Thoracic Cavity - Anatomy 08/14/17 Flashcards
What are the 4 parts to the sternum?
- Manubrium
- Sternal Angle
- Body
- Xiphoid Process
How many ribs are in the thoracic cavity?
12
True Ribs
1-7. Connect to sternum by costal cartilage
False Ribs
8-10. Connect indirectly to sternum
Floating Ribs
11-12. Do not connect with anything
What does the costal margin do?
Joins cartilage of ribs 7-10
Where does second rib attach?
Sternal angle
What are the 4 parts of rub structure?
- Head
- Tubercle
- Costal angle
- Costal groove
Where is the weakest part of the rib?
Just anterior to costal angle
What is an important part of the 1st rib?
Contains grooves for on superior surface for subclavian vein and artery
What ribs are most commonly fractured?
Ribs 3-8
Is first rib often fractured?
No - in protected position
What else is damaged in a rib fracture?
Vessels and nerves
What is flail chest?
Multiple ribs with multiple fractures that stack on top of each other
What important things enter the Superior Thoracic Aperature?
- Food
- Air
- Venous blood
- Vagus nerve
- Phrenic nerve
What passes through Inferior Thoracic Aperature?
- Food
- Vagus nerve
- Arterial blood in aorta
What is Thoracic inlet/outlet?
Superior/Inferior Thoracic Aperature
What are the 7 accessory muscles of respiration
1-3. Aterior/Middle/Posterior Scalene
- Pectoralis Major
- Serratus Anterior
- Subclavius
- Pectoralis Minor
What 2 things do all the scalene muscles do?
- Fix 1st and 2nd ribs in forceful inspiration
2. Innervate C3-C6 spinal nerves
What are the 4 attachments to the pec major?
- Clavicle
- Sternum to 7th rib
- Costal cartilage
- Bicipital groove of humerus
What muscle protracts and rotates scapula?
Serratus Anterior
What muscles pulls the clavicle down and forward?
Subclavius and Pec Minor
What are the 4 muscles of respiration?
1-3. External/Internal/Innermost Intercostals
4. Subcostal
Which muscle is most active in inspiration?
External intercostals
Which muscle is most active in exhalation?
Internal intercostals
What separates the innermost costals from that internal?
Nerves and vessels
What does the subcostal cross?
2 intercostal spaces
Why do we put our hands or bodies in certain positions when it is hard to breath?
It allows all accessory muscles to contribute
How does the thoracic wall move during flail chest?
Inward on inspiration, outward on on expiration
What 4 things does the Posterior Branch of the Intercostal Arteries supply?
- Spinal cord
- Back
- Muscle mm?
- Skin
How do costal grooves group the structures superior to inferior?
- Vain
- Artery
- Nerve
VAN
What do the Posterior Intercostal Arteries supply?
- Intercostal mm?
- Overlaying skin
- Parietal Pleura
What is the Parietal Pleura?
Membrane attached to inner surface of thoracic cavity
What do the Anterior Intercostal Arteries supply?
- ICS 1-9 including intercostal mm
- Overlying skin
- Parietal pleura
Where do the Internal Thoracic Arteries descend to?
Thorax posterior to clavicle
What does anastomose mean?
Two vessels bring together blood
What do the anterior and posterior intercostal veins do?
Anastomose with each other to drain vertebral venous plexuses
What is a plexus?
Intersecting nerves
What forms the intercostal nn? (nn?)
Anterior rami from T1-T11 thoracic spinal nerves
What thoracic nerve forms the subcostal
Anterior ramus T12
Where are intercostal grooves located?
Within the costal grooves on the ribs
What are the 5 branches to intercostal nerves?
- Rami communicantes
- Collateral branches
- Muscular branches
- Lateral cutaneous branches
- Anterior cutaneous branches
What does the Rami Communicantes supply?
Sympathetics to smooth muscles, walls of organs, glands
What do the collateral branches supply?
Intercostal muscles and parietal pleura
What do lateral cutaneous branches supply?
Skin of thoracic and abdominal walls
What do the anterior cutaneous branches supply?
Skin on anterior surface of thorax and abdomen
What happens in an intercostal nerve block?
Nerve endings in skin and transmission of impulses through sensory nerves are interrupted before they reach spinal cord and brain
How many nerves need to be anesthetized?
2 or more - want to inject as close to nerve as possible
Define collateral circulation
Alternate circulation around a blocked artery or vein via another path
