Which endocrine gland is part of both the nervous and the endocrine systems?

Hypothalamus is the link between both the nervous and the endocrine systems.

Hypothalamus: It is a small region of the brain which is located at the base of the brain, near to pituitary gland. While it's very small, it has three regions:

Anterior region, Middle region, Posterior region. Each of them contains different nuclei all regions vital function is releasing hormones.

Hypothalamus play main role in many important function:

1) Releasing hormones

2) Maintaining daily physiology cycle

3) Maintaining of sexual behavior

4) Regulating body temperature and emotional responses.