The TCM Spleen also controls the muscles, specifically the motor muscles of the 4 limbs. When there is a lack of Qi physical energy is depleted and weak muscles and tiredness are common complaints.
While I was in naturopathic medical school, many students clearly had weakened Spleens, myself included! Students are often Spleen Qi Deficient when they are continuously studying and getting ready for big exams. Since the Spleen houses the Intellect and helps with applied thinking, studying, memorizing, focus and concentration, excess studying and mental work for sustained periods of time tend to weaken the Spleen. Mental fog is often present along with feeling bored, uninterested and worrying more than usual. But not to worry, strengthening and toning the Spleen can be achieved with a good healthy diet, proper digestion and a lot of great restorative sleep post-exams!
On a lighter note, the Spleens brilliance is manifested in the lips! Red, moist and healthy lips are a sign of a strong Spleen. Kiss kiss!