Brodmann Area 4

Brodmann Area 4

Question 1. Write a short note on the Primary Motor Area.

Answer.

Primary Motor Area Location The primary motor area (Brodmann area 4) is located:

• Precentral gyrus
• Anterior wall of central sulcus
• Anterior part of paracentral lobule

Primary motor area

Primary Motor Area Representation of Body

• The body is represented upside down (inverted homunculus) in the primary motor area.
• The sequence of representation of body parts, from top to bottom, is leg, thigh, trunk, upper limb, face, larynx, lips, jaws, tongue, and pharynx.
• The area of the cortex representing a part of the body is not proportional to the size of that part, but to the skill of movements performed by that part. Thus, movements of the hands, lips, tongue, and larynx are represented by relatively large areas of the cortex.

Precentral gyrus

Primary Motor Area Functions

• It controls the voluntary movements of the opposite side of the body.
• It also controls the acts of micturition and defecation.

Primary Motor Area Applied Anatomy: A lesion in this area gives rise to upper motor neuron (UMN) type of paralysis on the opposite side of the body.