Anatomy - Osteology of the Thorax Flashcards
What does the thoracic skeleton protect?
- Thoracic organs2. GI organs3. Genitourinary system (kidneys)
5 bones of thorax?
- Clavicle2. Scapula3. Ribs4. Sternum5. Thoracic vertebrae
3 components of superior thoracic aperture?
- Body of T1 vertebra posteriorly2. Medial margin of ribs 1 laterally3. 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 2. Ribs 12 and distal ends of ribs 11 posterolaterally3. Distal cartilaginous ends of ribs 7 to 10 forming to costal margin anterolaterally 4. 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)2. IVC (T8) in central tendinous portion 3. Anterior and posterior vagal trunks (with esophagus)4. Right phrenic nerve (with IVC)5. Left phrenic nerve (through muscular part anterior to central tendon on left side)6. Right pericardiacophrenic artery (with IVC)7. 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 2. Thoracic duct (with aorta)3. Sympathetic trunks (posterior to medial arcuate ligament)4. Optional azygos vein (with aorta)5. Greater, lesser, and least splanchnics (through crura)6. 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 2. Neck: short flat region that separates head and tubercle3. 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 2. 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 2. 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 smoothInferior: 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:VeinArteryNerve
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 vein2. 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 clavicle2. Facet for articulation to costal cartilage of rib 1 3. 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 2. 4 more facets for articulation to costal cartilages of ribs 3, 4, 5, and 6 3. Demifacet for articulation to upper half costal cartilage of rib 7
Which portion of the sternum is variable in shape?
Xiphoid process
Can the xiphoid process be perforated?
YUP
Describe the xiphoid process at birth. How does it change?
Cartilaginous structure which later ossifies
What attachments does the xiphoid process of the sternum have?
Demifacet for articulation to lower half costal cartilage of rib 7
What connects to the sternum posteriorly?
Pericardium
Bone used for bone marrow aspiration?
Sternum in its internal aka medullary cavity
Describe the 8 structures of a typical thoracic vertebra.
- Heart shaped body with roughly equal dimensions in transverse and anteroposterior directions 2. Spinous process extending posterioly and inferiorly (more inferior than vertebral disc)3. 2 transverse processes club-shaped and extending posterolaterally 4. 2 laminae connecting spinous processes to transverse processes 5. 2 superior articular processes off of laminae that are flat and face posteriorly6. 2 inferior articular processes off of laminae facing anteriorly 7. 2 pedicles connecting the upper half of body to the transverse processes 8. Inferior and superior vertebral notches (rounded portions of pedicles)
What is the INTERvertebral foramen? What passes in it?
Circular hole between body and processes of vertebra formed by superior notch of one vertebra and inferior notch of anotherSpinal nerves pass through
Which part of the thoracic vertebrae overlap with the the same structures of the vertebra below?
Laminae
List the 6 sites of articulations with ribs of each thoracic vertebra. What does each articulate with?
- 2 superior costal demifacets off of the superior processes to articulate with head of own rib2.2 inferior costal demifacets off of the inferior processes to articulate with head of rib below 3. 2 transverse costal oval facets on inferior side of transverse process to articulate with tubercle of own rib
Which thoracic vertebrae lack inferior costal demifacets to articulate with head of rib below?
T10, T11, and T12: only have a single complete facet on each side of their body on the superior processes to articulate with own rib
Which rib lacks a smaller superior surface to articulate with inferior costal facet on the body of the vertebra above?
Rib 1
Which thoracic vertebrae lack transverse costal oval facets at end of transverse process to articulate with tubercle of own rib?
T11 and T12
How to tell difference between superior and inferior view of vertebrae?
Superior: spinous process looks like it’s going into pictureInferior: spinous process looks like it’s coming out of the pictureThis is because the spinous process extends inferiorly
What can you palpate on a patient’s spine?
Spinous processes of vertebrae
How do thoracic vertebrae articulate with each other?
Through the superior and inferior articulation processes
How do ribs 2-9 articulate with thoracic vertebrae?
- Smaller superior surface articulates with inferior costal demifacet on the body of the vertebra above 2. Larger inferior facet articulates with the superior costal demifacet of its own vertebra body 3. Articular part of tubercle articulates with oval facet on transverse process of associated vertebra
What does the sternal angle plane separate?
