Larynx

The larynx, often called the voice box, is an important organ located in the top part of the neck. It helps us breathe, make sounds, and protect our airway. When we swallow, the larynx works to stop food from going down the wrong way into our trachea, which is the tube that leads to our lungs.

The larynx has a special opening into the pharynx, called the laryngeal inlet, and this opening is usually about as wide as four to five centimeters across. Inside the larynx are the vocal cords, which vibrate to create our voice. The larynx can change both the pitch and volume of sounds, which is very important for speaking, singing, and other kinds of communication known as phonation.

It sits just below the point where the pharynx splits into two tubes: the trachea, which carries air to the lungs, and the esophagus, which carries food to the stomach. This special position helps the larynx do its jobs well.

Structure

The larynx, also called the voice box, is a triangle-shaped organ in the upper neck. It is made of special tissues called cartilages, connected by muscles and elastic material. Inside, there are two sets of folds. The upper folds are called vestibular folds or false vocal cords because they do not help with making sounds. The lower folds are the true vocal cords, which are needed for speaking and making other sounds. The space between the vocal cords is called the rima glottidis, and together with the vocal cords, it is known as the glottis.

The larynx sits in the front of the neck in adults, connecting the lower part of the throat to the windpipe. It is made of nine pieces of cartilage, three single and three pairs. These include the thyroid cartilage, which forms the Adam's apple, and the cricoid cartilage, which sits below it and connects to the windpipe. The epiglottis, a spoon-shaped piece of cartilage, helps keep food from entering the windpipe when swallowing.

The muscles inside the larynx help control the vocal cords for making sounds and for breathing. Some muscles pull the vocal cords apart for breathing, while others bring them together for speaking.

The larynx gets its nerve signals from branches of the vagus nerve. In children, the larynx starts higher in the neck and moves down as they grow.

Laryngeal cavity

The laryngeal cavity is the space inside the voice box. It goes from the top opening down to where it meets the windpipe, or trachea.

This space has two parts, split by the vocal folds. There is a small opening between them called the rima glottidis. The upper part is called the laryngeal vestibule. It is wide and triangle-shaped and has the vestibular folds. Below the vocal folds is the infraglottic cavity. It starts oval but gets wider and circular as it joins the trachea.

Function

The larynx, also called the voice box, helps us make sounds and protect our lungs. It is located at the top of the neck. When we speak, the larynx makes sounds and changes their pitch and loudness. The air we breathe out from our lungs also helps make our voice louder.

The larynx has special parts called vocal cords that can come close together to vibrate and make sound. These cords can change how tight they are and their length, which changes the pitch of our voice. During swallowing, the larynx moves to stop food or liquid from going into the lungs, helping keep us safe. It also helps us cough to clear our throat and can support us when we lift heavy objects.

Clinical significance

Disorders

The larynx can sometimes have trouble working properly. This might cause symptoms like hoarseness, losing your voice, sore throat or ears, or trouble breathing.

Some common issues include:

• Acute laryngitis: sudden swelling of the larynx from a cold or shouting.
• Chronic laryngitis: swelling from smoking, dust, yelling, or polluted air.
• Presbylarynx: age-related voice weakening.
• Ulcers: sores from long-term use of a breathing tube.
• Polyps and vocal cord nodules: small bumps from smoking or shouting.
• Two types of cancer of the larynx linked to smoking and drinking.
• Vocal cord paresis: weakness in the voice cords.
• Laryngopharyngeal reflux: stomach acid irritating the larynx, similar to gastroesophageal reflux disease (GERD).
• Laryngomalacia: a common condition in babies where the larynx collapses inward during breathing.
• Laryngeal perichondritis: inflammation causing breathing trouble.
• Laryngeal paralysis: when the larynx doesn’t open fully, affecting breathing, seen in some animals like dogs.

Treatments

When someone cannot use their larynx, they may use a special device called an electrolarynx to help them speak.

Larynx transplants are very rare. The first successful operation happened in 1998 at the Cleveland Clinic in Cleveland, Ohio, USA, and the second was done in 2010 at the University of California Davis Medical Center in Sacramento, California, USA.

Other animals

British scientist Victor Negus studied the larynx in the 1920s. He learned that the larynx moves as the tongue grows and settles into the throat, a process that ends around age six to eight. Some scientists think the human tongue helps shape the airway above the larynx, making our speech clearer. This helps us say sounds like those in "see" and "do" more easily.

Other animals also have a larynx, but it is usually simpler than ours. Frogs use their larynx to make calls, especially when looking for mates. Birds make sounds using a different organ called the syrinx. Many reptiles and amphibians lack vocal folds, so they cannot make complex sounds like humans and some lizards can.

History and etymology

The ancient Greek doctor Galen was the first to describe the larynx. He called it the most important tool for making voice sounds.

The word larynx comes from an old Greek word, λάρυγξ (lárunx), which means "larynx, gullet, throat".

Additional images

Larynx. Deep dissection. Anterior view.

Larynx. Deep dissection. Posterior view.