Week 2 - Thoracic Wall Flashcards
What is a dermatome?
An area of skin innervated by sensory fibres coming from a single spinal nerve
Dermatomes are important for understanding sensory nerve distribution.
Name the muscles of the pectoral region.
- Pectoralis major
- Pectoralis minor
- Intercostal muscles
These muscles play crucial roles in movement and respiration.
What is the function of external intercostal muscles?
Contraction for inspiration
The fibres are directed downward and forward.
What is the origin and insertion of external intercostal muscles?
Origin – lower border of the rib above
Insertion – upper border of rib below
These muscles extend from the rib tubercle to the costochondral junction.
What is the function of internal intercostal muscles?
Contraction for exhalation
The fibres are directed downward and backward.
What is the origin and insertion of internal intercostal muscles?
Origin - Inferior margin of costal cartilage and inner lip of costal groove
Insertion – Superior border of the rib below
These muscles run from the sternum to the angle of the rib.
What are the components found in all 11 intercostal spaces?
- Intercostal vein
- Intercostal artery
- Nerve
Below rib 12, the components include subcostal vein, artery, and nerve.
What does the internal thoracic artery branch into at the 6th intercostal space?
- Superior epigastric artery
- Musculophrenic artery
This artery is from the 1st part of the subclavian artery.
What types of spinal nerve innervation are involved in the thorax?
- Anterior root
- Posterior root with ganglion
- Spinal nerve
The thorax is innervated by ventral rami T1-T11 (intercostal and T12 subcostal nerves).
Which nerves supply the intercostal muscles?
Intercostal nerves arise from the anterior rami of thoracic spinal nerves T1 to T11
These nerves also supply the skin of the anterolateral part of the chest.
What is the role of T2 spinal nerve?
Innervates intercostal muscles of the second intercostal space and is sensory to the axilla and medial side of the arm
T2 forms part of the brachial plexus.
What are the branches of the intercostal nerve?
- Collateral branch
- Lateral cutaneous branch
- Anterior cutaneous branch
- Muscular branches
- Pleural & peritoneal branches
- White & grey rami communicans
These branches serve various functions including innervating muscles and providing sensory information.
True or False: The neurovascular bundle is located above the ribs.
False
The neurovascular bundles are found below the ribs.
What is the purpose of an intercostal nerve block?
To deliver anaesthetic agent to the nerve
The needle is inserted along the inferior margin of the rib.
What arteries supply the thoracic wall?
- Thoracic aorta
- Posterior intercostal arteries
- Subcostal arteries
- Subclavian artery
- Internal thoracic artery and branches
- Superior or supreme intercostal arteries
- Axillary artery
- Superior and lateral thoracic arteries
These arteries ensure adequate blood supply to the thoracic wall.
How many branches does the 1st part of the axillary artery have?
1 branch – superior thoracic artery
This part is located above the pectoralis minor.
Fill in the blank: The second part of the axillary artery has ______ branches.
2 branches – Lateral thoracic artery & thoraco-acromial branch
The thoraco-acromial branch includes the deltoid, acromial, clavicular, and pectoral branches.
Fill in the blank: The third part of the axillary artery has ______ branches.
3 branches – Suprascapular artery, posterior & anterior circumflex humeral arteries
These branches supply the shoulder region.
