Nerve Pathways

Nerve Pathways

1. Cord & Root Anatomy

   • Made up of
     • White Matter
     • Grey Matter
     • Dorsal Root
       • Entry Zone
       • Ganglion
       • Dorsal Ramus
     • Spinal Nerve
     • Ventral Ramus
     • Ventral Root

2. Spinal Nerves

   • Nerve Pathway
     • 31 pairs of spinal nerves (joining of ventral & dorsal roots)
   • Anterior/Ventral Rami (branch)
     • Upper and lower limbs, anterior trunk
   • Posterior/Dorsal Rami (branch)
     • Deeper muscles, dorsal trunk

3. Spinal Nerve Plexus

   • Cervical
     • C1-C4
     • Head, Neck, Superior chest and shoulders
       • Phrenic
   • Brachial
     • C5-T1
       • Shoulders and upper limbs
         • Musculocutaeneous, Median, Ulnar, Radial, Axillary
   • Lumbar
     • L1-L4
       • Antero-lateral adbom. Wall, part of lower limb
         • Femoral/ Obturator
   • Lumbosacral
     • L4-S3
       • Buttocks, perineum, lower limbs
         • Sciatic

4. Dermatomes

   • Skin area innervated by cutaneous sensory fibres of a single nerve root

5. Myotomes

   • Group of muscles innervated by the motor fibres of a single nerve root

6. Musculocutaneous Nerve

   • Lat. Cord of brachial plexus
   • Root value – C5,6 & 7
   • Laterally to axillary artery
     • descends between artery and coracobrachialis (pierces)
       • Passes distally between biceps and brachialis to lateral arm
         • At elbow – pierces deep fascia between biceps and brachioradialis

7. Median Nerve

   • Partly lateral and medial cord of plexus
     • Nerve Root – Med. C5,6,7 Lat. C8, T1
     • Under biceps brachii, lower part of the arm lies on brachialis and in the cubital fossa
       • Enters the forearm by passing between 2 heads of pronator teres and runs below the tendinous arch.
         • Descends on FDP until just above the wrist where it becomes superficial passing between tendons of FDS and FCR, deep to PL
           • Enters hand deep to flexor retinaculum

8. Radial Nerve

   • Post cord of brachial plexus
     • Root Value – C5,6,7,8 (T1)
       • Lies behind axillary and brachial artery passing ant. To tendons of subscap, lat dorsi and teres major
         • Enters posterior arm by passing through triangular space
           • Once through space enters the radial groove of humerus between lateral and medial heads of triceps
             • Pierces lateral intermuscular septum to enter anterior compartment, lies between brachialis and brachioradialis
               • Lies in front of the lateral epicondyle where it splits into superficial and deep branches

9. Ulnar Nerve

   • Medial Branch of brachial plexus
     • Nerve root – C8, T1
       • Medial to Axillary artery
         • Down medial aspect of arm to Brachial artery Pierces medial intermuscular septum into posterior compartment of arm
           • Between medial condyle & olecranon then anterior compartment of forearm
             • Medial aspect of forearm branching to superficial & deep components

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