THORACIC SKELETON ANATOMY

THORAX OVERVIEW

• The thoracic cage is a structure made up of bones and cartilage that plays a vital role in protecting the thoracic organs like the heart, lungs, and great vessels
• Composed of the ribs, thoracic vertebrae, and sternum, which together create a flexible yet sturdy framework crucial for breathing
• The thoracic cage forms a cavity that has two key openings

Thoracic Cage

• Consists of bony and cartilaginous structures
• Protects vital organs: heart, lungs, and great vessels
• Formed by ribs, thoracic vertebrae, and sternum
• Provides structural support and flexibility for breathing

Thoracic Cavity

• Houses and protects the heart and lungs
• Allows space for lung expansion during respiration
• Lined by the thoracic skeleton for protection and movement efficiency

Superior Thoracic Aperture

• Upper opening of the thoracic cavity
• Slopes downward and forward
• Boundaries:
  • First thoracic vertebra (back)
  • Manubrium of the sternum (front)
  • First ribs (sides)
• Allows passage of trachea, esophagus, and major blood vessels

Inferior Thoracic Aperture

• Lower boundary of the thoracic cavity
• Boundaries:
  • Twelfth thoracic vertebra
  • Eleventh and twelfth ribs (sides)
  • Costal cartilages of seventh to tenth ribs (front)
  • Subcostal angle formed at convergence
• Sealed by the diaphragm
• Separates thoracic cavity from the abdominal cavity
• Aids in respiration

THORACIC FEATURES

• The thorax features a well-designed framework that includes the costal arch for flexibility, intercostal spaces to facilitate rib movement, and the infrasternal angle as a key anatomical landmark
• These structures work together to protect vital organs and support efficient respiration through the expansion and contraction of the thoracic wall

Thoracic Skeleton

• Comprises the bones forming the thorax
• Bones of the Thorax:
  • Includes thoracic vertebrae, ribs, and sternum
• Ribs:
  • Twelve pairs of elastic, curved bones
  • Attach posteriorly to the vertebral column and anteriorly to the sternum via costal cartilages
  • Functions: provide structural support, protect thoracic organs, enable respiration through mobility
• Sternum:
  • Long, flat bone in the center of the anterior thoracic wall
  • Provides structural support
  • Articulates with clavicles (collarbones) and first seven pairs of ribs via costal cartilages

Infrasternal Angle

• Angle formed at the xiphoid process where the lower rib cage edges meet
• Serves as an anatomical landmark for diaphragm access

Costal Cartilages

• Hyaline cartilage connecting ribs to the sternum or each other
• Provides flexibility to the thoracic wall for respiration

Intercostal Spaces

• Spaces between adjacent ribs and their costal cartilages
• Eleven spaces on each side
• Contents:
  • Intercostal muscles
  • Membranes
  • Neurovascular bundles
• Function:
  • Allows rib movement during respiration
  • Aids in thoracic cavity expansion and contraction