Axilla and Brachial Plexus Flashcards
What are the two main channels of superficial veins? How do they communicate?
- basilic vein (medial side)
- cephalic vein (lateral side)
communicate via medial cubital vein in front of elbow
What does the basilic vein penetrate and with what?
What does it continue as?
Deep (brachial) fascia at the mid arm with the medial antebrachial cutaneous nerve
Continues as axillary vein
Pectoralis Major: N and A?
N: lateral (main) and medial pectoral nerve
A: flex, adduct, medially rotate humerus
Pectoralis minor: N and A?
N. Medial (main) and lateral pectoral nerves
A. Draws the scapula downward and forward, stabilizes it
remember: doesn’t attach to humerus!
- The ____ is a thickening of the ____ extending from the clavicle to the axillary fascia in the floor of the axilla
- It encloses …
- It forms …
- which is pierced by ___
- clavipectoral fascia; deep fascia
- subclavius and pectoralis minor
- costocoracoid membrane separating two muscles
- cephalic vein; lat. pectoral nerve; thoracoacromial artery
The costocoracoid membrane can be approaced from the ______ which is bounded by ____.
deltopectoral triangle
1) Clavicle
2) Deltoid muscle
3) Pectoralis major muscle
Subclavius: N and A?
N. Nerve to the subclavius
A. Depresses the lateral end of the clavicle, pulls the shoulder anteriorly, stabilizes the clavicle
what are the boundaries of the axilla?
- Anterior wall: Pectoralis major and minor muscles
- Posterior wall: Subscapularis, teres major, and latissimus dorsi muscles
- Medial wall: Ribs 1- 5, intercostal muscles, serratus anterior
- Lateral wall: Intertubercular (bicipital) groove of the humerus
What forms the axillary folds?
Lateral border of the pectoralis major forms the anterior axillary fold
The teres major and latissimus dorsi muscles form the posterior axillary fold
What are the apex and base of the scapula formed of?
- Apex formed by the convergence of three bones in its three major walls:
Clavicle - anterior
Scapula - posterior
First rib – medial
- Base - fascia and skin of the armpit
- What is in the axillary sheath?
- What is the axillary sheath formed by?
- Axillary artery and vein
Brachial plexus
axillary lymph nodes
- prevetebral fascia
Draw the brachial plexus.
Describe the divisons of each trunk of the brachial plexus.
Anterior = flexor
posterior = extensor
what contributes to the trunks of the brachial plexus?
a. Superior- C5 and C6
b. Middle - C7
c. Inferior C8 and TI
What contributes to the cords of the brachial plexus?
a. Posterior cord - all three posterior divisions of the three trunks
b. Lateral cord - anterior divisions of the superior and middle trunks
c. Medial cord - anterior division of the inferior trunk
What are the supraclavicular branches of the brachial plexus?
Roots:
1) Dorsal scapular nerve (C5) - rhomboids and levator scapulae muscle
2) Long thoracic nerve (C5, C6, and C7) - serratus anterior muscle
Upper trunk:
1) Nerve to the subclavius (C5 and C6) - subclavius muscle
2) Suprascapular nerve (C5 and C6) - supraspinatous and infraspinatous muscles
What are the infraclavicular branches of the brachial plexus
Lateral cord:
1) Lateral pectoral nerve- pectoralis major and minor muscles
2) Musculocutaneous nerve - muscles of the anterior arm compartment
(Ends as the lateral antebrachial cutaneous nerve)
3) Lateral root of the median nerve
Medial cord:
1) Medial pectoral nerve - Pectoralis major and minor muscles
2) Medial brachial cutaneous nerve
3) Medial antebrachial cutaneous nerve
4) Ulnar nerve
5) Medial root of the median nerve
Posterior cord:
1) Upper subscapular nerve - subscapularis muscle
2) Thoracodorsal nerve - latissimus dorsi muscle
3) Lower subscapular nerve - subscapularis muscle and teres major muscle
4) Axillary nerve - teres minor and deltoid muscles
(Ends as upper lateral brachial cutaneous nerve)
5) Radial nerve - Great extensor nerve of the upper limb
Describe Erb-Duchenne Palsy.
excessive increase in the angle between the neck and shoulder; C5 and C6
may involve (1) suprascapular (2) nerve to subclavius (3) musculocutaneous (4) axillary
Result: The upper limb hangs limply by the side, medially rotated by the unapposed action of the pectoralis major muscle. The forearm is pronated due to loss of action of the biceps (supination of the forearm). Loss of sensation along the lateral side of the limb.
