Npte - Msk - Brachial Plexus, Motor

Front 1

Musculocutaneous Nerve

• Roots, trunks, cord
• Innervation
• Loss

Back 1

• C5-C7, uperior and middle trunks, lateral cord
• Biceps brachii, brachialis, coracobrachialis
• Weak sh. flex. (pec major, delt), weak elbow flex. (brachioradialis), very weak supination (supinator)

Front 2

Axillary Nerve

• Roots, trunks, cord
• Innervation

Back 2

• C5-C6, superior trunk, posterior cord
• Teres minor, deltoid

Front 3

Axillary Nerve

• Lesion location
• Loss

Back 3

• Quadrangular space (Teres minor, teres major, long head of triceps, surgical neck of humerus); Surgical neck of humerus fx; Inferior GHJ dislocation; Poorly fitting crutches
• Paralyzed abduction, delt atrophy

Front 4

Median Nerve

• Roots, trunks, cord
• Innervation

Back 4

• C5-T1, superior, middle, and inferior trunks, medial and lateral cords
• Ant. forearm (except FCU and part of FDP), thenar muscles, lateral lumbricals

Front 5

Median Nerve

• Entrapment/Lesion locations
  

Back 5

• Supracondylar fx at the elbow
• Compression b/w pronator teres bellies (pronator teres syndrome)
• Compression b/w FDS/FDP 2º repeated gripping or medial epicondylitis
• Carpal tunnel (CTS)

Front 6

Median Nerve

• Loss
  

Back 6

• Forearm constantly supinated
• Weak wrist flexion always coupled with ulnar deviation
• Total loss of D2/D3 IP flexion (FDS/FDP loss), weak PIP flexion at D4/D5 (FDS loss)
• Thenar atrophy
• "Make a fist" elicits lack of flexion of D1-D3 (ape deformity)

Front 7

Radial Nerve

• Roots, Trunks, Cords
• Innervation

Back 7

• C5-T1; superior, middle, inferior trunks; posterior cord

• Triceps, posterior forearm (deep branch, which pierces supinator, terminating as post. interosseus n.)

Front 8

Radial Nerve

• Entrapment/Lesion locations

Back 8

• Axilla with poorly-fitting crutches
• Radial groove with humerus fx
• Lateral intermuscular septum as it courses posterior to anterior compartment of arm (radial tunnel syndrome)
• Traction injury of deep branch (motor) from radial head dislocation
  
• Arcade of Frohse with throwing (posterior interosseus n., aka supinator syndrome)

Front 9

Radial Nerve

• Loss

Back 9

• Tricep loss (axilla damage)
• Tricep weakness (2/3 innervation proximal to radial groove)
• Wrist-drop (axilla, radial groove, lateral intermuscular septum)
• Post forearm weakness (radial head dislocation and supinator syndrome do not affect ECRL)

Front 10

Ulnar Nerve

• Roots, trunks, cords
• Innervation

Back 10

• C8 and T1, inferior trunk, medial cord
• Flex. carpi ulnaris, half of flexor carpi profundus, med. 2 lumbricals, hand intrinsics

Front 11

Ulnar Nerve

• Entrapment/Lesion locations

Back 11

• Cubital tunnel (Direct trauma or DJD)
• Medial elbow (traction injury caused by UCL laxity)
• Compression 2º thickened retinaculum or hypertrophied FCU

Front 12

Ulnar Nerve

• Loss
  

Back 12

• Weak wrist flexion always coupled with radial dev. (FCU loss)
• Loss of finger abd./add. (interossei loss, leads to observable dorsal hollowing)
  
• Loss of D4/D5 DIP flexion, D1 adduction (adductor policis loss)
• Hypothenar atrophy
• Ulnar claw (lat. lumbrical loss)

Front 13

Dorsal Scapular Nerve

• Course
• Innervation
• Lesion locations
• Loss

Back 13

• Branches from C5 root, pierces middle scalene, runs posteriorly
• Rhomboids, levator scap
  
• Rare; with middle scalene injury
• Unopposed protraction

Front 14

Long Thoracic Nerve

• Course
• Innervation
• Lesion locations
• Loss

Back 14

• C5-C7, C5 and C6 piece middle scalene, then join C7
  
• Serratus anterior
• Susceptible to trauma with blow to posterior triangle of neck or ribs (with arm outstretched), radical mastectomies
• Scapular winging

Front 15

Suprascapular Nerve

• Course
• Innervation
• Lesion locations
• Loss

Back 15

• C5-C6, upper trunk, branches off posteriorly along the superior border of the scap through the suprascapular notch
• Supraspinatus, infraspinatus
• Suprascapular notch
• Atrophy of supra/infra, GHJ instability, weak abd/ER
  

Front 16

Lateral Pectoral Nerve

• Course
• Innervation
• Of note

Back 16

• C5-C7, superior and middle trunks, lateral cord, then sends a branch to meet with the medial pectoral nerve, forming the ansa pectoralis. The main branch passes inferiorly, piercing the claviculopectoral fascia
• Pec major
• Anesthetized for breast augmentation/mastectomy

Front 17

Medial Pectoral Nerve

• Course
• Innervation

Back 17

• C8-T1, inferior trunk, medial cord, then unites with branch of lat. pec n. forming the ansa pectoralis. It then traverses superficially, hitting pec minor and then the sternocostal head of pec major
  
• Pec minor and upper pec major

Front 18

Superior Subscapular Nerve

• Course
• Innervation

Back 18

• C5, C6, upper trunk, posterior cord
  
• Upper portion of subscap

Front 19

Thoracadorsal Nerve

• Course
• Innervation

Back 19

• C6, C7, C8, sup./mid./inferior trunks, posterior cord, then traverses inferomedially along posterior axilla to the lat
  
• Lat

Front 20

Inferior Subscapular Nerve

• Course
• Innervation

Back 20

• C5, C6, upper trunk, posterior cord
  
• Lower subscap, teres major