Muscles of the (Neck/Cervical & Thoracic Spine

Iliocostalis Cervicis

*Erector Spinae Muscle* Origin: Angles of the 1st-6th cervical ribs. Insertion: Transverse processes of the C4-C6 cervical vertebrae. Action: Extends neck vertebrae, laterally flexes neck vertebrae, rotates neck vertebrae to opposite side. Innervation: Dorsal rami of the cervical spinal nerves

Longissimus Thoracis =

*Erector Spinae Muscle* Origin: Sacrum; iliac crest; spinous processes of the lumbar vertebrae; transverse processes of the lower thoracic vertebrae Insertion: 2nd to 12th ribs; the costal processes of the lumbar vertebrae; the transverse process of the thoracic vertebrae. Action: Extension and lateral flexion of the trunk, neck and head. Innervation: Dorsal primary rami of the spinal nerves.

Longissimus Capitis

*Erector Spinae Muscle* Origin: Transverse processes of T1-T5; articular processes of cervical vertebrae C4-C7 Insertion: Posterior portion of mastiod process of temporal bone. Action: Extends and hyper-extends head. Flexes and laterally rotates head to same side. Innervation: Dorsal rami of spinal nerves.

Longissimus Cervicis

*Erector Spinae Muscles* Origin: Transverse processes of T1-T5 Insertion: Posterior tubercles of the transverse processes of the 2nd-6th cervical vertebrae. Action: Extends and hyper-extends nexk vertebrae. Laterally flexes neck, vertebrae to same side. Innervation: Dorsal rami of thoracic spinal nerves.

Semispinalis Capitis

*Transversospinalis Muscle Group* Origin: Transverse and articular processes of the vertebrae C3-T6 Insertion: Posterior occipital bone below the superior nuchal line. Action: Extension and lateral flexion of the cervical and thoracic spine and head. Innervation: Dorsal primary rami of the spinal nerves.

Semispinalis Cervicis

*Transversospinalis Muscle Group* Origin: Transverse processes of the vertebrae T1-T6 Insertion: Spinous processes of the C2-C5 vertebrae. Action: Inclination of the head; extension and rotation of the spinal column and head to the contralateral side. Innervation: Dorsal primary rami of the spinal nerves

Splenius Capitis

Origin: Caudal half of the ligamentum nuchae, spinous process of C7, and upper 4 thoracic vertebrae. Insertion: Lateral 1/3 of superior nuchal line and onto the mastoid process of the temporal bone. Action: Laterally flexes head, rotates head and neck to same side. When both muscles act, they extend neck and head. Innervation: Dorsal rami of the middle cervical spinal nerves.

Platysma

Origin: Inferior border of mandible, skin and subcutaneous tissue of the lower facet, subcutaneous skin over delto-pectoral region. Insertion: Fascia covering the superior parts of the deltoid and pectoralis major muscles, invests in the skin widely over the mandible. Action: Draws corners of mouth inferiorly and widens them for expressions of sadness and fright. Draws skin of neck superiorly when teeth are clenched, depresses mandible and lower lip, tenses the skin over the lower neck. Innervation: Facial Nerve

Subclavius

Origin: Junction of 1st rib and its costal cartilage. Insertion: Lower surface of clavicle. Action: Anchors and depresses clavicle, also stabilizes and pulls clavicle forward. Innervation: Nerve to subclavius C5,6

Splenius Cervicis

Origin: Ligamentum nuchae and the spinous processes of the vertebrae C7-T6 Insertion: Posterior tubercles of the transverse processes of the C1-C3 Action: Extends and hyper-extends head and neck. Laterally flexes neck and head and rotates neck and head to same side. Innervation: Dorsal primary rami of the spinal nerves.

Rectus Capitis Posterior Minor

Origin: Posterior tubercle, spinous process of the atlas, C1 Insertion: Medial part of the occipital bone below the inferior nuchal line. Action: bilaterally extends head Innervation: Suboccipital Nerve

Rectus Capitis Posterior Major

Origin: Spinous process of the axis, C2. Insertion: Lateral part of the occipital bone below the inferior nuchal line. Action: Bilaterally extends head, rotates head to the contracted side. Innervation: Suboccipital Nerve

Obliquus Capitis Inferior

Origin: Spinous process of the axis, C2. Insertion: Transverse process of the atlas, C1 Action: Rotates head to the contracted side. Innervation: Suboccipital Nerve

Spinalis Cervicis

Origin: Spinous processes of the vertebrae C6-C7. Insertion: Spinous processes of the upper cervical vertebrae. (C2) Action: Extends and hyper-extends the neck portion of the vertebral column. Extends, rotates, and laterally flexes the vertebral column. Innervation: Dorsal rami of lower cervical and thoracic spinal nerves.

Rectus Capitis Lateralis

Origin: Superior surface of the transverse process of the atlas. Insertion: Inferior surface of the jugular process of the occipital bone. Action: Bends the head laterally, to the same side. Innervation: C1-C2 spinal nerves.

Obliquus Capitis Superior

Origin: Transerve process of the atlas, C1 Insertion: Occipital bone below the superior nuchal line, between superior and inferior line of occiput. Action: Bilaterally extends head, laterally flexes to the contracted side. Innervation: Suboccipital Nerve

Middle Scalene

Origin: Transverse processes of C2-C7. Insertion: Superior surface of 1st rib, between tubercle and groove for subclavian artery Action: When neck is fixed elevates the 1st rib, when first rib is fixed, bends neck forward and rotates it to opposite side. Innervation: C3-C8 cervical nerves

Longus Colli

Origin: Transverse processes of C3-C5 Insertion: Anterior arch of the atlas Action: Flexes head and upper cervical spine. Innervation: C2-C6 spinal nerves.

Longus Capitis

Origin: Transverse processes of C3-C6 Insertion: Inferior surface of the basilar part of the occipital bone. Acton: Flexes head and upper cervical spine. Innservation: C1-C3 Spinal Nerves

Anterior Scalene

Origin: Transverse processes of C3-C6. Insertion: Onto the scalene tubercle of the first rib. Action: When neck is fixed, elevates the first rib, when first rib is fixed bends neck forward and laterally, and rotates it to the opposite side. Innervation: C4-C6 cervical spinal nerves

Posterior Scalene "2", 2nd Rib

Origin: Transverse processes of C4-C6. Insertion: Outer surface of the second rib. Action: Raises the second rib or bends and rotates the neck. Innervation: C6-C8 spinal nerves

Spinalis Capitis

Origin: Transverse processes of C7 and T1 through T6, and articular processes of 4th to 6th cervical vertebrae. Insertion: Between the superior and inferior nuchal line of the occipital bone. Action: Extends, rotates, and laterally flexes the vertebral column. Innervation: Posterior rami of the spinal nerves.

Sternocleidomastoid

Origin: manubrium of the sternum, medial portion of the clavicle. Insertion: Mastoid process of the temporal bone, lateral half of the superior nuchal line. Action: Bilaterally flexes the neck, rotates to side opposite of contraction, laterally flexes to contracted side. Innervation: Spinal Accessory Nerve, CN XI