Lecture 4: Diaphragm; Mechanisms of Breathing (& Breast) Flashcards
What is the median arcuate ligament?
Formed by crus over descending aorta - attach to lumbar vertebrae
What are the lengths of the crura?
Right L1-3/4
Left L1-2/3
What is the medial arcuate ligament?
Reflection of diaphragm over psoas major
What is the lateral arcuate ligament?
Reflection of the diaphragm over quadratus lumborum
What level does the IVC pierce the diaphragm and what is the function of this?
T8, when the diaphragm contracts it opens up orifice and promotes blood return to heart
What level does the oesophagus pierce the diaphragm and what is the function of this?
T10, when the diaphragm is expanding for breathing this orifice acts as a sphincter and closes off the stomach so that reflux of acidic stomach contents doesn’t occur when intra-abdominal pressures increase
What level does the aorta pierce the diaphragm?
T12
Where does the azygous vein move through the diaphragm?
Slings of crura
Where does the sympathetic trunk move through the diaphragm?
Enters under the median arcuate ligament
What nerve innervates the diaphragm and what spinal segments is it from?
Phrenic, C3,4,5
What does the phrenic nerve supply for the diaphragm?
Sensory to central tendon and pericardium, motor to all of diaphragm
What nerve provides sensory supply to the periphery of the diaphragm?
Intercostals
How do the lungs inflate?
Parietal pleura is attaches to the thoracic cage, due to surface tension, when the parietal pleura moves the visceral pleura moves. The visceral pleura is attached to the lungs so when it moves the lungs move - when the thoracic cage opens the lungs expand
What are rhythmic contractions controlled by?
Resp centre in brainstem
Where does pump handle occur?
Ribs 2-5 - sternum moves up and outward and expands thoracic cavity in anteroposterior direction
Where does bucket handle occur?
Ribs 7-10 - ribs move outwards - increase transverse diameter of thoracic cage
What muscles assist with expansion in respiration?
Scalene, external intercostals, medial internal intercostals
What muscles assist with collapse in respiration?
Lateral internal intercostals, abdominal muscles (increase pressure)
What are hiccups?
Quick inspirations due to spasmodic contractions of the diaphragm
What are hiccups caused by?
Irritation of the phrenic nerve, diaphragm or resp centre
What muscle does the mammary gland sit anterior to?
Pec Major
How many lobules are in each breast and where do they drain?
15-20 - lactiferous duct
How is the mammary gland attached?
Via suspensory ligament to skin and fascia
What fraction of the breast sits over what muscle?
2/3 pec major, 1/3 serratus anterior
What is the position of the nipple?
4th intercostal space
What is unique about the areola?
Sebaceous glands for lubrication
What is the difference between young and old breast tissue?
Young is dense, old is fatty
What is the blood supply to the mammary gland?
Internal thoracic, intercostals, subclavian
What are the lymphatics for the breast?
Sub alveolar plexus
Where is breast cancer usually derived from?
Glandular epithelium in lobules
What part of the breast can be confused with a swollen lymph node?
Axillary tail
Where is milk stored in the breast?
Lactiferous sinus
