessory nerve): Motor cells from the medulla to C6 supply cranial nerve 11, the spinal accessory nerve; it innervates trapezius (C3, C4) and sternocleidomastoid (C2–C4). Trapezius elevates the shoulders (most notably) and sternocleidomastoid turns the head. ADDITIONAL: The cervical plexus also provides innervation to the deep anterior vertebral muscles, which comprise the anterior and lateral rectus capitis muscles (C1, C2), longus capitis (C1, C2, C3), and longus colli (C2-;C6) muscles.  It also helps innervate the scalene and levator scapulae muscles.