Upper Limb: Brachial Plexus and Axillary Artery Flashcards
Axilla
- pyramidal space inferior to glenohumeral joint aka shoulder joint (when adducted, the space isn’t noticeable)
- passageway for neurovascular and muscular structures to enter and leave the upper limb)

What are the boundaries of the Axilla? (this provides context to what space looks like but won’t be tested)
- apex (1st rib and clavicle)
- Base (skin and subcutaneous tissue)
- Anterior (pectoralis major and minor)
- Posterior (scapula and subscapularis)
- Medial (Thoracic wall and serratus anterior)
- Lateral (Humerus)
What are the contents of the Axilla?
- Axillary artery and its branches
- Axillary vein and tributaries (vessel that empties into the main vessel kinda like a river)
- Axillary lymph nodes (drain upper limp and chest wall/boobies)
- Brachial plexus
What does the overall 3D shape of the axilla look like?
a pyramid. It consists of four sides, an open apex and base.
What is the Brachial Plexus
Major nerve network supplying the upper limb
What is the Brachial Plexus formed by?
Union of C5-C8 and T1 nerve roots
What are the 5 anterior rami roots of the brachial plexus?
C5 - T1
What are the 3 trunks of the brachial plexus?
superior, middle, and inferior
Toward the _____ root of the neck of the brachial plexus, the roots unite to form trunks
inferior
where do the trunks of the brachial plexus pass through?
anterior and middle scalene muscles
What are the components of the Brachial Plexus?
- Roots (C5- C8 and then T1)
- Trunks (Upper, Middle and Lower)
- Divisions (Anterior and Posterior)
- Cords (Posterior, Medial and Lateral) 5. Branches (5 total)
What are the branches from the roots of the Brachial Plexus?
- Dorsal scapular nerve (C5) - Rhomboids and levator scapulae
- Long thoracic nerve (C5 -C7) - Serratus anterior
- un-named muscular branches to deep cervical muscles

What do the roots combine to form?
3 Trunks
What are the 3 trunks of the Brachial Plexus?
- Superior (upper) trunk: C5 and C6
- Middle trunk: C7
- Inferior (lower) trunk: C8 and T1

What are the Branches of the Trunks of the Brachial Plexus?
- Suprascapular (C5 - C6)
- supr - and infraspinatus muscles - Nerve to subclavius (C5 and C6)
- Subclavius muscle

What does each trunk divide into?
An anterior and posterior division
What do the anterior divisions of the trunk supply?
supply the anterior (flexor) compartment
What do the posterior divisions of the trunk supply?
supply the posterior (extensor) compartment
Anterior divisions of the upper and middle trunks unite to form the ________________
lateral cord
Anterior division of the lower trunk continues as the _________________
medial cord
Posterior divisions of all three trunks unite to form the __________
posterior cord
Look at structure

Cords are named in relation to their position to what structure?
Axillary Artery
What are the branches from the posterior cord?
–Upper subscapular nerve-motor to subscapularis
–Lower subscapular nerve-motor to subscapularis and teres major
–Thoracodorsal nerve-motor to latissimus dorsi
What are the branches from the Medial cord?
–Medial cutaneous nerve of the arm-sensory to medial arm
–Medial cutaneous nerve of the forearm-sensory to medial forearm
–Medial pectoral nerve-motor to pec major and minor
What are the branches from the Lateral cord?
–Lateral pectoral nerve-motor to pec major
What is the role of the 5 terminal braches of the brachial plexus?
provide motor and sensory distribution to the upper limb
- Median nerve (M) - main trajectory are the muscles of the flexor compartment of forearm and part of the hands
- Muscultaneous - Later aspect of the M, supplying the flexor muscles of the arm
- Axillary nerve - comes off posterior curve and supplies deltoid and teres minor muscles
- Ulnar nerve - supplies some muscles in the flexor compartment of the nerve
- Radial nerve - comes off of posterior cord and takes care of extensor compartment of arm and forearm

