Muscles of Respiration Flashcards
How many layers of intercostals are there? Where are they located? What are they called (sup to deep?)
3 layers in the spaces between the adjacent ribs (intercostal space)
External intercostals, internal and innermost
How many pairs of muscles do each layer of intercostals have?
11 pairs
What are the attachments of the external intercostals?
actions?
superior attach: ribs 1 - 11 (fixed)
inferior attach: ribs 2-12
action: quiet and forced inspiration (through elevation of the ribs)
action: keep the intercostal spaces rigid
What are the attachments of the internal intercostals?
actions?
fibre direction?
superior attach: ribs 1 - 11 (fixed)
inferior attach: ribs 2-12
action: forced expiration
action: keep the intercostal spaces rigid
fibre direction: right angles (90 degrees) to external intercostals
What are the attachments of the innermost intercostals
actions?
superior attach: ribs 1 - 11 (fixed)
inferior attach: ribs 2-12
separated from the internal intercostals by the nerovascular bundle
action: forced expiration
action: keep the intercostal spaces rigid
Levator costarum
12 pairs superior attachment: TVPs of C7-T11 inferior attachment: ribs (immediately inferior) action: elevate the ribs accessory muscles to respiration
Subclavius
Medial attachment: 1st rib and its costal cartilage
lateral attachment: middle 1/3rd of the inferior surface of the clavicle
action: anchors, depresses and draws the clavicle medially
action: serves as cushion between fractured clavicle
What is the principle muscle of respiration?
The diaphragm
The diaphragm is what shape muscle? What does it divide?
It is a a dome shaped muscle. It divides the thoracic cavity and abdominal cavity
Where does the top of the diaphragm sit during inspiration?
expiration?
approximately 6th intercostal space during inspiration
4th intercostal space during exhalation
The diaphragm is divided into two components?
Muscular component and tendinous component
What are the attachments to the muscular component of the diaphragm?
Attaches inferiorly onto the:
posterior surface of the xiphoid process,
internal surfaces of lower 6 ribs (and their costal cartilages),
upper lumbar vertebrae via 2 muscular crura
medial arcuate ligaments (upper lumbar vertebral bodies to TVPs - travels over psoas)
lateral arcuate ligaments (L1 TVP to 12th rib - travels over QL)
The diaphragm Central Tendon
the muscular fibres converge radially into a strong aponeurotic tendon called the Central Tendon
Has a C-shaped appearance with a central, left and right ‘leaflet’
What is the action of the diaphragm?
with contraction, the diaphragm moves inferiorly so that it is flattened
What is the innervation of the diaphram?
phrenic nerve (C3,4,5) - C345 keeps the diaphragm alive
Contraction of the diaphragm causes _____ movements of the central tendon
inferior
as the diaphragm contracts it _____ and increases what?
flattens, increases the vertical imension of the thoracic cavity (increases thoracic volume
During inspiration the ribs are raised and move laterally which increases the transverse dimension of the thorax which called _____
the bucket-handle movement
As the ribs raise the anterior parts of the ribs and the sternum move anteriorly which increases the anteroposterior dimension of the thorax which is called ______
the pump-handle movement
What is the bucket handle movement?
During inspiration the ribs are raised and move laterally which increases the transverse dimension of the thorax
What is the pump-handle movement?
As the ribs raise the anterior parts of the ribs and the sternum move anteriorly which increases the anteroposterior dimension of the thorax (sternal angle increases)
What causes air to come in during inspiration?
the increases in vertical, transverse and AP dimensions create a negative pressure in the lungs which results in air being drawn in
During inspiration the thoracic volume _____ which _______ thoracic pressure AND the abdominal volume _____ which ____ abdominal pressure
increases, decreases
decreases, increases
During expiration the diaphragm ______ and moves _____
Relaxes (or eccentrically contracts)
Superiorly
