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CV > Thoracic Wall anatomy > Flashcards

Thoracic Wall anatomy Flashcards

1
Q

mediastinum

A

central space of thoracic cavity

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2
Q

manubriosternal junction (sternal angle/ angle of louis)

A

demarcates the articulation with the 2nd costal cartilage. Most important surface landmark on the thorax.

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3
Q

clavicle

A

subcutaneous throughout its length, functionally a part of the upper extremity, the sterno-clavicular articulation is the only boney articulation between the upper extremity and the axial skeleton thus it is the most frequently fractured bone in the body due to a fall on the outstretched upper extremity.

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4
Q

atypical vertebrae

A

TV1, TV10, TV11, TV12 have single facet for rib.

Remember the atypical vertebrae are all those with a 1 in their number

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5
Q

true ribs

A

(1-7) - attach directly to the sternum.

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6
Q

false ribs

A

(8-10) - attach to costal cartilage of rib above and form the infracostal (costal) margin.

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7
Q

floating ribs

A

(11-12) - not attached to the sternum, anteriorly end in muscle.

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8
Q

Anatomical features of typical ribs (3-9)

A
  1. Head – proximal end, articulates with adjacent vertebral bodies.
  2. Crest - has ligament that attaches to intervertebral disc.
  3. Neck – portion between head and tubercle.
  4. Tubercle – at junction of neck and body, articulates with transverse process
  5. Angle – the anterolateral angulation of the body just lateral to the tubercle.
  6. Shaft (body) – mid and distal portion of rib; each has a superior border, an inferior border, an internal and external surface.
  7. Costal cartilage – provides increased elasticity for thoracic wall.
  8. Costal groove – inferior portion has a concave internal surface which provides protection for the vein, artery and nerve.
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9
Q

Anatomical features of first rib

A

a. Broad, horizontal shaft with pronounced curvature.
b. Head has single facet for articulation with TV1.
c. Scalene tubercle provides attachment for anterior scalene muscle of neck
d. Shaft contains grooves for subclavian vein (anterior) and artery (posterior), on either side of scalene tubercle

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10
Q

anatomical features of 2nd rib

A

serratus anterior tuberosity on superior surface.

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11
Q

features of 10th rib

A

single articular facet on head for articulation with body of TV10

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12
Q

features of 11th, 12th rib

A

single articular facet on head; absence of neck/tubercle, end within abdominal wall muscles.

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13
Q

Rib clinical correlations

A
  1. Rib fractures often occur near angle because this is the weakest part of rib.
  2. Middle ribs are most frequently broken.
  3. Flail chest: results from multiple ribs broken in 2 or more places. This causes a loose segment of thoracic wall which causes paradoxical movement during respiration. (i.e. moves inward during inspiration, outward with expiration)
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14
Q

Manubrium

A
  1. Suprasternal notch (jugular notch) – anterior to TV2/TV3 intervertebral disc.
  2. Clavicular notch – for articulation with clavicle.
  3. Lateral facets for articulation with costal cartilage of ribs 1 and 2.
  4. Articulates with body of sternum (manubriosternal joint; symphysis).
  5. Sternal angle or Angle of Louis; located at manubriosternal junction. This is the key landmark for counting ribs.
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15
Q

sternal body articulation

A

articulates with costal cartilages of ribs 2-7.

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16
Q

xiphoid process

A
  1. Variable in shape (elongated, bifid, perforated).
  2. Cartilagenous but usually ossifies with age.
  3. Lateral demi-facets for articulation with the costal cartilage of 7th rib.
  4. Articulates with the body of the sternum (xiphisternal joint; synchondrosis).
  5. Infrasternal angle
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17
Q

clinical applications of sternum

A
  1. Pectus excavatum (anterior thoracic wall sunken-in) and pectus carinatum (anterior thoracic wall protrusion or “pigeon-breast”) are congenital anomalies resulting from malformation of sternum and ribs. Most cases are purely cosmetic but severe cases can cause respiratory and cardiac problems.
  2. Sternal angle demarcates the articulation of rib 2 (for rib and interspace counting). Also, a horizontal plane passed from the sternal angle to the disc between TV4-TV5 marks the boundary between superior and inferior mediastinum and is called the Transverse Thoracic Plane.
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18
Q

superior thoracic aperture

A

– junctional area between the neck and the thorax

a. Anterior boundary: suprasternal (jugular) notch of manubrium
b. Lateral boundary: 1st rib
c. Posterior boundary: 1st thoracic vertebra
d. CLINICAL CORRELATION: The superior aperture extends obliquely from 1st thoracic vertebra anteroinferiorly to the manubrium. The pleural space extends superiorly into the neck region. Thus, injury or surgery within the superior thoracic aperture may damage the pleural cavity and lungs (pneumothorax).

