Answer:
Involuntary motor commands to the erector spinae: it is the tegmentum
Houses the superior colliculi: it is the tectum
Site of neurons that produce dopamine: it is the substantia nigra
Motor axons from primary motor cortex to spinal cord: cerebral peduncles
Explanation:
The tegmentum is an area of the brainstem involved in unconscious perception and reflexive commands. The tectum is localized in front of the tegmentum, which has been involved in motor responses such as, for example, walking, swimming (in fish), etc. The substantia nigra is a region of the ventral midbrain with a high concentration of neuromelanin in its dopaminergic neurons. The substantia nigra has been associated with Parkinson's and Huntington's diseases. Finally, the cerebral peduncles are two structures on each side of the brainstem that attach this component of the brain with the cerebrum. The cerebral peduncles have been involved with motor skills, balance and posture control.
