Thoracic Wall Flashcards

1
Q

how can the body be divided

A

into 3 internal cavities

  1. thoracic
  2. abdominal
  3. pelvic
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2
Q

where does the thoracic cavity extend

A

from the thoracic inlet cranially to the diaphragm caudally

enclosed by bones of ribcage

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3
Q

what are the boundaries of the thoracic cavity

A

dorsal: thoracic vertebrae

ventral: sternum

cranial: thoracic inlet

caudal: diaphragm

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4
Q

what does it mean that the thoracic cavity is laterally compressed

A

its greatest dimension is in a dorsoventral direction –> deep and narrow

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5
Q

how does the shape of the thoracic cavity vary in breeds of dogs

A

some breeds like the deerhound have narrow thoracic cavities

bulldog –> barrel chested

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6
Q

where does the abdominal cavity run

A

from diaphragm cranially to the pelvic inlet caudally

dorsal roof: lumbar vertebrae and wall is composed entirely of muscle

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7
Q

where does the pelvic cavity run

A

through the pelvis

passing ventral to sacrum

extends from pelvic inelt cranially to the pelvic diaphragm or perinuem caudally

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8
Q

what are the functions of the thoracic and abdominal walls

A

support and protection for the vital organs (in thorax –> heart, lungs and major blood vessels such as aorta. in abdomen –> liver, GI tract, urinary system)

respiration (abdominal wall muscles have attachments along the caudal aspect of ribcage and therefore have an influence on its movement)

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9
Q

what are the body wall components

A

1. skin

2. cutaneous trunci muscle (closely adhered to it, twitching the skin –> present dorsally and laterally like a blanket but does not extend to midline, not present ventrally)

3. superficial fasci–> composed of loose CT and fat (glue that holds the skin and cutaneous trunci muscle onto underlying structures of trunk)

4. deep fascia & muscle: various muscles associated with thoracic and abdominal walls –> covered by and enclosed within layers of fibrous tissues

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10
Q

what are the thorax components

A

deep to the fascia and muscles

4. ribcage & intercostal muscles

5. pleura: fine layer of cells called the pleura that lines the thoracic cavity and encases all of its components

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11
Q

what are the abdominal wall components

A

6. peritoneum: fine layer of cells lining the cavity and encasing its contents –> adherent to inner surface of abdominal wall muscles

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12
Q

what are the components of the ribcage

A

13 thoracic vertebrae

13 pairs of ribs

12 intercostal spaces

8 sternebrae = sternum

ribs articulate with vertebrae and sternum

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13
Q

what is the dorsal roof of the ribcage composed of

A

13 thoracic vertebrae

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14
Q

what are the lateral walls of the ribcage composed of

A

13 pairs of ribs

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15
Q

what are the spaces between adjacent ribs called

A

intercostal spaces –> 12 of them on each side of the dog numbered from cranial to caudal

(1st intercostal space = is caudal to 1st rib and so on)

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16
Q

what is the ventral floor of the ribcage formed by

A

sternum and in the dog made up from 8 individual bones called sternebrae

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17
Q

where do the ribs articulate

A

articulate with vertebral column dorsally and the sternum ventrally

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18
Q

what is the proximal 2/3 and distal 1/3 component of each rib

A

proximal 2/3: bone

distal 1/3: cartilage –> costal cartilage

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19
Q

what is the boundary between the bone and costal cartilage called

A

costochondral junction

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20
Q

how do ribs articulate

A

the proximal end of the rib has a rounded head for articulation with the relevant vertebrae

short neck with a small boney bump or tuberculum for articulation with transverse process of relevant vertebra

the rest of the bone is referred to as the body of the rib

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21
Q

what do the distal end of the costal cartilages of ribs 1-9 articulate with

A

intersternebral cartilages

located between the adjacent sternebrae in the sternum

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22
Q

what do the costal cartilages of ribs 10-12 run together to form

A

the costal arch which helps contribute to the flexibility of the ribcage

23
Q

what is the costal cartilage of rib 13 associated with

A

not associated with anything –> floating rib

palpable in dog

24
Q

what does the head of ribs 1-10 articulate with

A

head articulates with:

cranial costal fovea of thoracic vertebrae of same number

caudal costal fovea of thoracic vertebra immediately cranial to it (head of rib 5 articulates with cranial costal fovea of the 5th thoracic vertebra and caudal costal fovea of the 4th thoracic vertebra)

