A grasp is an act of taking, holding or seizing firmly with (or as if with) the hand. An example of a grasp is the handshake, wherein two people grasp one of each other's like hands.
In zoology particularly, prehensility is the quality of an appendage or organ that has adapted for grasping or holding.
Grasping is often preceded by reaching, which is highly dependent on head and trunk control, as well as eye control and gaze. [1]
The development of grasping is an important component of child development stages, wherein the main types of grasps are:
Infants reach as early as 16 weeks of age and are able to perform certain actions that lead to grasping objects. The act of grasping is a two-stage motor skill that develops. The first stage, infants will reach out towards the desired object. In the second stage, the infants will then clench fingers once the object has made contact with the palm and close. Infants try to grasp an object before it is within reach by initiating arm and hand movements. The child will extend their grip more than necessary because their perception is less developed than an adult's grip. [5] Infants progress their grasping skills throughout time by practice and providing objects that are reachable. It is essential to provide infants with objects they can grasp in order to progress and further their development of the grasping skill; exposing infants to new objects to practice grasping will overall benefit this primitive motor skill and elevate the associated cognitive process. [6] Infants develop their reaching and grasping from making just contact with their hands, to using their palms to contact an object. Infant grasp is an extension of reaching and develops between six and nine months of age. Stable patterns of reaching in order to grasp continue to develop as the child grows and matures. By the age of 6, children are now learning hand placement on the writing utensil the correct way. [7]
Hand grasps can be grouped into taxonomies according to qualitative and quantitative properties, leading to specific clusters of movements. [8] In terms of synergies, there are three categories of hand movements. Simple synergies are present, when all the components of the hand are moving in a similar pattern. Conversely, it is called reciprocal synergies, when the fingers or thumbs are working in different patterns. Finally, sequential patterns are specific hand movements performed in a specific order. [9] Synergies are fundamental for controlling complex hand movements, such as the ones of the hand during grasping. The importance of synergies has been demonstrated for both muscle control and in the kinematic domain in several studies, lately on studies including large cohorts of subjects. [10] [11] [12]
The palmar grasp reflex (sometimes simply called grasp reflex) is among the primitive reflexes and appears at birth and persists until five or six months of age. [13] When an object is placed in the infant's hand and strokes their palm, the fingers will close and they will grasp it. The grip is strong but unpredictable; though it may be able to support the child's weight, they may also release their grip suddenly and without warning. The reverse motion can be induced by stroking the back or side of the hand.
A finger is a prominent digit on the forelimbs of most tetrapod vertebrate animals, especially those with prehensile extremities such as humans and other primates. Most tetrapods have five digits (pentadactyly), and short digits are typically referred to as toes, while those that are notably elongated are called fingers. In humans, the fingers are flexibly articulated and opposable, serving as an important organ of tactile sensation and fine movements, which are crucial to the dexterity of the hands and the ability to grasp and manipulate objects.
The thumb is the first digit of the hand, next to the index finger. When a person is standing in the medical anatomical position, the thumb is the outermost digit. The Medical Latin English noun for thumb is pollex, and the corresponding adjective for thumb is pollical.
The median nerve is a nerve in humans and other animals in the upper limb. It is one of the five main nerves originating from the brachial plexus.
A motor skill is a function that involves specific movements of the body's muscles to perform a certain task. These tasks could include walking, running, or riding a bike. In order to perform this skill, the body's nervous system, muscles, and brain have to all work together. The goal of motor skill is to optimize the ability to perform the skill at the rate of success, precision, and to reduce the energy consumption required for performance. Performance is an act of executing a motor skill or task. Continuous practice of a specific motor skill will result in a greatly improved performance, which leads to motor learning. Motor learning is a relatively permanent change in the ability to perform a skill as a result of continuous practice or experience.
Alien hand syndrome (AHS) or Dr. Strangelove syndrome is a category of conditions in which a person experiences their limbs acting seemingly on their own, without conscious control over the actions. There are a variety of clinical conditions that fall under this category, which most commonly affects the left hand. There are many similar terms for the various forms of the condition, but they are often used inappropriately. The affected person may sometimes reach for objects and manipulate them without wanting to do so, even to the point of having to use the controllable hand to restrain the alien hand. Under normal circumstances however, given that intent and action can be assumed to be deeply mutually entangled, the occurrence of alien hand syndrome can be usefully conceptualized as a phenomenon reflecting a functional "disentanglement" between thought and action.
The upper limbs or upper extremities are the forelimbs of an upright-postured tetrapod vertebrate, extending from the scapulae and clavicles down to and including the digits, including all the musculatures and ligaments involved with the shoulder, elbow, wrist and knuckle joints. In humans, each upper limb is divided into the arm, forearm and hand, and is primarily used for climbing, lifting and manipulating objects.
