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Skeletal

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the skeletal system is strong, light, adapted for protection, and adapted for motion axial longitudinal axis appendicular limbs and girdles also includes joints, cartilages, and ligaments

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functions support internal framework, supports/anchors all soft organs protection protect by surrounding softer body organs movement skeletal muscle attach to bones via tendons and are used as levers to move storage fat is found in internal cavities, Ca and P in bone tissue blood cell formation (hematopoiesis) in marrow of some bones

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types compact bone dense and smooth spongy bone small needle-like pieces with open spaces

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classification the shape of each bone determines its function long bones longer than they are wide shaft with a head at each end mostly compact all limb bones except metacarpals and metatarsals short bones generally cube shaped mostly spongy metacarpals and metatarsals

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flat bones thin, flat, and curved 2 thin layers of compact bone with a layer of spongy bone in between skull, ribs, sternum irregular bones do not fit any other category vertebrae and hips bone markings are where muscles/tendons/ligaments attach and where blood vessels/nerves pass

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structure of a long bone diaphysis the shaft mostly compact bone covered with periosteum epiphyses the ends of the long bones thin layer of compact bone surrounding spongy bone covered with cartilage to decrease friction yellow marrow (medullary) cavity storage area of fat tissue in adults contains red marrow in infants that make RBCs

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microscopic anatomy mature bone cells (osteocytes) are found in cavities (lacunae) and secrete a solid matrix lacunae are arranged in a circle (lamella) around a central canals (osteonic canal) several lamella (lamellae) surrounding a single central canal is an osteon canals run lengthwise thru the bone to carry blood vessels and nerves from end to end tiny canals (canaliculi) run horizontally to connect all lacunae allows all osteocytes to be well supplied with nutrients even though the matrix is solid larger canals (perforating) run horizontally between the osteons

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bone formation, growth, and remodeling the skeleton is formed from bone and cartilage 2 of the strongest tissues in the body babies have cartilage that is gradually replaced by bone (ossification) cartilage contains osteoblasts which secretes bone matrix bone matrix replaces cartilage matrix osteocytes replace chondrocytes cartilage becomes bone process is continually repeated result is bone growth to lengthen long bones growth hormone starts the process and sex hormones continue growth during puberty cartilage only remains in ears, nose, ends of ribs, and joints

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bones are continually remodeled to release Ca into the blood Ca levels drop below homeostatic levels parathyroid glands release hormone to activate bone-destroying cells (osteoclasts) bone matrix is broken down to release Ca into the blood to remove Ca from the blood blood Ca levels that are too high cause hypercalcemia Ca is removed from the blood and deposited into bone matrix to retain normal proportions during growth bones become thicker with age bones form larger projections in response to bulkier muscles osteoblasts lay down new matrix, become trapped, and become osteocytes

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Bone Fractures in youth, most fractures/breaks occur from trauma that twists or smashes bones in older adults, bones thin/weaken so fractures are more common fractures are set by reduction and immobilization closed reduction is by external manipulation open reduction is by surgery and requires bone to be pinned/wired hematoma forms where the bone breaks cartilage callus is replaced by osteoblasts and osteocytes to form a spongy bony callus bony callus continually remodeled and strengthened into a permanent patch

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Explain how this picture makes you feel and describe it using vocabulary you have learned about bones, tissues and integument.

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Axial Skeleton forms the longitudinal axis (skull, vertebral column, bony thorax) skull cranium encloses/protects brain frontal bone forehead/brows/superior orbit parietal bones superior and lateral cranium temporal bones inferior to parietal external auditory meatus ear canal styloid process needle-like projection for neck muscle attachments zygomatic process bridge that joins with zygomatic bone to form cheekbones mastoid process contains air cavities and provides attachment site for neck muscles jugular foramen allows for passage of jugular vein carotid canal allows for passage of carotid arteries

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occipital bone floor and back wall of skull foramen magnum passage of spinal cord to the brain occipital condyles rests the skull on the first vertebra sphenoid part of the floor of cranial cavity, part of the orbit ethmoid bone irregular and anterior to sphenoid, forms roof of nasal cavity and medial orbit

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facial bones holds the eyes in position attached to each other with sutures (except mandible) maxillae fuse to form upper jaw, carry teeth in alveolar margin palatine process hard palate zygomatic bones lateral orbits, connect with temporal bones to form cheekbones lacrimal bones medial orbits, groove for tear ducts nasal bones bridge of the nose vomer bone median line in the nasal cavity that forms the septum inferior conchae thin curved bone projecting into the nasal cavity mandible strongest bone of the face, lower jaw

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hyoid bone not a part of the skull be closely related to the mandible and temporal bone only bone not articulated with another bone suspended midneck above the larynx by attachments to the styloid process serves as a movable base for the tongue and attachment site for neck muscles fetal skull regions of skull are not yet ossified and are connected by fibrous membranes (fontanels) fontanels allow fetal brain to grow during late pregnancy and the skull to compress during birth

