Anatomy of the Muscular System: Introduction & Muscles of the Head, Neck, and Trunk

Anatomy of the Muscular System: Introduction & Muscles of the Head, Neck, and Trunk. Sternocleidomastoid Origin: Sternal end of clavicle and manubrium Insertion: Mastoid region of skull Action: Bilateral: Neck flexion Unilateral: Turns face to opposite side Innervation: Accessory nerve (CN XI) Splenius Capitis Origin: Spinous process/ligaments of inferior cervical vertebrae Insertion: Mastoid process, occipital bones of skull Action: Bilateral extend head Unilateral laterally flexes neck to same side Innervation: Cervical spinal nerves Longissimus cervicis Origin: transverse processes of superior thoracic vertebrae Insertion: transverse process of middle and superior cervical vertebrae Action: Bilateral extend head Unilateral laterally flexes neck to same side Innervation: Cervical and thoracic spinal nerves Longissimus thoracis Origin: Transverse process of inferior thoracic, superior lumbar vertebrae Insertion: Transverse process of middle and superior cervical vertebrae Action: Bilateral extend head Unilateral laterally flexes neck to same side Innervation: Thoracic and lumbar spinal nerves Thyrohyoid Origin: Thyroid cartilage of larynx Insertion: Hyoid bone Action: Elevates thyroid, depresses hyoid bone Innervation: Hypoglossal nerve