AN25.1-9 | Thorax — Glossary

The primary muscle of inspiration, a musculotendinous dome separating thorax from abdomen, supplied solely by the phrenic nerve (C3, C4, C5)

The trefoil-shaped aponeurosis of the diaphragm where the right, left, and anterior muscular fibres converge; the IVC passes through it at T8

The muscular origin of the diaphragm from L1-L3 vertebral bodies that forms the oesophageal hiatus at T10

Thickenings of fascia forming attachments for the diaphragm: median (over aorta), medial (over psoas), lateral (over quadratus lumborum)

The sole motor nerve to the diaphragm from C3, C4, C5; injury causes ipsilateral diaphragmatic paralysis

Opening in the central tendon of the diaphragm at T8 for the IVC; its position in tendon keeps it patent during contraction

Opening in the right crus of the diaphragm at T10 for the oesophagus and vagal trunks

Opening behind the diaphragm at T12 for the aorta, azygos vein, and thoracic duct

An extra rib from C7 vertebra that may compress the subclavian artery or lower trunk of the brachial plexus causing thoracic outlet syndrome

Funnel chest, a congenital depression of the sternum that may compress the heart in severe cases

Pigeon chest, an anterior protrusion of the sternum, associated with rickets and chronic childhood asthma

Compression of the subclavian vessels and brachial plexus at the thoracic outlet, often by a cervical rib or tight scalene muscles

Emergency decompression of tension pneumothorax by inserting a needle into the 2nd intercostal space at the midclavicular line

The anatomical triangle for chest drain insertion bordered by latissimus dorsi posteriorly, pectoralis major anteriorly, and nipple line inferiorly

Three or more adjacent ribs fractured in two places, creating a paradoxically moving segment during breathing

Local anaesthetic injection at the costal groove to block the intercostal nerve for rib fracture pain relief

The sharp angle between the diaphragm and chest wall on CXR; blunting indicates pleural effusion

The heart shadow on CXR; cardiothoracic ratio should be less than 50% on PA film

An emergency technique using sharp upward thrusts below the costal margin to expel a foreign body from the airway

A defect (usually posterolateral/Bochdalek) allowing abdominal viscera to herniate into the thorax, a neonatal surgical emergency

Referred pain from diaphragmatic irritation via the phrenic nerve (C4), seen in subphrenic abscess and ruptured spleen

Inward movement of the chest wall during inspiration, seen in flail chest and diaphragmatic paralysis