GENERAL INFORMATION
The geniohyoid muscle is a small, narrow muscle located above the mylohyoid, running from the chin (genial tubercle) to the hyoid bone. This muscle plays a crucial role in jaw movement, swallowing, and stabilising the hyoid bone. It assists in depressing the mandible (lowering the jaw) and elevating the hyoid bone during swallowing, making it an essential muscle for smooth oral function. The geniohyoid is part of the suprahyoid group of muscles. Which supports the floor of the mouth and helps coordinate activities such as chewing, swallowing, and speech.
ORIGIN
The geniohyoid muscle originates from the inferior mental spine (genial tubercle) of the mandible, located on the inside surface of the lower jaw.
INSERTION POINT
It inserts into the anterior surface of the body of the hyoid bone, just above where the hyoid connects to other suprahyoid muscles.
MAJOR ARTERIES
- Lingual Artery: Provides the primary blood supply to the geniohyoid muscle.
- Submental Artery: Also contributes to blood flow, ensuring oxygen and nutrients reach the geniohyoid muscle.
NEURAL INNERVATION
- Hypoglossal Nerve (Cranial Nerve XII): Innervates the geniohyoid muscle via branches of the C1 spinal nerve.
TRIGGER POINT
Trigger points in the geniohyoid muscle can cause pain and discomfort under the chin and jaw, particularly during swallowing or speaking. This trigger point can lead to tension in the throat and tightness when trying to lower the jaw or raise the hyoid bone. Trigger points may also contribute to referred pain in the neck or lower face.
CONCENTRIC FUNCTION
During concentric contraction, the geniohyoid muscle shortens to elevate the hyoid bone and depress the mandible, aiding in opening the mouth and facilitating swallowing.
ECCENTRIC FUNCTION
In eccentric contraction, the geniohyoid muscle lengthens while controlling the gradual lowering of the jaw and the return of the hyoid bone to its resting position. This function helps regulate smooth and controlled movement when closing the mouth after speaking or swallowing.
ISOMETRIC FUNCTION
The geniohyoid can stabilise the hyoid bone and lower jaw during isometric contraction, keeping them in a fixed position during sustained activities such as speaking, swallowing, or holding the mouth open.
RELATED MUSCLES – SCIENTIFIC NAMES
- Mylohyoid Muscle: Assists in elevating the hyoid bone and forms the floor of the mouth.
- Digastric Muscle: Elevates the hyoid and helps open the mouth.
- Stylohyoid Muscle: Elevates and retracts the hyoid bone during swallowing.
- Hyoglossus Muscle: Depresses the tongue and aids in swallowing and speech.
ANTAGONIST
- Masseter Muscle: Opposes the geniohyoid by elevating the mandible and closing the mouth during chewing.
- Temporalis Muscle: Acts as an antagonist by elevating and retracting the jaw during mastication (chewing).
COMMON INJURIES
- Geniohyoid Muscle Strain: Overuse or strain of the geniohyoid muscle, especially due to excessive speaking or chewing, can lead to discomfort and tension under the chin and jaw.
- Tmj Dysfunction: Dysfunction in the temporomandibular joint can lead to overcompensation by the geniohyoid, causing tension and pain during jaw movement.
- Swallowing Difficulties (Dysphagia): Strain or dysfunction in the geniohyoid muscle may result in discomfort or difficulty during swallowing, particularly when elevating the hyoid bone.
- Jaw Pain: Tightness or trigger points in the geniohyoid can contribute to pain in the jaw and under the chin, making it difficult to fully open or close the mouth.
- Neck Tension: Prolonged tension in the geniohyoid can contribute to neck stiffness and difficulty coordinating jaw movements during speech and swallowing.
EXERCISES
- Tongue Press Exercise: Press your tongue firmly against the roof of your mouth and hold for 5-10 seconds. This exercise strengthens the geniohyoid muscle, improving jaw movement and swallowing function.
- Chin Tuck Exercise: Gently tuck your chin towards your neck, engaging the geniohyoid muscle while improving neck posture and strengthening the muscles involved in swallowing.
- Jaw Opening Resistance: Place your hand under your chin and press lightly as you try to open your mouth. This exercise strengthens the geniohyoid and enhances control over jaw movements.
- Isometric Jaw Hold: Open your mouth halfway and hold for a few seconds, maintaining tension in the geniohyoid muscle. This exercise improves muscle endurance and stability.
- Neck Flexion With Resistance: Lie on your back and gently lift your head towards your chest while engaging the geniohyoid. This exercise strengthens the neck and improves control over swallowing.
STRETCHES
- Geniohyoid Stretch: Tilt your head back gently while opening your mouth wide. This stretch helps release tension in the geniohyoid and the muscles at the front of the neck.
- Jaw Stretch: Open your mouth as wide as possible, hold it for a few seconds, and then close it slowly. This stretch releases tightness in the geniohyoid muscle and improves jaw flexibility.
- Neck Side Stretch: Gently tilt your head towards one shoulder, holding for 20-30 seconds to release tightness in the geniohyoid and surrounding muscles.
- Chin-To-Chest Stretch: Tuck your chin towards your chest and hold for 10-15 seconds to stretch the back of the neck and release tension in the front of the neck, including the geniohyoid.
- Upper Trapezius Stretch: Sit or stand and gently tilt your head towards one shoulder while pulling your opposite shoulder down. This stretch helps relieve tension in the neck and jaw, benefiting the geniohyoid muscle.
