Part I. M + NAV Of Thoracic Wall Flashcards
4 muscles of thoracic wall:
External and internal intercostal m
Innermost intercostal m
Subcostal m
Transversus throacis m
How many pair of external intercostal m?
11 pair
Where is the location of external intercostal m?
Fill space from tubercles of ribs (posterior) to costochondral joints (anterior)
Most superficial in intercostal space
Fiber direction of external intercostal m?
Inferoanterior between 1 rib and the next one inferior to it
Fingers in front pockets
Action of external intercostal m?
Elevates ribs in forced inspiration
Maintain tonus in normal respiration
External intercostal membrane extends from?
Costochondral joint to sternum
How many pair of internal intercostal m?
11 pair
Location of internal intercostal m?
Fill space from sternum (anterior) to costal angle (posterolateral)
Middle layer in intercostal space
Fiber direction internal intercostal m
Inferoposterior between 1 rib and the next one inferior to it
(Opposite external)
Action of internal intercostal m
Depress ribs in forced expiration
Maintain tonus in normal respiration
internal intercostal membrane extends from
Costal angle to TPs of vertebrae
How many pair innermost intercostal m?
11
Location of innermost intercostal m
Fill lateral portion of intercostal space only
Inner layer in intercostal space
Fiber direction of innermost intercostal m
Similar to internal — inferoposterior
innermost intercostal m is separated from internal intercostal m by
Intercostal NAV
Action of innermost intercostal m
Depress ribs in forced expiration
Maintain tonus in normal respiration
Location of subcostal m
Internal surface of lower ribs near their angle
Fiber angle subcostal m
Very similar to internal intercostal m — inferoposterior
Which muscle crosses at least 1 rib to span 2+ intercostal spaces?
subcostal m
Action of subcostal m
Weekly depress ribs
Location of transversus throacis m?
Inner surface of anterior thoracic wall
transversus throacis m spans:
Superolaterally from inferior sternum to 2-6th costal cartilages
Action of transversus throacis m
Weakly depress ribs
May function in proprioception
Where are typical intercostal nerves?
3rd through 6th
Where are the 12 pair of thoracic spinal nerves? And what do they become?
Ventral rami fo T1-T11 spinal nerves become Intercostal N
Ventral rami T12 spinal nerves become Subcostal N
Dorsal rami pass posteriorly to innervate:
Vertebrae, joints, muscles and skin
What is the motor innervation of typical intercostal n?
Intrinsic muscle of thoracic wall
What is the sensory innervation of typical intercostal n?
To dermatome skin regions
5 branches of typical intercostal n
Collateral branch Lateral cutaneous branch Anterior cutaneous branch Muscular branch Rami communicantes
Where is the collateral branch of typical intercostal n?
Starts near angle of rib and passes along superior margin of lower rib
What does collateral branch of typical intercostal n innervate?
Intercostal muscles and parietal pleura
Where is lateral cutaneous branch of typical intercostal n?
Enters superficial fascia in midaxillary line
What does the lateral cutaneous branch of typical intercostal n innervate?
Sensory - skin in lateral thoracic region
Where is the anterior cutaneous branch of typical intercostal n?
Enters superficial fascia in parasternal line
Where does the anterior cutaneous branch of typical intercostal n innervate?
Sensory — skin in anterior thoracic region
What does the muscular branch of typical intercostal n innervate?
Motor — intrinsic muscle of thoracic wall
What is the rami communicantes of typical intercostal n?
Sympathetic connections between intercostal nerve and sympathetic trunk
What does the white ramus of the rami communicantes of typical intercostal n contain?
Presynaptic fibers leaving nerve to enter ganglion
What does the gray ramus of the rami communicantes of typical intercostal n contain?
Postsynaptic fibers leaving ganglion to enter nerve
Where are thoracoabdominal nerves?
7th-11th intercostal nerves
What do thoracoabdominal nerves do?
Cross costal margin passing from thorax to abdomen
What do thoracoabdominal nerves innervate?
Abdominal skin and musculature
Is it intercostal nerves or arteries that can be posterior or anterior?
Arteries (the nerve is simply Intercostal n.)
Where does the internal thoracic artery branch from and where does it bifurcate?
Subclavian A; Superior Epigastric & Musculophrenic A
What space does the internal thoracic artery bifurcate?
6th intercostal space
The ___th pair of Anterior Intercostal Arteries branch from_________________ artery while the ___th pair branch from _____________ artery.
1-6th pair branch from Internal Thoracic A
7-9th pair branch from Musculophrenic A
The ___ (number) pair of Posterior Intercostal Arteries branch from_________________ artery while the ___ (number) pair branch from _____________ artery.
1 and 2nd pair branch from Superior Intercostal A (from Costocervical Trunk)
3-11th pair (and Subcostal A) branch RIGHT from Descending Thoracic Aorta
The return system is called:
Azygos system
What does azygos mean?
Unpaired or single
What does the azygos system do overall?
Drains back, thoracoabdominal walls and mediastinal viscera
Provides alternate route for venous return from lower body (if needed)
The azygos v ascends at what location:
Posterior mediastinum on right side of T4-T12
Where does the azygos v drain?
Superior Vena Cava
Where does azygos v receive blood
Right 4th-11th posterior intercostal veins
Where is the hemiazygos v located?
It ascends posterior mediastinum on left side of T9-T12
At T9 what happens to Hemiazygos v?
Crosses vertebral bodies to drain into azygos v
Where does the hemiazygos v receive blood from?
9th-11th posterior intercostal vv
Accessory hemiazygos v is located where?
Descends posterior mediastinum on left side of T5-T8
At about T8 what happens to the Accessory Hemiazygos v?
Crosses vertebral body to drain into Azygos V.
Sometimes joins Hemiazygos V
Accessory hemiazygos v receives blood from
Left 4th-8th posterior intercostal vv
Where does the Superior Intercostal V receive blood from?
1-3rd Posterior Intercostal Vv
What does the Superior Intercostal V drain into on the Right?
Azygos V
The breast is innervated by
Anterior and lateral cutaneous branches of 2-6th Intercostal N
What does the Superior Intercostal V drain into on the Left?
Accessory Hemiazygos V or L Brachiocephalic V
The dorsal branches of the posterior intercostal arteries, supply what?
vertebral column, back muscles and skin
