Axilla and Arm Flashcards
What are the contents of the axilla?
Axillary artery, axillary vein and distal portion of the brachial plexus (all contained in the axillary sheath)
What are the boundaries of the axilla?
Anterior axillary fold- formed by pectoralis major
posterior axillary fold- formed by latissimus dorsi and teres major
*mid axillary line starts at the midpoint of the axilla and runs all the way down the torso
What are the main branches of the axillary artery
Part 1- superior thoracic a.
Part 2- Thoracoacromial a.
Lateral thoracic a.
Part 3- Subscapular a.
Anterior circumflex
humeral a.
Posterior circumflex
humeral a.
What artery runs with the long thoracic nerve?
lateral thoracic artery
What are the branches of the subscapular a?
circumflex scapular a.
thoracodorsal a.
What does the superior thoracic artery supply?
1st and 2nd intercostal spaces
What does the thoracoacromial a. supply?
pectoral muscles and deltoid
What does the lateral thoracic artery supply?
serratus anterior and pectoral muscles
What does circumflex scapular artery supply?
(branch off subscapular artery)
supplies scapular region
What does the thoracodorsal a. supply?
latissimus dorsi
What does the anterior circumflex a. supply?
shoulder and arm
anastomoses with posterior
What does the posterior circumflex a. supply?
shoulder and arm, anastomoses with anterior
What passes through the quadrangular space?
posterior circumflex humeral a. and axillary nerve.
What are the borders of the quadrangular space?
teres minor
teres major
humerus
long head of triceps
How can our body maintain blood flow to UE if axillary a. becomes occluded?
through the multiple anastomoses present around the shoulder
What are the major tributaries of the axillary vein?
cephalic vein
basilic vein
brachial veins
What is the brachial plexus?
network of nerves in the neck and axilla that gives rise to the nerves of the UE (including pectoral region)
ventral rami (C5-T1)
What are the roots of the brachial plexus? Where are they located?
Ventral rami of C5, C6, C7, C8 and T1
located in the neck
What are the trunks of the brachial plexus? Where are they located?
Superior (C5-C6)
Middle (C7)
Inferior (C8 and T1)
located in the neck
What are the division of the brachial plexus? Where are they located?
each trunk gives rise to a posterior and an anterior division
located deep to clavicle
What do the anterior divisions give rise to?
nerves of the anterior arm and forearm and palmar hand
What do the posterior divisions give rise to?
nerves of the posterior arm/forearm and dorsal hand
What are the cords of the brachial plexus?
Named for position relative to axillary artery
Lateral: formed by anterior divisions of superior and middle trunk (C5-C7)
Posterior: formed by posterior divisions of all trunks (C5-T1)
Medial: formed by anterior division of inferior trunk (C8-T1)
Where are the cords of the brachial plexus located?
distal to the clavicle
What are the 2 branches of the roots?
dorsal scapular nerve
long thoracic nerve
What does the dorsal scapular nerve innervate?
motor to levator scapulae and rhomboids
Where does dorsal scapular nerve travel?
with dorsal scapular a., medial to the medial border of the scapula
What does the long thoracic nerve innervate?
motor to serratus anterior
Where does long thoracic nerve travel?
with the lateral thoracic artery along the mid axillary line on the superficial surface of serratus anterior
What would a lesion of the long thoracic nerve result in?
winged scapula
What is the suprascapular nerve a branch off of?
the superior trunk
What does the suprascapular nerve innervate?
