Dorsal Scapular Nerve
Description[edit | edit source]
Dorsal Scapular Nerve is the branch of brachial plexus, arising from ventral ramus of C5 root. It is a motor nerve which arising from C5 root, pierce the middle scalene muscle, coursing deep to and supplying levator scapulae and the rhomboid muscles.
Emerging from the middle scalene, it passes posteriorly between the posterior scalene, levator scapulae, and the serratus posterior superior muscle. From this location, the DSN passes inferior and medial to the scapula, coursing anterior to the rhomboid minor and major. A this position, the DSN terminates by innervating the rhomboid major and minor on their anterior surfaces.
Function[edit | edit source]
It is a motor nerve so supplies 3 muscles for upper back ( levator scapulae, rhomboid major and minor). These muscles work dynamically and collectively are known as periscapular stabilizing muscles.
Associated structure[edit | edit source]
The dorsal scapular artery (DSA) follows the DSN to provide blood to the trapezius, levator scapulae, and rhomboid muscles. The DSA commonly spirals around the DSN as it runs medial to the scapula and anterior to the rhomboid muscles.
Clinical relevance[edit | edit source]
- Compression of the dorsal scapular nerve (DSN): It is a condition in which the dorsal scapular nerve entraps in the middle scalene muscle causing pain and stiffness in the shoulder girdle and limited end range motion, along with winging of scapula. The most common source of DSN entrapment is a hypertrophied middle scalene muscle.
- Anatomical variant : According to the study done by Nguyen et al. in 2016, out of 20 adult cadaver, approximately 70% of the DSNs originated from C5, with 74% piercing the middle scalene muscle. About 48% of the DSNs supplied the levator scapulae muscle only and 52% innervated both the levator scapulae and rhomboid muscles. 
- Dorsal scapular nerve is also associated with brachial plexus injury.
- DSN block is performed in Japanese pain clinics to treat neck pain and katakori (a unique symptom in Japanese population characterized by myofascial pain syndrome such as shoulder girdle pain).
Assessment[edit | edit source]
Assessment for DSN can be done by addressing the function of levator scapulae and rhomboids.
References[edit | edit source]
- Bishop KN, Varacallo M. Anatomy, shoulder and upper limb, dorsal scapular nerve. StatPearls [Internet]. 2020 Aug 10.
- The Dorsal Scapular Nerve - Everything You Need To Know - Dr. Nabil Ebraheim. Available from:https://www.youtube.com/watch?v=Zw1iD-2Vju8. last accesed: 29th January 2022
- Dorsal Scapular Nerve Entrapment. Available from: youtube.com/watch?v=2NtAUFKGnqc. Lasted accessed: 29th Janaury 2022
- Nguyen VH, Liu HH, Rosales A, Reeves R. A cadaveric investigation of the dorsal scapular nerve. Anatomy research international. 2016;2016.
- Tetsu S, Terayama H, Qu N, Yamazaki H, Sakamoto R, Tanaka O, Suyama K, Takenaka M, Suzuki T, Sakabe K. Anatomical variants of dorsal scapular nerve in relation to the middle scalene muscle in Japanese population. Medicine. 2018 Nov;97(47).