CADAVERIC STUDY OF THE MOTOR NERVES TO THE LEVATOR SCAPULAE MUSCLE

Understanding the surgical anatomic relationships of the motor nerves to the levator scapulae muscle is imperative for reducing postoperativ e shoulder dysfunction in patients undergoing neck dissection, To eluc idate this relevant anatomy, cervical (C3, C4) and brachial (C5 via do rsal scapular nerve) plexi contributions to the levator scapulae were assessed with respect to posterior triangle landmarks in 37 human cada veric necks, An average of approximately 2 (actual 1.92) nerves from t he cervical plexus (range 1 to 4 nerves) emerged from beneath the post erior border of the sternocleidomastoid muscle in a cephalad to caudad progression to enter the posterior triangle of the neck on their way to innervating the levator scapulae, These cervical plexus contributio ns exhibited a fairly regular relationship to the emergence of cranial nerve XI and the punctum nervosum along the posterior border of the s ternocleidomastoid muscle, After emerging from the posterior border of the sternocleidomastoid to enter the posterior triangle of the neck, cervical plexus contributions to the levator scapulae traveled for a v ariable distance posteriorly and inferiorly, sometimes branching or co ming together, Ultimately these nerves crossed the anterior border of the levator scapulae as 1 to 3 nerves (average 1.94) in a regular supe rior to inferior progression. The dorsal scapular nerve from the brach ial plexus exhibited highly variable anatomic relations in the inferio r aspect of the posterior triangle, and was found to penetrate or give branches to the levator scapulae in only 11 of 35 neck specimens, We have found that the levator scapulae receives predictable motor supply from the cervical plexus. Our data elucidate surgical anatomy useful to head and neck surgeons.