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19
Q

inferior thoracic aperture

A

) – junctional area between the thorax and abdominal cavity

a. Anterior boundary: xiphisternal joint
b. Lateral boundary: costal margin
c. Posterior boundary: 12th thoracic vertebra and 11th and 12th rib
d. CLINICAL CORRELATION: The inferior aperture extends obliquely from 12th thoracic vertebra anterosuperiorly to xiphisternal joint. The pleural space thus extends inferiorly to lie posterior to the abdominal region. Thus, injury or surgery in this region (ex. kidney biopsy) may damage the pleural cavity and lungs (pneumothorax).

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20
Q

sternocostal articulations

A

a. Articulation between costal cartilages and sternum (7 pair).
b. Joint capsule supported by anterior and posterior radiate ligaments.
c. 1st sternocostal joint is a synchondrosis, permitting no movement. (important in mechanics of respiration)
d. 2nd -7th sternocostal joints are synovial plane joints.

21
Q

costochondral articulations

A

a. Articulation between rib and costal cartilage.

b. Synchondroses; very little movement, frequently dislocated in minor trauma causing “rib separation”

22
Q

interchondral articulations

A

a. Articulation between costal cartilages of ribs 8-10 with costal cartilage above thus forming the costal margin

23
Q

costovertebral articulation

A

a. Articulation between rib head with vertebral bodies, intervertebral disc.
b. Synovial plane joints.
c. Ribs (2-9) articulate with adjacent vertebral bodies and intervertebral disc; an intra-articular ligament extends from the crest of the head to intervertebral disc limiting movement of this joint.
d. Ribs 1, 10, 11, 12 articulate only with the body of same numbered vertebra.
e. Radiate ligament supports the joint capsule.

24
Q

costotransverse articulation

A

a. Articulation between rib tubercle and vertebral transverse processes.
b. Synovial joints
c. Ribs 11 and 12 do not have costotransverse joints
d. Supporting ligaments – lateral, superior costotransverse ligament, costotransverse ligament.

25
Q

clinical correlations of ribs

A

rib “dislocation” occurs at sternocostal joints,

rib “separation” occurs at costochondral joint, rib “fracture” can occur anywhere

26
Q

3 layers of thoracic wall muscles

A

External intercostal muscle –> external intercostal membrane
Internal intercostal muscle –> internal intercostal membrane
Innermost intercostal muscle- a discontinuous sheet of muscle with 3 components:
post- subcostalis- spans 2 interspaces
lateral– innermost intercostal muscle
ant. transversus thoracis (sternocostalis)- spans 1 or 2 interspaces

27
Q

External intercostals

A
  1. Fibers pass infero-medially.

2. Anteriorly, at costchondral joint, muscle replaced by external intercostal membrane.

28
Q

Internal intercostals

A
  1. Fibers pass infero-laterally.

2. Posteriorly, at angle of rib, muscle replaced by internal intercostal membrane.

29
Q

Innermost intercostals

A
  1. Discontinous sheet of muscle – transversus thoracis (sternocostalis) anteriorly, innermost intercostal laterally and subcostalis posteriorly
  2. Neurovascular bundle runs between 2nd and 3rd layers (i.e. between internal intercostal and innermost intercostal muscles).
30
Q

Endothoracic fascia

A
  1. Connective tissue lining entire surface of internal thoracic wall and superior surface of diaphragm.
  2. Apical portion thickens and is called the suprapleural membrane or Sibson’s fascia.
  3. Adheres the parietal pleura to the thoracic wall.
31
Q

muscles of thoracic –> abdominal

A

External intercostal –> External abdominal oblique
Internal intercostal –> Internal abdominal oblique
Innermost intercostal –> Transversus abdominus

