In today’s episode of the PT on ICE Daily Show, #ICEPelvic faculty member April Dominick discusses the anatomy & physiology of phonation, the mechanics of breathing, and the relationship between the pelvic floor & the demands of speaking/singing. In addition, April covers unique considerations for professional singers & speakers and implications for physical therapy treatment.
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What’s up PT on Ice fam? This is Dr. April Dominick from the Ice Pelvic Faculty Division here today to talk about the pelvic floor and its role in breathing and voicing today. I have a feeling it’ll take your breath away. But first, some updates from our pelvic division. First, we have our last live course offering of 2023. It is happening December 2nd and 3rd. with Christina Prevett, and that is gonna be in Halifax, Nova Scotia. And let’s not forget about not one, but two of our online eight-week course offerings. Level one is going to kick off next year on January 9th, and the brand new level two advanced concepts are going to get rolling on April 30th. So head over to ptonice.com and secure your seat in one or all three of those offerings. So we wanted to hop on today to outline what we know about the pelvic floor and its essential tasks and things that you’ve probably already done today like breathing and talking.
THE PELVIC FLOOR & PHONATION
I’ll discuss the essential anatomy and then the structures that are involved and then we’ll unpack the complex physiology of breathing and voicing with a special focus on what the literature supports right now in terms of what the pelvic floor’s role is in phonation. Spoiler alert, there’s not a ton. And when I say phonation or voicing, all those terms mean talking. So we need to understand what normal function is in order to identify dysfunction during pelvic floor assessment, especially when it comes to an individual complaining of any bladder issues or bowel dysfunction, leakage, pelvic heaviness, or pain during tasks like breathing and talking, or yelling and singing, This can happen to anyone. Think about the last time you were in a really loud bar or at a concert and you’re yelling at someone or trying to talk to people and your voice gets a little fatigued. Maybe there’s some fatigue in the pelvic floor as well. This can also happen with other occupations that primarily use their voices. So I’m thinking about teachers, maybe chefs in a busy kitchen or coaches, professional singers even. Another point to bring up is breathing and more recently phonation have been used in the clinic by physical therapists to treat pelvic floor dysfunction. Yet we lack robust evidence to support these clinical practices. So when it comes to breathing and voicing, I want you right now to think of some body parts or structures that are involved. I’ll give you three seconds or you can pause.
THE ANATOMY OF PHONATION
Most of us probably thought of the obvious structures like the nose, the mouth, the lungs, and maybe even the diaphragm. And those are great starts. And we’re going to run through the other important players for breathing and voicing. Breathing and voicing work in a closed system, which involves the interplay of three regions. with different diaphragms. So the cervicothoracic diaphragm, the respiratory diaphragm, that’s the diaphragm that you think of when we talk about the diaphragm, the dome shape, and then the pelvic diaphragm. So when it comes to the cervicothoracic diaphragm, the major surrounding structures of interest are the oral and nasal cavity, the larynx, which is also known as the voice box, and that houses the vocal folds, the trachea, and then there’s supporting musculature. There’s paralangeal musculature like the SEM and scalenes, as well as the intercostal muscles. From a nerve standpoint, we cannot talk about the pelvic floor or voicing or breathing even without talking about the vagus nerve, as well as the phrenic nerve that runs along this area. The vagus nerve innervates the vocal folds and the phrenic nerve innervates the diaphragm. So that’s the cervicothoracic region and diaphragm. Then we’ve got the respiratory diaphragm. That’s going to separate the thoracic cavity from the abdominal cavity. And the diaphragm at rest, it’s that dome-shaped muscle And it’s got many origins, the xiphoid process, some of the lower ribs, the lumbar spine. Indirectly, it also attaches to the psoas and QL or quadratus lumborum. And then in that same region, we have the abdominals and they aid in power production for respiration or phonation. We’re talking the internal and the external obliques, the rectus, and then the transverse. Then we have the pelvic diaphragm, our third area. The pelvic floor muscles are actually the floor of this entire closed-core canister system. Its three layers involving the levator ani, the coccygeus, piriformis, optorenus, and ternus are all muscles that span from the pubic bone back to the coccyx, and then from the ischial tuberosity to the other ischial tuberosity. Functionally, the pelvic floor is involved in so many things, abdominal and pelvic support, modulation of intra-abdominal pressure, postural and respiratory support, bowel, bladder, sexual function and arousal, and reproductive function. When those pelvic floor muscles contract, they close off the urethral, vaginal and anal openings. When they relax, they open those openings so that if we need to, we can urinate or poop or do any of those things. So that’s the anatomy piece.
