Lecture Notes: Muscles of the Head and Neck

Key Muscles of the Face

Orbicularis Oculi

• Circular muscle around the orbit of the eye.
• Function: Closes the eye.

Frontalis

• Also known as the frontal belly of the occipital frontalis muscle.
• Location: Over the frontal bone.
• Function: Raises the eyebrows.

Orbicularis Oris

• Circular muscle around the mouth.
• Function: Compresses the lips.

Zygomaticus (Major and Minor)

• Function: Retracts and elevates the upper lip and corners of the mouth.
• Associated with smiling.
• Location: Near the zygomatic bone (cheekbone).

Lateral View of the Head

Epicranial Aponeurosis

• Connects frontal and occipital bellies of the occipital frontalis muscle.

Occipitalis

• Location: Over the occipital bone.
• Function: Retracts the scalp.

Muscles of Mastication

Temporalis

• Location: Over the temporal bone.
• Function: Elevates the mandible during chewing (mastication).

Masseter

• Connects the upper and lower jaw.

• Function: Elevates the mandible during chewing.

• Notes: Very powerful muscle.

• Note: Both temporalis and masseter elevate the mandible. Lowering is assisted by gravity.

Additional Muscles

Buccinator

• Function: Compresses cheeks (important for blowing and chewing).
• Role: Compresses cheeks against teeth during chewing.

Platysma

• Description: Thin, plate-like muscle on the front of the neck.
• Function: Tenses the skin of the neck.
• Notes: Often unnoticed unless injured (e.g., whiplash).

Sternocleidomastoid

• Origins: Sternum (sterno), clavicle (clido).
• Insertion: Mastoid process.
• Functions:
  • Flexes the neck when both sides contract.
  • Rotates the neck when one side contracts.

Conclusion

• These are the key muscles of the head and neck to be familiar with.

End of Lecture