Plexus Organization
The brachial plexus arises from the ventral rami of these spinal nerve levels
What are C5, C6, C7, C8, and T1
C5 and C6 unite at the lateral border of the middle scalene to form this trunk
what is the superior (upper) trunk
From C5, it supplies the levator scapulae and the rhomboids and typically pierces the middle scalene
what is the dorsal scapular nerve
This nerve innervates the deltoid and teres minor
what is the axillary nerve
Damage to the long thoracic nerve produces this classic scapular deformity
what is a winged scapula
In order from proximal to distal, these are the five structural stages of the plexus
what are Roots-> Trunks-> Divisions-> Cords-> Branches
This root continues on its own as the middle trunk
what is C7
what is the long thoracic nerve
What is the thoracodorsal nerve
Axillary nerve injury at the surgical neck of the humerus causes greatly decreased abduction and this weakened motion
what is weakened external rotation
The plexus is made up of 5 roots, ______ trunks, 6 divisions, _____ cords, and 17 branches
what is 3 trunks and 3 cords
C8 and T1 unite behind the anterior scalene to form this trunk
From C5-C6, it runs through the suprascapular notch under the transverse scapular ligament to supply the supraspinatus and infraspinatus
This nerve supplies flexor carpi ulnaris, the ulnar half of FDP, and all the interossei
what is the ulnar nerve
A mid-shaft humerus fracture along the radial groove threatens this nerve, classically producing wrist drop
What is the radial nerve
The clavicle divides the plexus into these two named portions. What are the portions and what do they contain?
What are the Supraclavicular (trunks and divisions) and Infraclavicular (Cords and branches) portions?
The anterior divisions of the superior and middle trunks unite to form this cord
what is the lateral cord
What is the musculocutaneous nerve
Pronator teres, FCR, palmaris longus, FDS, and FPL and pronator quadratus are supplied by this nerve
What is the median nerve
Loss of the deep radial branch past the supinator spares wrist extension position but knocks out extension of these digits.
what are the fingers and thumb
The roots of the plexus emerge between these two muscles of the neck
What are the anterior and middle scalene muscles
The posterior divisions of all three trunks unite to form this cord; the anterior divisions of the inferior trunk continue as the other cord
what are the posterior cord and the medial cord
With fibers from C5-T1, it winds around the radial groove, supplies triceps and brachioradialis, and continues as the PIN
What is the radial nerve
The deep branch of the radial nerve beyond supinator, supplying EDC, ECU, and extensor indicis, and the thumb extensors, is this nerve
What is the posterior inerosseous nerve (PIN)
A compressed disc impairing the C5 root fully knocks out this nerve, while only weakening muscles with additional root supply.
What is the dorsal scapular nerve