Structures of
Respiration
Respiration
The key components of this structure are the vertebral column, ribs, and sternum. Its function in respiration is to provide structural support, protection, and expansion space.
Bony Thorax
A flexible, cartilaginous tube ~11 cm long that bifurcates into right and left mainstream bronchi which then divide into secondary and tertiary branches.
Trachea
The primary muscle of inspiration
Diaphragm
Function is to elevate the sternum and clavicle and expand the upper thorax during inspiration. Active in speech breathing, and respiratory distress.
Sternocleidomastoid
Function is to depress ribs during forced expiration, decrease thoracic volume, and push air out.
Internal Intercostals
The key components of this structure are 12 pairs of ribs, divided into True (1-7), False (8-10), and Floating (11-12). Its function in respiration is to expand and recoil to allow lung volume changes.
Rib Cage
Where gas exchange occurs
alveoli
When a contraction occurs
diaphragm flattens and increases thoracic volume
Function is to elevate the first and second ribs and stabilize the upper thorax during inspiration.
Scalenes
Function is to compress abdominal contents and pull the sternum downward during forced expiration.
Rectus Abdominus
The key components of this structure are 7 cervical discs, 12 thoracic discs, 5 lumbar discs, the sacrum and the coccyx. Its function in respiration is to anchor the ribs and use the spinal nerves to control the diaphragm and muscles,
Vertebral Column
The right and left lungs have (blank) lobes
Right: 3, Left: 2
Located between ribs and running downward and forward. Elevate ribs during inspiration, increase anterior-posterior and transverse thoracic dimensions, and are active during quiet and forced inspiration.
External Intercostals
Function is to elevate the sternum and expand the rib cage during forced inspiration when the arm is fixed.
Pectoralis Major
Function is to compress the abdomen, flex and rotate the trunk, and support forced expiration. Its course is downward and medially (“hands in pockets”). Its insertion is the iliac crest, inguinal ligament, and abdominal aponeurosis.
External Oblique
The key components of this structure are the manubrium, body, and xiphoid process. Its key function in respiration is for central anterior rib attachment and to be a muscle anchoring site.
Sternum
The pleural linings are (blank) and prevent (blank)
Visceral Pleura (covers the lungs), Parietal Pleura (lines the inside of the thoracic cavity), and Pleural Fluid (reduces friction, creates surface tension).
Prevents lung collapse and supports smooth movement.
Origin and Insertion of the diaphragm
O: Xiphoid Process I: Central Tendon
Function is to elevate ribs 2–5 during deep inspiration when the scapula is fixed.
Pectoralis Minor
Function is to compress the abdomen, rotate and flex the trunk, and assist in forced expiration. Its course is upward and medially. Its insertion is the lower ribs (10–12) and abdominal aponeurosis.
Internal Oblique
The key components of this structure are hyaline cartilage that connects the ribs to the sternum. Its function in respiration is to provide flexibility for rib movement and contribute to thoracic recoil.
Costal Cartilage
The order of the pulmonary system is (blank)
Trachea → Bronchi → Bronchioles → Alveoli
Origin and Insertion of the External Intercostals
O: Inferior Surface of Ribs 1-11 I: Superior surface of the rib below
The additional accessory muscles of inspiration
Serratus Anterior, Levator Scapulae, and Trapezius
Function is to compress the abdominal cavity, support forced expiration, and maintain posture. It is also the deepest abdominal layer.
Transversus Abdominis