Week 4 - Respiratory Muscles

Question 1

Describe the changes to diameters of the thoracic cavity during inspiration

Answer 1

Increase in AP - ribs elevate carrying sternum up/ forwards
Increase in transverse diameter - 6-10 rib elevate
Increase in vertical diameter - diaphragm descends

Question 2

Describe the shape and position of the diaphragm

Answer 2

Unpaired, dome shaped skeletal muscle

Fills inferior thoracic aperture

Question 3

What is the zone of apposition

Answer 3

Area of attachment between diaphragm and rib cage, controlled by abdominal muscles

Question 4

What are the attachments of the diaphragm

Answer 4

Sternal part: Posterior aspect of xiphoid process
Costal part: Internal surfaces of lower costal cartilages and ribs 7-12
Lumbar part: Medial and lateral arcuate ligaments, bodies of vertebrae L1-L3 (+intervertebral discs), anterior longitudinal ligament
Central tendon of diaphragm

Question 5

What passes through the diaphragm and at what level?

Answer 5

IVC - T8
Oesophagus + Vagus Nerve - T10
Aorta - T12

Question 6

What are the attachments and functions of the External IC muscles?

Answer 6

Inferior margin of rib above and superior margin of rib below
Most active during inspiration, move ribs superiorly

Question 7

What are the attachments and functions of the Internal IC muscles?

Answer 7

Lateral edge of costal groove of rib above and superior margin of rib below, deep to Ext. IC
Most active during expiration, move ribs inferiorly

Question 8

What are the attachments and functions of the Innermost IC muscles?

Answer 8

Costal groove of ribs to superior border of immediate ribs below, depress ribs during forced expiration

Question 9

What additional muscles of inspiration can be recruited if in distress?

Answer 9

SCM
Scaleni
Serratus Anterior
Pec Major and Minor
Lat. Dorsi

Question 10

What are the muscles of forced expiration

Answer 10

Intercostals
Transversus Thoracis
Subcostals
Serratus Posterior Inferior
Abdominal Muscles