Cervical Spine and Skull Osteology Quiz

Cervical Spine, Cord and Nerves, and Skull Osteology

• Learning Outcomes:
  • Describe the structure of cervical vertebrae, focusing on atlas and axis.
  • Describe the joints between the vertebrae.
  • Describe the vertebral arteries and their course.
  • Discuss cervical spinal nerves.
  • Describe the spinal meninges and relate the anatomy to lumbar puncture.
  • Describe the osteology of the skull (frontal, posterior, superior, inferior views).
  • Describe the cranial fossae.

Vertebral Column

• Structure:
  • Composed of 7 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 4 coccygeal vertebrae.
  • Intervertebral discs act as cushions between vertebrae.
  • Cervical, thoracic, lumbar, and sacral/coccygeal curvatures.
  • Vertebral bodies increase in size from cervical to lumbar.

Functions of Vertebral Column

• Protection: Spinal cord and nerve roots, many internal organs.
• Base for attachment: Ligaments, tendons, and muscles.
• Structural support: Connects upper and lower body; supports balance and weight distribution.
• Flexibility and Mobility: Flexion, extension, lateral flexion, rotation, and combinations.

Curvatures of the Vertebral Column

• Primary (Kyphosis): First-formed curve in the vertebral column.
• Secondary (Lordosis): Develop in lumbar region (upright posture) and cervical region (head erect).

General Structure of Vertebrae

• Vertebral Bodies: The weight-bearing portion.
• Vertebral Arches: Protect the vertebral canal contents.
• Vertebral Canal: Houses the spinal cord, meninges, blood vessels, and roots of spinal nerves.

Vertebral Arch

• Pedicle: Part of the vertebral arch, resembling a foot.
• Lamina: Attached to the pedicle, shaped like a thin flat structure.
• Spinous Process: Posteriorly projecting portion.
• Transverse Process: Projects laterally.
• Superior & Inferior Articular Processes: Facilitate articulation with adjacent vertebrae.

Joints in the Vertebral Column

• Zygapophysial (Facet) Joints: Plane joints between articular processes.
• Secondary Cartilaginous Joints (Symphyses): Intervertebral discs connect the vertebral bodies.

Intervertebral Disc

• Annulus Fibrosus: Outer zone with high tensile strength connective tissue to attach to the adjacent vertebral bodies.
• Nucleus Pulposus: Inner, gelatinous structure composed of high resilience and 80-85% fluid cushioning.
• Cartilaginous Endplate: Fibrocartilage attaching to the vertebral body cartilaginous endplate.

Ligaments of the Vertebral Column

• Longitudinal Ligaments: (Anterior and Posterior) run along the anterior and posterior vertebral bodies.
• Ligamentum Flavum: Located between laminae, elastic in composition.
• Interspinous Ligament: Between the spinous processes.
• Supraspinous Ligament: Extends along the spinous processes.
• Ligamentum Nuchae: In the neck, thickened part of the supraspinous ligament.

Intervertebral Foramina

• Function: Allow spinal nerves and blood vessels to pass through.

Typical Cervical Vertebrae

• Characteristics:
  • Oval body, transverse foramina, and unique processes (e.g., anterior and posterior tubercles, a bifid spinous process).

Atypical Cervical Vertebrae

• Atlas (C1): Lacking a body and spinous process, characterized by superior and inferior articular facets, lateral masses.
• Axis (C2): Has a dens (odontoid process), which projects superiorly into the ring of the atlas: superior and inferior articular facets, and a prominent spinous process.
• Cervical 7 (C7): Known as the vertebra prominens, characterized by a long spinous process.

Atlanto-occipital Joint

• Synovial condyloid joints: Permit nodding flexion and extension.

Atlantoaxial Joint

• Synovial joints: Permit rotation.

Vertebral Arteries

• Function: Supply blood to the brain and spinal cord.
  • Arise from subclavian arteries, ascend through transverse foramina, enter foramen magnum, and branch into various vessels supplying the brain and spinal cord.

Cervical Spine Injury

• Clinical Considerations: In trauma patients, maintaining a neutral or stable neck position is essential to avoid spinal cord damage during airway management.

Spinal Cord

• Spinal cord continues from the brain stem, extends from the foramen magnum of the base of the skull to the lower edge of the first lumbar vertebra. Further divided by different sections.

Spinal Cord Segments and Spinal Nerves

• Cervical: 8 spinal nerves originate from the upper portion of the spinal cord

• Thoracic: 12 spinal nerves originate from the mid-portion of the spinal cord

• Lumbar: 5 spinal nerves originate from the lower portion of the spinal cord

• Sacral: 5 spinal nerves originate from the lower portion of the spinal cord

• Coccygeal: 1 spinal nerves originate from the coccygeal area

• Important Note: Spinal cord segments do not correspond exactly with spinal vertebra, with spinal cord segments lying above the vertebra; for example, the 1st spinal nerve originates above the 1st vertebra (C1).

Spinal Meninges

• Dura Mater: Outermost layer.
• Arachnoid Mater: Middle layer.
• Pia Mater: Innermost layer, closely adhered to the substance of the spinal cord.

Spinal Spaces

• Epidural/Extradural Space: Space containing fat and venous plexuses.
• Subdural Space: Space containing serous fluid.
• Subarachnoid Space: Contains CSF.

Lumbar Puncture (Tap)

• This procedure involves inserting a needle into the subarachnoid space to extract cerebrospinal fluid.
• Indications and Contraindications should be carefully considered for this procedure.

Cervical Plexus and Branching Spinal Nerves

• Formed from the anterior rami of C1-C4 spinal nerves
  • innervate the muscles of the neck, head, and shoulders.
• Brachial Plexus: formed from the anterior rami of C5-T1 spinal nerves, responsible for providing innervation to the arms and hands.
• Posterior Rami: Innervate the deep back muscles.

Cervical Sympathetic Trunk

• Network of sympathetic nerve fibers that connects to the spinal cord and to various areas throughout the body.

• Arterial and Venous Drainage

  • Anterior and posterior spinal arteries (and their branches) supply blood to the spinal cord

  • Veins draining the spinal cord form longitudinal channels.

    • One midline channel parallels anterior median fissure (anterior spinal vein)
    • one midline channel passes along the posterior median sulcus (posterior spinal vein)