Thorax Flashcards
How many apertures does the thoracic cavity have and which are these?
Two - superior and inferior thoracic apertures
To which regions does the thorax communicate with through the superior thoracic aperture/thoracic inlet?
Neck and upper limb
How is the superior thoracic aperture shaped? Why is it shaped like this?
Slopes antero-inferiorly because of the obliquity of first pair of ribs
How is the superior thoracic aperture bounded?
- Posteriorly: T1 vertebra
- Laterally: first pair of ribs and their costal cartilages
- Anteriorly: superior border of manubrium
To which region does the thorax communicate with through the inferior thoracic aperture/thoracic outlet?
- Abdomen
How is the inferior thoracic aperture bounded?
- Posteriorly: T12 vertebra
- Posterolaterally: 11th and 12th pairs of ribs
- Anterolaterally: joined costal cartilage of 7-10 ribs (form costal margin)
- Anteriorly: xiphisternal joint
How many types of ribs are there and which are these?
Three.
True, false, and floating
Which are the true ribs and what characterizes them as such?
1-7th ribs
- Attach directly to sternum anteriorly through own costal cartilages
Which are the false ribs and what characterizes them as such?
8-10th ribs
- Have cartilages on their anterior ends that are joined to cartilage of the rib just superior to them; thus, their connection with the sternum is indirect
Which are the floating ribs and what characterizes them as such?
11th and 12th
- Have rudimentary cartilages on anterior ends that don’t connect to sternum; instead, they end in posterior abdominal musculature
Which are the typical ribs and what are the parts that compose these?
3rd to 9tn
Parts: head, neck, tubercle, body
How many facets does the head of a typical rib have and how do they articulate with the vertebra?
2 facets separated by the crest of the head
- The inferior one articulates with the body of the numerically corresponding vertebra (at superior facet) and the superior one with the superior vertebrae (at inferior facet)
What does the neck of a typical rib connect?
Head with body at the level of the tubercle
Where is the tubercle of a typical rib and which parts compose its articular cavity?
At the junction of neck and body
- It has a smooth articular part and a rough nonarticular part
What attaches to or articulates with the articular and nonarticular part of the tubercle of rib?
Articular: for articulating with corresponding transverse process (synovial)
Nonarticular: fibrous attachment to process through costotransverse ligament
What are the two structural features of the body of the rib?
Angle: where the rib begins to turn anterolaterally
Costal groove: concavity on the inferior edge that runs along the internal surface of the body
Which are the atypical ribs?
1st, 2nd, 10 - 12th
What are the characteristics of the 1º rib?
- Shortest and most sharply curved of true
- 2 shallow horizontal grooves crossing its superior surface; these are separated by the scalene tubercle and ridge
- Articulates with T1 only
What are the characteristics of the 2º rib?
- Thinner and more typical
- Formations for attachment of serratus anterior and posterior scalene muscles
- Almost twice length of 1st
Which ribs have only 1 facet on their heads?
10-12th and 1st
Which ribs have no necks or tubercles?
11th and 12th
What are the costal cartilages?
Bars of hyaline cartilage that prolong ribs anteriorly and contribute to elasticity of thoracic wall
What is the sternum?
Flat, vertically elongated bone that forms the middle of the anterior part of the thoracic cage
Which parts constitute the sternum?
Manubrium, body, and xiphoid process