Classifications of Reflexes
Classifications of reflexes
A) Primitive reflexes and genetic sub-programs
1. Reflex responses to light touch:
Light touch produces a variety of reflex responses, depending upon the area stimulated and the age of the individual. The motor responses are most marked in the early months of life.
Grasp reflex (palmar and plantar):
Light touch of the palm or sole produces reflex flexion of the fingers or toes. The most effective way to elicit the reflex is to slide the stimulating object, such as a finger or pencil, across the palm or sole from the lateral border. A beautiful neurological organization of the palmar grasp reflex has been described, in which finger flexion follows a definite sequence: “middle - ring – little – index – thumb”. Chain responses follow the initial reflex producing two further stages, which are seen best in the palmer reflex. The first follows initial flexion of the digits and consists of tensing of the flexed muscles to produce a strong grasp. A strong tonic component at this stage of the reflex ensures maintenance of the grasp as long as the stimulus persists. The second stage occurs when traction is exerted by the stimulating finger or pencil. This is followed by a progressive contraction of the arm muscles, which is sometimes so strong that the baby can be lifted from the examination couch. The palmer and planter grasp reflexes are easily demonstrable in the neonate but then fade rapidly and become seldom seen after 4 or 5 months of age. Phylogenetically, the reflex is suggested to have a survival value by enabling the infant animal to cling to the mother's fur. • Placing reflex: Stimulation of the dorsum of the foot of the neonate produces complete flexion of the same leg. Probably, the easiest way to show this; and the method used in clinical examination, is to hold the infant upright and to let the dorsum of the foot touches the lower side of the edge of the examination table. The
A) Primitive reflexes and genetic sub-programs
1. Reflex responses to light touch:
Light touch produces a variety of reflex responses, depending upon the area stimulated and the age of the individual. The motor responses are most marked in the early months of life.
Grasp reflex (palmar and plantar):
Light touch of the palm or sole produces reflex flexion of the fingers or toes. The most effective way to elicit the reflex is to slide the stimulating object, such as a finger or pencil, across the palm or sole from the lateral border. A beautiful neurological organization of the palmar grasp reflex has been described, in which finger flexion follows a definite sequence: “middle - ring – little – index – thumb”. Chain responses follow the initial reflex producing two further stages, which are seen best in the palmer reflex. The first follows initial flexion of the digits and consists of tensing of the flexed muscles to produce a strong grasp. A strong tonic component at this stage of the reflex ensures maintenance of the grasp as long as the stimulus persists. The second stage occurs when traction is exerted by the stimulating finger or pencil. This is followed by a progressive contraction of the arm muscles, which is sometimes so strong that the baby can be lifted from the examination couch. The palmer and planter grasp reflexes are easily demonstrable in the neonate but then fade rapidly and become seldom seen after 4 or 5 months of age. Phylogenetically, the reflex is suggested to have a survival value by enabling the infant animal to cling to the mother's fur. • Placing reflex: Stimulation of the dorsum of the foot of the neonate produces complete flexion of the same leg. Probably, the easiest way to show this; and the method used in clinical examination, is to hold the infant upright and to let the dorsum of the foot touches the lower side of the edge of the examination table. The