Muscles of Respiration - midterm II

Proprioceptive Muscles of Respiration

• Muscles that may play a small role in respiration, but predominantly serve as proprioceptive structures • Serratus posterior inferior • Serratus posterior superior • Levator costarum

Muscles of respiration

• Muscles are contractile tissue 1. Diaphragm 2. External Intercostals 3. Internal Intercostals 4. Innermost Intercostals 5. Transversus thoracis (sternocostalis) 6. Subcostals 7. Superior/ Inferior • All muscles have at least two attachment sites (Origin and Insertion) • origin: non-mobile • mobile: contracts

Muscles of respiration -Primary/ Normal respiration

(peaceful breathing): • diaphragm • intercostal muscles

Muscles of respiration -Expiratory muscles

(used in forced expirium): • transverse abdominis • rectus abdominis • external oblique • internal oblique

Muscles of respiration -Accessory Muscles

(used in respiratory distress): • pectoralis major • pectoralis minor • anterior, middle and posterior scalene • lower aspect of serratus anterior • sternocleidomastoid • trapezius • latissimus dorsi • erector spinae • iliocostalis lumborum • quadratus lumborum

Chest Respiratory Movements -lateral view

Increased side to side diameter (intercostal muscles) + Increased A-P diameter (intercostal muscles) + Increased vertical length (diaphragm) = Increased intrathoracic volume, lungs then expand

Chest Respiratory Movements -anterior view

Increased side to side diameter (intercostal muscles) + Increased A-P diameter (intercostal muscles) + Increased vertical length (diaphragm) = Increased intrathoracic volume, lungs then expand

External Intercostals -intercostal muscles

Origin: Inferior aspect of rib above (lower border, forward fibers) Insertion: Superior aspect of rib (upper border of rib below) Action: Elevation and spreading ribs (forced inhilation) Nerve Supply: Intercostal Nerves -contributes to respiration by decreases the intrapleural pressure, expanding the lungs, facilitating air entry. It has a role in mechanical support of the chest wall during various movements involving trunk.

Diaphragm - muscles of respiration

Origin: Lower boundaries of the inferior thoracic apeture/ circumference Insertion: Central tendon Action: Enlarges thorax, causing inspiration Nerve Supply: Phrenic nerves "I Eat Delicious Apples" I - IVC E - Esophagus D - Descending A - Aorta

Transversus Thoracis (Sternocostalis) - intercostal muscles

Origin: Posterior aspect of sternal body and sternal ends of costal cartilages of rib 4-7 Insertion: Posterior aspect of ribs and costal cartilages of ribs 2-6 Action: Depresses ribs during forced expiration. Nerve Supply: Intercostal Nerves

Internal Intercostals -intercostal muscles

Origin: Superior aspect of inferior rib below (inner surface, lower border, backward fibers) Insertion: Inferior aspect of rib above Action: Exhalation, depression of ribs, pulling them together (interosis and interchondrial) Nerve Supply: Intercostal Nerves -contributes to respiration by forced exhalation

Subcostal muscles - intercostal muscles

Origin: Superior aspect of rib below (beneath the internal intercostal muscles at the vertebral ends of the ribs) Insertion: Inferior aspect of rib above (may skip 1 or 2 ribs) Action: assist in respiration, drawing ribs together, during forced exhalation Nerve Supply: Intercostal Nerves

Innermost Intercostals - intercostal muscles

Origin: Superior aspect of rib below (inner surface, lower border, backward fibers) Insertion: Inferior aspect of rib above Action: Forced expiration, depression of ribs, pulling them together Nerve Supply: Intercostal Nerves -contributes to respiration by pushing out air out of the lungs during forced expirium, in accessory respiratory musculature that's only active during forced breathing.

What are the contents of the intercostal spaces?

The eleven paired intercostal spaces contain the intercostal muscles, nerves, arteries, veins and investing fascia. Bordered by the rib, above and below, the deep fascia of the thorax, superficially, and the endothoracic fascia and pleura, internally, the intercostal space contains essential respiratory muscles, the nervous and vascular supply to the thoracic wall, and contributes to the thoracic cage. The intercostal spaces are filled by the three groups of intercostal muscles: external, internal, and innermost. They are traversed by the nerves, arteries and veins of the thoracic cage, such as intercostal arteries and veins.