Scapular spinal part of deltoid muscle - Upper extremity - Muscles of upper limb - e-Anatomy
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Scapular spinal part of deltoid muscle

Pars spinalis scapularis musculi deltoidei

  • Latin synonym: Pars spinalis musculi deltoidei
  • Synonym: Spinal part of deltoid muscle
  • Related terms: Spinal part; Deltoid (Spinal part); Deltoid: Spinal part; Deltoid : Spinal part; Deltoid - Spinal part

Definition

Muhammad A. Javaid

Scapular spinal part of deltoid muscle

Origin

Spine of the scapula

Insertion

Deltoid tuberosity of the humerus

Artery

Primarily, the posterior circumflex humeral artery

Innervation

Axillary nerve (C5, C6)

Action

Extension, external rotation, and assists in shoulder abduction

Origin

The scapular spinal part of the deltoid muscle originates from the lower lip of the crest of the spine of the scapula.

Insertion

The fibers of this part converge alongside the other deltoid fibers to form a thick tendon, which inserts into the deltoid tuberosity on the middle lateral side of the humerus.

Arterial Supply

The scapular spinal part is primarily supplied by the posterior circumflex humeral artery.

Innervation

It is innervated by the axillary nerve, which derives from the fifth and sixth cervical spinal roots (C5, C6).

Actions

  • The scapular spinal part primarily assists in shoulder extension and lateral (external) rotation of the arm.

  • It also contributes to arm abduction and works in synergy with the clavicular and acromial parts during complex shoulder movements.

Structure

The scapular spinal fibers are arranged in a unipennate pattern, running obliquely forward and laterally before merging into the common deltoid tendon.

References

  • Elzanie A, Varacallo MA. Anatomy, Shoulder and Upper Limb, Deltoid Muscle. [Updated 2024 Jan 30]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK537056/

  • Moser T, Lecours J, Michaud J, Bureau NJ, Guillin R, Cardinal É. The deltoid, a forgotten muscle of the shoulder. Skeletal Radiol. 2013 Oct;42(10):1361-75. doi: 10.1007/s00256-013-1667-7. Epub 2013 Jun 20. PMID: 23784480.

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