Biomechanics (Activity Analysis- Brushing Hair)

    An important activity I perform each day is brushing my hair. I typically perform this task in-front of my bathroom mirror and begin in a neutral standing position. To begin, I retain my hair brush from the bottom bathroom cabinet which requires a slight flex in the knee joint, and the hip joint to bend down, moving in a sagittal plane and frontal axis of motion. 

    Once in this position, I extend my arm at my elbow joint straight out in-front of me, within the sagittal plane and frontal axis, while having a flexed wrist. My hand is in an open kinematic chain, while being pronated and my fingers are abducted in order to grasp my hair brush. To hold the hair brush sturdy in my hand I must adduct the fingers and flex the IP joints of the hand wrapping the fingers around the handle. I am able to bring the brush to my hair by flexing the elbow and shoulder joint within the sagittal plane and frontal axis. Beginning with the anterior and superior portion of hair, I shorten the distance of flexion in the elbow joint while I brush down to the ends of my hair. The biceps brachii is the primary muscle involved in elbow flexion, producing a concentric muscle activation.

    The arthokinematics of the flexed shoulder is the convex head of the humerus rolling anteriorly and gliding posteriorly within the concave glenoid cavity, while the arthrokinematics of the flexed elbow is the concave surfaces of the radius and ulna rolling and sliding on the convex surface of the humerus anteriorly. 

    Brushing the side of my hair requires a small change in motion, while keeping the flexed elbow, the arm is abducted within the frontal plane/sagittal axis of motion, continuing the same motion of moving the hairbrush to the distal end of the hair. Brushing the back of my hair, my arm moves from the frontal plane to the transverse plane because my shoulder joint is internally rotated, allowing my arm to reach the posterior side of my head. 

    While brushing your hair may seem like an easy task to some individuals, it requires the ability to perform muscle actions within different planes, and the ability of the joints to allow for adequate range of motion (ROM).

Picture Received From: https://www.cravenaturals.com