A study by Rahnama L et al in 2015 was done to assess the thickness of the deep stabilising extensor muscles of the neck (cervical multifidus muscle, CMM) whilst contracting their shoulder muscles in 6 different directions.

The study compared the contraction of the CMM using a diagnostic ultrasound device between 20 healthy men, and 20 men with chronic mechanical neck pain.

The research found that contracting the shoulder muscles increased CMM thickness regardless of direction of force exertion. The increase in CMM thickness was observed in both healthy, and patient groups. In the patient group however, less CMM thickness changes were observed. The study also found that an increase in force production by the shoulder muscles also increased CMM thickness, with a larger effect being observed in the healthy participants compared to the patient population.

Shoulder strengthening exercises such as lateral raise, front raise, upright rows with resistance bands or dumbbells can strengthen the deep stabilising muscles of the neck.

The findings of the study indicate that the deep neck stabilising muscles are activated during performance of tasks by the upper extremities potentially as a means of stabilising the neck. Although this is not to be directly implied from the findings of the study, it can be postulated that shoulder strengthening exercises such as lateral raise, front raise, upright rows with resistance bands or dumbbells can strengthen the deep stabilising muscles of the neck.

Reference: 

Rahnama, Leila et al. 2015. Differences in Cervical Multifidus Muscle Thickness During Isometric Contraction of Shoulder Muscles: A Comparison Between Patients With Chronic Neck Pain and Healthy Controls. Journal of Manipulative & Physiological Therapeutics , Volume 38 , Issue 3 , 210 – 217