Anatomy and Physiology Series: Anatomy of Forced Exhalation

As discussed earlier, expiration is mainly the result of passive forces, but during speech (and singing), expiration requires more muscular effort.  This is referred to as "forced exhalation."  I'm going to talk a lot about the physiology in the next post, but first, let's get ourselves grounded in what muscles are involved.


The first group I'll introduce are...*drum roll*...the abdominal muscles!  This should come as no surprise to the experienced singer, but let's still go over where they are and what they do.  The abdominal muscles as a group are involved with changing the vertical dimension of the thorax through affecting the movement of the diaphragm.  (It'll go lower with relaxed abdominal muscles, and higher, faster with contracted abdominal muscles on the exhale.)  If you've ever wondered what the abdominals attach to, I would recommend reading about the abdominal aponeurosis.  (I'm not going to cover that here in the interest of space.)  So here are the muscles we'll go over: The internal and external oblique abdominis, transverse abdominis, and the rectus abdominis on the anterior (front) part of the body.  The posterior (or back) ones include the quadratus lumborum iliacus and psoas major and minor.  (Some say the latissimus dorsi muscles are also involved, but there is currently some doubt to this claim, so I'm excluding it here.)  I'm going to cover these muscles in this order:  Anterior first, going from the deepest muscle (furthest in the body) to the most superficial; then, we will cover the posterior muscles.


The deepest and most powerful abdominal muscle is the transverse abdominis.

This muscle originates from the posterior abdominal wall at the vertebral column and inserts into the abdominal aponeurosis and the inner surface of ribs 6-12.  It is here, at ribs 6-12 that this muscle, here's a fancy term for ya, interdigitates (or interconnects) with the fibers of the diaphragm.  It's lowest attachment is the pubic bone.  Contraction of this muscle significantly reduces the volume of the abdomen.  (It's the "sucking in the tummy" muscle, and it's a pretty powerful one.  Not the origin of your desired "six pack," though, since it's too deep in the body to see outlined through the skin.)


Next, the internal oblique abdominis, and it's between the external oblique and the transverse abdominis.  

It's origin is from the iliac crest and it inserts into the cartilaginous portion of the lower ribs.  If you want to rotate your trunk, this muscle contracts on one side of the body, but if you contract both sides, it flexes the trunk ("curls" your back) and compresses the abdomen.  


The external obliques are the most superficial of the abdominal muscles, meaning they are the closest to your skin.  They are also the largest of the abdominal muscle group (but not the most powerful, that's still the transverse abdominis).  

Contraction of these guys can rotate the trunk as well and can compress the abdomen and vertebral column by contracting both sides.  


The rectus abdominis muscles are the "six pack abs" group.  (You can see them as the "rectangular" muscles in white in the picture above.)  Contraction results in flexing the vertebral column.


The first posterior abdominal to discuss is the quadraus lumborum pictured in red here:

These muscles originate from the iliac crest and insert into the lumbar vertebrae and rib 12.  It assists you if you move your trunk laterally (ala salsa dancing), and contraction on both sides fixes the abdominal wall in support of compression (ala my yoga instructor's directions for a good hand stand...still working on that one).  


Psoas major and minor are relatively smaller muscles hanging out around the pelvic area.  If they assist with exhalation, they are similar to the quadratus lumborum.


Other muscles of forced exhalation are mainly involved in decreasing the size of the rib cage.  These include the internal and innermost intercostals, transversus thoracis, subcostals, and serratus posterior inferior.  


The internal intercostals are deep to the external intercostals and their fibers run perpendicular to the external intercostals.  These guys depress ribs 1-11.  The innermost intercostals are actually a separate group.  There are the deepest of the intercostal muscles.  They run parallel to the internal intercostals and also depress ribs 1-11.  

The transverse thoracis originate at the sternum and insert into the inside of the rib cage.  This muscle group also depresses the rib cage...big surprise, huh?  Shown in red below (the sternum is seen on your right):

Posterior thoracic muscles include the subcostals.  These guys run similarly to the internal intercostals, but they can span more than one rib depending on the person.

The serratus posterior inferior originate from the spinous process of thoracic vertebrae #11, 12 and lumbar vertebrae 1-3.  They insert into the lower five ribs and also aid in pulling the rib cage down.

If you're still awake, congratulations!  You've now entered full-on voice-science geek status.  (just kidding).  But seriously...although I won't go so far into detail during the physiology discussion, I believe it is very important to not only understand how inhalation and exhalation work from a biological standpoint, but it is also important to know how complex the act really is.  It involves a very complex muscular coordination that, for the most part, all goes on in the "background" of a person's brain function.  It is because this process usually happens automatically for most people during speech that I believe the training of "breath support" can become an incredibly frustrating endeavor for the professional voice user, and it can be equally frustrating for a voice teacher to explain in a 60 minute lesson.  

The singing world is full of many "schools" of breath support and navigating those schools can be very frustrating for the student of pedagogy.  I believe having a more thorough knowledge of the known functionality and coordination of breathing for speech can be incredibly useful when navigating the more abstract ideas for breath support.  

So there's my soap-box for today!  Onward to physiology of exhalation!

*Re-citing:  Much of my material is coming from:  Seikel, J. A., King, D. W., & Drumright, D. G. (2010). Anatomy and physiology for speech, language, and hearing. Clifton Park, NY: Delmar.