Anatomy dissection notes 9 Flashcards
What is the axilla ?
- It is the pyramidal space inferior to the shoulder joint and just superior to the armpit
- It is an important “gateway” for structures entering or leaving the upper limb e.g. arteries, veins, nerves and lymphatics.
What are the different borders and shape of the axilla (don’t want the muscles yet)?
It has a pyramidal type structure so has:
- Apex
- Lateral and medial walls
- Anterior and posterior walls
What are the anterior and posterior borders of the axilla (specifically looking for the muscles here)?
- Anterior wall - Pectoralis major and the underlying pectoralis minor and the subclavius muscles.
- Posterior wall – Formed by the subscapularis, teres major and latissimus dorsi.
What is the function of the pectoralis major ?
One of the main muscles of climbing and also an excessory muscle of respiration
Where can pulsations of the subclavian artery be felt ?
As it crosses the first rib
When does the subclavian artery become the axillary artery ?
At the lateral border of the first rib
What are the main contents within the axilla ?
- Axillary artery
- Axillary vein
- Brachial plexus
- Axillary lymph nodes
What spinal nerves (anterior rami) make up the brachail plexus ?
C5-T1
Describe the changes in the brachial plexus going from proximal to distal
Goes from Roots ===> Trunks ===> Divisions ===> Cords ===> Named nerves
Think - Really Tired, Don’t Care Now
How does the brachail plexus go from the root values to trunks ?
The anterior rami (C5-T1) mix to form superior, middle and inferior trunks
What nerve root values make up the different trunks of the brachial plexus ?
- Superior trunk = C5&6
- Middle trunk = C7
- Inferior trunk = C8 & T1
In terms of divisions what does each trunk give off and why is this relevant ?
Each trunk gives off an anterior and posterior division - relevant as these divisions branch of and join to form the cords
What are the different cords of the brachial plexus and how are they named?
- They are named according to there relationship to the axillary artery
- You have the medial, lateral and posterior cords
What divisions forms the different cords ?
- Medial cord = a direct continuation of the anterior division of the inferior trunk
- Lateral cord = formed from the anterior divisions of the superior and middle trunks
- Posterior cord = formed from the posterior divisions of all three trunks
The cords then branch into the named nerves what are the different named nerves formed?
- Ulnar
- Musculocutaneous
- Axillary
- Radial
- Median
How are each of the named nerves formed ?
- The ulnar nerve continues directly from the medial cord
- The musculocutaneous nerve continues directly from the lateral cord
- The posterior cord divides into the axillary nerve and radial nerve
- The medial and lateral cords both contribute the formation of the median nerve
What is the most lateral and what is the most medial of the named nerves in the brachial plexus ?
- Most lateral is the musculocutaneous nerve
- Most medial is the ulnar nerve
What does the musculocutaneous nerve innervate ?
- Coracobrachialis muscle
- Biceps brachii
- Brachialis muscle
Describe the route of the axillary and radial nerves and when they are vulnerable to injury due to there routes
- Both axillary and radial pass into the posterior compartment of the arm
- Axillary nerve lies superior to the radial
- Axillary nerve wraps around the surgical neck of the humerus - making it vulnerable in shoulder dislocations and fractures to the neck of the humerus
- Radial nerve wraps around the mid-shaft of the humerus - making it vulnerable to injury in mid-shaft fractures
What is the characteristic appearance of the median nerve ?
