Lecture 7, Sternum, Motion of The Thorax & Abdominal Muscles/Diaphragm

Question 1

Superior Thoracic Aperture

Answer 1

Superior thoracic aperture: The thoracic cavity communities with the neck and upper limb through the superior thoracic aperture (slopes antero-inferiorly)
Structures that leave and enter the cavity include the trachea, esophagus, vessels and nerves
The superior thoracic aperture is bounded:
- Posteriorly by T1 vertebra
- Laterally by the first pair of ribs and their cartilages
- Anteriorly by the superior border of the manubrium

Question 2

Inferior Thoracic Aperture

Answer 2

Inferior thoracic aperture: The thoracic cavity communicates with the abdomen through the inferior thoracic aperture, the diaphragm closes the inferior thoracic aperture separating the thoracic and abdominal cavities almost completely, inferior is much larger than the superior
The inferior thoracic aperture is bounded:
- Posteriorly by the T12 vertebra
- Posterolaterally by the 11th and 12th pair of ribs
- Anterolaterally by the joined costal cartilages of ribs 7-10 forming the costal margin
- Anteriorly by the xiphisternal joint

Question 3

3 classes of ribs

Answer 3

true (vertebrosternal) ribs (1st to 7th ribs) - attach directly to the sternum anteriorly through their own costal cartilages
false (vertebrochondral) ribs (8th to 10th ribs) - have cartilages on their anterior ends that are joined to the cartilages of the ribs, connection the sternum is indirect
floating (free) ribs (11th to 12th ribs, sometimes 10th) - have rudimentary cartilages on their anterior ends that do not connect even indirectly with the sternum, end up in the posterior abdominal musculature

Question 4

Typical ribs (3rd to 9th)

Answer 4

head - wedge-shaped and two facets that are separated by the crest of the head, one facet articulates with the body of the numerically corresponding vertebra and the other articulates with that of the superior vertebra
neck - connects the head to the body at the level of the tubercle
body -
tubercle (articular part/nonarticular part) - lump-like enlargement at the junction of the neck and body, smooth articular part for articulating with the corresponding transverse process of the vertebra, rough nonarticular part for a fibrous attachment to the process via the costotransverse ligament
costal groove - protects the intercostal nerve and vessels
angle - the region where the rib is the most strongly bent located on on the proximal part of the body of the rib
- a pair of superior articular facets that face posteriorly and a pair of inferior articulating facets that face anteriorly

Question 5

Sternum

Answer 5

manubrium - superior part of the sternum, roughly trapezoidal bone, T3 and T4 vertebrae and its thick superior border is indented centrally by the jugular notch. on each side, a clavicular notch articulates with the sternal end of the clavicle
manubriosternal joint (sternal angle) - the manubrium and body of the sternum lay in slightly different planes forming this, is loacted oppisite the second pair of costal cartilages at the level of the IV disc between the T
xiphisternalsternal joint
xihpoid process
costal notches