General Anatomy

• Vertebral Column


  Functions: Supports the head, Important attachment for muscles, Rib attachment, Encloses and protects the spinal cord, Provide flexibility and mobility of the trunk, Ability to transmit weight of head and body to the lower extremities
• Composition of the Vertebral Column

  • Cervical: 7
  • Thoracic: 12
  • Lumbar: 5
  • Sacrum: 5 → 1 (fused in adulthood)
  • Coccyx: 4 → 1 (fused in adulthood)
  • Total: 33 (pediatric), 26 (adult)
• Typical Vertebra

  • C3-C6, T5-T8, L1-L4
• Characteristics of a Typical Vertebra

  • Vertebral Body: Small (Cervical), Medium; Heart-shaped (Thoracic), Largest; Bean/Kidney-shaped (Lumbar)
  • Spinous Process: Short and bifid (Cervical), Long and inclined downwards (Thoracic), Short, flat and quadrilateral (Lumbar)
  • Transverse Process: Transverse foramen (Cervical), Conical (Thoracic)
  • Vertebral Foramen: Largest and triangular (Cervical), Smallest and circular (Thoracic), Triangular (Lumbar)
  • Facet Joints Orientation: Superior - Superior and posterior, Inferior - Inferior and anterior (Cervical), Superior - Posterior and lateral, Inferior - Anterior and lateral (Thoracic), Superior - Medial, Inferior - Lateral (Lumbar)
  • Facet Joints Inclination: 45° (Cervical), 60° (Thoracic), 90° (Lumbar)
• Characteristics of the Atypical Vertebra

  • Cervical: C1 (Atlas), C2 (Axis/Epistropheus), C7
  • Thoracic: T1, T2-T4, T9, T10, T11-T12
  • Lumbar: L5
  • Sacrum
  • Coccyx
• Atlanto-Occipital Joint


  Also known as YES joint, Type: condyloid joint, 50% flexion-extension
• Atlanto-Axial joint


  Also known as NO joint, Type: Pivot/trochoid joint, 50% rotation
• Intervertebral Discs


  Shock absorbers of the spine, Capable of withstanding compressive torsional and bending loads, Role is to bread and distribute loads in vertebral column and restrain excessive motion in vertebral segment
• Regions of Vertebral Disc

  • Nucleus Pulposus: Gel-like mass in center of disc under pressure, 80-90% water, 15-20% collagen, 25% of vertebral column height, Abundant in proteoglycans: imbibes water, absorbs pressure
  • Annulus Fibrosus: 50-60% collagen, Lamellae: protein that crisscross by 30°, Sharpey's fibers (results to herniated disc if damaged)
• Intersegmental Ligaments: Global Stability

  • Anterior Longitudinal Ligament: attached anterior of vertebral body, prevents hyperextension
  • Posterior Longitudinal Ligament: attached posterior of vertebral body inside spinal canal, prevents flexion; inferior continuation of tectorial membrane
  • Supraspinous Ligament: connects the tips of spinous process from C7-sacrum; inferior continuation of ligamentum nuchae
• Intrasegmental Ligaments: Segmental Stability

  • Ligamentum Flavum (yellow ligament): connects adjacent lamina
  • Ligamentum Nuchae: connects the tip of spinous process from C7-occiput; superior continuation of supraspinous ligament in cervical region
  • Interspinous Ligament: connects adjacent spinous process
  • Intertransverse Ligament: connect adjacent transverse process
• Other Ligaments (Cervical)

  • Alar Ligaments: attaches from the lateral lip of the foramen magnum to the transverse area of the atlas, limits skull and atlas rotation on axis
  • Anterior Axial Accessory (AAA) Ligament: from transverse process of atlas to the axis; assists the alar ligament
  • Transverse Ligament: holds the dens in place
  • Apical Ligament: from anterior surface of foramen magnum to apex of dens
  • Vertical Ligament: from anterior of foramen magnum to the body and/or base of the dens
  • Cruciform Ligament: cross-shaped; transverse + vertical ligament
• Nerve Supply of Vertebral Joints

  Innervated by the small meningeal branches of each spinal nerve, Joints between the articular processes are innervated by branches from the posterior rami of the spinal nerves
• Muscles of the Back (Superficial Layer)

