Muscles of ventilation

Muscles of Ventilation

Ventilation is the movement of air into and out of the lungs.

Respiration is the cellular process of breaking down chemical energy (substrates) to make ATP

C6H12O6 + 6 O2 6 CO2 + 6 H20 + E

Ventilation

• Inspiration (Inhalation): active process.– Requires muscular action– Change in thoracic volume change in

pressure. (Boyle’s Law)• Change in pressure drives air into lungs

• Expiration (exhalation): passive process– Occurs when muscles of breathing relax– Forced exhalation: muscular activity required

Resting Ventilation

• Two muscles of resting ventilation• Diaphragm– Origin: Xiphoid, ribs 7-12 and their costal cartilage,

anterior surface of lumbar vertebrae.– Insertion: Central tendinous sheet– Action: expand thoracic cavity, compresses

abdominopelvic cavity• Intrathoracic pressure and valsalva’s

Resting Ventilation

• External intercostals– Origin: Inferior border of each rib– Insertion: Superior border of the more inferior rib (the rib below the superior one)• Action: Lifts the lower rib to expand the thoracic cavity

Resting Exhalation

• This is a passive process in which the diaphragm and external intercostals relax and the thoracic cavity recoils back to its resting volume (gets smaller) forcing air from the lungs due to the increase in intrathoracic pressure.

Muscles of Inspiration during Exercise

• These muscles lift the clavicle and ribs• These are known as Accessory Inspiratory muscles.

These muscles (SCM, scalene, traps). Others to follow

• SCM: O and I will reverse in this case.• Scalene: Work in conjunction with SCM– O: Transverse processes of C2 – C7– I: First two ribs• Ant. and Middle scalene lift rib 1• Post. Scalene lifts rib 2

Muscles of Inspiration during Exercise

SCM: O and I will reverse in this case.Scalene: Work in conjunction with SCM

O: Transverse processes of C2 – C7I: First two ribs•Ant. and Middle scalene lift rib 1•Post. Scalene lifts rib 2

Muscles of Inspiration during Exercise

• Diaphragm• External intercostals – raises the ribs– Other Accessory Muscles

• Trapezius (upper fibers) – raises the clavicle• Serratus anterior – raises the ribs• Pec minor – raises ribs when scapula is fixed

Expiratory Muscles during Exercise

• Relaxation of diaphragm• Abdominal muscles • Internal intercostals

External Oblique

• Origin– Lateral side of ribs 5-

12• Insertion– Anterior iliac crest,

pubic crest• Location:

– Lateral/Anterior

• Movements – Flexion (together)– Ipsilateral flexion– Contralateral rotation

(independently)

Internal Oblique

• Origin– Anterior iliac crest

• Insertion– Cartilage of ribs

8-10

• Location: anterior/medial

• Movements (LS)– Flexion– Ipsilateral flexion

Fiber direction

Rectus Abdominis

• Origin– Pubic crest

• Insertion– Cartilage of ribs

5-7, xiphoid process

• Location: anterior

• Movements – Trunk flexion