Muscles of the head and neck

Muscles of the Neck, Head, and Back

Muscles of the Anterior Neck

  • Crucial muscles involved in swallowing and speech

    • Control positions of the larynx and hyoid bone

  • Key anatomical structures:

    • Hyoid Bone: Provides a stable base for tongue movement

    • Thyroid Cartilage: Part of the larynx

    • Thyroid Gland: Endocrine gland located in the anterior neck

    • Suprahyoid Muscles: Muscles above the hyoid bone, elevate hyoid and larynx during swallowing

    • Inferior Muscles: Muscles below the hyoid bone, depress hyoid and control larynx position

Suprahyoid Muscles

  1. Digastric Muscle

    • Consists of anterior and posterior bellies, elevates hyoid and larynx, depresses mandible

  2. Stylohyoid Muscle

    • Moves hyoid bone posteriorly, elevates the larynx

  3. Mylohyoid Muscle

    • Elevates hyoid bone, presses tongue against the roof of the mouth

  4. Geniohyoid Muscle

    • Raises hyoid bone, depresses mandible

Infrahyoid Muscles

  1. Omohyoid Muscle

    • Composed of superior and inferior bellies, depresses hyoid bone

  2. Thyrohyoid Muscle

    • Elevates the thyroid cartilage of the larynx

  3. Sternothyroid Muscle

    • Depresses the thyroid cartilage, aids in voice tone control

Muscles that Move the Head

  • Neck muscles essential for head stability and movement

    • Sternocleidomastoid

      • Major muscle responsible for lateral flexion and rotation; divides the neck into triangles

  • Table of Head Movements: Overview of various muscles involved in head movements

Key Muscles and Functions

  1. Sternocleidomastoid

    • Functions:

      • Unilateral: Rotates head to opposite side

      • Bilateral: Flexes the head

    • Origin: Sternum and clavicle

    • Insertion: Temporal bone and occipital bone

  2. Semispinalis Capitis

    • Functions: Extends and laterally flexes the head, rotates

    • Origin: Transverse processes of cervical and thoracic vertebrae

    • Insertion: Occipital bone

  3. Splenius Capitis

    • Functions: Rotates and extends the head

    • Origin: Spinous processes of cervical and thoracic vertebrae

    • Insertion: Temporal bone and occipital bone

  4. Longissimus Capitis

    • Functions: Rotates and extends the head

    • Origin: Transverse processes of cervical and thoracic vertebrae

    • Insertion: Temporal bone

Muscles of the Posterior Neck and the Back

  • Functions: Stabilization and movement of the vertebral column

Muscle Groups

  1. Splenius Muscles

    • Originate at midline, insert laterally and superiorly

    • Functions: Extension, lateral flexion, and rotation of head

  2. Erector Spinae Group

    • Main extensor of the vertebral column

    • Subgroups:

      • Iliocostalis: Cervicis, thoracis, lumborum

      • Longissimus: Capitis, cervicis, thoracis

      • Spinalis: Capitis, cervicis, thoracis

  3. Transversospinales Muscles

    • Stabilize the vertebral column through connections between vertebrae

    • Include semispinalis muscles related to their regions

  4. Multifidus Muscle

    • Located in the lumbar region, aids in vertebral column extension and lateral flexion

  5. Segmental Muscle Group

    • Includes interspinales and intertransversarii muscles, contributes to vertebral stability

  6. Scalene Muscles

    • Function in head movement and assist in breathing

    • Include anterior, middle, and posterior scalene muscles

Terms to Know

  • Fascicles: Bundles of muscle fibers that work together for movement.

  • Flexion: Bending of a joint to decrease the angle between body parts (e.g., neck bending forward).

  • Extension: Straightening a joint to increase the angle (e.g., tilting the head backward).

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