(C5-C6)
motor to supraspinatous and and infraspinatous
How does the suprascapular nerve travel?
with the suprascapular artery
“army over navy”
What does the musculocutaneous nerve innervate?
motor to the anterior compartment of the arm
sensory near the elbow, terminates as the lateral cutaneous nerve of the forearm
What does the median nerve innervate?
motor to most of the muscles of the anterior compartment of the forearm and some intrinsic hand muscles
sensory skin on part of the hand
carpal tunnel syndrome
involves compression of the median nerve as it passes deep to the flexor retinaculum at the wrist
What does the lateral pectoral nerve innervate?
motor to pectoralis major
What does the ulnar nerve innervate?
motor to 1.5 muscles of the anterior forearm and most intrinsic hand muscles
sensory to skin of part of the hand
Where can the ulnar nerve be compressed?
as it crosses the elbow joint as it is very superficial here
What does the medial pectoral nerve innervate?
pectoralis major and pectoralis minor
What does the medial cutaneous nerve of the arm innervate?
sensory innervation to skin of the medial arm
What does the medial antebrachial cutaneous nerve of the arm innervate?
sensory to skin of the anterior arm and medial forearm
Where does the axillary nerve travel?
travels through the quadrangular space with the posterior circumflex humeral artery and vein
What does the axillary nerve innervate?
motor to deltoid and teres minor
sensory to skin on lateral shoulder
Where does the radial nerve travel?
courses in the radial groove with the deep artery and vein of the arm
What does the radial nerve innervate?
Motor to all muscles of the posterior compartments of arm and forearm
sensory to skin of the posterior arm, forearm and hand
How can the axillary nerve be damaged?
with fracture of the surgical neck of the humerus
How can the radial nerve be damaged?
with mid shaft fracture of the humerus
What does the upper subscapular nerve innervate?
motor to superior portion of subscapularis
What does thoracodorsal nerve innervate?
motor to latissimus dorsi
What does the lower subscapular nerve innervate
motor to inferior portion of subscapularis and teres major
What do the C5-C6 brachial plexus roots generally innervate?
the muscles around the shoulder/arm
What do the C7-C8 brachial plexus roots generally innervate?
muscles in the hand
What is erb’s palsy? What causes this?
affects shoulder muscles and anterior arm muscles and C5-C6 dermatomes
UE presents in “waiter’s tip” position with adducted and medially rotated GHJ
caused by damage to C5-C6
What is Klumpke’s palsy? What causes this?
affects intrinsic hand muscles, resulting in full claw hand and affecting C8-T1 dermatomes
caused by damage to C8-T1
What is the innervation rule for the anterior arm?
musculocutaneous (C5-C7)
What are the action rules of the anterior arm
flex glenohumeral or elbow joint
supinate forearm
What are the muscles of the anterior compartment of the arm?
coracobrachialis
biceps brachii
brachialis
Attachments of coracobrachialis
origin: coracoid process of scapula
insertion: mid shaft of humerus
Action of coracobrachialis
flex GHJ
Attachments of biceps brachii
origin: SH- coracoid process
LH- supraglenoid
tubercle
insertion:
radial tuberosity and bicipital aponeurosis
Actions of biceps brachii?
flex elbow, supinate forearm
weakly flex GHJ
What does the biceps reflex test assess?
the musculocutaneous nerve and the C5-C6 spinal segments
Attachments of brachialis
origin: distal humerus
insertion: ulnar tuberosity
Action of brachialis
flex elbow joint
What is the innervation rule for the posterior compartment of the arm?
radial nerve (C6-8)
What is the action rule for the posterior compartment of the arm
extend elbow joint, extend glenohumeral joint
What is the muscle of the posterior compartment of the arm?
triceps brachii- long head, lateral head and medial head
Origin of triceps brachii?
Long head: infraglenoid tubercle of the scapula
Lateral head/Medial head: posterior humerus
insertion of triceps brachii
olecranon process of ulna
Actions of triceps brachii?
extend elbow
extend GHJ (long head only)
What does the triceps reflex test assess?
radial nerve and the C7-C8 spinal segments
anconeus
small muscle posterior to elbow joint, stabilizes elbow
Where does the axillary artery become the brachial artery?
at the inferior border of teres major
What supplies blood to the arm?
the brachial artery, this is where BP is usually measured
How could you control hemorrhage of the distal UE?
by mid arm compression of the brachial artery
What branches does the brachial artery give rise to?
- deep artery of the arm ( in radial groove with radial nerve)
- ulnar collateral arteries (anastomose around elbow)