32
Q

Movements of thoracic wall during respiration: A-P

A

A. Increase in anterior-posterior (A-P) diameter (“pump handle motion”)

  1. Rotational movement at the costotransverse joint causes elevation and depression of the most distal (anterior) portion of the upper ribs.
  2. Because of the inferior slope of the distal portions of the ribs, anterior elevation causes an increase in the A-P diameter of the thoracic wall.
  3. Note the importance of first rib fixation in mediating this motion.
33
Q

Movements of thoracic wall during respiration: transverse diameter

A

B. Increase in transverse diameter (“bucket handle motion”)

  1. Gliding movement at posterior (costovertebral and costotransverse) joints causes elevation and depression of lateral portions of ribs.
  2. Because of the inferior slope of the lateral portions of the ribs, lateral elevation also causes an increase in the transverse diameter of the thoracic wall.
34
Q

Movements of thoracic wall during respiration: vertical diameter

A
  1. Caused by contraction of the thoracic diaphragm. Fixed inferiorly so the central tendon lowers with inspiration, raises with passive expiration
  2. Thoracic diaphragm
    a. Innervated by the phrenic nerve ( “C3,4,5 keeps the diaphragm alive”)
    b. Musculotendinous septum separating the thoracic and abdominal cavities.
    c. Primary muscle of respiration especially quiet respiration.
    Flattens during contraction and increases intrathoracic volume.
    d. During deep expiration the superior surface extends to the 4th intercostal space; during forced inspiration the diaphragm can move down 10 cm (about 2 vertebral bodies).
    e. Openings in diaphragm: TV8 - IVC; TV10 - esophagus; TV12 - aorta
    (remember 8,10,12)
    f. Diaphragm is best viewed from the abdominal side
35
Q

Intercostal (11 pair) and subcostal (1 pair) nerves

A
  1. Ventral rami of the 12 pair of thoracic spinal nerves form 11 intercostal nerves and 1 subcostal nerve which travel in costal groove along the inferior border of the rib.
  2. Provide innervation to the muscles of the thoracic wall and the skin of the anterolateral thoracic and abdominal wall.
  3. Provide preganglionic sympathetic nerve cell processes from the spinal cord to the sympathetic chain via 14 pair of white rami communicantes.
  4. Provide postganglionic sympathetic nerve cell processes (via 31 pair of gray rami communicantes) to sweat glands, smooth muscle in arrector pili and smooth muscle in blood vessels of the thoracic and abdominal wall.
36
Q

What do dorsal rami do?

A

Intrinsic muscles of the back, skin of the back, facet joints. That’s it.

37
Q

Key dermatome areas on thorax

A

T4 (nipple in males), T6 (Xiphoid) T10 (belly butTEN)

Note: the C4 dermatome abuts the T2 dermatome anteriorly. (C5-8 & T1 form the brachial plexus)

38
Q

course of intercostal nerves

A

First, travel within endothoracic fascia. Near rib angle, nerves pass between 2nd and 3rd muscle layers (internal and innermost intercostal muscles.)

39
Q

Branches of intercostal nerves

A
  1. Rami communicantes – as above
  2. Muscular branches
  3. Collateral branch – given off near angle of rib, course along superior border of rib.
  4. Lateral perforating (cutaneous) branch - given off near mid axillary line (MAL), pierce the lateral body wall and divide into anterior and posterior cutaneous branches.
  5. Anterior perforating (cutaneous) branch – given off near the lateral border of the sternum, pierce the anterior body wall and divide into medial and lateral cutaneous branches supplying sensory innervation to the thoracic and abdominal walls. (Recall bandlike pattern of dermatomes)
40
Q

atypical intercostal nerves

A
  1. The ventral ramus of T1 divides into a large superior trunk which goes to brachial plexus and a small inferior trunk (1st intercostal nerve). Intercostal nerve 1 typically has no cutaneous branches; thus the T1 dermatome is not represented on the thoracic wall.
  2. The lateral cutaneous branch of intercostal nerve 2 (and often 3) forms the intercostobrachial cutaneous nerve, supplying skin and subcutaneous tissue of the axilla and medial brachial area.
  3. Intercostal nerves 7-11 and the subcostal nerve continue anterolaterally as thoracoabdominal nerves to supply skin and musculature of the lower thorax and abdominal wall almost to the pubic symphysis.
41
Q

Posterior intercostal arteries (11 pair) and subcostal artery (1 pair)

