While muscles often work in synergy to create in aggregate a given motion, they rarely work in isolation. Nonetheless, to test the deltoid muscles, which are innervated primarily by the C5 nerve root and to a lesser extent the C6 nerve root, patients simultaneously raise both arms in front of them as the examiner provides resistance to this movement. The biceps muscles are innervated by the C5 and C6 nerve roots. To test the strength of the biceps, hold the patient’s wrist from above and provide resistance and instruct him or her to flex the hand up to the shoulder. Next, test the triceps muscle strength. Patients should start from a fully flexed position and extend their forearm against resistance provided by the examiner. The triceps muscle, the major elbow extensor, is primarily innervated by C7 nerve roots and to a lesser extent a C6 and a C8 (long head of the triceps) component. Wrist flexion is predominantly C7 and to a lesser extent C6 can be tested by having the patient flex their wrist. Wrist extensors are innervated predominantly C6 and to a lesser extent C7 nerve roots can be tested by having patients extend their wrists while the clinician is providing resistance. Examine the patient’s hands for signs of thenar and hypothenar muscle wasting. To test grip strength, ask patients to make a tight fist around the examiner’s fingers and instruct them to not let go as the examiner tries to remove them. Grip strength is a test of intrinsic hand muscles and finger flexion, which is innervated by the C8 nerve root. Thumb abduction, which is primarily innervated by the T1 nerve root, is tested by having patients abduct the thumb. Thumb opposition is innervated by the C8 and T1 nerve roots and is tested by having patients touch the tip of their thumb to the tip of their pinky finger as the clinician is applying resistance to the patients’ thumb.

Hip flexion is tested by having the patient lie supine and raising each leg separately as the examiner is providing resistance. Hip flexion is innervated by the L2 and L3 nerve roots and tests the iliopsoas muscle. The L2, L3, and L4 nerve roots provide innervation for adduction of the hip. Hip adduction is tested by the examiner placing his or her hands on the inner thighs of the patients and instructing them to bring both legs together. The gluteus maximus and gluteus minimus muscles are tested by having the examiner’s hands on the patient’s outer thighs and providing resistance while the patients move their legs apart. Innervation for this movement comes primarily from L5, and S1 nerve roots, and to a lesser extent the L4 nerve root. Extension of the hip is tested by having the patient lie supine with one leg raised, the examiner placing a hand under the patient’s thigh, and then instructing the patient to press down on the examiner’s hand. This tests the gluteus maximus, and innervation comes primarily from the L5 and S1 nerve roots. The L3 and L4 nerve roots provide innervation for knee extension by the quadriceps muscle. Extension at the knee can be tested by the examiner placing a hand on the anterior surface of the lower leg to provide resistance and having the patient “kick out.” This movement tests the quadriceps muscle, and innervation is provided by the L3 and L4 nerve roots. The hamstring muscles are innervated by the L5 and S1 nerve roots, which allow for flexion at the knee. Test flexion at the knee by placing a hand on the pack of patients’ calves and instructing them to pull the lower leg back. Dorsiflexion of the ankle is tested by placing a hand on top of the ankle and having patients pull their foot up towards their face as the examiner is applying resistance. This tests muscles in the anterior compartment of the lower leg, and innervation comes primarily from the L5 and sometimes the L4 nerve root. Next, hold the bottom of the patient’s foot to provide resistance and instruct them to “step on the gas pedal” to test the gastrocnemius and soleus muscles. This ankle plantar flexion receives innervation from the S1 and S2 nerve roots. To test the extensor hallucis longus muscles, which are innervated by the L5 nerve root, ask the patient to move the large toe up towards the patient’s face while providing resistance.