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8 Cards in this Set
- Front
- Back
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parts and attachments of the diaphragm and its nerve supply
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N: C3,4,5 (phrenic n. 2/3 motor, 1/3 sensory)
- Muscle fibres attach to the central tendon - Anterior fibres are more horizontal - Lateral and posterior fibres are more vertical (hence domes of diaphragm descend when muscle fibres contract) |
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the locations of the diaphragmatic hiatuses and name the structures that pass through & behind the diaphragm
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Structures passing through:
(1)Venal caval hiatus: IVC, branches of the right phrenic nerve (2)Oesophageal hiatus: oesophagus, vagal trunks (T8 in the right crus) (3) Aortic hiatus: abdominal aorta, thoracic duct, azygos vein Thoracic splanchnic nerves (carry preganglionic sympathetic fibres into abdomen) pass through the crura *Note that the abdominal aorta, strictly speaking, passes behind the diaphragm |
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Diaphragm Function
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- Principal muscle of respiration
- Thin, domed sheet of muscle (skeletal muscle) - Nerve supply: left & right phrenic nerves (C3-5) - Separates thoracic & abdominal cavities - Forms roof of abdominal cavity - Inspiration – diaphragm contracts and descends - Expiration – diaphragm relaxes and ascends |
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Diaphragm Attachments
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Muscle fibres originate peripherally and
insert on the central tendon Origins of the diaphragm: - sternal part (back from xiphoid process) - costal part (lower 6 costal cartilages) - lumbar part (left & right crus & arcuate ligaments) Insertion of the diaphragm: - central tendon (trifoliate shape) |
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Diaphragm Innervation MOTOR
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Motor supply
Left & right phrenic nerves (C3,4,5) supply each hemidiaphragm (via the inferior surface) Damage to phrenic nerve leads to paralysis of ipsilateral hemidiaphragm |
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Diaphragm Sensory Supply
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Sensory supply
Central part: sensory fibres travel in phrenic nerve; Pain referral to left or right shoulder (C4 dermatome). Peripheral part: sensory fibres travel in lower 6-7 intercostal nerves & subcostal nerve (T12). Pain felt in distribution of these nerves. BUT ALSO Pericardium and parietal pleura - can refer as C4 shoulder pain |
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Phrenic Nerve Lesion
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A phrenic nerve lesion will result in a raised hemidiaphragm on inspiration, ipsilateral to the lesion
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Dome shape comes about because the...
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• The anterior fibres are more horizontal, while the posterior and lateral fibres are more vertical. Hence
the domed shape. • All fibres originate peripherally from sternal, costal and lumbar attachments and insert at the central tendon |
