1- Introduction Flashcards
What defines two distinct apertures in the thoracic cage? What are these structures?
The boney structures define the two distinct apertures in the thoracic cage. These structures are:
1) Superior thoracic aperture (Inlet)
2) Inferior Thoracic Aperture (Outlet)
What does the thoracic cavity contain?
Thymus Heart Lungs Distal part of trachea Most of esophagus
What are the boundaries and contents of the Thoracic Inlet?
Boundaries:
- First pair of ribs and cartilage
- Manubrium sterni (superior border)
- First Thoracic Vertebra (T1)
Contents:
- APEX of the lungs!
- Trachea
- Esophagus
- Vagus N. (CN X), phrenic n. (C3,4,5)
What are the boundaries and contents of the thoracic outlet (inferior thoracic aperture)?
Boundaries:
- the 12th thoracic vertebra (T12)
- the 12th pair of ribs
- costal margin = costal cartilages 7-10
Contents:
NOTHING!
What are important landmarks of the thoracic cage?
- Xiphoid process
- Sternal angle of Louis
- Costal cartilage of 2nd rib/manubriosternal joint
- Angle of Louis
What level is the xiphoid process?
T10 or T11
Where is the sternal angle?
Lower border of T4
Where is the costal cartilage of the 2nd rib?
With the manubrialsternal joint
What is the angle of Louis and what is important about it?
The angle of Louis is the angle ormed between the Manubrium and the body of the sternum (manubrialsternal joint).
The angle of Louis marks the 2nd costal cartilage for counting intercostal spaces.
It denotes the level of the:
1) Aortic arch and branches of the aortic arch
2) bifurcation of the trachea (carina)
3) T4/T5 intervertebral disc
What part of the body is the thorax?
The superior part of the trunk between the neck and the abdomen.
Describe the shape of the ribs in the thoracic cage?
THe ribs are narrow, curved, flat bones
How many ribs are there? What’s are special aspects of the ribs?
12 pairs of ribs:
- Longest: Rib 7
- Shortest: Rib 12
- Ribs 3-9 : TYPICAL RIBS
- Ribs 1,2,10,11,12 : ATYPICAL RIBS
- Ribs 1-7 articulate directly with the sternum through their costal cartilages and are TRUE RIBS
- Ribs 8,9,10 : share a common costal cartilage and are the FALSE RIBS
- Ribs 11-12 : do not articulate anteriorly and end among the muscles of the body wall = FLOATING RIBS
Where is the costal groove?
Located on the inferior aspect of the ribs
What is the function of the costal groove?
To shelter the intercostal neurovascular bundle (vein, artery, nerve - VAN)
Describe the first rib and nearby contents. What is particular about the first rib?
The first rib is short and broad, forms part of the thoracic inlet, and it has a groove for the SUBCLAVIAN vein and artery.
Identify the grooves for the subclavian artery and vein on the first rib
Page 8
Identify the tubercle for muscle attachment on the second rib
Page 8
Identify the shaft and tubercle on the second rib
Page 8
Identify the costal angle, head and tubercle on the 11th rib
Page 8
Identify the costal angle on a typical rib
Page 7
What is the anatomy of an intercostal space (I.e. contents and boundaries)
Boundaries
Intercostal mm: external and innermost
Contents:
Internal m
Vein
Artery nerve
What are the functions of the thoracic cage?
Protection of internal organs
Framework for attachment of muscles
Assists in respiration
During inspiration, how do the walls of the thoracic wall move?
The thorax widens as the ribs elevate.
As the ribs elevate, the middle parts of the lower ribs move laterally (“bucket handle movement”)
As the upper ribs are elevated, the anterior-posterior diameter of the thorax is increased (“pump handle movement”) w/ greater excursion (increase) occurring inferiorly.
Overall increase in AP and transverse diameters of the thoracic cage
What is bucket handle movement?
The lateral movement of the middle parts of the lower ribs when they are elevated
What is the pump-handle movement?
When the AP diameter of the thorax is invaded as the upper ribs are elevated.
What are the general muscles of the thoracic wall?
Diaphragm Serratus anteriorm m Serratus posterior superior and inferior mm Pectoralis major and minor mm. Intercostal mm
What muscles comprise of the intercostal muscles?
External innercostal muscle
Internal innercostal muscle
Innermost muscle group, which contains the innermost proper, subcostalis m, and sternocostalis m (aka. Transverse thoracis m)
What are the three parts of the innermost muscle and where do they lay?
a) Innermost proper - between the ribs
b) subcostalis - at the angle of the ribs
c) sternocostalis - near the sternum
What is another name for the sternocostalis part of the innermost muscle?
transversus thoracis
What is the origin, insertion, nerve supply and action of the external intercostal muscle?
Origin: Lower borders of ribs 1-11
Insertion: upper boarders of ribs 2-12
Nerve supply: corresponding intercostal n.
Action: elevate the rib cage: inspiration
What direction do the fibers run for the external intercostal muscles?
downward and forward
Where is the external intercostal membrane?
at the costochondral joint
What is the origin, insertion, nerve supply and action of the external intercostal muscle?
Origin: N/A
Insertion: N/A
Nerve supply: Corresponding intercostal nerve
Action: Expiration (passive)
What is the origin, insertion, nerve supply and action of the innermost intercostal muscle?
Origin: Depends on part
Insertion: N/A
Nerve supply: Corresponding intercostal nerve
Action: Expiration (passive function)
What is the origin, insertion, nerve supply and action of the serratus anterior muscle?
Origin: Ribs 1-8
Insertion: costal surface of scapula, superior and inferior angles of the medial border of the scapula
Nerve supply: long thoracic nerve (c5,c6,c7)
Action: Rotates the scapula, abducts the arm, elevates the arm above the horizontal, assists in respiration
What happens if you damage the long thoracic nerve?
Damage serratus anterior muscle motion. This causes:
- winging of the scapula
- loss of elevation of arm
- problems with respiration
What is the general anatomy of the diaphragm?
a dome-shaped structure that separates the thoracic cavity from the abdomen. The diaphragm has a peripheral muscular part and a centrally placed tendon.
What are the three openings of the diaphragm and at what vertebrae level are they?
Aortic Opening (T12) Esophageal Opening (T10) Caval Opening (T8)
What are the contents of the aortic opening?
Thoracic aorta
Thoracic duct
greater splachnic nerves (T5-9)
Azygos vein
What are the contents that pass through the esophageal opening (T10)?
- Esophagus
- Right and left vagus nerves
- esophageal brach of the last gastric artery and vein
What are the contents that pass through the Caval Opening (T8)?
Phrenic nerves (C3,4,5)
IVC
Lymphatics
What arteries are considered part of the thoracic wall and where do they supply??
Internal Thoracic/musculophrenic artery [subclavian] - anterior aspect of the thoracic wall && Anterior intercostal arteries to ICS 1-6
Highest intercostal artery (costocervical trunk [subclavian branch]) - Intercostal space 1
Posterior intercostal arteries: Intercostal space 1-11 (thoracic aorta)
Subcostal arteries - intercostal space 12 (thoracic artery)
True or false: All posterior arteries come from the aorta.
True
