Heart + lungs Flashcards
What is the mediastinum + what structures does it contain
- the space b/t the lungs
contains:
- trachea + bronchi
- heart + vessels to + from it
- nerves
- oesophagus
Describe the position of the lungs in terms of ribs
2nd ribs - right + left lung almost converge
4th pair - left lung moves away from midline (accomodate heart)
6th pair - right lung, costal cartilage + pleura move from midline
8th pair - both pleura pass mid-clavicular line
10th pair - pleura finishes anteriorly (mid-axillary line)
12th pair - pleura finishes posteriorly
Describe the position of the heart
- directly posterior to sternum
- opposite T5-T8
- in contact w/ diaphragm
- anterior + inferior to mediastinum
What muscles are involved in inspiration
- diaphragm
- external intercostals
What muscles are involved in forceful exhalation
internal intercostals
Diaphragm
o = sternal -> inner part of xiphoid process
costal -> inner surface of lower 6 ribs
lumbar -> upper 2-3 lumbar vertebrae
i = central tendon
a = draws central tendon down during inspiration to increase volume of thoracic cavity
n = phrenic
External intercostals
o = inferior border of ribs
i = superior border of ribs below -> run obliquely down + forward
a = helps expand thoracic cavity during inspiration by elevating ribs
n = intercostal
Internal intercostals
o = inferior border of ribs
i = inner lip of superior border of ribs below -> run obliquely down + back
a = fix intercostal spaces during expiration / aid forced expiration by depressing ribs
n = intercostal
What is the pericardium
the membrane covering the heart / inner = serous, outer = fibrous
What structures pass through the inferior thoracic inlet (6)
- inferior vena cava
- descending aorta
- oesophagus (through oesophageal hiatus)
- thoracic duct
- azygos vein
- sympathetic chain
What is the pleura
Serous membrane arranged as a closed sac
- parietal pleura lines thoracic cavity
- visceral pleura lines lungs
