Cervical spine

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Done

Parent item

Spine

Sub-item

Cervical muscles

C1

C2

General

• Accepted diameter of congenitally narrow cervical canal <12mm

Bony anatomy

• Relationship between surface anatomy and C spine level
• For ACDF planning
• Inferior edge of mandible: C2
• Hyoid bone: C3
• Thyroid cartilage: C4-C5
• Cricoid ring: C6

• C7 transverse process only possesses a posterior tubercle

• 1- Posterior tubercle of C1;

• 2- Lamina of C2;

• 3- Spinous process of C2;

• 4- pedicle of C2;

• 5- Superior facet joint of C2;

• 6- Inferior facet joint of C2;

• 7- Lateral mass of C1.

• The vertebral artery is illustrated.

Ligaments

• The intradural segment of the vertebral arteries and the dura lining the anterior margin of the foramen magnum have been removed to expose the
• Tectorial membrane, a rostral extension of the posterior longitudinal ligament,
• Vertebral venous plexus, which courses just outside the dura.

• The tectorial membrane has been removed to expose the
• Cruciform ligaments:
• Horizontal portion:
• Aka transverse ligament of the atlas
• Extends laterally to be attached to the medial edges of the lateral masses of the atlas,
• Vertical portion:
• Ascends to attach to the anterior margin of the foramen magnum deep to the tectorial membrane.
• Alar ligaments:
• The alar ligaments pass upward and laterally and attach to the lateral edges of the foramen magnum.
• Anterior meningeal arteries pass along the dura and ligamentous structures in the anterior spinal canal.

• The vertical portion of the cruciform ligament has been folded downward to expose the synovial joint between the anterior surface of the cruciform ligament and the posterior surface of the dens.

• There is also another synovial joint between the anterior surface of the dens and the posterior surface of the anterior atlantal arch.

• The apical ligament of the dens extends upward to be attached to the margin of the foramen magnum.

Nerves

C1 is a pure motor root and does not have dorsal root ganglion

• Suboccipital nerve
• Aka: dorsal ramus of the C1 nerve root
• Function
• innervates the
• 3 muscles bordering the suboccipital triangle
• Superior oblique
• Inferior oblique
• Posterior rectus capitis Major
• rectus capitis posterior minor
• Collectively, the suboccipital muscles function as the head's postural muscles, assisting in head extension and rotation. The suboccipital muscles turn the head by rotating the atlas and axis.
• The suboccipital nerve may also fuse with the C2 and C3 dorsal rami as part of the Cruveilhier plexus

• C1, although predominantly motor, gives a small meningeal branch that supplies dura around the foramen magnum; C1–C3 meningeal branches ascend through the foramen magnum and other skull base canals to innervate the anterior and lateral posterior fossa dura.

• C2 is the first sensory root and has a dorsal root ganglia

Triangles

Suboccipital triangle

• Borders
• Superior oblique
• Which passes from the C1 transverse process to the occipital bone
• Inferior oblique
• Which extends from the transverse process of C1 to the spinous process of C2
• Rectus capitis posterior major
• Which extends from the occipital bone below the inferior nuchal line to the spinous process of C2.

• Contents
• Vertebral artery
• As it passes behind the superior facet of C1 and across the upper edge of the posterior atlantal arch.
• Suboccipital nerve

• Clinically
• Used for far lateral approaches
 

 

Biomechanics

• Normal range of motion in the cervical spine
• Flexion: 45 degrees
• Extension: 55 degrees
• Lateral bending: 40 degrees
• Rotation to each side: 70 degrees

• The normal thickness of the prevertebral soft tissue anterior to the cervical spine on plain x-ray lateral images
• At C2, it is 6 mm
• At C6, it is -22 mm