Nerve pathways
Axillary
Origin : Posterior cord (C5–C6)
Course :
● Descends laterally posterior to axillary artery and anterior to
subscapularis
● Passes posteriorly at lower border of subscapularis together with
posterior circumflex humeral vessels via quadrangular space
● Divides:. Anterior branch winds around surgical neck of humerus and
supplies anterior deltoid. Posterior branch supplies teres minor and
posterior deltoid. Continues as upper lateral cutaneous nerve of the arm
after passing around deltoid
, Musculocutaneous nerve
Origin : Large terminal branch of
lateral cord (C5–C7)
Course :
● Descends from lower border of
pectoralis minor, lateral to axillary
artery
● Pierces coracobrachialis and
descends diagonally between biceps
and brachialis to lateral side of arm
● Pierces deep fascia of antecubital
fossa and continues as lateral
cutaneous nerve of the forearm
● Divides: anterior and posterior
branches
Ulnar nerve
Origin : Large terminal branch of the medial cord (C7,
C8, T1)
Course :
● Descends medial to brachial artery and anterior to triceps as far as the
insertion of coracobrachialis
● Penetrates medial intermuscular septum and enters posterior
compartment to continue descent anterior to medial head of triceps
● Passes posterior to medial epicondyle
● Enters anterior compartment between humeral and ulnar heads of
flexor carpi ulnaris
● Descends medially, anterior to flexor digitorum profundus and
posterior to flexor carpi ulnaris
● Pierces deep fascia lateral to flexor carpi ulnaris and proximal to flexor
retinaculum
Axillary
Origin : Posterior cord (C5–C6)
Course :
● Descends laterally posterior to axillary artery and anterior to
subscapularis
● Passes posteriorly at lower border of subscapularis together with
posterior circumflex humeral vessels via quadrangular space
● Divides:. Anterior branch winds around surgical neck of humerus and
supplies anterior deltoid. Posterior branch supplies teres minor and
posterior deltoid. Continues as upper lateral cutaneous nerve of the arm
after passing around deltoid
, Musculocutaneous nerve
Origin : Large terminal branch of
lateral cord (C5–C7)
Course :
● Descends from lower border of
pectoralis minor, lateral to axillary
artery
● Pierces coracobrachialis and
descends diagonally between biceps
and brachialis to lateral side of arm
● Pierces deep fascia of antecubital
fossa and continues as lateral
cutaneous nerve of the forearm
● Divides: anterior and posterior
branches
Ulnar nerve
Origin : Large terminal branch of the medial cord (C7,
C8, T1)
Course :
● Descends medial to brachial artery and anterior to triceps as far as the
insertion of coracobrachialis
● Penetrates medial intermuscular septum and enters posterior
compartment to continue descent anterior to medial head of triceps
● Passes posterior to medial epicondyle
● Enters anterior compartment between humeral and ulnar heads of
flexor carpi ulnaris
● Descends medially, anterior to flexor digitorum profundus and
posterior to flexor carpi ulnaris
● Pierces deep fascia lateral to flexor carpi ulnaris and proximal to flexor
retinaculum
