Joints Articulations 3 functional classes of joints o Synarthrotic joints A nonmovable joint All are composed of dense fibrous CT Ex skull sutures teeth in sockets 4 types Suture o Fibrous joint o Adjacent bones in cranium Gomphosis o Fibrous joint o Teeth in sockets Synchondrosis o Hyaline cartilaginous joint o Joint between epiphyses and diaphysis of growing bones Synostosis bony joint o Occurs when two bones fuse and the joint becomes a o When ossification occurs with age between some cranial sutures in the epiphyses and diaphysis of long bones o Amphiarthrotic joints A slightly moveable joint Connected by Dense fibrous CT Cartilage 3 types Syndesmosis o Ligaments between distal end of tibia and fibula o Hyaline cartilage connecting the ribs to the sternum o Most moveable o Fibrous joint 2 bones bound by ligament o Ex distal radius and ulna Synchondrosis Symphysis o Bones bound by hyaline cartilage o Ex rib attachment to sternum o Least moveable o Bones jointed by fibrocartilage o Ex pubic symphysis o Diarthrotic joints A freely moveable joint Ex shoulder elbow carpal joints All are synovial joints Joint in which 2 bones are separated by a space in a joint called a Fibrous capsule the outer part of the synovial joint fused with cavity ligaments Synovial membrane inside the capsule and secretes synovial fluid Synovial fluid lubricates articular cartilage to reduce friction Synovial cavity the space inside the joint between the two articulating bones Articular cartilage hyaline cartilage that covers the ends of the bones in the synovial cavity 3 structural classes of joints o Fibrous joints Collagen fibers span the space between joints Ex skull sutures teeth in sockets Bones joined by fibrous dense regular CT very strong No joint cavity 3 types Sutures o Present only in the skull short fibrous material connecting adjacent cranial bones o Amphiarthrotic joints in the skull of a child because this allows for growth and expansion of the brain to reach the normal brain size of about 3 5 pounds When average size is reached sutures ossify Dense regular CT Bone tissue o The ossified suture is known as synostoses These are synarthrotic joints The cranial bones are not moveable forming a cranial vault to protect the brain Syndesmoses o 2 types Gomphoses Chord of dense fibrous CT ligament Synarthrotic joints Membranous dense fibrous CT interosseous membrane Amphiarthrotic joints between ulna and radius allowing for pronation o Short fibrous chords known as periodontal ligaments Connect the cementum around the root of the tooth to the alveolar socket in the mandible maxilla o Amphiarthrotic joints in a child milk teeth This allows for movement and eventually the loss of the deciduous teeth When amphiarthrotic in older people periodontal disease of tooth loss occurs o Synarthrotic joints in permanent teeth o Cartilaginous joints 2 bones are bound to each other by cartilage No joint cavity Ex intervertebral discs 2 types Synchondroses o Synarthrotic joints Cartilaginous joints with bones connected by hyaline cartilage not moveable Symphyses o Amphiarthrotic joints Cartilaginous joints with bones connected by fibrocartilage The epiphyseal plate is an example of which type of cartilaginous joints What type of cartilaginous joints are the intervertebral discs Synchondosis Symphysis o Synovial joints Bones are held together by ligaments Has a joint cavity which allows for movement of the bones at the joint site filled with synovial fluid which as a lubricant for bones to move at joints All are diarthrotic some are more moveable than others Ex shoulder elbow knee 6 types o Both bone 1 2 are flat bones o Gliding movement Plane joints Hinge joints Pivot joints o Bone 1 is trough bone 2 has a cylindrical projection o Flexion extension o Bone 1 has a rounded protrusion bone 2 has a ring sleeve o Allows for rotation in order to do no motion o Atlanto axial joint Condyloid joints depression Saddle joints o Bone 1 has an oval protrusion bone 2 has an oval o Allows for head to move up and down in yes motion o Atlanto occipital joint o Bone 1 concave convex bone 2 convex concave Bone 1 and 2 never have the same thing its one or the other o Carpometacarpal joint of the thumb only example in human body Ball and socket joints Arthritis a disease characterized by inflammation of synovial membranes that causes o Bone 1 has a spherical head bone 2 as a cuplike socket o All movements are allowed ex shoulder stiff and painful joints Muscular System Neuromuscular junction o Forms between the axon terminal and the motor end plate of the sarcolemma of skeletal muscle fiber No direct contact because there s a gap called the neuromuscular cleft which is filled with extracellular fluid from the interstitial cells o Motor end plate highly involuted region of sarcolemma which has the highest number of acetylchlorine receptors o When motor neuron is activated the axon generates and translates electrical signals called action potentials that will travel down the axon to axon terminals Axon terminals release the neurotransmitter acetylchlorine into the neurotransmitter cleft Acetylcholade binds to receptors at the motor end plate to initiate an action potential that will travel across the entire sarcolemma o Action potential travels into t tubules of triad and the electrical signal causes Ca2 to be released from the terminal cisternae of SR Ca2 released from SR into the sarcoplasm is required for skeletal muscle contraction SR is well developed and stores more Ca2 than required for contraction How do skeletal muscles attach to structures in the skeletal system o Indirect attachment The epimysium of the skeletal muscle is extended by a tendon which attaches the skeletal muscle to the surface of a bone 99 9 of skeletal muscles are attached like this Advantages of indirect attachment Allows for more skeletal muscle to be attached to the bone because better packaging o Agonistic synergistic and antagonistic muscles have to be attached to the same bone Allows for bones to act as levers when skeletal muscles contract Prevents direct contact between rough surface of bone and skeletal muscle Protection movements better packaging The epimysium fuses directly with the fibrous layer of the periosteum of Different aspects of skeletal muscle fiber o Myofibrils arranged in an alternating pattern inside resulting in striations of o Direct attachment the bone skeletal muscle Run the entire length of skeletal muscle fiber and is composed
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