Thread by @spheno_xiphoid

The deep neck flexors lie at the core of the neck, protecting vital structures and keeping the head held upright. They not only shape the appearance of the neck but —when weak— can produce symptoms of dysautonomia, TMD, headaches, shoulder pain, and more.

The deep neck flexors (DNFs) refer to the longus capitis and longus colli, both positioned on the anterior portion of the spine stretching all the way from the occiput to the third thoracic vertebra. The rectus capitis anterior and lateralis are sometimes included in this group.

As their name suggests these muscles primarily help perform flexion of the cervical spine and the cranium. However they also help to stabilize the cervical spine, maintaining relationships between vertebrae as well as the skull at the atlanto-occipital joint.

The slight oblique orientation of their fibers suggests these muscles help to generate or stabilize small degrees of lateral flexion that occur during gait. This is part of the spine’s role as an engine, though the DNFs are likely not major movers.

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Packed with muscle spindles, these muscles are important for proprioception and form reflex loops alongside the vestibular system, eyes, suboccipital muscles, and other cervical muscles. This is to help stabilize the head during motion.

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When the DNFs are weak, inflamed, or inhibited in some way, the preferred lordotic shape of the neck can become warped, leading to a number of different problems including:

-Irritation of various nerves including sympathetic and parasympathetic (dysautonomia)
-Impaired blood/lymph/CSF flow to/from brain
-Distortion of upper airway and esophagus
-Changed behavior of the cranial bones and mandible
-Altered position and movement of the entire spine

Adjacent to the DNFs lies the carotid sheath --which contains the vagus nerve-- and a bundle of sympathetic nerve fibers known as the sympathetic trunk. Chronically weak and inflamed DNFs can irritate these structures, skewing the state of the autonomic nervous system.

Because of their attachment to the atlas, dysfunctional DNFs can alter the behavior of the atlanto-occipital joint. This can affect the vertebral artery while also choking the flow of CSF to and from the brain. Headaches often result from this phenomenon.

The collapse of the cervical curve can also warp the shape of the upper airway and esophagus. Combined with the previously mentioned disruptions to the autonomic nervous system, functions like breathing and swallowing can become more difficult.

Strengthening these muscles isn’t always as simple as doing “chin tucks”. Most of the time this movement is done when the neck is an already compromised position, just amplifying the issue(s). Avoid the exercise unless you know how to activate your DNFs correctly.

One of the primary concerns for training the deep neck flexors is compensation from the suprahyoid muscles. These will often pick up the slack when the DNFs are less active. This changes the position of the hyoid bone which can then alter the mandible and tongue as well. When doing any sort of DNF exercise you may need to consciously relax these muscles or prevent them from contracting. This can take practice but will become distinctive with time.

Instead of chin tucks try these exercises instead. They focus on being able to flex your cranium and cervical spine simultaneously while keeping your suprahyoid muscles from taking over. Perform the exercise slowly and feel the contraction.

Since they work with the suboccipitals and the eyes, lateral eye movement and “nose circles” are great exercises for the DNFs. Feel them turn on as you perform these different movements.

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A helpful cue for upright posture is to feel your cranium being pulled up and away from the ground. Again, relax the suprahyoid muscles and feel your DNFs activate slightly to achieve this position.

https://x.com/spheno_xiphoid/status/1891896073578229974?s=20

Training muscles like the sternocleidomastoid and trapezius is also necessary for function of the neck as a whole. Both are likely to be weak in conjunction with the DNFs.

https://x.com/spheno_xiphoid/status/1953128722200182857?s=20

Other neck muscles like the scalenes are also usually implicated in DNF dysfunction. They may need to be strengthened as well. Note the proximity to one another.

Distraction exercises for the cervical curve can help reshape neck ligaments when combined with exercises.

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After you’ve improved proprioception of the deep neck flexors you can feel them every time you take a step. They help to maintain the position of the neck as you walk, preventing collapse of the curve. Keep this in mind as you move.

Long term habits are equally important to dedicated exercises. Be mindful of how you use your neck when scrolling your phone or doing just about anything else. Ask yourself if you feel your DNFs are being utilized correctly and adjust accordingly.