Applied Anatomical Concepts

Question 1

Inspiration and Expiration

Answer 1

Inspiration: increase in intrathoracic volume = decreased intrathoracic pressure. parietal pleura is pulled with the movement of the ribs and diaphragm. visceral pleura moves with parietal pleura (surface tension). lung volume increases. air moves into lungs.
Expiration: decreased intrathoracic volume = increased intrathoracic pressure. pleura moves with elastic recoil and parietal pleura moves with the ribs/diaphragm. air moves out

Question 2

Dimensional changes

Answer 2

Thoracic breathing: lateral/transverse diameter & anteroposterior diameter.
Abdominal breathing: vertical diameter

Question 3

Details of dimensional changes

Answer 3

Lateral diameter of thorax: lateral edges of ribs elevated supero-laterally during inspiration and lateral diameter increases - also known as bucket handle movement.
Anteroposterior diameter of thorax: anterior ends of ribs raised during inspiration, elevation causes sternum to be raised, movement facilitated by costal cartilages, pump handle movement.
Vertical diameter: via diaphragm which forms floor of thoracic cavity, resting position of diaphragm is domed, upon contraction, diaphragm descends 5-10 cm

Question 4

Muscles in breathing

Answer 4

Quiet breathing: inspiration - external ics, scalene muscles, diaphragm; expiration - passive (elastic recoil).
Forced breathing: inspiration - those in quiet inspiration + pectoral muscles, sternocleidomastoid (SCM), latissimus dorsi; expiration - internal ics, oblique and transverse abdominal muscles, quadratus lumborum

Question 5

Diaphragm

Answer 5

sheet of skeletal muscle with a central tendon
Pericardium attached to middle of tendon on its superior surface
Diaphragmatic (parietal) pleura lines its superior surface
Origin: 3 parts - sternal (xiphoid process), costal (costal cartilages of ribs 7-10, ribs 11 and 12), lumbar (medial and lateral arcuate ligaments and lumbar vertebral bodies)
Insertion: central tendon

Question 6

Lumbar attachments of Diaphragm

Answer 6

Lumbar parts of diaphragm arises from the medial and lateral arcuate ligaments and from the lumbar vertebral bodies via right and left crura.
The right and left crura meet to form the median arcuate ligament to form aortic hiatus

Question 7

Openings and Blood Supply and Action of Diaphragm

Answer 7

Openings: opening for inferior vena cava (T8), oesophageal hiatus (T10), aortic hiatus (T12) - the thoracic duct and azygos vein also pass through the aortic hiatus.
Blood Supply: superior and inferior phrenic arteries
Actions: alters volume of thorax/abdomen, quiet inspiration (2cm), forced inspiration (7-10cm descends), aids venous return, hiccups, urinating/defecation, lifting heavy objects, child birth

Question 8

Phrenic Nerve

Answer 8

Arises from ventral rami of C3, C4 & C5
Enter superior mediastinum lateral to Vagus nerve
Motor: diaphragm (sole supply)
Sensory: pericardium, parietal pleura, parietal peritoneum, central region of diaphragm

Question 9

Pancoast Tumour

Answer 9

recurrent laryngeal nerve compression

• pancoast tumour is located at apex of the lung
• if on left side, can cause recurrent laryngeal nerve compression
• vocal cord paralysis = hoarseness

Question 10

Coronary Circulation Dominance

Answer 10

Blockage of the main right or left coronary artery will have different outcomes depending on coronary artery dominance.
Coronary artery dominance is also important when planning for a coronary artery bypass graft.
Arteriograms are used to determine coronary artery dominance