Nerves and Vasculature of the upper extremity Flashcards
Dorsal scapular nerve
- This nerve will emerge very early from the brachial plexus, from the C5 root
- it is the first branch off of the plexus
- you will be able to see it running posteriorly to the rhomboids and levator scapulae.
Suprascapular nerve
- This nerve will run posteriorly from the brachial plexus towards the scapula.
- this branches off the superior trunk of the brachial plexus
- It runs through the suprascapular notch inferior to a ligament forming a bridge across the notch (called the transverse scapular ligament) to reach the supraspinatus and then through the spine of the scapula to reach the infraspinatus.
Lateral pectoral nerve
This nerve runs from the lateral cord of the brachial plexus to the pectoralis major.
Medial pectoral nerve
This nerve is usually the first branch from the medial cord, and it runs through the pectoralis minor, innervating it on its path to the pectoralis major.
Medial brachial and medial antebrachial cutaneous nerves
These nerves will branch distal to the medial pectoral nerve off of the medial cord. They run to the skin of the medial arm and forearm.
Long thoracic nerve
- this branches off the C5 root of the brachial plexis
This nerve runs tight to the thoracic wall, innervating the serratus anterior muscle.
This is also visible running with the serratus anterior on the superficial dissection
Thoracodorsal nerve
This nerve can be seen branching off the posterior cord and running to the latissimus dorsi muscle.
Upper subscapular and lower subscapular nerves:
These nerves branch from the posterior cord, with the upper branching proximal to the thoracodorsal nerve and the lower branching distal to the thoracodorsal nerve, in most cases.
They run posteriorly to the subscapularis and teres major (lower only) muscles
Axillary nerve
- this is a terminal branch of the brachial plexus
- This nerve branches from the posterior cord and runs posterolaterally.
It travels with the posterior circumflex humeral artery through a space between the surgical neck of the humerus
- innervates teres minor and the deltoid
Radial nerve
This nerve branches from the posterior cord and runs to the posterior side of the arm. It is larger than the axillary nerve.
- this is a terminal branch
- this innervates the deep and superficial muscles of the forearm as well as the triceps brachii and the brachioradialis
Ulnar nerve
The ulnar is the most medial terminal branch of the brachial plexus, branching from the medial cord.
It continues along the medial side of the arm and passes around the medial epicondyle of the humerus on its path to the forearm.
This nerve is responsible for our “funny bone.”
- innervates the flexi carpi ulnaris
- It also innervates most muscles in the hand, except the thenar eminence muscles and lateral two lumbricals.
You can also see it enter the hand and send branches to the skin of the 5th digit and lateral aspect of the 4th digit.
Median nerve
- this is a terminal branch
- this is the the middle nerve formed from the “M” of the brachial plexus, as it receives contributions from both the medial and lateral cords.
It travels through the anterior arm and forearm and innervates most of the muscles of the anterior arm
- it enters the hand and supply the skin of the lateral half of the 4th digit and digits 1-3, the muscles of the thenar eminence, and lateral two lumbricals.
Musculocutaneous nerve
- this is the terminal branch off of the lateral cord
The musculocutaneous nerve pierces (and supplies) the coracobrachialis muscle in the arm and then runs between the biceps brachii and brachialis muscles.
It emerges on the lateral aspect of the arm as the lateral antebrachial cutaneous nerve.
Subclavian artery
This is the primary artery providing the arm with blood.
- this has the suprascapular artery branching off of it
- this turns into the axillary artery
Axillary artery:
This artery is continuous with the subclavian artery from the lateral border of the first rib to the inferior border of the teres major muscle.
this artery has three sections that it can be divided into to divide up where the branches come from
There are several branches off of the axillary artery. - Suprascapular artery - Superior thoracic artery - Lateral thoracic artery - Thoracoacromial trunk - Posterior and anterior circumflex humeral arteries - Subscapular artery Thoracodorsal artery Circumflex scapular artery
Suprascapular artery
You can observe this in the deep dissection running over the transverse scapular ligament of the suprascapular notch and traveling to the supraspinatus.
This artery runs posteriorly with the suprascapular nerve to supply the supraspinatus and infraspinatus.
- this is a branch off of the subclavian artery
Superior thoracic artery:
This is the only branch off of the first part of the axillary artery. It will run inferiorly to the superior thoracic wall.
Lateral thoracic artery
This artery branches from the second part of the axillary artery and runs with the long thoracic nerve along the lateral thoracic wall to supply the lateral wall and the serratus anterior.
Don’t confuse the lateral thoracic artery and long thoracic nerve!
Thoracoacromial trunk:
This is a short trunk off of the superior side of the second part of the axillary artery.
It branches almost immediately into four parts that supply the acromion, deltoid, pectoral muscles, and clavicle
Posterior and anterior circumflex humeral arteries
These arteries branch from the third part of the axillary artery.
They wrap around the surgical neck of the humerus and anastomose (join) with each other to provide circulation to this region via multiple routes.
They sometimes branch from a common trunk, or they can branch separately from the axillary artery.
- the posterior circumflex humeral artery runs posteriorly around the humerus with the axillary nerve, while the anterior circumflex humeral artery runs anteriorly around the humerus.
Subscapular artery
The subscapular artery is a short branch off the third part of the axillary artery.
- but it is the largest branch
As it runs inferiorly, it gives off two branches. You can also observe these on the plastinated tissue.
gives off the circumflex artery and the thoracodorsal artery
Circumflex scapular artery
This runs posteriorly around the lateral scapula.
- a branch of the subscapular artery
Thoracodorsal artery:
This artery runs with the thoracodorsal nerve to the latissimus dorsi muscle.
- a branch of the subscapular artery
Brachial artery
This artery is continuous with the axillary artery at the inferior border of the teres major. It continues through the brachium to supply muscles of the anterior arm.
Deep brachial artery:
This is the only branch of the brachial artery you are responsible for in this unit.
It branches from the brachial artery in the mid-arm region and runs posteriorly.
Ulnar and radial arteries:
The brachial artery divides into the radial and ulnar arteries in the cubital fossa.
They run on the side of the antebrachium (forearm) of the bone with the same name.
Superficial and deep palmar arches
These are formed from the ulnar and radial arteries.
Digital arteries
These branch form the superficial and deep palmar arches and travel to the sides of each digit.
cephalic vein
runs on the lateral aspect of the forearm and arm
- this drains into the axillary vein
- a superficial vein that originates on the forearm
basilic vein
runs on the medial aspect of the forearm and arm.
- this merges with the brachial to form the axillary vein
median cubital vein
- joins the basilic and cephalic veins in the cubital fossa.
The median cubital vein is a common site for blood draws.
where does the blood go from the radial and ulnar veins
- the blood drains into the brachial vein
- this then joins the basilic vein to become the axillary vein
- the axillary vein becomes the subclavian vein at the border of the first rib
brachial vein
this drains the blood from the muscles of the arm
- joins the basilic vein to become the axillary vein
axillary vein
this drains the brachial and basilic vein
subclavian vein
a paired large vein, one on either side of the body, that is responsible for draining blood from the upper extremities, allowing this blood to return to the heart.
1st part of the axillary artery
- this branches into the superior thoracic artery
- this section is proximal to the pectoralis minor
2nd part of the axillary artery
- this has two branches
- thoracoacromial trunk
- lateral thoracic artery
- this is the portion that is under the pectoralis minor
3rd part of the axillary artery
- this has three branches
- subscapular artery
- anterior circumflex humeral artery
- posterior circumflex humeral artery
