ACTION: Splenius: neck rotation. Semispinalis: neck extension.
REFERRAL: occiput, neck, upper shoulder
COMMENTS:These three muscles make up the majority of deep neck muscles under the trapezius. Since they are layered and close, usually you just work on them all together. It is important to note that they all attach to the middle of the back- so when dealing with neck pain, you must release down the back as well.
The splenius capitis can be palpated directly by finding the space between the trapezius and the sternocleidomastoid at the top of the neck. Both splenius muscles are a potent source of headaches.
The semispininalis capitis is deep to the splenius capitis, and is often a cause of neck pain. Even through its main action is extension, restriction in this muscle can cause pain on rotation at the end of the range.