We present an alternative treatment to the quantum spherical spin model on ͑d Ն 2͒-dimensional hypercubic lattices, focusing on the effects of quantum ͑g͒ and thermal ͑T͒ fluctuations, under a uniform magnetic field h, on the correlation function, correlation length, entropy, specific heat, and energy gap in the excitation spectrum. Explicit expressions for such quantities are provided close to the d Ն 2 quantum ͑g = g c , T =0͒ and d Ն 3 thermal ͓T = T c ͑g͔͒ phase transitions in h = 0, including the low-T quantum regimes near the quantum critical point. In particular, the calculation of the correlation function and correlation length generalizes the results on the g = 0 classical spherical model. At T = 0, the zero-field system is gapless at and below g c ; however, a gap opens in the quantum-disordered ground state, g Ͼ g c . Conversely, the null gap for T Յ T c ͑g 0͒ becomes finite as T → T c ͑g 0͒ + ; thus, quantum fluctuations suppress the critical prefactors of observables near T c ͑g 0͒, though they are irrelevant to the universality class shared with the gapless classical spherical model. The results on the entropy and specific heat in g 0 circumvent the drawback in classical spherical models concerning the third law of thermodynamics, as T → 0.