The left cerebral hemisphere is one of the two longitudinal cerebral halves of the human brain. Like its opposite on the right side, it is divided into four lobes; frontal, temporal, parietal, and occipital. The left cerebral hemisphere is connected to the right hemisphere through the corpus callosum.
The primary motor area (motor strip) of left cerebral hemisphere controls movement of the right side of the body. This is due to the fact that pyramidal nerve cell myelinated fibers cross over to the opposite side at the decussation of the pyramids on anterior side of the medulla oblongata. Depending on the severity, a stroke affecting the left cerebral hemisphere may result in functional loss or motor skill impairment of the right side of the body, and may also cause loss of speech.
Superior Function
Linear and analytical reasoning and language skills such as oral articulation of words and grammar comprehension are often lateralized to the left hemisphere of the brain, which contains the Broca's cortical area and the Wernicke's. Dyscalculia is a neurological syndrome associated with damage to the left temporo-parietal junction.
Below, image of left cerebral hemisphere; external, lateral side.