  • Trapezius: upward rotation of scapula; shawl muscle (upper, middle, lower)
  • Levator Scapulae: elevates the scapula; downward rotation of scapula
  • Latissimus Dorsi: broadest/widest muscle; also known as crutch-walking muscle
  • Rhomboids major/minor: retract shoulder, downward rotator
• Muscles of the Back (Intermediate Layer)

  • Serratus Posterior: Superior - inspiration, Inferior - expiration
• Muscles of the Back (Deep Layer)

  • Splenius: bandage muscle (Capitis, Cervicis)
  • Erector Spinae: longitudinal muscle, chief erector of spine (Iliocostalis, Longissimus, Spinalis)
  • Transversospinalis/Oblique Muscles (SaMuRai): Semispinalis, Multifidus (strongest from forward flexion to neutral), Rotatores = Obliques
  • Interspinalis: connects the spinous process
  • Intertransversarii: connects the transverse process
• Blood Supply of the Back

  • Arteries: Cervical (branches from occipital, vertebral, deep cervical arteries), Thoracic (branches from posterior intercostal arteries), Lumbar (branches from subcostal and lumbar arteries), Sacral (branches from iliolumbar and lateral sacral arteries)
  • Veins: External vertebral venous plexus, Internal vertebral venous plexus (drained by intervertebral veins)
• Lymph Drainage of the Back

  • Deep lymph vessels follow the veins and drain into the deep cervical, posterior mediastinal, lateral aortic, and sacral nodes
  • Lymph vessels from the skin of the neck drain into the cervical nodes
  • Those from the trunk above the iliac crests drain into the axillary nodes
  • Those from below the level of the iliac crests drain into the superficial inguinal nodes
• Nerve Supply of the Back

  • Skin and muscles supplied in a segmental manner by the posterior rami of the 31 pairs of spinal nerves
  • Posterior rami of C1, C6, C7, C8, L4, L5 supply the deep muscles but not the skin
  • Posterior ramus of C2 (greater occipital nerve) supplies the skin of the scalp
• Spinal Cord


  Cylindrical mass of neural tissue, occupying the upper 2/3 of Vertebral Canal, Starts: Foramen magnum, Ends L1-L2 vertebrae
• External Structures of the Spinal Cord

  • Conus Medullaris: Conical inferior end
  • Filum Terminale: Filament extending from the conus and attaches to 1st segment of the coccyx
  • Cauda Equina: Horsetail composed of rootlets of lumbosacral plexus
• Roots of the Spinal Nerves


  • Anterior or motor roots
  • Posterior or sensory roots
  • They unite to form a spinal nerve
• Blood Supply of the Spinal Cord

  • Anterior Spinal Artery: anterior upper 2/3 of SC
  • Posterior Spinal Artery: posterior upper 1/3 of SC
  • Radicular Artery: reinforcement of the anterior and posterior spinal arteries
  • Artery of Adamkiewicz: largest radicular artery (T8-L4)
  • Watershed Area: poorest blood flow (T4-T6 upper thoracic, midthoracic)
• Meninges of the Spinal Cord

  • Dura Mater: Outermost layer, thick and durable
  • Arachnoid Mater: Middle layer, web-like structure
  • Pia Mater: Innermost layer, thin and delicate
• Spaces Associated with Meninges

  • Epidural Space: Between dura mater and vertebral wall, contains fat and small blood vessels
  • Subdural Space: Potential space between dura mater and arachnoid mater
  • Subarachnoid Space: Between arachnoid mater and pia mater, filled with cerebrospinal fluid
• Cerebrospinal Fluid

  Clear, colorless body fluid found in the brain and spinal cord, Produced primarily in the choroid plexus of the brain's ventricles
• Functions of Cerebrospinal Fluid

  • Protection: Acts as a cushion, protecting the brain and spinal cord from trauma
  • Buoyancy: Reduces the effective weight of the brain, preventing it from compressing against the skull base
  • Chemical Stability: Maintains a stable chemical environment by removing waste products and providing nutrients
  • Intracranial Pressure Regulation: Helps maintain a stable pressure within the cranium