If your patient severed (cut) his S1 nerve, he would NOT be able to do which of the following? Dorsiflex his foot Evert his foot Invert his foot Plantarflex his foot

The S1 nerve, also known as the first sacral nerve, plays a crucial role in motor control and sensory perception in the lower limbs. If a patient were to sever their S1 nerve, they would experience a loss of certain functions in their foot.

Here are the functions of the foot and whether they would be affected by severing the S1 nerve:

1. Dorsiflexion: This is the action of raising the foot upwards towards the shin. The S1 nerve does not primarily control this action. The primary nerve responsible for dorsiflexion is the deep fibular (peroneal) nerve, which is a branch of the common fibular (peroneal) nerve. Therefore, a patient with a severed S1 nerve would still be able to dorsiflex their foot.

2. Eversion: This is the action of turning the sole of the foot outwards. The S1 nerve does contribute to this action. Therefore, a patient with a severed S1 nerve would not be able to evert their foot.

3. Inversion: This is the action of turning the sole of the foot inwards. The S1 nerve does not primarily control this action. The primary nerves responsible for inversion are the tibial nerve and its branches. Therefore, a patient with a severed S1 nerve would still be able to invert their foot.

4. Plantarflexion: This is the action of extending the foot downwards away from the shin (like pressing a gas pedal). The S1 nerve does contribute to this action. Therefore, a patient with a severed S1 nerve would not be able to plantarflex their foot.

In conclusion, if a patient severed their S1 nerve, they would not be able to evert or plantarflex their foot.