Diaphragm Anatomy Quiz

– Severe kyphoscoliosis can impact respiratory function – Rib anatomy:

• A typical rib consists of a head, neck, body, tubercles, facets, and articulations
• Ribs 11 and 12 do not have tubercles and do not articulate with the sternum – Ribs and their posterior articulations:
• Posteriorly, ribs articulate with thoracic vertebrae
• Head and necks of ribs 2–9 articulate with two vertebral bodies and the centrum of the next superior vertebra
• Rib 1 articulates only with T1
• Tubercle of rib articulates with costal facets of adjacent thoracic vertebral transverse processes – Three types of ribs:
• True ribs (1st–7th) attach directly to the sternum
• False ribs (8th, 9th, and usually 10th) have indirect attachment to the sternum
• Floating ribs (11th and 12th) have no sternal connection

– Ribs and their anterior articulations:

• Ribs 1–10 articulate anteriorly with the sternum
• 1st pair articulates with the manubrium, 2nd pair with manubrium and body, 3rd–6th pairs with the body, and 7th pair with the body and xiphoid process
• 8th–10th pairs attach to the 7th costal cartilage

– Rib orientation is oblique

• In adults, ribs course in an oblique, inferior direction from their thoracic vertebral articulation to their anterior sternal articulation
• Infants’ ribs are horizontal
• The sternal attachment is at a lower level than the vertebral articulation

– Sternum anatomy:

• The sternum consists of the manubrium, body, and xiphoid process
• Manubrium is the uppermost portion, lies in the same plane as the 2nd thoracic vertebra, and is where the tip of the endotracheal tube should be located
• Body is the largest portion and is formed by four sternabrae
• Xiphoid process is the lowermost and smallest portion and begins as hyaline cartilage, ossifying into bone after age 40

– Surface anatomy of the anterior thoracic wall:

• Clavicle and the thoracic cage provide surface landmarks
• Jugular notch is located between the medial ends of the clavicles
• Intermammary cleft superficially marks the division of the breasts
• Cutaneous innervation of the anterior thoracic wall is from ventral rami and forms dermatomes, with the nipple in the T4 dermatome, xiphoid process in the T6 dermatome, and umbilicus in the T10 dermatome

– Sternal angle:

• The junction of the manubrium and body of the sternum is known as the sternal angle or the manubriosternal joint and correlates with several structures, including the carina of the trachea, the start and end of the aortic arch, and the border between the superior and inferior mediastina, as well as the thoracic duct shifting to the left of the esophagus.

– Functions of the diaphragm:

• The diaphragm is the primary muscle of inspiration, with its contribution varying based on body position
• It separates the thoracic cavity from the abdominal cavity
• During respiration, it flattens and increases the vertical dimension of the thoracic cavity
• It aids in venous return by causing pressure changes in the thoracic and abdominopelvic cavities.

– Diaphragm functional characteristics:

• The diaphragm is not a single muscle but is embryologically derived from two separate hemi-diaphragms that fuse during gestation
• The right hemi-diaphragm is normally slightly higher than the left, with the right dome resting on the liver and the left dome resting on the fundus of the stomach.

– Under abnormal conditions, one hemi-diaphragm may be incapacitated, resulting in ipsilateral diaphragm paralysis and paradoxical movement when viewed by fluoroscopy.