Cervical Spine Myology

Nuchal ligament

Fibrous lamina projecting from the spinous process of C7 and the external occipital protuberance
Continuous with the supraspinous ligament of the thoracic and lumbar region
Functions as an extended tendon for muscle attachment to vertebral osteology
Limits hyperflexion of cervical spine
Helps maintain a level head when running

Acts as a spring like structure to spring the neck back after flexion

Trapezius

Origin = medial 1/3 superior nuchal line of occipital bone, external occipital protuberance, ligamentum nuchae, C7-T12 spinous processes and corresponding supraspinous ligaments
Insertion = upper fibres to posterior border of lateral 1/3 clavicle, middle fibres from medial margin of acromion and superior lip of crest of spine of scapula, lower fibres from tubercle at medial end of spine of scapula
Direction of fibres = upper downwards and laterally, middle horizontally and lower superiorly and laterally
Nerve supply = spinal accessory nerve C2, C3, C4
Action = upper fibres elevate the shoulder girdle and on reverse origin insertion extend c spine bilaterally and side flexion of c spine unilaterally, middle fibres retract the shoulder girdle, lower fibres depress the shoulder girdle

Sternomastoid (sternocleidomastoid)

Origin = sternal head from anterior surface of manubrium; clavicular head from upper surface medial 1/3 clavicle
Insertion = mastoid process and lateral 1/3 superior nuchal line
Nerve supply = cranial accessory nerve (XI); anterior primary rami C2, C3
Action = both flex the neck; one produces lateral flexion to same side and rotation to opposite side

Scalenus anterior

Origin = transverse processes C3-C6
Insertion = scalene tubercle inner border first rib
Nerve supply = anterior primary rami C4, C5, C6
Action = laterally flex neck to same side and flex neck; on reverse origin insertion they lift the ribs to assist forced inspiration

Scalenus medius

Origin = transverse processes C1-C7
Insertion = upper surface first rib
Nerve supply = anterior primary rami C3, C4, C5, C6, C7
Action = laterally flex and flex the neck; on reverse origin insertion they lift the ribs to assist forced inspiration

Scalenus posterior

Origin = transverse processes C4-C6
Insertion = outer surface second rib
Nerve supply = anterior primary rami C6, C7, C8
Action = laterally flex neck; on reverse origin insertion lift ribs to help with forced inspiration

Longus colli

Origin = inferior oblique fibres from anterior aspect of bodies T1-T4 vertebrae, middle vertical fibres from anterior aspect of the bodies of T1 – T3 & C5 – C7, superior oblique fibres from anterior tubercles of the transverse processes of C3 – C5
Insertion = inferior oblique fibres anterior tubercles of the transverse processes of C5 – C6 vertebrae, middle vertical fibres anterior aspect of the bodies of C2 – C4 vertebrae, superior oblique fibres anterior tubercle of the atlas
Direction of fibres = inferior oblique fibres obliquely upwards and laterally, middle vertical fibres, vertically superior oblique fibres
Nerve supply = anterior primary rami of C3-C6
Action = cervical flexion (bilateral action), cervical lateral flexion (unilateral action), very important dynamic stabiliser of the Cx. spine

Iliocostalis cervicis

Origin = Angles of ribs 3 - 7
Insertion = Transverse processes of C4 – C7
Nerve supply = Dorsal primary divisions of spinal nerves
Actions = Extension & lateral flexion of Cx. spine

Longissimus cervicis

Origin = Transverse processes of T1 – T6
Insertion = Transverse processes of C2 – C6 (Posterior tubercles)
Nerve supply = Dorsal primary divisions of spinal nerves
Action = Extension & lateral flexion of Cx. spine

Longissimus capitis

Origin = Transverse processes of T1 – T5, articular processes of C5 - C7
Insertion = Posterior aspect of mastoid process
Nerve supply = Dorsal primary divisions of spinal nerves
Action = Extension of Cx. Spine and rotation to same side

Spinalis cervicis

Origin = Ligamentum nuchae, C7 spinous process
Insertion = Spinous process of axis (C2)
Nerve supply = Dorsal primary divisions of spinal nerves
Action = Extension Cx. Spine

Spinalis capitis

Origin = Transverse processes of T1-T6, articular processes of C4-C7
Insertion = Medial impression between superior and inferior nuchal lines on base of the skull
Nerve supply = Dorsal primary divisions of spinal nerves
Action = Extension of Cx. Spine and slight rotation to the opposite side

Accessory muscles to inspiration

Some cervical and thoracic musculature has an important functional role in assisting with inspiration, particularly forced inspiration
Sternocleidomastoid and scalenes improve intrathoracic pressure through elevation of the ribcage
Iliocostalis cervicis and thoracic improve intrathoracic pressure through extension of the spine
Hypertrophied accessory musculature can be a clinical sign of respiratory distress