The motor cortex is the region of the cerebral cortex involved in the planning, control, and execution of voluntary movements. The motor cortex is an area of the frontal lobe located in the posterior precentral gyrus immediately anterior to the central sulcus.
Fine motor skills are the coordination of small muscle movements which occur e.g., in the fingers, usually in coordination with the eyes. In application to motor skills of hands the term dexterity is commonly used.
The term 'dexterity' is defined by Latash and Turrey (1996) as a 'harmony in movements' (p. 20). Dexterity is a type of fine coordination usually demonstrated in upper extremity function.
Motor control is the regulation of movements in organisms that possess a nervous system. Motor control includes conscious voluntary movements, subconscious muscle memory and involuntary reflexes, as well as instinctual taxis.
In physiology, motor coordination is the orchestrated movement of multiple body parts as required to accomplish intended actions, like walking. This coordination is achieved by adjusting kinematic and kinetic parameters associated with each body part involved in the intended movement. The modifications of these parameters typically relies on sensory feedback from one or more sensory modalities, such as proprioception and vision.
The carpometacarpal (CMC) joints are five joints in the wrist that articulate the distal row of carpal bones and the proximal bases of the five metacarpal bones.
Child development stages are the theoretical milestones of child development, some of which are asserted in nativist theories. This article discusses the most widely accepted developmental stages in children. There exists a wide variation in terms of what is considered "normal", caused by variations in genetic, cognitive, physical, family, cultural, nutritional, educational, and environmental factors. Many children reach some or most of these milestones at different times from the norm.
Gross motor skills are the abilities usually acquired during childhood as part of a child's motor learning. By the time they reach two years of age, almost all children are able to stand up, walk and run, walk up stairs, etc. These skills are built upon, improved and better controlled throughout early childhood, and continue in refinement throughout most of the individual's years of development into adulthood. These gross movements come from large muscle groups and whole body movement. These skills develop in a head-to-toe order. The children will typically learn head control, trunk stability, and then standing up and walking. It is shown that children exposed to outdoor play time activities will develop better gross motor skills.
Primitive reflexes are reflex actions originating in the central nervous system that are exhibited by normal infants, but not neurologically intact adults, in response to particular stimuli. These reflexes are suppressed by the development of the frontal lobes as a child transitions normally into child development. These primitive reflexes are also called infantile, infant or newborn reflexes.
Eye–hand coordination is the coordinated motor control of eye movement with hand movement and the processing of visual input to guide reaching and grasping along with the use of proprioception of the hands to guide the eyes, a modality of multisensory integration. Eye–hand coordination has been studied in activities as diverse as the movement of solid objects such as wooden blocks, archery, sporting performance, music reading, computer gaming, copy-typing, and even tea-making. It is part of the mechanisms of performing everyday tasks; in its absence, most people would not be able to carry out even the simplest of actions such as picking up a book from a table.
In physiology, an efference copy or efferent copy is an internal copy of an outflowing (efferent), movement-producing signal generated by an organism's motor system. It can be collated with the (reafferent) sensory input that results from the agent's movement, enabling a comparison of actual movement with desired movement, and a shielding of perception from particular self-induced effects on the sensory input to achieve perceptual stability. Together with internal models, efference copies can serve to enable the brain to predict the effects of an action.
The palmar grasp reflex is a primitive and involuntary reflex found in infants of humans and most primates. When an object, such as an adult finger, is placed in an infant's palm, the infant's fingers reflexively grasp the object. Placement of the object triggers a spinal reflex, resulting from stimulation of tendons in the palm, that gets transmitted through motor neurons in the median and ulnar sensory nerves. The reverse motion can be induced by stroking the back or side of the hand. A fetus exhibits the reflex in utero by 28 weeks into gestation, and persists until development of rudimentary fine motor skills between two and six months of age.
A hand is a prehensile, multi-fingered appendage located at the end of the forearm or forelimb of primates such as humans, chimpanzees, monkeys, and lemurs. A few other vertebrates such as the koala are often described as having "hands" instead of paws on their front limbs. The raccoon is usually described as having "hands" though opposable thumbs are lacking.
Fine motor skill is the coordination of small muscles in movement with the eyes, hands and fingers. The complex levels of manual dexterity that humans exhibit can be related to the nervous system. Fine motor skills aid in the growth of intelligence and develop continuously throughout the stages of human development.
Tenodesis grasp and release is an orthopedic observation of a passive hand grasp and release mechanism, affected by wrist extension or flexion, respectively. It is caused by the manner of attachment of the finger tendons to the bones and the passive tension created by two-joint muscles used to produce a functional movement or task (tenodesis). Moving the wrist in extension or flexion will cause the fingers to curl or grip when the wrist is extended, and to straighten or release when the wrist is flexed.
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