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.

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