Advanced Neuro Levels (Step 1 Deep Dive)

Neuro Levels Mastery

Match the Root Level to the specific Clinical Presentation, Muscle, or Reflex.

Nerve Root

Clinical Picture / Motor / Sensory

Upper Extremity (C5-T1)

Level	Motor & Nerves	Reflex	Sensory & Clinical Notes
C5	Deltoid (Abduction) Infraspinatus (Lat. Rotation) Biceps (Flexion) Axillary n. Suprascapular n.	Biceps	Sensory: Lateral Arm (Axillary Patch) Pathology: Erb-Duchenne Palsy ("Waiter's Tip"). Arm hangs by side, medially rotated.
C6	Wrist Extensors (ECRL/ECRB) Biceps (Flexion) Radial n. Musculocutaneous n.	Brachioradialis (Biceps shared)	Sensory: Lateral Forearm, Thumb, Index Finger. Pathology: Weak wrist extension + numb thumb/index.
C7	Triceps (Elbow Extension) Wrist Flexors Finger Extensors Radial n.	Triceps	Sensory: Middle Finger (dorsal/palmar). Pathology: "Wrist Drop" components (Radial), weakness in "pushing" (Triceps).
C8	Finger Flexors (Distal) Hand Grip Strength Median/Ulnar n.	None	Sensory: Ring & Little Finger, Medial Forearm. Pathology: Klumpke Palsy (lower trunk). "Claw Hand" (Intrinsic weakness).
T1	Finger Abduction/Adduction (Interossei) Ulnar n.	None	Sensory: Medial Arm (distal to axilla). Pathology: Intrinsic hand muscle atrophy.

Lower Extremity (L4-S1)

Level	Motor & Nerves	Reflex	Sensory & Clinical Notes
L4	Quadriceps (Knee Extension) Tibialis Anterior (Dorsiflexion) Femoral n. Deep Peroneal n.	Patellar (Knee Jerk)	Sensory: Medial Leg, Medial Malleolus, Medial Foot. Pathology: Difficulty climbing stairs (Quads), rising from chair.
L5	Extensor Hallucis Longus (Big Toe Extension) Gluteus Medius (Hip Abduction) Deep Peroneal n. Sup. Gluteal n.	None (Medial Hamstring - minor)	Sensory: Lateral Leg, Dorsum of Foot, Webspace 1-2. Pathology: Foot Drop (steppage gait), Trendelenburg Sign (Hip drop).
S1	Gastrocnemius/Soleus (Plantar Flexion) Gluteus Maximus (Hip Extension) Peroneals (Eversion) Tibial n. Inf. Gluteal n.	Achilles (Ankle Jerk)	Sensory: Posterior Leg, Lateral Foot, Sole, Little Toe. Pathology: Difficulty walking on toes. Weak hip extension.