“waiter’s tip position”
Describe Klumpke’s Palsy.
excessive abduction of the arm.; C8 and T1
ulnar nerve
Result: The hand has a clawed appearance caused by hyperextension of the knuckle joints and flexion of the interphalangeal joints. The extensor digitorum is unopposed by the lumbricals and interossei and extends the metacarpophalangeal joints. The flexor digitorum superficialis and lateral portion of the flexor digitorum profundus are unopposed by the lumbricals and interossei and flex the middle and terminal phalanges respectively. In addition, loss of sensation will occur along the medial side of the arm of the upper limb.
Describe lesion of the long thoracic nerve.
paralysis of serratus anterior muscle
Result: winging of scapula when pushing against a fixed object, weakening of trapezius (scapula can’t be fixed), impairment of abduction
Describe Thoracic outlet syndrome (TOS)
- Thoracic outlet syndrome is a condition involving compression of brachial plexus nerves, subclavian vessels, or both, because of an inadequate passageway just above the first rib and behind the clavicle.
- Symptoms include neck, shoulder, and arm pain, numbness, or impaired circulation to the extremities.
What are the three passageways in which TOS can occur?
Interscalene triangle (most important):
• Anterior scalene (anterior)
• Middle scalene (posterior)
• Medial border of first rib (Inferior)
costoclavicular triangle:
• Middle third of clavicle (anterior)
• First rib (postero-medial)
• Upper border of scapula (postero-lateral)
Subcoracoid space:
• Beneath the coracoid process just deep to the pectoralis minor muscle
- What are the borders of the axillary artery?
- What defines the three parts?
- subclavian a. / lateral border of the first rib / axillary a. / inferior border of the teres major muscle / brachial a.
- pectoralis minor muscle
what forms the M of the brachial plexus?
musculocutaneous; medial; ulnar
what are the branches of the axillary artery?
- The ______ vein is a contiuation of the ___ vein starting at ___.
- What are tributaries of it?
- axillary vein; basilic vein as it crosses the lower border of the teres major.
- Tributaries of the axillary vein:
a. Venae comitantes of the brachial artery
b. Cephalic vein
c. Tributaries corresponding to the branches of the axillary artery
What muscles connect the upper limb to the vertebral column?
- trapezius
- latissimus dorsi
- levator scapulae
- rhomboid
Trapezius: N and A?
N. Accessory nerve (CN XI)
A. Upper fibers - elevate the scapula
Middle fibers - retract the scapula
Lower fibers - depress the scapula
Superior + Inferior - upward rotation of the scapula (necessary for abduction)
Latissimus Dorsi: N and A?
N. Thoracodorsal nerve
A. Extends, adducts, and medially rotates the humerus
Levator Scapulae: N and A?
N. Dorsal scapular nerve and ventral rami C3, C4
A. Elevates the scapula, tilts the glenoid cavity downward, helps retract the scapula
Rhomboid muscles: N and A?
N. Dorsal scapular nerve
A. Retract the scapula, rotate the scapula inferiorly
What muscles connect the upper limb to the thoracic wall?
- serratus anterior
- pectoralis major
- pectoralis minor
- subclavius
Serratus anterior: N and A?
N. Long thoracic nerve
A. Protracts the scapula, fixes the scapula, rotates the glenoid cavity upward
What are the interinsic shoulder muscles (aka. scapular muscles)?
- Deltoid
- Supraspinous
- Infraspinous
- Teres Minor
- Teres Major
- Subscapularis
Deltoid: N and A?
N. Axillary nerve
A. Anterior fibers - Flex and medially rotate the humerus
Middle fibers - Abduct the humerus
Posterior fibers - Extend and laterally rotate the humerus
Supraspinous: N and A?
N. Suprascapular nerve
A. Abducts the humerus
Infraspinous: N and A?
N. Suprascapular nerve
A. Laterally rotates the humerus
Teres major: N and A?
N. Lower subscapular nerve
A. Extends, adducts, and medially rotates the humerus
Teres minor: N and A?
N. Axillary nerve
A. Laterally rotates the humerus
Subscapularis: N and A?
N. Upper and lower subscapular nerves
A. Medially rotates the humerus
What are the three important regions of the axilla?
- quadrangular space
- traingular space
- triangular interval
Quadrangular space: borders and contents? What can damage this?
- Borders:
a. Superior - Teres minor
b. Inferior - Teres major
c. Medial - Long head of the triceps brachii
d. Lateral Surgical neck of the humerus
- Contents:
a. Axillary nerve
b. Posterior circumflex humeral artery
posterior dislocation of humerus can damage this
Triangular space: borders and contents?
- Borders:
a. Teres minor
b. Teres major
c. Long head of triceps brachii
- Contents - Circumflex scapular vessels (or their branches)
Triangular interval: Borders and contents? What can damage it?
- Borders:
a. Teres major
b. Long head of the triceps brachii
c. Shaft of the humerus
- Contents:
a. Radial nerve
b. Profunda brachii artery
most frequent fracture location of humerus can damage