25
what are each components of the rib
**proximal end = bone** head = blue tuberculum = light blue body **distal end = cartilage** costal cartilage
26
what does the tuberculum of ribs 1-10 articulate with
transverse process of the thoracic vertebra of same number
27
what does the head of the 1st rib articulate with
T1 and also C7 (last cervical vertebra --\> has a pair of caudal costal fovea to accomodate this)
28
what do the head and the tuberculum of ribs 11-13 articulate with
the head articulates only with thoracic vertebra of same number and no longer bridges over intervertebral disc space --\> movement is possible between adjacent vertebra towards the caudal part of the thoracic region and the thoracolumbar junction
29
what are the ligaments that hold the ribs in place
1. intercapital ligament 2. costo-transverse ligament 3. radiate ligament
30
where does the intercapital ligament run and what does it merge with
runs between the heads of each pair of corresponding right and left ribs runs over the dorsal surface of the intervertebral disc space and merges with 1. fibres of dorsal longitudinal ligament 2. annulus fibrosis of intervertebral disc
31
what does the intercapital ligament support
supports intervertebral disc stabilizes the ribs reduces chance of contents of the intervertebral disc space moving dorsally into the vertebral canal
32
what is the intercapital ligament associated with
ribs 1-10
33
why is the intercapital ligament not present in ribs 11-13
the vertebral body of corresponding vertebra and don't span the intervertebral disc space so this ligament is absent
34
what is the function of the costo-transverse ligament
the tuberculum of each rib articulates with the short transverse process of the corresponding vertebra and is held in place by this ligament ## Footnote **#2**
35
what is the function of radiate ligament
head of the rib is held in place ventrally by this ligament supports the joint capsule and merges with the fibres of annulus fibrosus of intervertebral disc sapce (yellow)
36
identify the costal ligaments
1. intercapital ligament (red on diagram and red pin) 2. costo-transverse ligament (pink on diagram and yellow pin) 3. radiate ligament (yellow on diagram and green pin)
37
what gives the rib cage flexibility
presence of cartilage components of the ribcage and the flexibility possible at the articulations between the ribs and the thoracic vertebrae and sternum
38
how does the diaphragm attach
around the caudal border of the ribcage and the last sternebra --\> known as xiphoid
39
how does inspiration occur
its an active process diaphragm contracts and flattens and ribs are pulled laterally and cranially by accessory inspiratory muscles increases the volume of the thoracic cavity and therefore sucks air into the resp system
40
how does expiration occur
passive process diaphragm relaxes and becomes dome shaped --\> ribcage collapses caudally and medially which decreases the volume of the thoracic cavity and forces air out of the resp system
41
what is the function of the internal intercostal muscles and what direction do they run in
fill each space completely from dorsal to ventral and have fibres that run in a cranio-ventral direction
42
what is the function of the external intercostal muscle
ensure that ribs move together during inspiration and expiration and function as single unit inspiration is an active process --\> most important during this component of the resp cycle
43
where do the external intercostal muscles run to and what direction are there fibres
run as far distally as the costo-chondral junction fibres run in a caudo-ventral direction
44
what are these structures
pink: external intercostal muscles yellow: internal intercostal muscles
45
what are the superficial thoracic wall muscles
1. foreleg: extrinsic muscles of forelimb (associated with producing movement) 2. latisimmus dorsi (caudo-dorsally) 3. pectoral muscles (ventrally) 4. external abdominal oblique muscles (caudo-ventral portion)
46
what is the function of the external abdominal oblique muscles and how do intercostal muscles assist
1. support weight of abdominal contents 2. its origin along the caudal ribs means that it is exerting a constant force on the ribs in a caudal direction --\> assists with passive collapse of ribcage during expiration 3. following strenous exercise --\> active contraction assits with increasing resp rate (intercostal muscles ensure that whole ribcage moves together in a caudal direction to compress the thoracic cavity and produce an increase expiratory effort) --\> responsible for abdominal effort or "heaving flanks" observed after exercise
47
what is the blood supply to the thoracic cavity and where do they run
intercostal vein, artery: each intercostal space is associated with an intercostal artery and vein run down caudal aspect of the rib to the level of the costochondral junction --\> branch to run down both sides of rib ventrally the intercostal arteries communicate with internal thoracic artery that runs along the length of the ventral aspect of the thorax
48
which arteries need to be taken into consideration during surgical incisions
if making a surgical incision in the intercostal space --\> aim for middle of space because of the intercostal vein and arteries the internal thoracic artery may be encountered if incision extends far distally in the intercostal space
49
what is the nerve supply to the thoracic cavity
intercostal nerves
50
what is the function of the serratus ventralis muscle
located between the limb and trunk with origins along the cervical vertebrae and ribs --\> insertion onto the dorsal border of the scapula suspends the weight of the animal's thorax between the forelimbs if increasing resp rate --\> major accessory inspirator muscle --\> pulls ribs cranially and laterally if an animal is demonstrating an increased inspiratory effort either due to disease or exercise --\> they will stand with elbows abducted (away from midline)
51
what are the thoracic wall muscles
1. foreleg 2. latissimus dorsi muscle 3. pectoral muscles 4. external abdominal oblique muscle 5. serratus ventralis muscle
52
what are these structures
1. cutaneous trunci muscle 2. superficial fascia 3. deep fascia and muscle 4. ribcage and intercostal muscle 5. pleura 6. peritoneum
53
what are the superficial supply of the body wall
1. cranial superficial epigastric artery 2. caudal superficial epigastric artery
54