What is the Difference Between Suprahyoid and Infrahyoid Muscles

The key difference between suprahyoid and infrahyoid muscles is that suprahyoid muscles are the group of muscles that lie superiorly to the hyoid bone in the neck, while infrahyoid muscles are the group of muscles that lie inferiorly to the hyoid bone in the neck.

The hyoid bone is a ‘U’ shaped bone located in the interior neck. Structurally, hyoid bone has five major parts: a body (central part of the bone), two greater horns and two lesser horns. The elevation of the hyoid bone facilitates swallowing. Hyoid bone also acts as a muscle attachment site in the neck. Movements of hyoid bone alter the size and shape of the upper airway. Suprahyoid and infrahyoid muscles are two types of muscles attached to the hyoid bone. Suprahyoid muscles lie above the hyoid bone, while infrahyoid muscles lie beneath the hyoid bone. These muscles play very important roles in stabilizing the trachea, swallowing, and speech.

CONTENTS

1. Overview and Key Difference
2. What are Suprahyoid Muscles
3. What are Infrahyoid Muscles
4. Similarities – Suprahyoid and Infrahyoid Muscles
4. Suprahyoid and Infrahyoid Muscles in Tabular Form
5. Summary – Suprahyoid vs Infrahyoid Muscles

What are Suprahyoid Muscles?

Suprahyoid muscles are a group of muscles located above the hyoid bone of the neck. These muscles are attached superiorly to the hyoid bone. The facial artery supplies blood to suprahyoid muscles. There are four muscles belonging to suprahyoid muscles. They are digastric, stylohyoid, geniohyoid, and mylohyoid muscles. These muscles are also known as accessory muscles of mastication since they are mainly involved in mastication and swallowing. Other than that, digastric, mylohyoid and geniohyoid muscles contribute to the floor of the mouth.

Figure 01: Suprahyoid Muscles

Suprahyoid muscles attach the mandible to the hyoid bone and help in lowering the mandible. Moreover, suprahyoid muscles elevate the hyoid bone. Since the larynx is also attached to the hyoid bone, suprahyoid muscles are responsible for elevating the larynx as well.

What are Infrahyoid Muscles?

Infrahyoid muscles are a group of muscles located inferiorly to the hyoid bone in the neck. They are four infrahyoid muscles: omohyoid, sternohyoid, sternothyroid and thyrohyoid. These muscles are strap-like muscles, and they help to depress the hyoid bone.

Figure 02: Infrahyoid Muscles

When compared to suprahyoid muscles, infrahyoid muscles act antagonistically, depressing the hyoid bone in the actions of swallowing and speech. Infrahyoid muscles attach hyoid bone to the sternum, larynx and scapula.

What are the Similarities Between Suprahyoid and Infrahyoid Muscles?

  • Both suprahyoid and infrahyoid muscles are comprised of four muscles in each type.
  • They are found near the hyoid bone in the neck.
  • Both muscles are responsible for the positioning of the hyoid bone.
  • They are involved in swallowing and speech.

What is the Difference Between Suprahyoid and Infrahyoid Muscles?

Suprahyoid muscles are a group of muscles that lie superiorly to the hyoid bone, while infrahyoid muscles are a group of strap-like muscles that lie inferiorly to the hyoid bone. So, this is the key difference between suprahyoid and infrahyoid muscles. Moreover, suprahyoid muscles include the digastric, geniohyoid, mylohyoid, and stylohyoid, while infrahyoid muscles include the omohyoid, sternohyoid, sternothyroid, and thyrohyoid. Besides, cranial nerves innervate suprahyoid muscles. In contrast, ansa cervicalis and C1 axons travel with the hypoglossal nerve innervate infrahyoid muscles.

The below infographic lists the differences between suprahyoid and infrahyoid muscles in tabular form for side by side comparison.

Summary – Suprahyoid vs Infrahyoid Muscles

Suprahyoid and infrahyoid muscles are two groups of neck muscles that are responsible for positioning the hyoid bone in the neck. Suprahyoid muscles lie above the hyoid bone, while infrahyoid muscles lie beneath the hyoid bone. There are four suprahyoid muscles: mylohyoid, geniohyoid, stylohyoid, and digastric muscles. There are four infrahyoid muscles: sternohyoid, omohyoid, sternothyroid, and thyrohyoid muscles. Suprahyoid muscles help in elevating the hyoid bone, while infrahyoid muscles help in depressing the hyoid bone. Thus, this is the summary of the difference between suprahyoid and infrahyoid muscles.