- Superior and inferior mediastinum2. Trachia branching out into bronchi3. Boundaries of the aortic arch4. Vertebral level between T4 and T55. Second rib joins sternum6. Azygos vein drains to SVC7. Manubrium and body of sternum join8. Uppermost level of the pericardium 9. Superior limit of pulmonary trunk
Attachments of the diaphragm?
- Xiphoid process2. Costal margin3. Ends of ribs 11 and 124. Ligaments that span across structures of the posterior abdominal wall5. Vertebrae of the lumbar region 6. Pericardium through central tendon
What is the posterior attachment of the diaphragm called? What does it attach to?
Median arcuate ligament to T8/T9
Blood supply of diaphragm? Which part is the largest blood supply?
- Superiorly: pericardiacophrenic and musculophrenic arteries (branching from the internal thoracic arteries), superior phrenic arteries (from thoracic aorta), and intercostal arteries2. Inferiorly: inferior phrenic arteries*** branching from the abdominal aorta
Describe the venous drainage of the diaphragm.
Veins parallel arteries and drain into:1. Brachiocephalic veins2. Azygos system of veins3. Abdominal veins: left suprasternal vein and IVC
Innervation of diaphragm? Why?
Phrenic nerves that innervate it from its abdominal surface + peripheral areas are innervated by intercostal nerves Because the tissues that initially give rise to diaphragm are in anterior position on embryological disc before the head fold develops
What is the coracoid process?
Small knob below the acromion of the scapula
Can you see the transverse costal facets on a superior or an inferior view of a vertebra?
Inferior view
Name of joint between body and of sternum and xiphoid process?
Xiphisternal joint
When looking at osteology of thorax from the anterior view, how to recognize T1?
It’s the vertebra visible right above the jugular notch
Is the jugular notch palpable on a cadaver?
Nope only the living
Shape of clavicle?
S
What is the tissue you see in ICS if all the intercostal structures are removed?
Parietal pleura
How is the diaphragm anchored to the lumbar vertebrae?
Musculotendinous crura which blend with the anterior longitudinal ligament of the vertebral column (2 of them: L and R)
Which diaphragmatic crura is longest and broadest?
Right crus
Attachement of right crus of diaphragm?
L1 to L3 and intervening vertebral discs
Attachement of left crus of diaphragm?
L1 to L2 and intervening vertebral discs
What connects the diaphragmatic crura? Relation to aorta?
Median arcuate ligament, anterior to the aorta
Origins of the diaphragm?
- Sternum and xiphoid process anteriorly2. L1 to L3 lumbar vertebrae and the arcuate ligaments posteriorly3. Costal margin peripherally
What are the 3 ligaments of the diaphragm?
- Median arcuate ligament2. Medial arcuate ligament3. Lateral arcuate ligament
What is the medial arcuate ligament? Attachments?
Tendinous arch formed by the fascia covering the upper part of the psoas major muscle Attachments:- Medially: sides of L1 and L2- Laterally: transverse process of L1
Position of medial arcuate ligament relative to the diaphragmatic crura?
Lateral
What is the lateral arcuate ligament? Attachments?
Tendinous arch formed by a thickening of fascia covering the quadratus lomborum Attachments:- Medially: transverse process of L1- Laterally: rib 12
What are the domes of the diaphragm produced by?
- Liver on right + some contribution from right kidney and right suprarenal gland2. Fundus of stomach and spleen on left with contribution from left kidney and left suprarenal gland
Surface projection of right dome of diaphragm during expiration?
Rib 5
Surface projection of left dome of diaphragm during expiration?
5th ICS
Which structure passes anteriorly to the diaphragm from the thorax? Position relative to ribs?
Superior epigastric vessels (just deep to the ribs)
What membrane covers the ribs?
Periosteum
What can the mobility of the ribs be exploited for?
To access the thoracic cavity during thoracotomy
What kind of patients have more elastic rib costal cartilage? What is a consequence of this?
ChildrenCompression may cause injury to the organs without fracturing the ribs
Which rib is the least likely to be fractured? Why?
1 because it is broad and flat and protected by the clavicle
Which ribs are most likely to be fractured?
2-7
What can happen to the ribs with old age? Consequence of this?
Ossification of costal cartilages which become radio-opaque and cause confusion in chest films (looks like cancer) and loss of rib resiliency
What can be a complication of flail chest? Explain.
Broken rib punctures the lining of the lung pleura: pneumothorax
How long after pneuomothorax can you live for?
30 min
Is the sternum often fractured? Why/Why not?
