Which group of neck muscles lies between the sternocleidomastoid and the anterior edge of the trapezius?

• A. Scalenes
• B. Splenius Capitis
• C. Levator Scapulae
• D. Longus Coli

Answer: (A)

The muscles in that space are the scalene muscles. The anterior, middle, and posterior scalenes run along the lateral neck from the cervical vertebrae to the first and second ribs, and they sit between the sternocleidomastoid in front and the anterior edge of the trapezius behind. They form part of the floor of the posterior triangle of the neck, placing them exactly in the zone described. Their role includes elevating the first two ribs during deep breathing and aiding neck flexion and lateral bending.

Splenius capitis stays more toward the back of the neck, deeper to trapezius, and isn’t the group that occupies that lateral space between SCM and trapezius. Levator scapulae runs from the cervical vertebrae to the scapula and lies mainly medially and posteriorly, not between SCM and the trapezius. Longus coli is an anterior neck muscle along the front of the vertebral column, far from this lateral region.