17 Anatomy of Breathing 2 - Thoracic wall

Anatomy of Breathing

Thoracic Wall

  • Presenter: Niggy Gouldsborough

Bony Thorax

  • Definition: Forms the skeleton of the chest wall.

  • Components:

    • Sternum

    • Ribs: 12 pairs

    • Thoracic vertebrae: 12

The Sternum

  • Common Name: Breast bone

  • Parts:

    • Manubrium

    • Body

    • Xiphisternum (not shown)

  • Reference: (Gosling et. al., 2018)

Ribs

  • Attachment:

    • Attached by head and tubercle to the thoracic vertebrae.

  • Orientation: Slope downwards and forwards.

  • Connection: Ribs 1-10 are attached by costal cartilage to the sternum.

  • Classification:

    • 7 pairs: True ribs

    • 3 pairs: False ribs

    • 2 pairs: Floating ribs

  • Anatomy: Head, tubercle, shaft.

Thoracic Vertebrae

  • Components:

    • Body

    • Transverse processes

  • Articulation:

    • Head of rib articulates with the body of the thoracic vertebra.

    • Tubercle of rib articulates with the transverse process of the thoracic vertebra.

Intercostal Muscles (Lateral View)

  • Layers:

    • External intercostal muscles: Superficial layer.

    • Internal intercostal muscles: Middle layer.

    • Innermost intercostal muscles: Deep layer.

  • Location: Span the intercostal spaces between the ribs.

  • Reference: (Gosling et al, 2018)

Function of Intercostal Muscles

  • External Intercostals: Fibres run downwards and forwards.

  • Internal Intercostals: Fibres run downwards and backwards.

  • Reference: (Ashton, 2015)

Intercostal Vessels and Nerves

  • Location: Course in the intercostal spaces between the internal intercostal and innermost intercostal muscles.

  • Function: Supply the muscles, adjacent skin, and pleura.

  • Components:

    • External intercostal muscle

    • Internal & innermost intercostal muscles

    • Nerve, artery, vein

  • Reference: (Drake et. al., 2018)

Diaphragm

  • Structure: Dome-shaped skeletal muscle with a central tendon.

  • Function: Separates the thorax from the abdomen.

  • Attachments:

    • Xiphisternum

    • Costal margin

    • 11th & 12th ribs

    • Lumbar vertebrae

  • Openings: for inferior vena cava, oesophagus, and aorta.

  • Connection: Fibrous pericardium fused to central tendon.

  • Innervation: By the phrenic nerve.

  • References:

    • (Gosling et al, 2018)

    • (Moore et. al., 2018)

Diaphragm Anatomy

  • Parts:

    • Right & left crus arise from lumbar vertebrae.

    • Attachments: Costal margin and 11th & 12th ribs, xiphisternum.

  • Structures Passing Through:

    • Inferior vena cava

    • Oesophagus

    • Aorta

  • Historical Reference: Gray, H. Anatomy of Human Body 1918. Bartelby.com, 2000.