What to know about the sternothyroid

The sternothyroid muscle is present in the front region of the neck. It is part of the infrahyoid muscle group and aids functions such as swallowing and speech.

Certain health conditions may affect the sternothyroid muscle, or the infrahyoid muscle group, and can result in speaking, chewing, and swallowing difficulties.

This article explores the anatomy and functions of the sternothyroid and conditions that may affect the muscle.

Definition

The sternothyroid muscleTrusted Source is part of the infrahyoid muscle groupTrusted Source of the neck, along with the:

• omohyoid muscle
• sternohyoid muscle
• thyrohyoid muscle

The infrahyoid muscles are an anterior neck muscle group, which means they are present at the front of the neck. Some people may also refer to the infrahyoid muscle group as the strap musclesTrusted Source. This name refers to the muscles having a long and flat shape, similar to a belt or strap.

Anatomy

The sternothyroid muscleTrusted Source makes up a layer of the infrahyoid muscles, along with the thyrohyoid muscle. The sternohyoid and omohyoid muscles make up the superficial, or top, layer of the infrahyoid muscle group.

The sternothyroid attachesTrusted Source to the upper portion of the sternum, also known as the breastbone, and the thyroid cartilage, also known as the Adam’s apple. It overlies the superior, or upper, portion of the thyroid gland. The thyroid is a butterfly-shaped gland that sits in the front of the neck. It is responsible for regulating metabolism by producingTrusted Source substances such as thyroid hormones.

Connective tissue joins the sternothyroid and sternohyoid muscles. Doctors may refer to these two muscles as paired muscles. During some forms of surgery, a doctor may cut through this tissue. A surgeon will typically attempt to separate the left- and right-sided muscles but divide the connective tissue between them and spread them sideways.

Function

The role of the sternothyroid muscle is to depress the hyoid boneTrusted Source and the larynxTrusted Source during speech and swallowing, along with the other infrahyoid muscles. The hyoid boneTrusted Source refers to a small U-shaped bone, and the larynxTrusted Source is often known as the voice box. As such, the sternothyroid muscle plays a role in speaking, swallowing, and chewing by supporting and moving these structures.

The sternothyroid muscle, along with the other muscles of the infrahyoid muscle group, also contributes to protecting other important structures in the neck, such asTrusted Source:

• the esophagus
• blood vessels
• the thyroid gland
• the trachea

Health conditions  

• Conditions involving the sternothyroid muscle or the infrahyoid muscle group may affect various body functions, including speaking, chewing, and swallowing.

Dysphagia

• Dysphagia is the medical term to describe swallowing difficulties. A person who experiences dysphagia may have weaknessTrusted Source in the infrahyoid muscles, including the sternothyroid muscle. However, this is one of many possible causes of dysphagia, and isolated weakness of these muscles is quite rare.

Speaking difficulties

• Certain muscle conditions may result in the muscles of the neck region experiencing an imbalance in tension and causing issues with speech.

  Muscle tension dysphonia is a condition that causes the sound of a person’s voice to change and become difficult to understand. This results from excessive tension in the extrinsic muscles, such as the infrahyoid muscle group.

  This causes the larynx to have an improperTrusted Source position and creates tension in the vocal folds. Not only can this cause a change in a person’s voice, but it can also cause issues with swallowing and breathing and result in tenderness in the neck.

Masses in neck

• A leiomyomaTrusted Source, also known as a fibroid, is a type of smooth muscle tumor that presents more commonly in premenopausal females. Evidence suggests that approximately 12%Trusted Source of leiomyomas occur in the head and neck region. However, leiomyomas in the sternothyroid, or other strap muscles, are extremely rare. A person with leiomyoma in their sternothyroid muscle may feel a mass in their neck. The size of the mass may vary.

Muscle paralysis

• The ansa cervicalisTrusted Source describes a neural loop that supplies nerves to the sternothyroid, omohyoid, and sternohyoid muscles. As such, injury to the ansa cervicalis may result in infrahyoid muscle weakness or paralysis. A person with an ansa cervicalis injury may experience symptoms such asTrusted Source:

  • a hoarse voice
  • difficulty swallowing
  • tightness in the throat

  Injury may occur to the ansa cervicalis following surgery or due to trauma to the head or neck region.

Thyroid issues

• Some people may experience issues with their thyroid gland, including underactivity — hypothyroidism — or overactivity — hyperthyroidism. Muscle weakness can occur with both conditions, which may impact the sternothyroid. In some people, the thyroid gland may swell and enlarge. This is known as a goiter. Hypothyroidism and hyperthyroidism can both cause goiter.

  Goiter may affect the sternothyroid muscle as well as the other muscles of the infrahyoid muscle group. It may also compress other structures, such as the esophagus. A person with a goiter may experienceTrusted Source:

  • difficulty swallowing
  • a hoarse voice
  • a choking sensation
  • coughing
  • shortness of breath

Summary

• The sternothyroid is a muscle present at the front of the neck. It is one of the muscles that form the infrahyoid muscle group. The sternothyroid helps depress the hyoid bone and larynx, meaning it aids functions such as swallowing, speaking, and chewing. It also protects other important structures in the neck.

  Certain conditions may affect the sternothyroid, which can result in difficulty with swallowing, speaking, and chewing.

• Source - Medical News Today