Chapter 2 - Anatomy of Respiration

Pectoral girdle

scapula & clavicle

function: support upper extremities & attach to sternum at manubrum

Ribs

• 7 true ribs 

• 3 false ribs 

• 2 floating ribs 

functions: protection and aiding respiration

Parts of sternum

manubrium sterni, corpus, xiphoid or ensiform process

Cervical vertebrae

7

transmit spinal cord (vertebral foramen), veins and arteries (transverse foramina), attach to other vertebrae (articular facets)

Thoracic vertebrae

12

hold spinal cord (vertebral foramen), attach to other vertebrae (articular facets), articulate with ribs (costal facets) 

Lumbar vertebrae

5

hold spinal cord (vertebral foramen), attach to other vertebrae (articular facets), support entire weight 

Sacral vertebrae

5

inferior to lumbar vertebrae, structural support, pelvic stability 

Coccyx

4 vertebrae fused together

Pelvic girdle

Ilium, sacrum, pubic bone, ischium 

Functions: support lower extremities, carries weight, provides stability, point of attachment for muscles

How does a rib connect to vertebrae?

What is pleurae

surround important structures in the thoracic cavity

Visceral pleura

cover each kung

Parietal pleurae

inside thoracic cavity

• Mediastinal pleura 

• Diaphragmic pleura 

• Costal pleurae 

• Apical pleurae: superior-most region of rib cage

How does the pleural lining keep lungs attached?

The space between the visceral and parietal pleura provides a sealed connection between the lungs and rib cage to support breathing. This space contains pleural fluid that allows pleura to slide against each other as the lungs and rib cage expand, mechanical coupling creates like a vacuum sealed pleural linkage. 

Diaphragm

• Main inspiratory muscle 

• Origin: xiphoid process, inferior margin of ribs 7-12, L1-L5 traverse process 

• Insertion: central tendon (broad flat sheet, crescent shaped provides floor for the heart) 

• Openings: vena cava (foramen vena cava), esophagus (esophageal hiatus), abdominal aorta (aortic hiatus) 

 

Anterior thoracic muscles of inspiration

Structure: external intercostals, internal intercostals (interCHONDRAL portion) 

Functions: run between the ribs to elevate the ribs 

Accessory muscles of neck

Structure: Sternocleidomastoid muscle, scalene muscles 

Functions: stability, control neck flexion and extension, clavicular breathing

Muscles of forced expiration

Internal intercostal (interOSSEOUS portion) 

transverse abdominis, internal oblique abdominis, external oblique abdominis, rectus abdominis

Abdominal muscles of respiration

Structure: transverse abdominis, internal oblique abdominis, external oblique abdominis, rectus abdominis 

Function: contraction of abdominal muscles, squeezing of the abdomen, compression/elevation of viscera

Boyle’s Law

for gas in an enclosed sealed space and at a constant temperature, pressure is inversely proportional to volume (more volume = less pressure, less volume = more pressure)