thoracic

• Thoracic wall


  The framework of the thoracic cage includes the vertebral column behind, the ribs and intercostal spaces on either side, and the sternum and costal cartilages in front
• Thoracic wall


  • Flattened in front and behind but rounded at the sides
• Boundaries of the thoracic wall

  • Anterior: Sternum
  • Lateral: Ribs
  • Superior: Thoracic outlet
  • Inferior: Diaphragm
• Sternum


  Located in the midline of the anterior chest wall and consists of three parts: the manubrium sterni, the body of the sternum, and the xiphoid process

  
• Manubrium


  • The upper part of the sternum, articulates with the body of the sternum at the manubriosternal joint, also articulates with the clavicles and the 1st and 2nd costal cartilages on each side
• Body of the sternum


  • Articulates with the manubrium above and the xiphoid process below, also articulates with the 2nd to the 7th costal cartilages on each side
• Xiphoid process


  • A thin cartilaginous plate that ossifies at its proximal end during adulthood, no ribs or costal cartilages are attached to it
• Sternal angle


  Aka angle of Louis, formed by the articulation of the manubrium with the body of the sternum, can be identified by a transverse ridge on the anterior aspect of the sternum, lying at the level of the 2nd costal cartilage
• Xiphisternal joint


  Located opposite the body of the ninth thoracic vertebra

  
• Categories of ribs

  • True ribs (1st to 7th)
  • False ribs (8th to 10th)
  • Floating ribs (11th and 12th)
• Typical rib


  • Consists of a head, neck, tubercle, shaft, and angle
• 1st rib


  • Clinically significant due to its proximity to the lower nerves of the brachial plexus and the subclavian artery and vein
• 2nd rib


  • Has Tuberosity for serratus anterior muscle
• Rib 11


  • Single facet on head, short neck, lacks tubercle, has a slight costal groove

  
• Rib 12


  • Single facet on head, lacks tubercle, angle, costal groove

  
• Costal cartilages


  Connect the upper seven ribs to the sternum, while the 8th to 10th ribs are attached to the cartilage above them, the 11th and 12th ribs do not attach to the sternum but end in the abdominal musculature

  
• Joints of the chest

  • Manubriosternal Joint
  • Xiphisternal Joint
  • Costrochondral joints
  • Costovertebral joints
• Manubriosternal Joint


  Cartilaginous joint between the manubrium and the body of the sternum, allows a small amount of angular movement during Respiration
• Xiphisternal Joint


  Cartilaginous joint between the xiphoid process (cartilage) and the body of the sternum, the xiphoid process usually fuses with the body of the sternum during middle age

  
• Costochondral joint


  Connects the ribs to the costal cartilages, contributing to the flexibility and stability of the thoracic cage, consists of hyaline cartilage which provides smooth articulation and helps absorb shock during movement

  
• Costovertebral joint


  Articulations between the proximal ends of the ribs and their corresponding vertebrae

  
• Costal cartilages


  The 1st costal cartilages articulate with the manubrium by cartilaginous joints that permit no movement, the 2nd to 7th costal cartilages articulate with the lateral border of the sternum by synovial joints, the 6th, 7th, 8th, 9th, and 10th costal cartilages articulate with one another along their borders by small synovial joints, the cartilages of the 11th and 12th ribs are embedded in the abdominal musculature
• Thoracic Outlet


  Vital anatomical region where structures from the neck and upper limbs pass through to enter or exit the thorax
• Location and Boundaries of Thoracic Outlet

  • Situated at the superior aspect of the thorax, connecting it to the root of the neck, positioned obliquely, facing upward and forward, Posterior: T1 Vertebra, Lateral: medial borders of the 1st ribs and their costal cartilages, Anterior: superior border of the manubrium sterni

  
• Structures passing through the Thoracic Outlet

  • Subclavian artery and vein
  • Brachial plexus
• Muscles of the Thoracic Wall

  • External Intercostal
  • Internal Intercostal
  • Innermost Intercostal
• External Intercostal Muscle


  Positioned as the outermost layer, fibers run downward and forward from the lower border of one rib to the upper border of the rib below, extends forward to the costal cartilage, where it turns into a flat tendon called the anterior (external) intercostal membrane

  
• Internal Intercostal Muscle


  Occupies the intermediate layer, fibers oriented downward and backward from the groove beneath one rib to the upper border of the rib below, extends backward from the sternum to the rib angles, where it forms the posterior (internal) intercostal membrane

  
• Innermost Intercostal Muscle


  Deepest layer, resembling the transversus abdominis muscle in the abdomen, incomplete muscle layer crossing multiple intercostal spaces, connected internally to fascia and parietal pleura, and externally to intercostal nerves and vessels, divided into three somewhat distinct portions
• Respiratory muscles

  • Inspiratory (Relaxed: Diaphragm, External Intercostals; Forced: Pecs Minor, Scalenes, SCM, Serratus anterior)
  • Expiratory (Relaxed: None/Passive Recoil; Forced: Abdominals, Serratus posterior)
• Diaphragm


  Thin muscular and tendinous septum that divides the chest cavity from the abdominal cavity, primary muscle of respiration, dome-shaped with a peripheral muscular part and central tendon
• Openings of the Diaphragm

  • Aortic Hiatus
  • Esophageal Hiatus
  • Vena Caval Foramen (Caval Opening)
• Aortic Hiatus


  Located at the level of the 12th thoracic vertebra, through which the aorta, thoracic duct, and azygos vein pass
• Esophageal Hiatus


  Situated at the level of the 10th thoracic vertebra, through which the esophagus and vagal trunks pass
• Vena Caval Foramen (Caval Opening)


  Positioned at the level of the 8th thoracic vertebra, through which the inferior vena cava penetrates the diaphragm to reach the abdominal cavity
• Expiratory muscles

  • Internal Intercostal
  • Abdominals
• Internal Intercostal


  Compress ribs (AP and lateral diameter)

  
• Abdominals

  Compress abdominal viscera forcing diaphragm superiorly
• Thoracic Cage mechanism

  • Pump Handle Motion
  • Bucket handle motion
  • Caliper motion
  • Diaphragm
• Pump Handle Motion

  Sternum and rib 1 – 6, increases sternum and A – P Diameter