Musculus Levator Scapulae: Structure, Function & Diseases

Musculus levator scapulae is a muscle of the secondary back musculature. This skeletal muscle is primarily responsible for elevating the shoulders. In many cases, back-related pain symptoms are rooted in incorrect loading or posture of the levator scapulae muscle.

What is the levator scapulae muscle?

The autochthonous back musculature or locomotor back musculature is referred to as the most important part of the active back locomotor system and is composed of different skeletal muscles. In addition to the autochthonous portion, the human back musculature embraces a secondary portion. The secondary back musculature includes all muscles that arise from limb buds. These muscles correspond to the dorsal shoulder girdle and are divided into three distinct layers: superficial, middle and deep. The levator scapulae muscle is a muscle of the middle layer, also known as the scapulae elevator. The levator scalpulae muscle takes its origin from the transverse processes of the first and second cervical vertebrae and from the posterior tuberosities of the third and fourth cervical vertebrae, which attach to the medial border of the scapula and to the superior angle of the scapula. In the literature, the skeletal muscle of the secondary shoulder muscles is also referred to as the levator anguli scapulæ muscle.

Anatomy and structure

The long and fine levator scapulae muscle originates at the level of the first and second cervical vertebrae and the third and fourth cervical vertebrae. The individual fibers of the skeletal muscle descend steeply in the lateral direction and in the caudal direction, aligning with the scapula. At the medial angle of the scapula and at the medial edge of the bone above the spina scapulae, they each find an insertion. The lateral border of the levator scapulae muscle meets the accessorius nerve. The muscle itself is not innervated by this nerve, but by the dorsal scapular nerve, which is a bundle of fibers from the brachial plexus. In addition to these nerve fibers, the muscle receives fibers from the third and fifth cervical nerves from the cervical plexus. In the lateral triangle of the neck, the levator scapulae muscle breaks out during contraction at the medial border of the trapezius muscle. Meanwhile, on the anterior side of the neck, it attaches to the scalenus muscles, with which it fuses completely in individual cases. The muscle receives its blood supply from the dorsalis scapulae artery.

Function and tasks

The functions of the levator scapulae muscle derive from the term “shoulder elevator.” The secondary back muscle lifts the scapula by means of contraction in the craniomedial direction. It is also involved in shoulder rotation medially in interaction with other muscles of the same region. More specifically, the levator scapulae muscle assists in the medial rotation of the lower shoulder edges. Because of this function, the muscle is considered a depressor. With the return of the elevated arm, it is responsible for the depression of the arm from elevation. In addition, the angulus inferior is moved away from the body by the muscle contraction. The result is a slight tilt of the scapulae still upward. However, contrary to what the name suggests, the skeletal muscle does not only move the shoulder blades and the arm. Once the shoulder blade is held in a fixed position, the contraction of the levator scapulae muscle also moves the neck. More precisely, the skeletal muscle inclines the neck or cervical spine to the same side of the shoulder when the shoulder position is fixed. Thus, the skeletal muscle is responsible for lateral flexion of the cervical spine. Despite the multifunctionality, the most important function is perceived to be the function that is included in the name of the muscle. Thus, shoulder elevation is the main function of the levator scapulae muscle. A condition for the fulfillment of this main function is the integrity of the motor innervation.

Diseases

The levator scapulae muscle is a skeletal muscle that relatively often acquires pathologic significance. In clinical practice, various clinical pictures and patterns of complaints are observed that are directly related to the back muscle. Rather rarely, paralysis of the muscle occurs, which is based on isolated damage to the dorsal scapular nerve. This nerve is responsible for the motor connection of the skeletal muscle to the central nervous system and can be damaged, for example, by trauma, by poisoning, malnutrition, inflammation or tumors.Lesions of the dorsal scapular nerve partially or completely paralyze the levator scapulae. Paralysis of the muscle is noticeable through symptoms such as poor posture. These malposition symptoms include wing-like protrusion of the scapulae. Since the muscle can no longer be contracted during paralysis symptoms, the tissue regresses over time. This phenomenon is known as muscle atrophy, as is not uncommon in the context of persistent paresis. In most cases, paralysis of the muscle occurs in combination with paresis of the rhomboid muscles and thus does not present as an isolated paralysis. Affected patients usually do not register any clear symptoms for a long time, since the levator scapulae muscle is rather negligible in the context of everyday movements. For this reason, the diagnosis of paresis is often made much too late to be able to intervene positively. Far more frequently than paresis, a stiffening or misuse of the levator scapulae muscle is diagnosed in clinical practice. The skeletal muscle is in many cases the origin of pain symptoms close to the back. Stiffening of the shoulder lever, for example, can underlie chronic back pain. The causes of this phenomenon are manifold. Overly heavy shoulder bags, for example, put just as much strain on the secondary back muscle as spasmodically raised shoulders in everyday work or sideways sleeping positions without a head support.