NOPE because of resiliency of costal cartilages
What is the rate of mortality of sternal fractures? Why?
25-45%Due to potential heart injurt
What are the 3 diameters of the thoracic cavity? What is each changed by? How is each increased during inspiration?
- Vertical: diaphragm moves inferiorly and pushes down on abdominal organs2. Antero-posterior: fixed 1st rib - external intercostals as chest moves outward3. Transverse: fixed 1st rib - external intercostals: bucket handle arrangement
Which ribs are NOT mobile?
Ribs 11 and 12
Is the clavicle palpable across its entire length?
YUP
Describe the 2 ends of the clavicle.
- Acromial end is flat with an oval facet for articulation with acromion of scapula2. Sternal end is more robust with a larger facet for articulation with manubrium and 1st costal cartilage
Describe the 2 parts of the inferior surface of the lateral third of the clavicle. Purpose?
- Trapezoid line = lateral roughening 2. Conoid tubercle Purpose = attachment of coracoclavicular ligament
Which surface of the clavicle is smoother: superior or inferior?
Superior
What 5 portions of the scapula can be palpated on a patient?
- Spine2. Acromion 3. Tip of coracoid process 4. Inferior angle 5. Medial border
Shape of sternoclavicular joint?
Saddle shaped
How many ligaments in the sternoclavicular joint? Describe them.
- Anterior and posterior sternoclavicular ligaments 2. Interclavicular ligament: links ends of 2 clavicles on superior surface of manubrium3. Costoclavicular ligament: between clavicle and 1st costal cartilage and rib
Describe the parts of the scapula.
- 3 angles2. 3 borders3. 2 surfaces
Clinical significance of xiphoid process?
It adults around age 40 and patient may become aware of it
If you needed to make an incision in an intercostal space, where in the space in terms of height, would make the incision, high or low in the space?
Low in the intercostal space
Name of joint between transverse process and tubercle?
Costotransverse joint
How are intervertebral discs named?
By the vertebra above them
What would black areas on skin and tips of fingers indicate? What bone structure in the thorax can cause this? Treatment?
Platelet emboli = clots carried from a source to reside in small vessels which they may occlude Cervical ribs can cause these as they are found on the undersurface of the distal portion of the subclavian artery and reduce the diameter and cause eddy currents => atheroma => blood clot which gets dislodged and flow distally to block blood flow to fingers/hands => DISTAL EMBOLIZATION Treatment: surgical excision of cervical ribs
What happens if you have an infected emboli in the heart?
Bacteria will grow on the valve and will be showered into the peripheral circulation
Other than distal emboli, what 2 other diseases can cervical ribs cause?
- Tension in T1 nerve => sensory disturbance over medial aspect of forearm + wasting of intrinsic muscles of the hand2. Compression of subclavian vein => axillary vein thrombosis
What is the distal end of a rib?
Anterior end = costal cartilage
Describe the joint at the head of each rib.
Joint is divided into 2 synovial compartments by an intra-articular ligament, which attaches the crest of the rib head to the adjacent intervertebral disc and also separates the two articular surfaces on the head of the rib Whole joint is surrounding by one single joint capsule attached to the outer margins of the combined articular surfaces of head and vertebral column
Describe the costotransverse joint.
Synovial joint stabilized by 2 ligaments:1. Costotransverse ligament: medial to the joint and attaches the neck of the rib and to the transverse process 2. Lateral costotranverse ligament: lateral to the joint and attaches the tip of transverse process to nonarticular part of tubercle
What is the superior costotransverse ligament?
Ligament connective superior surface of rib neck to superior transverse process (of above vertebra)
Are are sternocostal joints synovial?
No, not the 1st one: fibrocartilaginous connection, but other ones are until 7th
Which sternocostal joint has 2 compartments? Describe it.
Joint with 2nd costal cartilage has an intrarticular ligament
What kind of joints are the manubriosternal and xiphisternal ones?
Symphysis
What are interchondral joints?
Synovial joints between costal cartilages of ribs 7 to 10 (sometimes 5 and 6 too)
Which joints for the costal margin?
Interchondral joints
What separates the ICS/ribs from pleura?
Endothoracic fascia
What are cervical ribs? Implications?
Accessory rib articulating with C7 and attaching anteriorly to anterior aspect of rib 1 via a cervical band (not visualized on radiography) => structures that normally pass over rib 1 now pass over the cervical rib and its band