THE PHYSIOLOGY OF PHONATION
Now I want to go into the relevant physiology when it comes to pressure generation and management. So breathing is the transmission of air into and out of the lungs. Sounds simple. Right? No, not so much. We’re going to go through how each region that we just discussed supports respiration in two forms, inhalation and exhalation. For the cervicothoracic diaphragm, the vocal folds are there and they march their own drums. So during inhalation and exhalation, those vocal folds stay open, and that’s to allow airflow in and out. In terms of the intercostals, during inhalation, the external intercostals are going to elevate the ribs and go upwards and outwards, which expands the thoracic cavity, and then they’ll relax on exhalation. The SEM and scalenes are going to assist in the inhalation portion as well as provide some postural support for the head and neck. So that was a cervicothoracic diaphragm.
THE MECHANICS OF BREATHING
Now we’re going to go into the respiratory diaphragm physiology and mechanics of breathing. So during inhalation, that dome-shaped muscle contracts and changes from dome-shaped and then flattens as it descends towards the abdominal cavity. This is going to create a vacuum that pulls air in. And then during exhalation, that flat diaphragm passively relaxes and returns back to its dome shape. Then we have the abdominal muscles. They are a little more straightforward. On inhale, they’re going to relax and expand outward. On exhalation, they’re going to contract and draw inward. Then we have the pelvic diaphragm. So during inhalation, the pelvic floor muscles relax and elongate. Then on exhalation, in the presence of now increased intra-abdominal pressure, the pelvic floor should contract and lift, which closes those openings, preventing any unwanted leakage or prolapse symptoms. And we have a few confirmations of this happening in the literature. In 2011, there was a group Telus et al, and they confirmed that these pelvic floor movements are happening with respiration during real-time dynamic MRI. We love some of that research. We also have other studies that show, hey, via EMG activity, there’s actually some pelvic floor activity prior to resisted expiration. And this is cool because it demonstrates that maybe the pelvic floor has some sort of neural pre-planning during the expiration phase. So I know that was a lot of information, so I’m going to put it all together for you in terms of respiration, what’s happening from head to floor. During inhalation, the vocal folds are open to allow the air to flow in. The external intercostals are going to elevate the ribs up and out. The SCM lifts the sternum. and clavicles, the diaphragm contracts and descends downward, the abdominals expand outwardly in response to the displaced organs, and then the pelvic floor elongates inferiorly. Whereas exhalation is more of a passive process of the muscles relaxing. But it can be a forced process as well, like during exercise or playing an instrument, or if we’re under any stress, So now I’ll run through the muscle responses during passive expiration, which is essentially inhalation in reverse. The respiratory diaphragm and inspiratory muscles relax, the pelvic floor and abdominals, synergistically contract, and there’s this beautiful parallel lift of the pelvic diaphragm and the respiratory diaphragm upon exhalation. And then finally, those vocal folds, remember they stay open. so that air can exit the body. So that is respiration. It is the foundation and the power source when it comes to phonation or talking. As far as phonation goes, the entire body is a vocal organ. So the next time someone asks you at a party, hey, do you play any instruments? Be sure and tell them, heck yeah, I play this little thing, the voice. So next I’m going to detail the symptoms or systems involved in voice production. And I’ll point out the differences in function of the two major muscles between respiration and phonation. As I said, the voice is a highly complex instrument involving many different body parts.
THE FOUR SYSTEMS OF PHONATION
And so we’re gonna think of phonation as comprised of four major systems. And these systems are like a four-legged stool. When they’re all working in sync, that stool or the voice is nice and stable. When one leg of the stool is a little off, then your whole stool is wobbly and your voice is a little wobbly. Another key thing to remember is that phonation occurs during the exhalation portion of respiration. So the first of the four systems is the air pressure system. It’s going to manage pressure and flow. It sets vibration in motion. We can liken that air pressure system to a musician’s breath as they are playing the saxophone. In the human body, the structures that are involved in the air pressure system are the trachea, the chest wall, the lungs, diaphragm. Then we move on to the second of the four systems, the vibratory system. It’s made up of material that can vibrate when activated. So if we’re thinking about the saxophone, we’re thinking about the reed as the vibratory system. This creates pitch. In the human body, the vocal folds, are what create pitch. They open and close, and that lets short puffs of air come through the glottis at high speeds. And the number of vibrations per unit of time is what creates pitch. Low pitch is the result of the vocal folds shortening and vibrating more slowly. Whereas high pitch is created by lengthening the vocal folds and vibrating more quickly. Loudness is determined by the subglottal pressure which is generated by the abdominals and modulated by the pelvic floor. And then we have our third system, the resonators. They are going to amplify the vibrating sound. It’s the actual physical saxophone itself. They affect the richness of the vocal tone. In the human body, that’s going to be the throat, the oral and nasal cavities. This is what is going to create someone’s recognizable voice. Then the final and fourth system is the articulators. They are unique to the human voice. So there is no analogy for an instrument here. Articulars add quality and timbre. They modify sound shapes as they leave the mouth, which creates recognizable words. And these are the tongue and the soft palate, the lips. So in summary, for phonation or voicing, the voice is produced via the interaction of those four systems. Subglottal pressure creates sound pressure and intensity, via rapid oscillations, the vocal folds produce sound pitch. Via the vocal tract, the glottal sound is articulated, adding in someone’s unique voice timbre. And then intra-abdominal pressure is controlled and generated with the rest of the core canister. And that’s going to be mostly the pelvic floor and abdominals helping out with that piece. So during phonation, the primary muscles and their actions involved in the inhalation portion remain the same. So prior to speaking, we usually inhale and then we talk, talk, talk. The exhalation portion of respiration is like I said, when we phonate.
