Back to Your Roots
Which root levels contribute to each of the terminal branches?
Musculocutaneous C5, C6, C7
Median C5-T1
Ulnar C8-T1
Axillary C5,C6
Radial C5-T1
Compare the naming of the trunks vs cords of the BP.
trunks: superior, middle, inferior because they are stacked in that position within the neck
cords: lateral, posterior, medial because of their position relative to the axillary a.
Where does the subclavian turn into the axillary artery?
lateral border of 1st rib
What 1 nerve branches from the lateral cord and what does it innervate?
lateral pectoral nerve - pectoralis major m.
What terminal branches arise from the posterior cord?
axillary
radial
During what type of surgery is the long thoracic nerve commonly injured? What condition results?
axillary lymph node dissection
radical mastectomy
Winged scapula - difficulty raising UL above 90
Erb's palsy affects which part of the BP?
Klumpke's palsy?
superior trunk
inferior trunk
How many divisions of the BP are there?
6 total: 3 anterior divisions & 3 posterior divisions
3 posterior all come together to form the posterior cord
What 3 nerves branch directly from the posterior cord & what muscles do they innervate?
upper subscapular
thoracodorsal
lower subscapular
What are the motor and sensory territories of the Musculocutaneous nerve?
Motor: anterior arm compartment (coracobrachialis, brachialis, biceps brachii)
Sensory: lateral forearm
Intervertebral disc herniations at which levels would affect the axillary nerve?
axillary nerve receives contributions from c5, c6, so IV disc herniations at C4/C5, C5/C6 levels would affect axillary nerve
The suprascapular nerve branches from which part of the plexus? What does it innervate?
superior trunk
supraspinatus & infraspinatus mm.
What bone is located at approximately the divisions of the BP, separating the cervical and axillary regions?
clavicle
supraclavicular vs infraclavicular branches
What 3 nerves branch from the medial cord? What do they innervate?
Medial pectoral n. - pectoralis major & minor mm.
Medial cutaneous n of arm - sensation to medial arm
Medial cutaneous n of forearm - sensation to medial forearm
Name a location where the radial nerve is commonly injured. What motor & sensory deficits would result? What is the condition called?
1/3 to midshaft fx of the humerus
Motor: posterior forearm muscles (2 of 3 head of triceps are intact since they already received innervation)
Sensory: posterior forearm and dorsum of hand
Wrist drop
What nerve branches from C5 nerve root and innervates 3 muscles? What muscles?
Dorsal scapular n.
Rhomboid major & minor
levator scapulae
How would the patient present with an inferior trunk injury of the BP? (i.e. what deficits would they have?)
ulnar claw
loss of sensation to medial arm, medial forearm, and medial palm
1. Compare FDS and FDP.
2. Compare sensory territory of the hand.
FDS: flexes PIP of digits II-V & all tendons innervated by Median n.
FDP: flexes DIP of digits II-V & tendons of digits II&III are innervated by median n; tendons of digits IV&V are innervated by ulnar n.
Palmar hand: medial - ulnar n; lateral - median n.
Dorsal hand: medial - ulnar n; lateral - radial n.
Injury to the lateral cord would mostly affect which terminal branch?
musculocutaneous
Name a location where the axillary nerve is commonly injured. What motor & sensory deficits would result?
surgical neck humeral fx; quadrangular space
Motor: deltoid (abduction 15-90) & teres minor (lateral rotation)
Sensory: lateral shoulder skin; skin overlying deltoid; sargeants patches
Intervertebral disc herniations at which levels would affect the ulnar nerve?
Ulnar nerve receives contributions from C8 and T1, so IV disc herniations at C7/T1, and T1/T2 vertebral levels would affect ulnar nerve
Name the condition: Upper limb adducted & medially rotated, elbow extended, wrist flexed
Erb's Palsy
Describe what muscles would be affected by a median nerve injury at the elbow vs wrist.
Elbow: all median n. innervated forearm muscles + thenar LOAF
Wrist: thenar LOAF
Injury to the medial cord would result in what sensory and motor deficits?
Nerves most affected: medial pectoral, medial cut. n. of arm, medial cut. n. of forearm, ulnar
Name a location where the ulnar nerve is commonly injured. What motor & sensory deficits would result?
medial epicondyle fx of humerus; hamate fx (Guyon's canal); Klumpke's palsy also affects ulnar n.
Motor: hypothenar LOAF, PADs & DABs, adductor pollicis
Sensory: palmar aspect of digit 5 and half of digit 4; medial wrist