Lecture 22: Thorax I, Thoracic Wall Flashcards
What are body walls
Heterogenous stratifications of different tissue layers
Thorax definition
Cranial trunk between neck and abdomen
Thoracic cavity is protected by what structure
Rib cage
Thoracic cavity is limited caudally by what structure
Diaphragm
Rib cage definition (formed by what 3 structures)
Bony structure formed by ribs, thoracic vertebrae, and sternum
How many ribs do dogs have
26 (13 pairs)
6 joints of rib cage
-intervertebral
-costovertebral
-costochondral
-sternocostal
-eternal
-intercostal
Costochondral joint definition
Strong union of periosteum of ribs and perichondrium of costal cartilage (of sternum)
but not every rib attaches to sternum
Sternocostal joints definition
True ribs
4 intervertebral ligaments
-supraspinal
-interspinal
-dorsal intervertebral
-ventral intervertebral
Which 2 joints allow volume changes of the thorax
-costovertebral
-sternocostal
Where do costovertebral joints attach
At head of rib in ball and socket connection
Intercostal joints are
False ribs
Articulations of ribs 9-12 vs 1-8
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
How does rib 13 differ
-floating rib
-doesn’t articulate with ribs or costal cartilages
Muscles of the thorax (7)
-lavatories costarum
-intercostales external
-intercostales interni
-retractor costae
-transversus thoracis
-Rectus thoracis
-diaphragm
Lavatores costarum: OINA
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
Intercostales externi: OINA
O - caudal borders of ribs
I - cranial borders and lateral surfaces of caudal rib
N - intercostal nerves
A - draw ribs cranially in inspiration
Which way to fibers of intercostales externi extend
Caudoventrally
Intercostales interni: OINA
O - cranial borders of ribs
I - caudal borders of preceding ribs
N - intercostal nerves
A - pull ribs caudally during expiration
Which way do fibers of intercostales interni extend
Cranioventrally
Retractor costae: OINA
O - transverse processes of first 3/4 lumbar vertebrae
I - caudal borders of last rib
N - lumbar nerves
A - retract last rib during expiration
Transversus thoracis: OINA
O - eternal ligament at midline
I - cartilages of ribs from 2 to 8
N - spinal nerves
A - draw ribs caudomedially, assisting in expiration
Rectus thoracis: OINA
O. Ventral region of 1st rib
I - by aponeurosis to origin of Rectus abdominis
N - intercostal nerves
A - advance ribs cranially during inspiration
Which 3 thoracic muscles advance the ribs cranially during inspiration
Rectus thoracis
Intercostales externi
Lavatories costarum
Which 2 thoracic muscles pull ribs caudally during expiration
Intercostales interni
Transversus thoracis
Diaphragm definition
Broad, unpaired muscle that divides thoracic and abdominal cavities
4 regions of diaphragm (muscles)
-central tendon
-costal regions
-sternal region
-lumbar region
What nerve innervates diaphragm
Phrenic
Origin of costal regions of diaphragm
Costal arch
Origin of sternal region of diaphragm
Xiphoid cartilage
Origin of lumbar region of diaphragm
Ventral surface of lumbar vertebrae
Insertion of costal/sternal/lumbar region of diaphragm
Central tendon
Action of costal/sternal/lumbar regions of diaphragm
Increase volume of thoracic cavity during inspiration
Hiatus vs foramen
Hiatus = incomplete opening
Foramen = complete opening
3 openings in diaphragm
-aortic hiatus
-esophageal hiatus
-foramen vena cavae
aortic hiatus allows for passage of what 3 structures
-aorta
-azygous vein
-thoracic duct
Esophageal hiatus allows for passage of what structure
Esophagus
Foramen vena cavae allows for passage of what structure
Caudal vena cava
What happens during inspiration (ribs, sternum, diaphragm movements)
-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
Movements of rib cage and diaphragm during expiration
-diaphragm moves cranially with relaxation
-ribs move ventrally and caudally to compress rib cage
-sternum compresses caudally and dorsally
-thoracic volume decreases
2 main vessels supplying blood to thoracic wall (dorsal and ventral)
Dorsal = dorsal intercostal branches off aorta
Ventral = ventral intercostal branches off internal thoracic
What do dorsal intercostal arteries do with ventral intercostal branches
Anastomose
Blood drainage of thoracic wall (dorsal and ventral)
Dorsal: to azygous vein
Ventral: to internal thoracic vein
Innervation of thoracic wall (hint: which nerves and ramus)
-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
Patterning of intercostal arteries, veins and nerves
From top to bottom: artery, vein, nerve
Surrounded by intercostal externi/interni, parietal/visceral pleura
