Lecture 22: Thorax I, Thoracic Wall

Question 1

What are body walls

Answer 1

Heterogenous stratifications of different tissue layers

Question 2

Thorax definition

Answer 2

Cranial trunk between neck and abdomen

Question 3

Thoracic cavity is protected by what structure

Answer 3

Rib cage

Question 4

Thoracic cavity is limited caudally by what structure

Answer 4

Diaphragm

Question 5

Rib cage definition (formed by what 3 structures)

Answer 5

Bony structure formed by ribs, thoracic vertebrae, and sternum

Question 6

How many ribs do dogs have

Answer 6

26 (13 pairs)

Question 7

6 joints of rib cage

Answer 7

-intervertebral
-costovertebral
-costochondral
-sternocostal
-eternal
-intercostal

Question 8

Costochondral joint definition

Answer 8

Strong union of periosteum of ribs and perichondrium of costal cartilage (of sternum)
but not every rib attaches to sternum

Question 9

Sternocostal joints definition

Answer 9

True ribs

Question 10

4 intervertebral ligaments

Answer 10

-supraspinal
-interspinal
-dorsal intervertebral
-ventral intervertebral

Question 11

Which 2 joints allow volume changes of the thorax

Answer 11

-costovertebral
-sternocostal

Question 12

Where do costovertebral joints attach

Answer 12

At head of rib in ball and socket connection

Question 13

Intercostal joints are

Answer 13

False ribs

Question 14

Articulations of ribs 9-12 vs 1-8

Answer 14

1-8: bony portion articulated with vertebrae and cartilaginous portion articulates with sternum
9-12: part of costal arch/false ribs, articulate with adjacent cartilages

Question 15

How does rib 13 differ

Answer 15

-floating rib
-doesn’t articulate with ribs or costal cartilages

Question 16

Muscles of the thorax (7)

Answer 16

-lavatories costarum
-intercostales external
-intercostales interni
-retractor costae
-transversus thoracis
-Rectus thoracis
-diaphragm

Question 17

Lavatores costarum: OINA

Answer 17

O - transverse processes of thoracic vertebrae
I - lateral surfaces and cranial borders of dorsal ends of ribs located caudal to vertebral origin
N - intercostal nerves
A - draw ribs in cranially in inspiration and/or produce rotation and lateral flexion of vertebral column

Question 18

Intercostales externi: OINA

Answer 18

O - caudal borders of ribs
I - cranial borders and lateral surfaces of caudal rib
N - intercostal nerves
A - draw ribs cranially in inspiration

Question 19

Which way to fibers of intercostales externi extend

Answer 19

Caudoventrally

Question 20

Intercostales interni: OINA

Answer 20

O - cranial borders of ribs
I - caudal borders of preceding ribs
N - intercostal nerves
A - pull ribs caudally during expiration

Question 21

Which way do fibers of intercostales interni extend

Answer 21

Cranioventrally

Question 22

Retractor costae: OINA

Answer 22

O - transverse processes of first 3/4 lumbar vertebrae
I - caudal borders of last rib
N - lumbar nerves
A - retract last rib during expiration

Question 23

Transversus thoracis: OINA

Answer 23

O - eternal ligament at midline
I - cartilages of ribs from 2 to 8
N - spinal nerves
A - draw ribs caudomedially, assisting in expiration

Question 24

Rectus thoracis: OINA

Answer 24

O. Ventral region of 1st rib
I - by aponeurosis to origin of Rectus abdominis
N - intercostal nerves
A - advance ribs cranially during inspiration

Question 25

Which 3 thoracic muscles advance the ribs cranially during inspiration

Answer 25

Rectus thoracis Intercostales externi Lavatories costarum

Question 26

Which 2 thoracic muscles pull ribs caudally during expiration

Answer 26

Intercostales interni Transversus thoracis

Question 27

Diaphragm definition

Answer 27

Broad, unpaired muscle that divides thoracic and abdominal cavities

Question 28

4 regions of diaphragm (muscles)

Answer 28

-central tendon -costal regions -sternal region -lumbar region

Question 29

What nerve innervates diaphragm

Answer 29

Phrenic

Question 30

Origin of costal regions of diaphragm

Answer 30

Costal arch

Question 31

Origin of sternal region of diaphragm

Answer 31

Xiphoid cartilage

Question 32

Origin of lumbar region of diaphragm

Answer 32

Ventral surface of lumbar vertebrae

Question 33

Insertion of costal/sternal/lumbar region of diaphragm

Answer 33

Central tendon

Question 34

Action of costal/sternal/lumbar regions of diaphragm

Answer 34

Increase volume of thoracic cavity during inspiration

Question 35

Hiatus vs foramen

Answer 35

Hiatus = incomplete opening Foramen = complete opening

Question 36

3 openings in diaphragm

Answer 36

-aortic hiatus -esophageal hiatus -foramen vena cavae

Question 37

aortic hiatus allows for passage of what 3 structures

Answer 37

-aorta -azygous vein -thoracic duct

Question 38

Esophageal hiatus allows for passage of what structure

Answer 38

Esophagus

Question 39

Foramen vena cavae allows for passage of what structure

Answer 39

Caudal vena cava

Question 40

What happens during inspiration (ribs, sternum, diaphragm movements)

Answer 40

-diaphragm contracts and moves caudally -ribs and sternum expand (ribs move dorsally and cranially to expand rib cage, cranial lift of sternum) -volume of thorax increases

Question 41

Movements of rib cage and diaphragm during expiration

Answer 41

-diaphragm moves cranially with relaxation -ribs move ventrally and caudally to compress rib cage -sternum compresses caudally and dorsally -thoracic volume decreases

Question 42

2 main vessels supplying blood to thoracic wall (dorsal and ventral)

Answer 42

Dorsal = dorsal intercostal branches off aorta Ventral = ventral intercostal branches off internal thoracic

Question 43

What do dorsal intercostal arteries do with ventral intercostal branches

Answer 43

Anastomose

Question 44

Blood drainage of thoracic wall (dorsal and ventral)

Answer 44

Dorsal: to azygous vein Ventral: to internal thoracic vein

Question 45

Innervation of thoracic wall (hint: which nerves and ramus)

Answer 45

-Intercostal nerves within intercostal spaces -Ventral rami from T1-T11: motor innervation to intercostal muscles, Sensory afferent from skin Sympathetic to sweat glands and blood vessels of thoracic/abdominal walls

Question 46

Patterning of intercostal arteries, veins and nerves

Answer 46

From top to bottom: artery, vein, nerve Surrounded by intercostal externi/interni, parietal/visceral pleura