Osteology of the Thorax Flashcards
What does the thoracic skeleton protect?
- Thoracic organs
- GI organs
- Genitourinary system (kidneys)
5 bones of thorax?
- Clavicle
- Scapula
- Ribs
- Sternum
- Thoracic vertebrae
3 components of superior thoracic aperture?
- Body of T1 vertebra posteriorly
- Medial margin of ribs 1 laterally
- Manubrium anteriorly
Vertebral level of superior margin of manubrium?
T2/T3
Plane of superior thoracic aperture?
Oblique because ribs 1 slope inferiorly
Position of pleura at thoracic aperture?
Superior aspects of pleural cavities lie on either side of the entrance to the mediastinum
Where do the structures that pass between upper limb and thorax pass in relation to the ribs and lungs?
Over ribs 1 and superior part of pleural cavities
Is the superior thoracic aperture expandable?
NOPE
Is the inferior thoracic aperture expandable?
YUP
How do structures pass from the abdomen to the thorax?
Either through or posterior to the diaphragm
What types of elements forms the inferior thoracic aperture?
Bones, cartilage, and ligaments
Skeletal elements of the inferior thoracic aperture?
- Body of vertebra 12 posteriorly
- Ribs 12 and distal ends of ribs 11 posterolaterally
- Distal cartilaginous ends of ribs 7 to 10 forming to costal margin anterolaterally
- Xiphoid process anteriorly
What types of elements forms the superior thoracic aperture?
Skeletal elements only
Vertebral level of joint between costal margin and xiphoid process?
T9/T10
Is the posterior margin of the inferior thoracic aperture superior or inferior to the anterior margin?
Inferior
When viewed anteriorly, is the inferior thoracic aperture tilted superiorly or inferiorly?
Superiorly
Most superior edge of the manubrium?
Jugular notch
Are both thoracic apertures open?
Nope, only the inlet, the outlet is closed by diaphragm
What is the acromion?
Most superior edge of the scapula that articulates with the clavicle
In what manner do muscle fibers of the diaphragm arise?
Radially, from the margins of the inferior thoracic aperture to converge into a large central tendon
Is the posterior attachment of the diaphragm superior or inferior to the anterior attachment?
Inferior
Which diaphragm dome reaches higher? To what rib level?
Right one is higher, up to rib 5
Which 7 structures penetrate the diaphragm? At what vertebral level?
- Esophagus (T10 to left of midline)
- IVC (T8) in central tendinous portion
- Anterior and posterior vagal trunks (with esophagus)
- Right phrenic nerve (with IVC)
- Left phrenic nerve (through muscular part anterior to central tendon on left side)
- Right pericardiacophrenic artery (with IVC)
- Esophageal branches of left gastric artery (with esophagus)
Which structure passes posteriorly to the diaphragm from the thorax? At what vertebral level or position?
- Aorta (T12) posterior to median arcuate ligament
- Thoracic duct (with aorta)
- Sympathetic trunks (posterior to medial arcuate ligament)
- Optional azygos vein (with aorta)
- Greater, lesser, and least splanchnics (through crura)
- Hemiazygos vein (through left crus)
Do all ribs have a costal cartilage?
YUP, but small on ribs 11 and 12
Do all ribs articulate with the vertebral column?
YUP
True ribs? Why?
1-7
Because they articulate with the sternum with their own costal cartilage
False ribs? Why?
8-10: because their costal cartilages articulate anteriorly with the costal cartilage of the rib above them
11-12: because they do not articulate with the sternum = floating ribs
Characteristics of posterior end of ribs? Describe each
- Head: 2 articular surfaces separated by a crest
- Neck: short flat region that separates head and tubercle
- Tubercle: projects posteriorly from junction of neck and shaft and has 2 regions
Which ribs have a different connection to the vertebral column than the others?
Rib 1, 10, 11, and 12
Which rib cannot be palpated?
Rib 1
Typical ribs?
3-10
Atypical ribs?
1, 2, 11, 12
Other name for dorsal view of ribs?
Superior view
Describe the 2 articular surfaces of the head of typical ribs.
- Smaller superior surface articulates with inferior costal demifacet on the body of the vertebra above
- Larger inferior facet articulates with the superior costal demifacet of its own vertebra body
Describe the 2 regions of the tubercle of typical ribs.
- Articular part: medial with oval facet for articulation with oval facet on transverse process of associated vertebra
- Raised nonarticular part: roughened by ligament attachments
How many surfaces does the shaft of a typical rib have?
2: interior and exterior
Describe the superior and inferior margins of typical ribs.
Superior: rounded and smooth
Inferior: sharp
At what point does the shaft of typical ribs bends?
The angle: site lateral to the tubercle
Describe the twist of the shaft of typical ribs.
Gentle twist causing the external surface of the ribs to face somewhat superiorly
What is found in the costal groove of the ribs?
VAN:
Vein
Artery
Nerve
Describe the shape of rib 1.
Flat in horizontal plane
How many articular surfaces does rib 1 have?
2: 1 on the head (the inferior one) and one of the tubercle
Does rib 1 have a tubercle that articulates?
YUP, but it has another tubercle, the scalene tubercle on the superior surface of the rib, which separates 2 smooth grooves that cross the rib midway along the shaft
What are the 2 grooves of rib 1 caused by?
- Anterior groove: subclavian vein
2. Posterior groove: subclavian artery
Describe the shaft of rib 1 other than where its grooves are.
Roughened by muscles and ligaments
Describe the shape of rib 2.
Same as rib 1 but twice as long
What is particular about the shape of ribs 11 and 12?
They do not have tubercles or necks
In what direction do ribs 11 and 12 point?
Anteriorly
What attachments does the manubrium of the sternum have?
- Oval fossa for articulation with clavicle
- Facet for articulation to costal cartilage of rib 1
- Demifacet for articulation to upper half costal cartilage of rib 2
Describe the anterior surface of the body of the sternum.
Has transverse ridges that come from embryologic development
What attachments does the body of the sternum have?
- Demifacet for articulation to lower half costal cartilage of rib 2
- 4 more facets for articulation to costal cartilages of ribs 3, 4, 5, and 6
- Demifacet for articulation to upper half costal cartilage of rib 7
Which portion of the sternum is variable in shape?
Xiphoid process