Head and Neck Anatomy: Muscles and Vasculature

Key Muscles of the Head and Neck

  • Masseter Muscle:
      - Origin: Maxilla and zygomatic bones (cheekbones).
      - Insertion: Mandible (bottom corner of the jawbone).
      - Function: Elevates the mandible to help close the mouth and aid in chewing.

  • Sternocleidomastoid Muscle:
      - Origin: Paired muscle with two heads; sternal head from the manubrium of the sternum and clavicular head from the medial third of the clavicle.
      - Insertion: Mastoid process of the temporal bone and occipital bone.
      - Functions:
        - Bilateral contraction: Neck flexion (bringing the chin toward the chest).
        - Unilateral contraction:
          - Lateral flexion (bringing the ear to the shoulder).
          - Opposite side rotation (turning the head away from the contracting muscle).

Arterial Blood Supply to the Head and Neck

  • Aorta: The main vessel where blood exits the heart.

  • Brachiocephalic Artery: First branch of the aorta; splits into:
      - Right Subclavian Artery: Supplies blood to the right upper arm.
      - Right Common Carotid Artery: Supplies blood to the right side of the neck.

  • Left Common Carotid Artery: Directly branches from the aorta to supply the left side of the neck.

  • Left Subclavian Artery: Directly branches from the aorta to supply the left arm.

Venous Drainage of the Head and Neck

  • Brachiocephalic Veins: Return blood to the heart from the arms and head.

  • Subclavian Veins: Drain blood from the arms.

  • Internal Jugular Veins: Return blood from the brain, face, and neck.

  • External Jugular Veins: Return blood from the scalp, face, mouth, and neck.