Final answer:
The claim that intrinsic muscles of the foot primarily evert and invert the foot is false. Intrinsic muscles support the arch and toe movement, while eversion and inversion are controlled by extrinsic muscles such as the fibularis brevis and longus, and the tibialis posterior.
Step-by-step explanation:
The statement that the intrinsic muscles of the foot act primarily to evert and invert the foot is false. Inversion and eversion are movements controlled by muscles that are not considered part of the intrinsic group. The intrinsic muscles originate and insert within the foot itself, which differs from the muscles that control inversion and eversion that span the ankle and foot. The intrinsic muscles primarily support the foot's arch and contribute to toe movements. On the dorsal side, there is only the extensor digitorum brevis, which extends the toes. The plantar group, consisting of four layers, generally flexes the toes. The fibularis brevis and fibularis longus muscles are responsible for eversion and plantar flexion at the intertarsal joints, while the tibialis posterior is involved in inversion and plantar flexion.
The intrinsic muscles of the foot primarily act to evert and invert the foot. Inversion is the turning of the foot to angle the bottom of the foot toward the midline, while eversion turns the bottom of the foot away from the midline. These motions are important for stabilizing the foot during activities like walking, running, and sports.
For example, when you walk on an uneven surface or change direction quickly while playing basketball, the intrinsic muscles of the foot help to keep your foot stable and prevent injuries.
Therefore, the statement 'The intrinsic muscles of the foot act primarily to evert and invert the foot' is true.