A

Originate from:
a.Thoracic (descending) aorta – segmentally provides posterior intercostal arteries
11 and subcostal artery.
b. Costocervical trunk (branch of subclavian artery) – provides superior (highest or supreme) intercostal artery which supplies the posterior 1st and 2nd intercostal spaces.
2. Course and branches
a. Travel with and follow the same course and distribution of intercostal nerves.
b. Posterior branches – given off near vertebral column; supplies skin, subcut. tissue, and intrinsic muscles of back, as well as the spinal cord and vertebral column. (same course and distribution as the doral rami of spinal nerves)
c. Collateral branch – given off near angle of the rib.
d. Lateral perforating (cutaneous) branch – given off near the MAL.
e. Anterior perforating (cutaneous) branch – given off in parasternal area.

42
Q

Anterior intercostal arteries (9 pair)

A
  1. Originate from:
    a. Internal thoracic artery (formerly called internal mammary artery, know both names since some physicians, especially surgeons, still use the old name)
  2. Branch of the subclavian artery.
  3. Descends along internal surface of anterior thoracic wall lateral to sternum.
  4. Near 6th or 7th costal cartilage, divides into two terminal branches: musculophrenic and superior epigastric arteries.
  5. Directly provides anterior intercostals arteries 1-6.
    b. Musculophrenic artery
  6. Follows costal arch and provides anterior intercostal arteries to lower intercostal spaces.
    1. Course and branches
      a. Typically, two anterior intercostal arteries supply each intercostal space.
      b. Anastomose with the posterior intercostal arteries.
      c. Perforating and muscular branches follow same pattern as the nerves.
      CLINICAL CORRELATION: The internal thoracic artery is the preferred conduit used for coronary artery bypass grafting (CABG).
43
Q

Intercostal veins

A
  1. The 1st–3rd posterior intercostal veins unite to form the superior intercostal vein; drains directly into the brachiocephalic vein (left) or azygos (right).
  2. Anterior intercostal veins drain to internal thoracic veins.
  3. Posterior intercostal veins 4-11 (and 12) drain to the azygos system of veins
    Vein (superior)
    Artery (middle)
    Nerve (inferior)
    CLINICAL CORRELATION: – a needle or chest tube placed into the intercostal space should be inserted at the superior border of the rib to avoid the neurovascular bundle.
44
Q

where does the neurovascular bundle course?

A

between the 2nd and 3rd muscle layers

45
Q

Contents of intercostal space from superior to inferior

A

VAN (Vein, Artery, Nerve)

46
Q

openings of the thoracic diaphragm

A

The thoracic diaphragm has 3 opening for passage of the IVC (TV8), the esophagus (TV 10) and the aorta (TV 12).

47
Q

thoracocentesis needle placement

A

In thoracocentesis (or chest tube placement) the needle is placed over the superior border of the rib to avoid damage to the vein, artery, or nerve that courses along the inferior border of the rib in the costal groove.

48
Q

intercostal nerve block

A

When performing intercostal nerve block, anesthetic agent is infiltrated along the inferior border of the rib.

49
Q

Lymphatics of the thoracic wall

A

A. superficial structures –> axillary lymph nodes.
B. Parasternal nodes (Along the lateral border of the sternum. Afferents: anterior thoracic wall, superior portion of the abdominal wall, superior surface of the liver, and the medial portions of the mammary gland. Efferents: bronchomediastinal trunk.)

C. Intercostal nodes (Located near the heads and necks of the ribs. Afferents: posterolateral thoracic wall. Efferents: thoracic duct or right lymphatic duct (1st – 6th spaces); also spread to abdomen and enter cisterna chyli directly (7th – 11th spaces).)

D. Diaphragmatic (phrenic) nodes

  1. Anterior diaphragmatic nodes (Located near the xiphoid process on the superior surface of diaphragm. Afferents: anterior diaphragm; superior surface of the liver. Efferents: drain to parasternal nodes.)
  2. Lateral diaphragmatic nodes (Located where phrenic nerves pierce diaphragm. Afferents: central diaphragm, superior surface of liver. Efferents: to parasternal and posterior mediastinal lymph nodes.)
  3. Posterior diaphragmatic nodes (Located near the aortic hiatus. Afferents: posterior portion of diaphragm. Efferents: posterior mediastinal nodes)

CV (15 decks)

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