A to Z Entries
Clare E. Milner in Functional Anatomy for Sport and Exercise, 2019
The wrist and hand contain many bones and joints, giving the region high flexibility. The hand is the major point of contact between the body and objects in the surrounding world; the flexibility of this region enables an individual to adapt easily to different holding and gripping requirements. The wrist and hand are also strong enough to support the entire body in sports such as gymnastics. The proximal bones of the wrist are the radius and ulna of the forearm (see elbow and forearm – bones). The eight carpal bones are the scaphoid, lunate, triquetral, pisiform, trapezium, trapezoid, capitate, and hamate. These bones are arranged in two rows; the first four are more proximal and the last four more distal. The bones of the hand are the five metacarpals and the 14 phalanges of the digits – the thumb has two, whereas the fingers each have three (Figure 26).
Planning and control of object grasping: kinematics of hand pre-shaping, contact and manipulation
Youlian Hong, Roger Bartlett in Routledge Handbook of Biomechanics and Human Movement Science, 2008
The hand is a uniquely complex sensory and motor structure of fundamental importance to our motor behaviour, whether it is used for artistic expression and communication, tool making and use, or perception. To address the seemingly simple question of: ‘How does the central nervous system (CNS) control the hand?’ requires understanding of its biomechanical structure and neural mechanisms. The complex nature of such organization has prompted scientists over the past three decades to use a wide range of multi-disciplinary approaches – on human and non-human primates – to unravel the intricate mechanisms underlying hand function, ranging from recording from motor and sensory cortical neurons to recording the activity of motor units of hand muscles, from imaging neural activity of the brain during object grasping to measuring the movement and force coordination patterns of the digits.
Answers
Calver Pang, Ibraz Hussain, John Mayberry in Pre-Clinical Medicine, 2017
This question focuses on the anatomy of the hand. The ulnar and radial arteries anastomose in the wrist to form arches. These arches combined with other branches to supply the hand and digits. The three main nerves that supply the hand include the ulnar, median and radial. The effect of cutting the ulnar nerve at the wrist involves motor loss, which includes the intrinsic muscles, except for those that supply the median nerve, which results in a claw hand. Sensory loss will be present on the medial side of the palm, palmar surface of the little and medial half of the ring fingers and the dorsal aspect of the distal and middle phalanges of these fingers. If the median is affected at the wrist there will be motor loss of the thenar muscles and the first and second lumbricals, which will result in wasting of the thenar muscles and inability to oppose the thumb. Sensory loss will be present on the lateral 3½ digits including their nail beds and the thenar area. If the radial nerve is affected at the wrist there will be no motor deficit, but only sensory loss will be present on the radial half of the dorsum of hand and dorsal aspect of radial 3½ digits.
Effect of hand postures and object properties on forearm muscle activities using surface electromyography
Published in International Journal of Occupational Safety and Ergonomics, 2020
Kyung-Sun Lee, Myung-Chul Jung
Upper limb musculoskeletal disorders (MSDs) are the commonest form of occupational disease in Europe [1]. The incidence of hand and wrist problems accounts for approximately 50% of the total number of upper extremity injuries or illnesses [2]. These are a concern in various industrial fields, along with the physical risk factors associated with their causation. MSDs, illnesses, injuries and discomfort are multifaceted problems and result from various factors [3]. The hand and wrist are frequently used in the activities of daily living and in industrial fields to grip, grasp, press and touch [4]. This high use can cause numerous MSDs and work-related injuries to the hand and wrist relative to the upper extremities. MSDs, injuries and discomfort occur when a task requires an awkward posture, a repetitive motion or hand strength that exceeds a person's physical ability.
Effect of Stroke on Joint Control during Reach-to-Grasp: A Preliminary Study
Published in Journal of Motor Behavior, 2020
Sandesh Raj, Natalia Dounskaia, William W. Clark, Amit Sethi
Movements were recorded using a 14 camera VICON motion capture system (Vicon Nexus, Oxford Metrics In., Oxford, UK) at a sampling frequency of 100 Hz. Thirty six reflective markers were placed bilaterally on the arms and hands and on the trunk. Marker placement is shown in Figure 1A. The Plug-In-UE marker set was used that includes separate markers and marker clusters. The marker placement was defined by standard upper extremity kinematic data collection protocols as explained in detail in Patterson, Bishop, McGuirk, Sethi, and Richards, (2011). The MotionMonitor software (Innsport inc.) was used to filter the marker coordinate data with a fourth order bidirectional low-pass Butterworth filter with a cutoff frequency of 7 Hz and to calculate shoulder and elbow angles in three-dimensional (3D) space using the Euler approach. Only the joint angles in the parasagittal plane (flexion/extension at the shoulder and elbow and ulnar/radial deviation at the wrist) were used for analysis (Figure 1B). The pronation/supination of the forearm was ignored as it did not affect the wrist angle in the parasagittal plane. The wrist angle was defined as the projection on the parasagittal plane of the angle between the longitudinal axes of the forearm and hand.
Reconstruction of postburn contractures due to tandir oven
Published in Journal of Plastic Surgery and Hand Surgery, 2020
Hakan Cinal, Ensar Zafer Barin, Murat Kara, Kerem Yilmaz, Harun Karaduman, İhtişam Zafer Cengiz, Oguz Boyraz, Osman Enver Aydin, Onder Tan
One hundred and thirty-seven contracture release surgery were performed in 45 hands in 40 cases. Most frequently the middle finger was operated upon in the hand region (Table 1). No dominant lateralization was detected in patients. The severity of hand contractures according to the McCauley classification is shown in Table 2. Fifty-five operations were performed on 18 cases other than hand localization. Most commonly the foot, ankle and toes, then the popliteal and neck region were operated upon (Table 1). Also, in one patient, the foot was operated due to syndactyly between first and second toes, while meatomy was performed in one male patient with genital region burns. In one case, the contracture of the ear was loosened with V-Y plasty, and the ear was reconstructed with costal cartilage graft. One hundred and sixty-three (84.9%) surgeries out of total 192 contracture release surgery were applied to the hand and foot region.