Surface Anatomy of the Thorax

Surface Anatomy of the Thorax

• Surface anatomy studies the body's superficial features and their relation to deeper structures.
• Key thoracic contents include the heart, lungs, trachea, and esophagus, all enclosed by the ribcage formed by the first ten ribs.

Thoracic Structure Overview

• 12 thoracic vertebrae each correspond with a rib.
• Esophagus runs posteriorly, while the trachea, which bifurcates for air delivery, lies anterior.
• The heart is located anterior to the trachea, flanked by the lungs, surrounded by pleural membranes.

Ribcage and Sternum

• Anterior ribcage includes costal cartilages that articulate with the sternum, composed of three parts: manubrium, body, and xiphoid process.
• Clavicle links the manubrium to the scapula, while the coracoid process projects anteriorly from the scapula.

Surface Palpation Techniques

• Locate the jugular notch at the top of the rib cage and feel for aortic pulsations.
• Move laterally to palpate the clavicle and the coracoid process beneath it.
• Sternal angle is the joint between the manubrium and sternum body; a key landmark for anatomical reference.

Intercostal Space Identification

• The second costal cartilage indicates the location of the second rib, with intercostal spaces palpable below.
• Costal margin is demarcated by the tenth rib, costal cartilages, and the xiphoid process.

Musculature of the Thorax

• Palpate the deltoid and pectoralis major; the latter slightly obscured in women by breast tissue.
• The linear alba is a key indentation running vertically along the abdominal muscles.
• Rectus abdominis appears as vertical muscular segments known as the "six-pack."

Important Neck Muscles

• The sternocleidomastoid runs from the neck to the manubrium; palpate it on either side for identification.

Relation to Deeper Structures

• Trachea palpable between sternocleidomastoid muscles; tracheal rings also felt until engulfed by the sternum at the jugular notch.
• Lung apex is 2-3 cm above the clavicle; bases are around the sixth or seventh intercostal space.
• Left lung's oblique fissure runs along the seventh rib; right lung's fissure follows the sixth intercostal space.

Heart Location and Auscultation Points

• The heart is centrally positioned in the thorax, extended into the left thoracic area primarily by the left and right ventricles.
• The apex of the heart is palpated at the left fifth intercostal space.
• Valve auscultation points:
  • Aortic valve: second intercostal space near the sternum.
  • Pulmonary valve: same horizontal plane as aortic, but left side; locate around the third intercostal space.
  • Tricuspid valve: palpate three intercostal spaces down from the aortic valve position.
  • Mitral valve: located in the fifth intercostal space, lateral to the midpoint of the clavicle.

Mnemonic for Valve Order

• Use "A Place To Meet" to remember the order of aortic, pulmonary, tricuspid, and mitral valves.

Surface Anatomy of the Thorax

• Surface anatomy examines superficial body features and their connection to deeper structures.
• Thoracic cavity contains crucial organs such as the heart, lungs, trachea, and esophagus.
• The ribcage is formed by the first ten ribs, providing a protective enclosure.

Thoracic Structure Overview

• Comprises 12 thoracic vertebrae, each matching a rib.
• The esophagus is situated posteriorly, while the trachea, bifurcating for air transport, is found anteriorly.
• The heart is located anterior to the trachea, positioned between the lungs and enveloped by pleural membranes.

Ribcage and Sternum

• The anterior ribcage features costal cartilages that connect to the sternum, which consists of three sections: the manubrium, body, and xiphoid process.
• The clavicle connects the manubrium to the scapula, with the coracoid process extending anteriorly from the scapula.

Surface Palpation Techniques

• Identify the jugular notch atop the rib cage to feel aortic pulsations.
• Palpate laterally to locate the clavicle and surrounding coracoid process.
• The sternal angle marks the junction of the manubrium and sternum body, serving as an important anatomical landmark.

Intercostal Space Identification

• The second costal cartilage signals the position of the second rib, with palpable intercostal spaces beneath it.
• The costal margin is defined by the tenth rib, costal cartilages, and xiphoid process.

Musculature of the Thorax

• Palpate visibly the deltoid and pectoralis major muscles, the latter partially obscured by breast tissue in women.
• The linear alba is a prominent vertical tendon along the abdominal muscles.
• Rectus abdominis is identified as vertical muscle segments, commonly referred to as the "six-pack."

Important Neck Muscles

• The sternocleidomastoid muscle runs from the neck to the manubrium, easily palpated on both sides.

Relation to Deeper Structures

• The trachea can be palpated between the sternocleidomastoid muscles, with tracheal rings discernible until obscured by the sternum at the jugular notch.
• The lung apex reaches 2-3 cm above the clavicle, while the bases are around the sixth or seventh intercostal space.
• The left lung's oblique fissure aligns with the seventh rib; the right lung's fissure corresponds to the sixth intercostal space.

Heart Location and Auscultation Points

• Centrally located in the thorax, the heart extends into the left thoracic area due to the left and right ventricles.
• The apex of the heart is palpated at the left fifth intercostal space.
• Valve auscultation points include:
  • Aortic valve: located at the second intercostal space near the sternum.
  • Pulmonary valve: in the same plane as the aortic but on the left, around the third intercostal space.
  • Tricuspid valve: three intercostal spaces below the aortic valve position.
  • Mitral valve: situated in the fifth intercostal space, lateral to the clavicle midpoint.

Mnemonic for Valve Order

• Use "A Place To Meet" to remember the sequence of valve auscultation: aortic, pulmonary, tricuspid, and mitral.