The Anatomy of Sleep Apnea

Features of Airway, Face May Play a Key Role in Disrupted Breathing

The lungs and airway are visualized in a man with sleep apnea. Science Picture Co/Collection Mix: Subjects/Getty Images

Obstructive sleep apnea is a common condition, and your anatomy may predispose you to it. What kind of features might your doctor observe that could increase your risk of having the condition? Learn how your anatomy might lead to sleep apnea and what factors, both within and beyond your control, might contribute to it. 

Understanding Sleep Apnea in its Context

When sleep apnea occurs because of the collapse of the upper airway, anatomy has a significant role to play.

This obstruction may occur within the nose or, more often, at the back of the mouth and throat. The soft tissues of the palate, tonsils, adenoids, and tongue may relax and fall into the airway and temporarily close it off. As a result, your sleep is disrupted as you have to partially awaken to resume breathing. During these episodes, the effort to breathe continues with movement of the chest and abdomen observed, yet the airway tube is blocked. This may cause a reduced airflow, called hypopnea, or an entirely absent airflow, called apnea.

In considering the airway as a long tube that extends from the tip of the nose to the lungs, it is easy to understand how collapse at multiple points along its path may contribute to sleep apnea. Therefore, a proper understanding of the role of your anatomy can be helpful to unravel why you may experience the condition. It also sheds light on why sleep apnea can begin in childhood and persist throughout life.

Evaluating Your Anatomy and Risks of Sleep Apnea

It is clear that multiple factors may predispose an individual to sleep apnea. Although we may picture an obese, middle-aged man when we think of someone with sleep apnea, this may not always be the case. In fact, anatomical features may predispose people of healthy weight, the young, and even women.

Consider some of the contributing factors based on a careful physical examination by your doctor:


Okay, so you can’t set aside this as an obvious risk factor. Gaining weight can worsen the condition, even if your anatomy also has a role. The additional fat (or adipose) tissue can deposit, crowd, and narrow the airway. A large stomach may press upon and diminish the volume of our lungs. The weight on our chest can also fall backwards and collapse the throat when we lie on our backs. In fact, obesity in combination with sleep apnea may lead to obesity hypoventilation syndrome. In this syndrome, carbon dioxide is retained overnight and this can lead to morning headaches, confusion, and other problems. Weight loss, especially 10% or more, can improve the degree or presence of sleep apnea. Start by assessing your body mass index. If it is elevated, focus on diet and exercise to reduce the risk.

Neck Size

Being overweight or obese can cause enlargement of the size of your neck.

This, in turn, can contribute to sleep apnea. This additional girth may collapse the airway, especially when sleeping on your back. Gravity will push these tissues downward and cause the obstruction that characterizes sleep apnea. In general, this is considered a risk factor when the neck is larger than 16 inches (40 cm) in women and 17 inches (43 cm) in men. 

Nasal Septum and Enlarged Turbinates

To evaluate snoring and sleep apnea, it is important to look to your nose. Snoring occurs due to vibration of soft tissues, often at the throat. If you can’t breathe well through your nose, you are more likely to breathe through your mouth. This can lead to a dry mouth at night, louder snoring, and a higher risk of sleep apnea. 

People with a deviated nasal septum may have difficulty breathing through the nose. The septum is a midline piece of cartilage that separates the left and right nasal passages. In addition, the nose goes through a process called the nasal cycle, alternating sides through which you breathe. As a result, when the cycle shifts to the obstructed side, it can be harder to breathe through the nose and sleep-disordered breathing may occur. A deviated nasal septum may be present from birth or occur secondary to trauma. It can be corrected with surgery called septoplasty.

Another potential source of nasal obstruction are nasal turbinates. These shelves of tissue are present at three levels within the nose. They serve to warm and moisten the air that enters the body. In addition, they may capture allergens. Among those with allergies, these tissues can swell and block the nose. The lower set of turbinates can be observed from the nostrils, but the higher ones cannot be visualized without a piece of equipment called an endoscope. These tissues may be reduced with saline, steroid sprays (Flonase, Astelin, Nasonex, etc.), or with a minor surgical procedure called radiofrequency ablation.


When peering into the mouth, it is important to look up to assess another risk factor for sleep apnea: the palate. The roof of the mouth is divided into the hard palate and soft palate. The hard palate is towards the front of the mouth with a bony support. The roof of the mouth is the floor of the nasal cavity. Therefore, a high and arched palate may lead to less space within the nose. This can reduce airflow. If the airway is a tube for air, it can collapse more easily when the amount of air traveling through it is reduced.

In addition, the soft palate towards the back of the mouth may have a role. This tissue may be excessive. It can be redundant, appearing like draped fabric. With snoring and sleep apnea, the soft palate can also become red and swollen, making matters worse. Surgery can target and remove this tissue to varying degrees of success.

Tonsils and Adenoids

Enlarged tonsils can have a significant role in sleep apnea, especially among children. In fact, this has historically been a major factor in children aged 4 to 8 years old with the condition. Their airways are proportionally smaller and large tonsils can lead to obstruction, snoring, and sleep apnea. The treatment of choice, when these swollen tissues are present, is tonsillectomy. In addition, associated tissues within the throat called adenoids may also be removed.


The final component within the mouth is equally important: the tongue. A large, wide, or elongated tongue may be a sign of sleep apnea. It may fall back into the airway and block it off during sleep. Macroglossia may be present in certain disorders, such as Down’s syndrome. The tongue rests in the lower jaw and when the mandible is recessed, there is less space for the tongue to sit. As a result, its edge can be pressed into the teeth, leading to a phenomenon called tongue scalloping (imagine the scalloped edge of a seashell). Therefore, the structure of the jaws are also important to consider. Surgical debulking of the base of the tongue can be done, but it is commonly avoided. Treatment with a hypoglossal nerve stimulator may also be helpful.

Jaw Structure: The Maxilla and Mandible

If the jaws are set too far back within the skull, this can compromise the space of the airway. The upper jaw, called the maxilla, is often recessed among Asian ethnicities, increasing the risk of sleep apnea. As an example, it is estimated that 15% of Chinese people have sleep apnea, compared to less than half that rate among Caucasians. In addition, a small (micrognathia) or recessed (retrognathia) lower jaw, or mandible, can also contribute to sleep apnea due to its impact on the position of the attached tongue. Surgical advancement of the jaws forward can be highly effective, especially in late adolescence.

Treatments Effective Despite Anatomy Features

If you are concerned that your anatomy might contribute to your risk of sleep apnea, consult with your doctor and seek evaluation by a sleep specialist. As these features often run in families, if you have been diagnosed with sleep apnea you might consider the signs of sleep apnea in your children. These fixed structural features may make it a chronic condition, but there are surgical treatment options available in select cases. Though some elements may be beyond your control, the good news is that sleep apnea is treatable.


Kryger, MH et al. "Principles and Practice of Sleep Medicine." Elsevier. 5th edition. 2011.

The International Classification of Sleep Disorders. American Academy of Sleep Medicine. 2nd edition. 2005.

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