The autochthonous back muscles or local back muscles are referred to as the most important part of the active back movement apparatus and is composed of different skeletal muscles. In addition to the autochthonous portion, the back muscles of humans encompass a secondary share. Secondary back muscles include all muscles that emerge from limb buds.
These muscles correspond to the dorsal shoulder girdle and are subdivided into three distinct layers: a superficial, a middle and a deep layer. The levator scapulae muscle is a middle-layer muscle known as the scapula. The levator scalpula muscle originates from the transverse processes of the first and second cervical vertebrae and the posterior tubercles of the third and fourth cervical vertebrae, which begin at the scapular margin and at the upper scapular angle. In the literature, the skeletal muscle of the secondary shoulder musculature is also referred to as the levator anguli scapulæ muscle.
The long and fine levator scapulae originates at the level of the first and second cervical vertebrae as well as the third and fourth cervical vertebrae. The individual fibers of the skeletal muscle fall in the direction of lateral and caudally steep and align themselves on the shoulder blade. At the medial scapula angle and at the medial margin of the bone above the scapular spine, they will each find one approach.
The lateral margin of the levator scapulae muscle hits the accessory 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 of the third and fifth cervical nerves from the cervical plexus. In the lateral cervical triangle, the levator scapulae muscle breaks during contraction at the medial border of the trapezius muscle. Meanwhile, on the anterior side of the neck, he adapts to the scalenus muscles, which in some cases completely grows together. The muscle receives its blood supply through the dorsal scapular artery.
The functions of the levator scapulae muscle come from the term "shoulder lift". The secondary dorsal muscle raises the scapula by contraction in the craniomedial direction. He is also involved in the interplay with other muscles of the same region in the shoulder rotation medially. More specifically, the levator scapulae muscle supports the medial rotation of the lower shoulder margins. Because of this function, the muscle is considered a depressor.
With the return of the raised arm he is responsible for the depression of the arm from the elevation. In addition, the inferior angulus is moved away from the body by muscle contraction. The result is a slight tilt of the shoulder blades still up. The skeletal muscle moves, unlike the name suggests, but not just the shoulder blades and the arm. Once the scapula is held in a fixed position, the contraction of the levator scapulae muscle also moves the neck.
The skeletal muscle tilts the neck or cervical spine at a fixed shoulder position, more specifically, to the same shoulder side. Thus, the skeletal muscle is responsible for the lateral flexion of the cervical spine. The most important function, despite the multifunctionality, is the function that has flowed into the name of the muscle. The shoulder lift is thus the main task of the levator scapulae muscle. A condition for fulfilling this main function is the integrity of the motor innervation.
The levator scapulae muscle is a skeletal muscle that relatively often gains pathological significance. In everyday clinical practice, different clinical pictures and complaints are observed that are directly related to the back muscle. Rarely does a paralysis of the muscle occur, which is based on isolated damage to the dorsal scapular nerve.
This nerve is responsible for the motor attachment of the skeletal muscle to the central nervous system and can be damaged, for example, by trauma, poisoning, nutritional deficiencies, inflammation or tumors. Lesions of the dorsal scapular nerve paralyze the levator scapulae partially or completely. A paralysis of the muscle is manifested by symptoms such as bad posture. These malformation symptoms include the wing-like protrusion of the shoulder blades. Since the muscle can no longer be contracted in cases of paralysis, the tissue returns with time.
This phenomenon is known as muscle atrophy, which is not uncommon in the context of persistent paresis. In most cases, muscle paralysis occurs in combination with paresis of the rhomboid muscle and does not appear as isolated paralysis. Affected patients usually do not register any clear symptoms for a long time because the levator scapulae is rather negligible in the context of everyday movements. For this reason, the diagnosis of paresis is often made too late to be able to intervene positively. Far more frequently than the paresis, a stiffening or incorrect loading of the levator scapulae muscle is diagnosed in clinical practice.
The skeletal muscle is in many cases the origin of pain syndrome near the back. Stiffeners of the shoulder lifter can underlie chronic back pain, for example. The causes of this phenomenon are many. Too heavy shoulder bags strain the secondary back muscle, for example, as well as convulsively raised shoulders in everyday working or lateral sleeping positions without a head support.Tags: