L4 Nerve Root (L4)

Authors

Affiliations

Nate Yomogida, PT, DPT

Doctor of Physical Therapy

B.S. in Kinesiology

Chloë Kerstein, PT, DPT

Doctor of Physical Therapy

B.A. in Neuroscience

Figure 1: Nerve roots extending from the spinal cord¹

Peripheral Nerve Supply

Nerve	Roots	Motor Innervation	Cutaneous Innervation
Obturator N.	L2, L3, L4
Femoral N.	L2, L3, L4
Superior Gluteal N.	L4, L5, S1	Gluteus Medius Gluteus Minimus Tensor Fascia Latae (TFL)	None
Sciatic N.
Common Fibular N.	L4, L5, S1, S2
Tibial N.	L4, L5, S1, S2, S3

Muscle Innervation

Motor Innervation

Muscle	Origin	Insertion	Innervation	Action
Adductor Longus	Superior pubis ramus Anterior side of Pubic Symphysis	Linea aspera	Obturator n. L2 - L4	Hip: Adduction, Flexion, Extension Pelvis: Frontal plane stabilization, Sagittal plane stabilization
Adductor Magnus	Inferior pubic ramus Ischial ramus Ischial tuberosity	Medial lip of Linea aspera Adductor tubercle	Obturator n. Tibial n. L2 - L4	Hip: Adduction, Flexion, Extension, IR Pelvis: Frontal stabilization, Sagittal stabilization
Articular genus	Anterior Femoral shaft	Suprapatellar recess of knee joint capsule	Femoral n. L2 - L4	Knee: Extension Knee Jt. Capsule: Retraction of the suprapatellar bursa to prevent entrapment
Extensor digitorum longus	Lateral condyle of Tibia Fibular head and medial surface IO membrane	Dorsal aponeurosis of 2-5th distal phalanges	Deep Fibular n. L4 - L5	TCJ: DF STJ: INV or EV (position dependent) 2nd-5th Toe: MTP Extension, PIP Extension, DIP Extension
Extensor Hallucis Longus	Fibula (middle 1/3 of medial surface) IO membrane	Dorsal aponeurosis of 1st distal phalanx	Deep Fibular n. L4 - L5	TCJ: DF STJ: Inversion 1st Toe: MTP Extension, IP Extension
Fibularis tertius	Anterior border of Distal Fibula	Shaft or Base of 5th MT	Deep Fibular n. L4 - L5	TCJ: DF STJ: Eversion
Gluteus medius	Ilium	Greater trochanter (lateral surface)	Superior gluteal n. L4 - S1	Entire mm.: Abduction, Frontal stabilization Anterior fibers: Flexion, IR Posterior fibers: Extension, ER (when <60° HF), IR (when &gt60° HF)
Gluteus Minimus	Ilium gluteal surface (inferior to gluteus medius origin)	Greater trochanter (anterolateral surface)	Superior gluteal n. L4 - S1	Entire mm.: Abduction, Frontal stabilization Anterior fibers: Flexion, IR Posterior fibers: Extension, ER (when <60° HF), IR (when &gt60° HF)
Obturator externus	Outer surface of Obturator membrane Adjacent bony boundaries	Trochanteric Fossa	Obturator n. L3 - L4	Hip: Adduction, ER Pelvis: Sagittal Stabilization
Popliteus	Lateral Femoral Condyle Posterior horn of Lateral Meniscus	Posterior surface of Tibia	Tibial n. L4 - S1	Knee: Flexion, Unlocks the knee via knee IR
Rectus femoris	AIIS Acetabular roof	Tibial tuberosity via Patellar ligament	Femoral n. L2 - L4	Hip: Flexion Knee: Extension
Tensor Fascia Latae	ASIS	IT Band	Superior gluteal n. L4 - S1	Tenses fascia latae Hip: Abduction, Flexion, IR Flexed knee: ER Extended knee: Locks out extension
Tibialis Anterior	Tibia (Upper 2/3 of lateral surface) IO membrane Superficial crural fascia	Medial cuneiform (Medial & plantar surface) 1st Metatarsal (medial base)	Deep Fibular n. L4 - L5	TCJ: DF STJ: Inversion
Tibialis posterior	IO membrane Adjacent Tibia Adjacent Fibula	Cuneiforms 2-4 MT bases	Tibial n. L4 - L5	TCJ: PF Arch support: Transverse arch, Longitudinal arch
Vastus intermedius	Anterior Femoral shaft	Tibial tuberosity via Patellar ligament	Femoral n. L2 - L4	Knee: Extension
Vastus lateralis	Lateral lip of Linea aspera Lateral surface of Greater trochanter	Tibial tuberosity via Patellar ligament Tibial tuberosity and patella via Patellar retinacula	Femoral n. L2 - L4	Knee: Extension
Vastus medialis	Linea aspera Intertrochanteric line	Tibial tuberosity via Patellar ligament Patellar retinacula	Femoral n. L2 - L4	Knee: Extension

Dermatome

Figure 2: Dermatomal cutaneous distribution¹

Figure 3: Dermatomal cutaneous distribution (Posterior)¹

Femoral nerve

Femoral nerve L4 innervations

• Quadriceps
  • Rectus Femoris²
  • Vastus lateralis²
  • Vastus intermedius²
  • Vastus medialis²
  • Articularis Genus²

Examination

Deep Tendon Reflex

• Patella reflex (L2, L3, L4, but predominantly L4)

Neural Tension

The Active Slump Test applies a neural tension on the Sciatic n. and the L4 and L5³

References

1.

Gray H. Anatomy of the Human Body. 20th ed. (Lewis WH, ed.). Lea & Febiger; 1918. https://www.bartleby.com/107/

2.

Gilroy AM, MacPherson BR, Wikenheiser JC, Voll MM, Wesker K, Schünke M, eds. Atlas of Anatomy. 4th ed. Thieme; 2020.

3.

APTA. Current Concepts of Orthopaedic Physical Therapy. 5th ed.; 2024.