The longus colli & capitis muscles are extremely important with respect to cervical and especially atlantal (craniocervical) stability and alignment.

These muscles are very often weak, especially in patients with hingeneck postures, prior whiplash injuries, and similar.

Between the longus colli, capitis and the cervical alar fascia, courses the sympathetic chain. If the longii are severely weak, these nerves may become entrapped, leading to many strange problems such as vision disorders (improper ocular focus), tinnitus, and even atrial fibrillation, as these nerves directly innervate the ear's tympanic plexus, eye's ciliary muscles, cardiac plexus, and so on. The possibilities here are endless, it really is a rabbithole, and I have seen some very interesting cases both being triggered and resolving by rehabilitating these muscles.

Weakness of these muscles may also promote hyoidal muscle clenching, which will often contribute to TMD, as it pulls the mandibular condyle posteriorly. This creates an evil circle, as the longii will be stimulated even less, as the hyoidal muscles overtake their role. It is therefore incredibly important to stop clenching these in posture, and rather (re)learn to stabilize the craniocervical junction with the longus capitis and colli muscles.

Read more in my atlas article:
https://treningogrehab.no/atlasjoint...