Cardiorespiratory Flashcards
What are the openings of the thoracic cavity called?
The superior and inferior thoracic aperture
3 divisions of the thoracic cavity
- Right pleural cavity
- Left pleural cavity
- The mediastinum
Describe the main structures of the sternum
Most superior is the manubrium with jugular notch at top.
Followed by the body, at junction between manubrium and body is the sternal angle.
Most inferiorly is the xiphoid process.
How many ribs are there?
12
Ribs are divided into 3 categories, what are these?
- True ribs (R1-7) vertebrosternal
- False ribs (R8-10) vertebrochondral
- Floating ribs (R11-12) vertebral
Describe the true ribs
Attach from the vertebra posteriorly and to the sternum anteriorly via costal cartilages
Describe the false ribs
Attach posteriorly to the vertebrae, and attach indirectly to sternum via costal cartilages (they attach to the costal cartilage of the superior rib above them)
Describe the floating ribs
No attachment on the anterior aspect, no costal cartilages, do attach posteriorly to thoracic vertebrae
Describe the features of typical ribs
- Head (end which articulates posteriorly with thoracic vertebrae)
- Neck
- Tubercle (articulates with transverse process of a thoracic vertebra)
- Body
How many thoracic vertebrae are there?
12
Describe the 5 main features of thoracic vertebrae
- Vertebral body
- Transverse processes (left and right) have facets to articulate with ribs
- Spinous process (long and slender, central)
- Pedicle (stub of bone connecting lamina to vertebral body)
- Lamina (links each transverse process with spinous process)
- Intervertebral foramen for spinal nerves
Describe the facets present on the thoracic vertebrae
Each vertebrae has 6 facets:
- 2 inferior costal facets for head of rib
- 2 superior costal facets for head of rib
- 2 facets for the tubercle of the rib
Summary: rib articulates at 2 points for head and 1 point for tubercle
Name the 5 muscles of the thoracic wall
- External intercostal muscle
- Internal intercostal muscle
- Innermost intercostal muscle
- Transversus thoracis
- Subcostal muscle
Describe the external intercostal muscle
Many slips of muscle that run down the full length of the thoracic wall. Elevate the ribs during inspiration.
Describe the internal intercostal muscle
Lies deep to external intercostal muscle, muscle fibres run perpendicular to ext inter muscle fibres.
Run right up to the sternum.
Depresses the ribs in forced expiration.
Describe the innermost intercostal muscle
Lies deep to the internal intercostal muscle. Fibres run in the same direction.
Relatively small muscle.
Involved in forced expiration.
Describe the transversus thoracis
Fan out from sternum.
Aids internal intercostal muscle in depressing the ribs.
Describe the subcostal muscle
A variable muscle- not always present.
Aids expiration.
Where are neurovascular structures located?
Between the internal intercostal muscle and the innermost intercostal muscle
In what order do the neurovascular structures lie?
Vein superior, artery in the middle, nerve inferior. (V A N)
What is the collateral neurovascular bundle?
A smaller bundle of neurovascular structures which runs at the inferior border of the thoracic space- order of structures is opposite to normal (N A V)
Describe the blood supply and drainage of the thoracic cavity
Internal thoracic artery and internal thoracic vein are the main collection of vessels and travel down either side of the sternum.
Intercostal veins drain into internal thoracic vein.
Intercostal arteries branch from the internal thoracic artery.
Describe the diaphragm
A flat muscle (musculotendinous sheet) dividing the thoracic cavity from the abdominal cavity.
Describe the innervation of the diaphragm
Diaphragm is innervated by the Phrenic nerve.
Root values for Phrenic nerve- C3, C4,C5
“C3, C4, C5 keep the diaphragm alive”