Levator scapulae; Origin, Nerve Supply, Functions

Levator scapulae
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Levator scapulae is a skeletal muscle situated at the back and side of the neck. As the Latin name suggests, its main function is to lift the scapula. The levator scapulae originate from the posterior tubercle of the transverse process of cervical vertebrae one to four. The muscle is inserted into the medial border of the scapula extending from a superior angle to junction of the spine and medial border of the scapula.[rx]

The levator scapulae may lie deep to the Sternocleidomastoid at its origin, deep or adjacent to the splenius capitis at its origin and mid-portion, and deep to the trapezius in its lower portion.

At a Glance 0f Levator Scapulae

  • Function – Elevates the scapula.
  • Origin – Transverse processes of the C1 to C4 vertebrae
  • Insertion – Medial border of the scapula
  • Innervation – C3, C4, and the Dorsal scapular nerve (C5)

Levator scapulae

Relations

One of the muscles within the floor of the posterior triangle of the neck, the superior part of levator scapulae is covered by sternocleidomastoid and its inferior part by the trapezius. It is bounded in front by the scalenus medius and behind by splenius cervicis. The spinal accessory nerve crosses laterally in the middle part of the muscle and the dorsal scapular nerve may lie deep to or pass through it.[rx]

Origin of Levator Scapulae

Levator scapulae is a thin muscle that descends from the neck to the scapula. It originates from the transverse processes of C1 (atlas), C2 (axis), C3, and C4. The fibers run diagonally from these points to the medial scapular border just above where the spine of the scapula connects. Origination points of this muscle can vary in the neck and posterior skull.

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Nerve supply

The levator scapulae are supplied by two or three branches of the fourth and fifth cervical nerves,[rx] and frequently by a branch from the dorsal scapular nerve.[rx]

Blood supply

The levator scapulae are supplied by the dorsal scapular artery. Normally, this artery has a small branch which passes laterally to the supraspinatus fossa of the scapula, and in a third of cases, this branch supplies the muscle. If the dorsal scapular artery comes off the transverse cervical artery, the parent transverse cervical artery splits, the dorsal scapular artery passes medially, while the transverse cervical artery passes laterally.[rx]

The Functions of Levator Scapulae

  • Function: Elevates the scapula. When the spine is fixed, levator scapulae elevates the scapula and rotates its inferior angle medially.[rx] It often works in combination with other muscles like the rhomboids and pectoralis minor to rotate down.
  • Elevating or rotating one shoulder at a time would require muscles to stabilize the cervical spine and keep it immobile so it does not flex or rotate. Elevating both at once with equal amounts of pull on both sides of cervical spinal origins would counteract these forces. The downward rotation would be prevented by the co-contraction of other muscles that elevate the spine, the upper fibers of the trapezius, which is an upward rotator.
  • When the shoulder is fixed, levator scapulae rotates to the same side and flexes the cervical spine laterally.[rx] When both shoulders are fixed, a simultaneous co-contraction of both levator scapulae muscles in equal amounts would not produce lateral flexion or rotation and may produce straight flexion or extension of the cervical spine.
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References

Levator scapulae


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