Motor signs: it is not possible by clinical examination to detect wasting or muscle weakness of all the muscles which are partially supplied by L4, but an obvious one is quadriceps femoris, which receives a large contribution from this root. Some wasting of quadriceps may be apparent. Also tibialis anterior and tibialis posterior both receive a significant contribution from L4, so that there may be some detectable weakness of inversion of the foot.
Sensory signs: some blunting of sensation over the antero-medial aspect of the shin may occur as far as the 'bunion' area of the foot (the metatarsophalangeal joint of the big toe).
Reflex jerks: because of the effect on the quadriceps muscle there may be loss of the knee jerk.
Last reviewed 01/2018