Muscles lower jaw and tongue

Muscles That Move the Lower Jaw

Overview

• The muscles involved in the movement of the lower jaw and tongue play crucial roles in chewing, swallowing, and speaking.

Muscles That Move the Lower Jaw

1. Masseter Muscle:

   • Known as the "powerhouse of chewing."

   • Primary function: Elevates the mandible to close the mouth.

   • Location: Lateral surface of the face.

   • Functionality: Capable of exerting significant force to bite through tough foods, critical for breaking down food types from plants to meat.

2. Temporalis Muscle:

   • Assists the masseter muscle in closing the jaw.

   • Function: Retracts the mandible.

   • Location: Positioned on the side of the head.

   • Interaction: Feel contraction when chewing by placing fingers on the temple.

3. Medial Pterygoid Muscle:

   • Supports jaw closure by working with the masseter.

   • Function: Elevates the mandible and assists in grinding food.

   • Location: Inside of the jaw (deep within the oral cavity).

4. Lateral Pterygoid Muscle:

   • Functions in the protrusion of the mandible.

   • Allows for side-to-side movements during chewing and food manipulation.

   • Location: Also positioned inside the jaw, deep within the oral cavity.

Coordination of Muscles for Chewing

• The combination of masseter, temporalis, medial pterygoid, and lateral pterygoid muscles enables effective chewing.

• This intricate interplay optimizes digestion and nutrient extraction, showcasing adaptation to dietary needs.

Summary of Jaw Muscle Functions

• All muscles of mastication are located within the cheek and originate from skull processes, allowing for increased leverage during chewing.

Muscles That Move the Tongue

Overview

• The tongue is a versatile muscle essential for tasting, chewing, swallowing, and speaking.

• It comprises extrinsic and intrinsic muscles that contribute to its unique movements.

Extrinsic Tongue Muscles

1. Genioglossus Muscle:

   • Origin: Genial tubercles of the mandible.

   • Function: Allows the tongue to move downward and forward; essential for speech and swallowing.

2. Styloglossus Muscle:

   • Origin: Styloid process of the temporal bone.

   • Function: Moves the tongue up and back; aids in chewing and articulation.

3. Palatoglossus Muscle:

   • Origin: Soft palate.

   • Function: Elevates the back of the tongue; important in the swallowing process.

4. Hyoglossus Muscle:

   • Origin: Hyoid bone.

   • Function: Moves the tongue downward and flattens it; aids in precise movements for speech and chewing.

Intrinsic Tongue Muscles

• Origin: Entirely within the tongue, providing intricate shape changes.

• Function: Enable skilled movements such as rolling and flattening the tongue, crucial for phonetics in human language.

Coordination of Tongue Muscles

• The combined actions of extrinsic and intrinsic muscles allow complex tongue movements necessary for effective speech and swallowing.

• The remarkable adaptability of the tongue facilitates various functions, enhancing the sensory experience of eating.

Everyday Connection: Anesthesia and Tongue Muscles

• During general anesthesia, body homeostatic controls are paused, affecting muscles critical for breathing and tongue movement.

• The relaxed state of the tongue can block airways; hence, endotracheal intubation is performed to maintain an open airway.

• After surgery, breathing functions gradually restore, and patients often experience a sore throat.

Terms to Know

• Deglutition: The act of swallowing, moving food or liquid from the mouth to the stomach.

• Styloid Process: A bony projection on the temporal bone that serves as the origin for the styloglossus muscle.

• Protrusion: The action of pushing or extending a body part outward, such as the tongue.