13B Back

Learning Objectives

• Identify these structures in the thoracic, lumbar, & sacral regions and diagram their components:

  • Vertebra

  • Spinal ligaments

  • Spinal discs

• Describe the anatomic pathology, radiologic appearance, and consequences of:

  • Kyphosis

  • Lordosis

  • Scoliosis

• Describe the anatomic pathology and consequences of:

  • Herniated disc

  • Sciatica

  • Osteoporosis

  • Spondylosis

  • Spondylolysis

  • Spondylolisthesis

• Describe the surface landmarks of the back and trace the courses of:

  • Vessels

  • Lymphatics

  • Nerves supplying the back

  • Differentiate between sensory dermatomes and motor nerve distribution

• Identify the layers of the spinal cord and their contribution to central nervous system function

• Describe the anatomic pathology and consequences of:

  • Spina bifida occulta

  • Spina bifida cystica

  • Spina bifida with meningocele and meningomyelocele

  • Neural tube defects

  • Rachischisis

• Identify and describe the actions of the muscles of the back.

Thoracic Vertebrae

• Differences in Vertebrae:

  • Cervical Vertebrae:

  • Transverse foramina present

  • Bifid spinous processes

  • Thoracic Vertebrae:

  • Long, angled transverse processes

  • Costal facets for rib articulation

  • Lumbar Vertebrae:

  • Wide blade-like transverse processes

  • Largest bodies among the vertebrae

Vertebral Structures

• Key features in vertebrae:

  • Thoracic:

  • Head of rib

  • Neck of rib

  • Rib tubercle

  • Body of rib

  • Superior costal demifacet

  • Transverse costal facet

Movement of the Rib Cage

• Superiority and Anterior Movement of Sternum:

  • Pump Handle Movement

  • Pump handle, bucket handle described in movement dynamics

• Joints of the Rib Cage:

  • Sternal angle representing joint connections

  • Manubriosternal joint (symphysis) as a fibrocartilaginous joint

  • Costotransverse joint for rib elevation and movement with vertebral body

Pathology of Thoracic Vertebrae

• Trauma:

  • Compression fractures primarily observed at T1 level

  • Rare due to rib cage support but significant forces required to damage thoracic vertebrae

  • 15-20% of thoracic fractures can lead to permanent paraplegia due to high-energy impact

Curvature of the Spine

• Spinal Curvatures:

  • Cervical Lordosis:

  • Facilitates head balance

  • Thoracic Kyphosis:

  • Protects vital organs such as heart and lungs

  • Lumbar Lordosis:

  • Acts as a shock absorber

  • Sacral Kyphosis:

  • Completes the curvature distribution across the spine

Hyperkyphosis

• Definition:

  • Exaggerated anterior curvature of the thoracic spine with Cobb angle greater than 50 degrees

  • Associated functional impairments including:

  • Thoracic pain associated with lower pulmonary function

  • Increased risk of fractures and overall mortality rates among older adults

  • Etiology: Often related to osteoporosis leading to structural deformities of thoracic vertebrae

  • Treatment: No definitive corrective measures

Scoliosis

• Definition: Once diagnosed when lateral Cobb angle exceeds 10 degrees

• Features:

  • Characterized by both lateral bending and rotational twisting of the spine

  • Typically takes a ‘C’ or ‘S’ shape formation

• Vertebral Rotation:

  • Each vertebra rotates toward the convex side of the curve, resulting in rib prominence on the convex side and a flatter rib cage on the concave side

Treatment of Scoliosis

• Interventions:

  • Bracing and physical therapy or potential surgical interventions depending on severity of curvature

Lumbar Vertebrae

• Key Features:

  • Differences from Other Vertebrae:

  • Large kidney-shaped vertebral bodies designed for weight-bearing

  • Presence of wide and blade-like transverse processes

Lumbar Pathologies

Hypolordosis | Lordosis

• Normal lordosis: inward curve significant for posture management

• Conditions: Hypolordosis and hyperlordosis are linked to potential back pain issues.

Spondylolysis

• Definition:

  • Destruction of the pars interarticularis, commonly at L5 (90% cases)

  • Etiology: Caused by repetitive hyperextension and microtrauma over time leading to weakness in structure, often exacerbated by rapid adolescent growth

• Symptoms: Low back pain, Scotty Dog “collar” appearance on X-ray

Ankylosing Spondylitis

• Definition:

  • A chronic inflammatory disease often presenting before age 45 leading to stiffening and chronic back pain

• Symptoms includes: Morning stiffness, limited spinal mobility leading to kyphotic posture over time

• Treatment Options: Include NSAIDs and physical therapy

Spondylolisthesis

• Definition:

  • Occurs following spondylolysis with displacement, most commonly at L4-L5

• Symptoms: Pain and neurologic deficits due to tension on nerve roots

Sciatica

• Definition:

  • Irritation or compression of the sciatic nerve leading to pain and other symptoms extending from the lower back to the foot

• Etiologies include: Herniated disc, degenerative changes, or spondylolisthesis

Herniated Disc

• Definitions:

  • Bulging, extrusion, and sequestration classified based on the degree and state of nucleus pulposus migration.

• Pathophysiology: Bulging may lead to pain if it impinges onto nerve roots.

Spinal Cord Anatomy

Fundamental Components:

1. Gray Matter:

   • Location for neuron cell bodies and synapses critical for integrating signals

2. White Matter:

   • Myelinated fibers transmitting action potentials up and down the cord

3. Protective Layers:

   • Pia Mater: Soft inner layer sealing the CNS

   • Dura Mater: Tough outer fibrous layer protecting the spinal cord

4. Subarachnoid space: filled with cerebrospinal fluid (CSF) for cushioning and nourishment of the spinal cord

Spinal Cord Pathology

• Spina bifida occulta:

  • Attainable asymptomatic gap in the vertebral canal with associated skin abnormalities resulting from neural tube development issues.

• Meningocele and Myelomeningocele are varied types of spina bifida involving more severe functional consequences with potential need for surgical intervention.

Back Muscles

• Classification:

  • Superficial: Movement of upper limbs

  • Intermediate: Primarily involved with elevation and depression of the ribs

  • Deep: Main contributors to posture and spinal movement

  • Key Muscles Include: Trapezius, latissimus dorsi, serratus posterior (superior and inferior), Erector Spinae group, and transversospinales (multifidus, rotatores, semispinalis).

Arterial Supply to Back

• Key Arteries:

  • Posterior Intercostal and Lumbar Arteries: main sources for muscles and structures surrounding the spinal region

  • Thoracodorsal and Dorsal Scapular Arteries support the major upper back muscles.

Lymphatics

• Flow Complexity: Superficially follows veins, while deeper lymphatics trail arteries.

• Node connections: Include axillary and lumbar nodes contributing to overall systemic lymph drainage.