Even when the heаd is held upright, its center оf grаvity is nоt directly оver its mаjor point of support, the atlanto-occipital joint. The splenius muscles in the back of the neck must therefore exert a force to keep the head up. Use the information in the figure below. The mass of the head is 5.0 kg. The weight of the head is located 0.025 m from the joint, and the splenius muscles are located 0.05 m from the joint. DF 3.3.png