I recently shared a quirky vocal-pedagogy video featuring Jacob Gonzalez (Baldwin Wallace) singing “Come Back” from Dogfight, and within days it surpassed 400,000 views on Instagram and TikTok.
If you missed it, here it is:
In the clip I point out Jacob’s right-foot turn-out (hip external rotation) and a right-ward jaw deviation — a sign that his left pterygoid muscles may be shortened and overactive.
Since the video went live, I’ve heard from many singers and voice teachers wanting to understand the neuromechanics behind what they saw. Here’s the breakdown.
When I see one foot that keeps externally rotating, I start to wonder about the activation in a part of the brain called the ponto-medullary reticular formation (called “PMRF” from here on out).
The PMRF is a web of neurons in your brainstem that helps regulate posture, muscle tone, reflexes, and whole-body coordination. It sends fast signals down the spinal cord (through the reticulospinal tract) to organize global movement patterns and stabilize the body during action. You have a right and a left PMRF, and they may not be equally active.
In the upper body, a sleepy PMRF-side can result in an overactivity of flexor muscles (things like your pec, biceps, wrist pronators, and finger/thumb flexors.)
Some of this research comes out of stroke rehab:
“In a unilateral brain injury, (there is an involuntary increase) in elbow, wrist and finger flexion in the same arm, a phenomenon referred to as the flexion synergy. (There is) a developmental brainstem reflex (showing) that anatomically diffuse reticulospinal motor pathways (i.e., PMRF) are active during synergy expression.”1
In the lower body, the pattern seen in gait is that a less-active PMRF results in an external rotation of the lower extremity (turned-out foot).
In a fast-paced master class like the one in the video, I don’t get to take history on a singer, so I like to use muscle tests to get information quickly. My hypothesis is that a weak thumb extensor might indicate a less-active PMRF side (if the thumb flexors are OVERACTIVE, the thumb extensors may be UNDERACTIVE).
To fix this imbalance, one strategy is to activate a cranial nerve on the ipsilateral (same) side.
Since Jacob’s jaw was deviating right, I knew his RIGHT trigeminal nerve in the mandibular (V3) branch might be underactive. When he moved his jaw to the LEFT, he activated his RIGHT trigeminal nerve through the action of the pterygoid muscles, which may have zinged down his brainstem and created a more active PMRF/reticulospinal tract on the same side. This in turn might explain the stronger thumb extensor test (remember, a sleepy PMRF may create more thumb/finger FLEXION, resulting in weak thumb/finger EXTENSION through reciprocal inhibition).
(Want to explore how this all ties into voice training? My Singing Athlete Certification is expanding with new cohorts in the next three months. Choose your preferred dates here.)
A muscle test is a cool data point (which you can see on Jacob’s face.) But of course, the best reassessment is the way his voice sounded when his jaw was in a better position.
Your singing voice is governed by reflex pathways in the brainstem — including the PMRF. If one side is under-engaged, it can lead to asymmetrical nerve firing in your vocal control system. In other words: nerves that fire together wire together.
When things go right with your voice, you can be sure that your brain enjoyed that stimulus, and that drill should remain an element of your training program.
1McPherson JG, Chen A, Ellis MD, Yao J, Heckman CJ, Dewald JPA. Progressive recruitment of contralesional cortico-reticulospinal pathways drives motor impairment post stroke. J Physiol. 2018 Apr 1;596(7):1211-1225. doi: 10.1113/JP274968. Epub 2018 Feb 19. PMID: 29457651; PMCID: PMC5878212.