What does the supra-infraclavivular parts of the Brachial Plexus include?
–Roots, trunks and divisions of the brachial plexus
–Dorsal scapular, long thoracic nerve, nerve to subclavius and suprascapular nerve
What does the »Infraclavicular parts of the Brachial Plexus include?
–Cords and terminal branches of the brachial plexus
–Lateral cord: 1 branch; Medial and Posterior Cords: 3 branches each
–5 terminal branches (ulnar, median, radial, musculocutaneous, axillary)
What are common locations of injury for the axillary nerve?
Surgical neck of humerus
What are common locations of injury for the radial nerve?
spiral fracture along the distal third of humerus
improper use of crutches
Whats a common location of injury for the ulnar nerve?
Medial epicondyle, hitting the funny bone
_________ is a network of nerve fibers that supplies the skin and musculature of the upper limb
brachial plexus
The roots of the brachial plexus converge to form three trunks. What trunk is the combination of C8 and T1 roots?
inferior trunk
The lateral cord of the brachial plexus is formed by:
anterior division of the superior and middle trunks
Which of the following muscles does the axillary nerve innervate?
deltoid
What is the axillary artery a continuation of?
subclavian artery (once it reaches its first rib, it becomes axillary artery
Where is the 1st part of the axillary artery located?
Located between the lateral border of the 1st rib and the medial border of pec minor
The axillary artery can be classified by its position relative to which muscle?
pectoralis minor
The second part of main branches of the axillary artery includes:
thoracoacromial trunk and lateral thoracic artery
The ___________ or shoulder blade is the bone that connects the clavicle to the humerus. The scapula forms the posterior aspect of the shoulder girdle.
scapula
The _______ is the shallow depression of the scapula found on the lateral angle.
glenoid fossa

The _________is a small projection of the scapula that extends anteriorly from the spine of the scapula.
acromiom

The ______ originates from the superolateral surface of the costal scapula. It is a hook-like projection, which lies just underneath the clavicle.
coracoid process.
The costal surface contains a large concave depression over most of its surface called _____________.
subscapular fossa
What does the proximal aspect of the humerus articulate with to form the glenohumeral joint?
glenoid fossa of the scapula
The __________is located laterally on the humerus and has anterior and posterior surfaces.
greater tubercle
The ________is a shallow depression that runs diagonally down the posterior surface of the humerus, parallel to the deltoid tuberosity.
radial groove
What innervates the supraspinatous and infraspinatous
Suprascapular nerve
The _____________ are a group of four muscles that originate from the scapula and attach to the humeral head.
rotator cuff muscles
teres minor + infraspinatus =
lateral rotation
What does the infraspinatous do to the humerus?
abducts
What are the 3 heads of the triceps?
- lateral head
- medial head
- long head
Which space has the following anatomic borders; the teres minor the teres major muscle, the long head of the triceps brachii muscle, and the humeral surgical neck.
quadrangular space
The posterior humeral circumflex artery is a vessel arising from the axillary artery at the ________ part of the arm.
proximal
The _________ is a depression in the lateral part of the superior border of the scapula, which runs medial to the coracoid process
suprascapular notch
The suprascapular nerve travels_______ the suprascapular ligament
under
The axillary sheath contains the brachial plexus nerves and the _________.
axillary artery
The _________ is a network of nerve fibers that supplies the skin and musculature of the upper limb. It begins in the root of the neck, passes through the axilla, and runs through the entire upper extremity.
brachial plexus
T or F?
Once the anterior and posterior divisions have entered the axilla, they combine together to form three cords, named by their position relative to the axillary artery.
True
What are the terminal braches of the Brachial Plexus?
- Musculocutaneous Nerve
- Axillary Nerve
- Median Nerve
- Radial Nerve
- Ulnar Nerve
The radial and axillary nerves arise from the ________ of the brachial plexus
posterior cord