COMPARING EXHALATION TO ACTIVE SPEAKING
So I’m going to talk about the two differences between quiet exhalation and actual phonation or speaking. One is that the vocal folds don’t stay open like they do in quiet exhalation. During phonation, they are doing the vibration, opening, and closing through the different frequencies to produce pitch. Second, when it comes to the pelvic floor, there’s very little research on what it’s actually doing when we are phonating. Aliza Rudofsky is paving the way in these uncharted waters when it comes to research on the pelvic floor, phonation, and the voice, A study she published in 2020 looked at the glottis and the pelvic floor via bladder displacement. So they used 2D ultrasound imaging and folks without pelvic floor dysfunction. She had participants in a standing position. We love that because most singers stand or most people when we’re talking, going about life, we’re either sitting in an upright position or likely standing. And she had participants, she cued them to do a pelvic floor contraction, to do a pelvic floor strain, as if they had to go to the bathroom. And she also gave them some cued phonation tasks, like saying, ah, for three seconds at different pitches. She also had them take a note and go from low to high. And then she had them do some grunting. She found that during the pelvic floor contraction, the bladder moved cranially, or upwards, and during straining, the bladder moved caudally, or downwards. This is what we would expect. Interestingly, for the phonation tasks, she found that the bladder displacement was significantly different than that that she saw with the pelvic floor contraction. And remember, with pelvic floor contraction, we tend to see more of a cranial displacement, but with these glottal tasks, she found there was more of a caudal displacement towards the feet. And again, that’s different from what we normally see with expiration. So this was some novel information about what’s happening with the pelvic floor during phonation. She also recently did, and Aliza did an interview in August 2023, and she talked about some of the research she’s currently conducting, still doing data collection, but she’s having folks without pelvic floor dysfunction say on one exhale, one, two, three, four. And what she’s finding is there again is a tendency towards pelvic floor lengthening that’s happening and there’s also this buoyant nature of the pelvic floor with a specific up and down response to each of those numbers. So again, that’s early data collection, but really cool to hear about what could be happening that’s a little different than what we would likely hypothesize with the pelvic floor and phonation. And to me, that buoyancy kind of likens to running. So in running, we know that with repeated impact, the pelvic floor is responding like a trampoline. It’s going up and down. It’s automatically doing this. And so this sounds to me very similar to that. Quiet respiration requires much lower subglottal pressure than phonation. So per Aliza’s work, in those without pelvic floor dysfunction, as subglottal pressure demand increases, with the task of voicing, the pelvic floor has an overall tendency towards lengthening and then potentially going up and down with each voicing. Clinically, we can use these results to coach and educate patients, maybe those who are pre-abdominal or pelvic surgery or during pregnancy. We can talk to them about what may happen to the pelvic floor if it’s unable to support those higher subglottal pressures that occur with certain phonation, like yelling or even singing. The pelvic floor system may give way in the form of urinary or fecal incontinence, pelvic pain, and feelings of heaviness. especially in that immediate phase, postpartum, vaginal delivery, or cesarean section because we just don’t quite have those muscles or that muscular support to help with managing the intraabdominal pressure. And now I want to wrap everything up because that was a lot of information. So in terms of respiration and phonation, We can agree that those are both very complex systems of the body that use a number of body structures that start from the glottis and make their way down to the pelvic floor. Respiration is the process of inhalation and exhalation. During inhalation, the vocal folds, stay open, the SEM and external intercostals lift, the diaphragm contracts, and descends down, the abdominal slightly expands, pelvic floor elongates. Exhalation is either passive or forced, and generally the reverse process. When it comes to phonation, there are four main pressure systems in place. The air pressure system, the vibratory system, the resonators, and the articulators. They all work together to create unique vocalization. During the exhalation portion of phonation, everything stays the same with the exception of those vocal folds, moving back and forth, opening and closing, and then the pelvic floor showing a tendency towards lengthening with a potential buoyant response to each individual vocalization. The inability to support the intrabdominal pressure generated by these tasks with higher sub throttle pressure, such as phonation, may result in pelvic floor dysfunction. Clinicians can use this data as a preliminary sounding board for blending the intricacies of the vocal respiratory and pelvic floor systems, especially when they’re treating someone who’s coming in for pelvic floor and or vocal dysfunction, as we eagerly await even more research for these systems. Thank you so much for listening. And if you all celebrate Thanksgiving, have a wonderful week.
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