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A classic example of a syncytium is the formation of skeletal muscle.Large skeletal muscle fibers form by the fusion of thousands of individual muscle cells. The multinucleated arrangement is important in pathologic states such as myopathy, where focal necrosis (death) of a portion of a skeletal muscle fiber does not result in necrosis of the adjacent sections of that same skeletal muscle ...
The laminar coat is separable into two layers; the lamina densa and lamina lucida. In between these two layers can be several different types of ions, including calcium. [18] Cardiac muscle like the skeletal muscle is also striated and the cells contain myofibrils, myofilaments, and sarcomeres as the skeletal muscle cell.
Muscles are often classed as groups of muscles that work together to carry out an action. In the torso there are several major muscle groups including the pectoral , and abdominal muscles ; intrinsic and extrinsic muscles are subdivisions of muscle groups in the hand , foot , tongue , and extraocular muscles of the eye .
Each capsule consists of two layers or membranes: an outer (fibrous membrane, fibrous stratum) composed of avascular white fibrous tissue; an inner (synovial membrane, synovial stratum) which is a secreting layer; On the inside of the capsule, articular cartilage covers the end surfaces of the bones that articulate within that joint.
The skeletal system serves as a framework for tissues and organs to attach themselves to. This system acts as a protective structure for vital organs. Major examples of this are the brain being protected by the skull and the lungs being protected by the rib cage. Located in long bones are two distinctions of bone marrow (yellow and red).
At each end of the muscle fibre, the surface layer of the sarcolemma fuses with a tendon fibre, and the tendon fibres, in turn, collect into bundles to form the muscle tendons that adhere to bones. The sarcolemma generally maintains the same function in muscle cells as the plasma membrane does in other eukaryote cells. [4]
Each Haversian canal generally contains one or two capillaries and many nerve fibres. The channels are formed by concentric layers called lamellae , which are approximately 50 μm in diameter . The Haversian canals surround blood vessels and nerve cells throughout bones and communicate with osteocytes (contained in spaces within the dense bone ...
A true endoskeleton is derived from mesodermal tissue. In three phyla of animals, Chordata, Echinodermata and Porifera (), endoskeletons of various complexity are found.An endoskeleton may function purely for structural support (as in the case of Porifera), but often also serves as an attachment site for muscles and a mechanism for transmitting muscular forces as in chordates and echinoderms ...