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Acutiramus is a genus of giant predatory eurypterid, an extinct group of aquatic arthropods. Fossils of Acutiramus have been discovered in deposits of Late Silurian to Early Devonian age. Eight species have been described, five from North America (including A. cummingsi , the type species) and two from the Czech Republic (with one of them ...
The muscles of the hand can be subdivided into two groups: the extrinsic and intrinsic muscle groups. The extrinsic muscle groups are the long flexors and extensors. They are called extrinsic because the muscle belly is located on the forearm. The intrinsic group are the smaller muscles located within the hand itself. The muscles of the hand ...
Superior rectus muscle; Inferior rectus muscle; Medial rectus muscle; jaw (muscles of mastication, the closing of the jaw is adduction): masseter; pterygoid muscles (lateral and medial) temporalis; vocal folds. Lateral cricoarytenoid muscle
The chelicerae of Acutiramus likely served as slicing or shearing devices, adding to the evidence that it would have occupied a distinct ecological niche. A significantly less active predator, Acutiramus might have been a scavenger or ambush predator, feeding on soft-bodied animals. [18]
1.1 Arm and shoulder. 1.2 Hand and wrist. 2 Lower limb. ... of hand at wrist [3] ... Gluteus maximus muscle; Gluteus medius muscle;
The five muscles acting on the wrist directly — flexor carpi radialis, flexor carpi ulnaris, extensor carpi radialis, extensor carpi ulnaris, and palmaris longus — are accompanied by the tendons of the extrinsic hand muscles (i.e. the muscles acting on the fingers). Thus, every movement at the wrist is the work of a group of muscles ...
In primates, the arm is adapted for precise positioning of the hand and thus assist in the hand's manipulative tasks. The ball and socket shoulder joint allows for movement of the arms in a wide circular plane, while the structure of the two forearm bones which can rotate around each other allows for additional range of motion at that level.
It is considered an extrinsic hand muscle because it acts on the hand while its muscle belly is located in the forearm. Together the flexor pollicis longus, pronator quadratus, and flexor digitorum profundus form the deep layer of ventral forearm muscles. [2] The muscle is named from Latin 'deep bender of the fingers'.