Separate multiple e-mails with a ;. The joints of the fingers are simple hinge joints. In a power grip an object is held against the palm and in a precision grip an object is held with the fingers, both grips are performed by intrinsic and extrinsic hand muscles together. Most importantly, the relatively strong thenar muscles of the thumb and the thumb's flexible first joint allow the special opposition movement that brings the distal thumb pad in direct contact with the distal pads of the other four digits.
Without this complex movement, humans would not be able to perform a precision grip. In addition, the central group of intrinsic hand muscles give important contributions to human dexterity. The palmar and dorsal interossei adduct and abduct at the MCP joints and are important in pinching. The lumbricals, attached to the tendons of the flexor digitorum profundus FDP and extensor digitorum communis FDC , flex the MCP joints while extending the IP joints and allow a smooth transfer of forces between these two muscles while extending and flexing the fingers.
The motor and sensory supply of the upper limb is provided by the brachial plexus which is formed by the ventral rami of spinal nerves C5-T1. In the posterior triangle of the neck these rami form three trunks from which fibers enter the axilla region armpit to innervate the muscles of the anterior and posterior compartments of the limb. In the axilla, cords are formed to split into branches, including the five terminal branches listed below. Motor innervation of upper limb by the five terminal nerves of the brachial plexus : .
Collateral branches of the brachial plexus: . The skeletons of all mammals are based on a common pentadactyl "five-fingered" template but optimised for different functions.
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While many mammals can perform other tasks using their forelimbs, their primary use in most terrestrial mammals is one of three main modes of locomotion: unguligrade hoof walkers , digitigrade toe walkers , and plantigrade sole walkers. Generally, the forelimbs are optimised for speed and stamina, but in some mammals some of the locomotion optimisation have been sacrificed for other functions, such as digging and grasping. In primates , the upper limbs provide a wide range of movement which increases manual dexterity. The limbs of chimpanzees , compared to those of humans, reveal their different lifestyle.
The chimpanzee primarily uses two modes of locomotion: knuckle-walking , a style of quadrupedalism in which the body weight is supported on the knuckles or more properly on the middle phalanges of the fingers , and brachiation swinging from branch to branch , a style of bipedalism in which flexed fingers are used to grasp branches above the head.
To meet the requirements of these styles of locomotion, the chimpanzee's finger phalanges are longer and have more robust insertion areas for the flexor tendons while the metacarpals have transverse ridges to limit dorsiflexion stretching the fingers towards the back of the hand. The thumb is small enough to facilitate brachiation while maintaining some of the dexterity offered by an opposable thumb.
In contrast, virtually all locomotion functionality has been lost in humans while predominant brachiators, such as the gibbons , have very reduced thumbs and inflexible wrists. In ungulates the forelimbs are optimised to maximize speed and stamina to the extent that the limbs serve almost no other purpose. In contrast to the skeleton of human limbs, the proximal bones of ungulates are short and the distal bones long to provide length of stride; proximally, large and short muscles provide rapidity of step.
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The odd-toed ungulates , such as the horse , use a single third toe for weight-bearing and have significantly reduced metacarpals. Even-toed ungulates , such as the giraffe , uses both their third and fourth toes but a single completely fused phalanx bone for weight-bearing. Ungulates whose habitat does not require fast running on hard terrain, for example the hippopotamus , have maintained four digits.
In species in the order Carnivora , some of which are insectivores rather than carnivores , the cats are some of the most highly evolved predators designed for speed, power, and acceleration rather than stamina. Compared to ungulates, their limbs are shorter, more muscular in the distal segments, and maintain five metacarpals and digit bones; providing a greater range of movements, a more varied function and agility e.
Some insectivorous species in this order have paws specialised for specific functions. The sloth bear uses their digits and large claws to tear logs open rather than kill prey. Other insectivorous species, such as the giant and red pandas , have developed large sesamoid bones in their paws that serve as an extra "thumb" while others, such as the meerkat , uses their limbs primary for digging and have vestigial first digits. The arboreal two-toed sloth , a South American mammal in the order pilosa , have limbs so highly adapted to hanging in branches that it is unable to walk on the ground where it has to drag its own body using the large curved claws on its foredigits.
From Wikipedia, the free encyclopedia. Upper limb Front of right upper extremity. Main article: Shoulder girdle. Main article: Arm. Main article: Forearm.
Main article: Wrist. Main article: Hand. Main article: Forelimb.
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This section relies largely or entirely on a single source. Relevant discussion may be found on the talk page. Please help improve this article by introducing citations to additional sources. July Chimpanzees maintain some of the dexterity brachiating gibbons lack. A bush pig , an ungulate with remaining non-weight-bearing digits, and the skeleton of the extinct Malagasy hippopotamus. A grooming lynx and a two-toed sloth "at home". Retrieved June RadioGraphics 28 : — Sellers, Bill Kaplan Medical.
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Demonstrate increased competency in the diagnosis and treatment of common hand conditions and injuries. Gain experience in the emergency management of common hand injuries. Gain experience in the resuscitation and early management of traumatic hand injuries. Understand the principles and management of subspecialty hand surgery which may include replantation, brachial plexus injuries, peripheral nerve injuries, tendon injuries, fractures and reconstructive wrist surgery.
Attitudinal Gain experience in approaching and attending to the patient with an upper extremity injury or deformity. Gain experience in working with a group of other physicians, nurses and paramedical personnel. Learn the value of working in a cohesive, multidisciplinary team setting and appreciate the contributions of each group. Technical Knowledge of surgical exposures in the hand and wrist.