Posterior Scalene

Origin

The scalenius posterior muscle originates from the posterior tubercles of the transverse processes of the lower cervical vertebraeSmallest vertebrae; have transverse foramina for vertebral arteries; often bifid spinous processes.. Specifically, it arises from the posterior tubercles of the fourth, fifth, and sixth cervical vertebrae.

Insertion

The muscle inserts onto the second rib, specifically on the external surface of the second rib.

Actions

Postural Support

Assistance in Breathing

Assistance in Neck Movement

The posterior scalene is the smallest and most tucked-away of the scalene trio, but it’s still important. The anteriorThe front of the body or toward the front when standing in the anatomical position. and middle scalenes are the big ropes tying your neck to your first rib. The posterior scalene is the thinner rope at the back of the bundle.

It originates from the transverse processes of C4–C6 vertebrae. This is a shorter span than the middle scaleneLateral flexor Next to the anterior scalene; bends neck sideways. It descends to insert on the second rib, instead of the first. That difference makes it unique—the posterior scalene is the only one of the three that attaches to the second rib.

Functionally, it works in the same family of motions:

• Unilateral contraction bends the neck laterally (bringing your ear toward your shoulder).
• Bilateral contraction can help flex the neck forward a little.
• Most importantly, when you take a deepAway from the surface of the body. breath, it lifts the second rib. This action helps with inspirationThe process of inhaling, driven by diaphragm and external intercostal contraction.. It expands the upper chest.

Clinically, the posterior scalene isn’t as directly involved in the “scalene gap” for the brachial plexusA network of nerves in the neck and shoulder that control the upper limbs. and subclavian artery. That area is more between the anterior and middle scalenes. However, it can still tighten and contribute to neck stiffness or postural problems.