The Back

• Back


  Extends from the skull to the tip of the coccyx, can be defined as the posterior surface of the trunk
• Vertebral Column


  • Central bony pillar of the body
  • Supports the skull, pectoral girdle, upper limbs, and thoracic cage
  • Transmits body weight to the lower limbs
  • Gives great protection
• Composition of Vertebral Column

  • 7 cervical vertebrae
  • 12 thoracic vertebrae
  • 5 lumbar vertebrae
  • 5 sacral vertebrae
  • 4 coccyx vertebrae
  • Total: 33 (pediatric), 26 (adult)
• Typical Vertebrae


  • Have a rounded body anteriorly, and a vertebral arch posteriorly creating an enclosed space called the vertebral foramen
  • The Vertebral arch gives rise to 7 processes: 1 spinous process, 2 transverse processes, 4 articular processes
• Spinous process


  Directed posteriorly from the junction of the 2 Lamina
• Transverse processes


  Directed laterally from the junction of the lamina and pedicles
• Articular processes


  Vertically arranged and consist of 2 superior and 2 inferior processes, arising from the junction of the laminae and pedicles, with articular surfaces covered in hyaline cartilage
• Vertebral notches


  Superior and inferior notches in the pedicles, forming the intervertebral foramen
• Sacrum


  • Five fused rudimentary vertebrae
  • Wedge-shaped, concave bone
  • Upper border (base) articulates with the 5th lumbar vertebra
• Sacral Promontory


  Anterior and upper margin of the first sacral vertebra
• Coccyx


  • Consists of four vertebrae fused together to form a single small triangular bone
  • Articulates at its base with the lower end of the sacrum
  • The first coccygeal vertebra is usually not fused or is incompletely fused with the second vertebra
• Atlanto-occipital joint


  • Type: condyloid joint
  • Allows 50% flexion-extension
• Atlantoaxial Joints


  • Type: pivot/trochoid joint
  • Allows 50% rotation
  • Three synovial joints: one between the odontoid process and the anterior arch of the atlas, two between the lateral masses of the bones
• Intersegmental Ligaments: Global Stability

  • Anterior Longitudinal Ligament
  • Posterior Longitudinal Ligament
  • Supraspinous Ligament
• Intrasegmental Ligaments: Segmental Stability

  • Interspinous ligament
  • Intertransverse ligaments
  • Ligamentum flavum
  • Ligamentum Nuchae
• Ligamentum Nuchae


  Connects the tip of spinous process from C7-occiput; superior continuation of supraspinous ligament in cervical region
• Ligaments of the Atlanto-axial Joint

  • Apical Ligament
  • Alar Ligaments
  • Anterior Axial Accessory (AAA) Ligament
  • Transverse Ligament
  • Vertical Ligament
  • Cruciform Ligament
  • Cruciate Ligaments
• Membrana Tectoria


  Upward continuation of the posterior longitudinal ligament, attached to the occipital bone just within the foramen magnum, covering the posterior surface of the odontoid process and the apical, alar, and cruciate ligaments
• Intervertebral Discs


  • Act as "shock absorbers" of the spine
  • Capable of withstanding compressive, torsional and bending loads
  • Serve as semi-elastic discs between rigid vertebrae
• Regions of Intervertebral Disc

  • Annulus Fibrosus (peripheral part)
  • Nucleus Pulposus (central part)
• Annulus Fibrosus


  Peripheral part of intervertebral disc, composed of fibrocartilage with collagen fibers in concentric layers
• Nucleus Pulposus


  Central part of intervertebral disc, 50-60% collagen, with lamellae that crisscross by 30°
• Lumbosacral Angle


  Appears during development
• Post-Birth Cervical Curve


  Forms when the child can raise and poise the head, making the cervical part of the vertebral column concave posteriorly
• Post-Birth Lumbar Curve


  Forms toward the end of the first year when the child begins to stand, making the lumbar part of the vertebral column concave posteriorly
• Sagittal Plane Regional Curves of Adult Vertebral Column

  • Cervical: Posterior concavity
  • Thoracic: Posterior convexity
  • Lumbar: Posterior concavity
  • Sacral: Posterior convexity
• Types of Vertebral Column Movements

  • Flexion (anterior movement)
  • Extension (posterior movement)
  • Lateral Flexion (bending to one side)
  • Rotation (twisting)
  • Circumduction (combination of previous movements)
• Muscles Involved in Cervical Region Movements

  • Flexion: Longus cervicis, scalenus anterior, sternocleidomastoid
  • Extension: Postvertebral muscles
  • Lateral Flexion: Scalenus anterior and medius, trapezius, sternocleidomastoid
  • Rotation: Sternocleidomastoid (one side), splenius capitis (opposite side)
• Muscles Involved in Thoracic Region Movements

  • Rotation: Semispinalis, rotatores muscles (unilateral contraction), oblique muscles of anterolateral abdominal wall
• Muscles Involved in Lumbar Region Movements

  • Flexion: Rectus abdominis, psoas muscles
  • Extension: Postvertebral muscles
  • Lateral Flexion: Postvertebral muscles, quadratus lumborum, oblique muscles of anterolateral abdominal wall, psoas muscles (possible involvement)
  • Rotation: Rotatores muscles, oblique muscles of anterolateral abdominal wall
• Superficial Muscles Connected with the Shoulder Girdle

  • Trapezius
  • Levator Scapulae
  • Latissimus Dorsi
  • Rhomboids major/minor
• Trapezius


  Involved in upward rotation of the scapula; also known as the "shawl muscle" (upper, middle, lower parts)
• Latissimus Dorsi


  Broadest/widest muscle; also known as the "crutch-walking muscle"
• Deep Muscles or Postvertebral Muscles Belonging to the Vertebral Column

  • Semispinalis
  • Multifidus
  • Rotatores
• Deep Muscles of the Back (Postvertebral Muscles)


  • Form a broad, thick column of muscle tissue alongside the spinous processes of the vertebral column
  • Extend from the sacrum to the skull, supporting the vertebral column
  • Function as strings that extend or rotate one or several vertebrae when pulled
• Muscles of the shoulder girdle

  • Trapezius
  • Latissimus dorsi
  • Rhomboid muscles
• 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