L1 Nerve Root (L1)

Authors
Affiliations

Doctor of Physical Therapy

B.S. in Kinesiology

Doctor of Physical Therapy

B.A. in Neuroscience

Figure 1: Nerve roots extending from the spinal cord1

Peripheral Nerve Supply

Peripheral Nerves Originating from L1 Nerve root
Nerve Roots Motor Innervation Cutaneous Innervation
Ilioinguinal N.

L1

Iliohypogastric N.

L1

Genitofemoral N.

L1, L2

Motor Innervation

Dermatome

Figure 2: Dermatomal cutaneous distribution1
Figure 3: Dermatomal cutaneous distribution (Posterior)1

Compression

Compression of L3 nerve root includes:

  • Pain in the middle lumbar spine, upper buttock, whole anterior thigh and knee, medial knee, and just above the ankle2
  • Dural signs of prone knee flexion
  • SLR will occassionally be positive2
  • ↓ Extension ROM
  • Weakness
    • Slight weakness of iliopsoas2
    • Gross loss of quadriceps strength2
  • Hypoesthesia of the medial aspect of the knee and lower leg2
  • Patellar reflex Absent (0) or reduced (1)

References

1.
Gray H. Anatomy of the Human Body. 20th ed. (Lewis WH, ed.). Lea & Febiger; 1918. https://www.bartleby.com/107/
2.
Dutton M. Dutton’s Orthopaedic Examination, Evaluation, and Intervention. 5th ed. McGraw Hill Education; 2020.

Citation

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