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vertebral column (spine) made of 26 irregular bones (reinforced by ligaments), the sacrum, and coccyx separated and cushioned by flexible intervertebral discs supports the skull and protects the spine all have 6 common features: body weight-bearing part, anterior side vertebral arch formed from the joining of all extensions vertebral foramen spinal cord canal transverse processes 2 lateral projections spinous process posterior projection superior articular processes projections allowing vertebra to articulate (join) together

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cervical vertebrae (C1-C7) 7 vertebrae in the neck region first is the atlas (supports the skull and allows anterior/posterior movements) second is the axis (allows lateral movements) remaining 5 are smallest and lightest all have transverse foramen for vertebral arteries travelling to the brain

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thoracic vertebrae(T1-T12) next 12 vertebrae from the most superior rib to the most inferior rib designed to articulate with the head of the ribs lumbar vertebrae (L1-L5) lower back massive bodies to withstand heavy stresses

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sacrum fusion of 5 vertebrae articulates with L5 (superior), the coccyx (inferior), and the ilium (laterally) coccyx (tailbone) fusion of 3 to 5 small vertebrae remnant of mammalian tails

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bony thorax (thoracic cage) thoracic vertebrae 12 vertebrae that articulates with the ribs sternum (breastbone) fusion of 3 bones (manubrium, body, and xiphoid process) contains hematopoietic tissue

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ribs 12 pairs that all articulate with the thoracic vertebrae first 7 pairs are true ribs articulate with the sternum by costal cartilage next 5 pairs are false ribs articulate indirectly to sternum or not at all (last 2 pair lack articulation and are floating ribs)

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appendicular skeleton composed of 126 bones of the limbs the pectoral and pelvic girdles (attach the limbs to the axial skeleton)

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pectoral girdle consists of two bones (clavicle, scapula) very light and allows upper limb to have exceptionally free movement attaches to the axial skeleton at only one point (sternoclavicular joint) clavicle is a slender, doubly curved bone attaches to the manubrium of the sternum medially and to the scapula laterally acts as a brace to hold the thorax helps prevent shoulder dislocation

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scapula is triangular not directly attached to the axial skeleton loosely held in place by trunk muscles glenoid cavity is a shallow socket that receives the head of the arm bone (poorly reinforced by ligaments) loose attachment of the scapula allows it to slide back and forth against the thorax

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bones of the upper limbs arm is formed by a single bone (humerus) forearm is formed by two bones (radius and the ulna) (in anatomical position, the radius is lateral and the ulna is medial) hand consists of the carpals, the metacarpals, and the phalanges (carpals form the wrist, metacarpals form the palm, phalanges forms the fingers)

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pelvic girdle is formed by two coxal bones (hip bones) hip bones, sacrum, and coccyx form the bony pelvis each hip bone is formed by the fusion of three bones (ilium, ischium, and pubis) ilium - large, flaring bone, forms most of the hip bone ischium - the most inferior part, receives body weight when sitting pubis - the most anterior part all fuse at a deep socket (acetabulum) that receives the head of the femur

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bones of the lower limbs carry total body weight when standing bones are much thicker and stronger than the comparable bones of the upper limb femur only bone in the thigh heaviest/strongest bone in the body head articulates with the acetabulum neck is a common fracture site slants medially as it turns downward (bring knees in line with the body's center of gravity) tibia is larger, medial, and the proximal end articulates with the distal femur to form the knee fibula lies alongside the tibia, is thin, sticklike, and has no part in forming the knee

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foot is composed of tarsals, metatarsals, and phalanges tarsus (ankle) supports body weight especially the calcaneus (heel) and talus serves as a lever that propels the body forward when walking/running bones are arranged to form three strong arches two longitudinal (medial and lateral) and one transverse ligaments/tendons hold bones firmly in the arched position but allow movement

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joints (articulations) with one exception (hyoid) every bone forms a joint with at least one other bone two functions - hold the bones together securely / give the rigid skeleton mobility classified in two ways - functionally and structurally

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functional - focuses on the amount of movement freely movable joints (limbs) immovable / slightly movable joints (axial skeleton)

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structural - fibrous, cartilaginous, and synovial joints fibrous immovable cartilaginous bone ends connected by cartilage slightly movable (intevertebral joints) synovial surfaces enclosed by a capsule of tissue and ligaments are freely movable more flexibility than other joint types (flexibility varies slightly)

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inflammatory disorders of joints bursitis - inflammation of bursae or synovial membrane sprain - ligaments / tendons are damaged by excessive stretching or torn away from the bone arthritis - over 100 different inflammatory or degenerative diseases that damage the joints acute forms of arthritis usually result from bacterial invasion (treated with antibiotics) chronic forms of arthritis osteoarthritis - usually slow / irreversible, rarely crippling rheumatoid arthritis - autoimmune disease, cartilage is destroyed, scar tissue forms, bone ends connect, scar tissue ossifies, bone ends become fused gouty arthritis - uric acid accumulates in blood, may be deposited as crystals in the soft tissues of a single joint

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