Upper Cervical Spine Anatomy and Function

Upper Cervical Spine Anatomy

• The upper cervical spine comprises the occiput, atlas (C1), and axis (C2).
• Joints of the upper cervical spine include the occipitoatlantal (OA) and atlantoaxial (AA) joints.
• The alar and transverse ligaments support the upper cervical spine, holding the dens in place. Injury to these ligaments can permit movement of the dens.
• Biomechanically, the occipitoatlantal joint facilitates flexion, extension, and lateral flexion, but no rotation.
• The atlantoaxial joint primarily permits rotation, accounting for 70% of total cervical rotation.
• In the lower cervical spine, lateral flexion and rotation couple ipsilaterally.
• To close a facet on one side, extend, side bend, and rotate the cervical spine towards that side. Conversely, to open a facet, flex, side bend, and rotate the spine away from that side.
• In the upper cervical spine, lateral flexion and rotation couple contralaterally.

Upper Cervical Spine Musculature

• The suboccipital muscles include the rectus capitis posterior major, rectus capitis posterior minor, oblique capitis inferior, and oblique capitis superior.
• These form a triangular structure at the base of the skull on both sides.
• The greater occipital nerve passes through this triangle.
• Origin: Axis and Atlas. Insertion: Occipital Bone. Action: Extension, side-bending, and rotation of the upper cervical spine. These muscles are important for supporting the head during activity.
• Fatigue in these muscles can lead to spasms and greater occipital nerve entrapment, causing cervicogenic headaches.
• Forward head posture increases the weight load on the upper cervical spine, potentially leading to suboccipital muscle inflexibility and pain.

Signs and Symptoms of Upper Cervical Spine Dysfunction

• Pain in the cervical spine (upper or lower, potentially both at once).
• Cervicogenic headaches.
• Limited range of motion (ROM) in the cervical spine, particularly at the OA and AA joints.
• Neurological or cranial nerve symptoms in the upper cervical spine.
• Lower cervical spine issues might manifest as cervical radiculopathy (pain radiating into upper extremities).

Tension and Mechanical Headaches

• Tension headaches can result from extended forward head posture and suboccipital muscle spasm.
• Symptoms often start in the occiput and radiate to the parietal, frontal, and temporal regions, potentially even behind the eyes.
• Cervicogenic headaches and tension headaches frequently coexist.

Causes of Upper Cervical Spine Issues

• Upper or lower cervical spine disc dysfunction (although discs are absent at OA & AA).
• Upper or lower cervical spine facet dysfunction (a common cause).
• Upper or lower cervical spine postural dysfunction (from poor posture over time).
• Upper cervical spine instability (rare 0.1-0.6%).
• Down Syndrome (increased risk, 10-20% occurrence, 1-2% symptomatic).
• Rheumatoid Arthritis.
• Cervical spine trauma (like whiplash).

Upper Cervical Spine Interventions

• Manual therapy is effective for treating pain, headaches, and limited movement in the upper cervical spine and provides greater short-term pain relief than exercise alone.
• Pre-manual therapy screening is necessary for upper cervical spine instability and vertebral artery dysfunction risk.
• Therapeutic exercises are crucial for treating upper cervical spine instability and vertebral artery dysfunction.

Evaluation of the Upper Cervical Spine

• Tests for vertebral artery assessment include the prone vertebral artery test and the supine vertebral artery test, along with the Sharp-Purser test, alar ligament test and transverse ligament stress test.
• The gold standard for assessment is a plain radiograph (or MRI) to evaluate the atlas dens interval (ADI).
• An ADI greater than 3-4 mm is considered abnormal, indicating possible alar ligament or transverse ligament injury; instability of the ligaments would permit movement of the dens causing injury to the spinal cord.
• Cervical spine injuries are more likely in collision athletes due to axial load impact to the head and neck.

Specific Tests

• Prone Vertebral Artery Test: Patient in prone, actively extending the upper cervical spine, monitored for dizziness or CN (cranial nerve) dysfunction or dizziness.
• Supine Vertebral Artery Test: Similar to prone, but performed in supine position. Multiple stages progressing from minimal to full.
• Sharp-Purser Test: Used to assess upper cervical instability. The patient is seated in slight flexion. This is helpful in patients with axial load type of injuries, whiplash, tension/cervicogenic headaches.
• Alar Ligament Stress Test: The clinician passively side bends the upper cervical spine while stabilizing C2, looking for changes in the alar ligament.
• Transverse Ligament Stress Test: Patient in supine, clinician attempts anterior movement of the occiput and C1 on C2, monitor for cranial nerve symptoms.

Explore the intricate anatomy of the upper cervical spine, including the occiput, atlas, and axis. This quiz covers joint functions, ligament support, and the biomechanics involved in movement. Test your knowledge on the unique attributes of the upper cervical spine and its musculature.