Infrahyoid muscles

Infrahyoid muscles are a group of four muscles located beneath the hyoid bone in the neck. These muscles include the sternohyoid, omohyoid, sternothyroid, and thyrohyoid muscles. They are primarily responsible for the downward movement of the hyoid bone and larynx during swallowing and speech.

Anatomy

The infrahyoid muscles are situated in the anterior part of the neck, beneath the hyoid bone. They are divided into two groups: the superficial group, which includes the sternohyoid and omohyoid muscles, and the deep group, which includes the sternothyroid and thyrohyoid muscles.

Sternohyoid

The sternohyoid muscle is a thin, narrow muscle attaching the hyoid bone to the sternum. It functions to depress the hyoid bone after it has been elevated during swallowing.

Omohyoid

The omohyoid muscle, named for its two bellies separated by an intermediate tendon, extends from the upper border of the scapula to the lower border of the hyoid bone. It aids in lowering the hyoid bone and larynx during swallowing and speech.

Sternothyroid

The sternothyroid muscle is a wide, thin muscle that lies under the sternohyoid muscle. It depresses the thyroid cartilage and plays a crucial role in vocal pitch modulation.

Thyrohyoid

The thyrohyoid muscle, located above the sternothyroid, depresses the hyoid bone and elevates the larynx, playing a significant role in speech and swallowing.

Function

The primary function of the infrahyoid muscles is to depress the hyoid bone and larynx during swallowing and speech. This action helps in the opening of the esophagus, allowing food and liquid to pass into the stomach. Additionally, these muscles play a role in the modulation of vocal pitch.

Clinical significance

Dysfunction or injury to the infrahyoid muscles can lead to difficulties in swallowing and speech. Conditions such as dysphagia (difficulty swallowing) and dysphonia (voice disorders) may occur if these muscles are affected.

See also

• Hyoid bone
• Swallowing
• Speech
• Dysphagia
• Dysphonia

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