Skeletal

Skeletalthe skeletal system is strong, light, adapted for protection, and adapted for motionaxial longitudinal axisappendicular limbs and girdlesalso includes joints, cartilages, and ligaments

functionssupport internal framework, supports/anchors all soft organsprotection protect by surrounding softer body organsmovement skeletal muscle attach to bones via tendons and are used as levers to movestorage fat is found in internal cavities, Ca and P in bone tissueblood cell formation (hematopoiesis) in marrow of some bones

typescompact bone dense and smoothspongy bone small needle-like pieces with open spaces

classificationthe shape of each bone determines its functionlong bones longer than they are wideshaft with a head at each endmostly compactall limb bones except metacarpals and metatarsalsshort bones generally cube shapedmostly spongymetacarpals and metatarsals

flat bones thin, flat, and curved2 thin layers of compact bone with a layer of spongy bone in betweenskull, ribs, sternumirregular bones do not fit any other categoryvertebrae and hipsbone markings are where muscles/tendons/ligaments attach and where blood vessels/nerves pass

structure of a long bonediaphysis the shaftmostly compact bonecovered with periosteumepiphyses the ends of the long bonesthin layer of compact bone surrounding spongy bonecovered with cartilage to decrease frictionyellow marrow (medullary) cavity storage area of fat tissue in adultscontains red marrow in infants that make RBCs

microscopic anatomymature bone cells (osteocytes) are found in cavities (lacunae) and secrete a solid matrixlacunae 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 endtiny canals (canaliculi) run horizontally to connect all lacunaeallows all osteocytes to be well supplied with nutrients even though the matrix is solidlarger canals (perforating) run horizontally between the osteons

bone formation, growth, and remodeling

the skeleton is formed from bone and cartilage2 of the strongest tissues in the bodybabies have cartilage that is gradually replaced by bone (ossification)cartilage contains osteoblasts which secretes bone matrixbone matrix replaces cartilage matrixosteocytes replace chondrocytescartilage becomes boneprocess is continually repeatedresult is bone growth to lengthen long bonesgrowth hormone starts the process and sex hormones continue growth during pubertycartilage only remains in ears, nose, ends of ribs, and joints

bones are continually remodeled to release Ca into the bloodCa levels drop below homeostatic levelsparathyroid glands release hormone to activate bone-destroying cells (osteoclasts)bone matrix is broken down to release Ca into the bloodto remove Ca from the bloodblood Ca levels that are too high cause hypercalcemiaCa is removed from the blood and deposited into bone matrixto retain normal proportions during growthbones become thicker with agebones form larger projections in response to bulkier musclesosteoblasts lay down new matrix, become trapped, and become osteocytes

Bone Fracturesin youth, most fractures/breaks occur from trauma that twists or smashes bonesin older adults, bones thin/weaken so fractures are more commonfractures are set by reduction and immobilizationclosed reduction is by external manipulationopen reduction is by surgery and requires bone to be pinned/wiredhematoma forms where the bone breakscartilage callus is replaced by osteoblasts and osteocytes to form a spongy bony callus bony callus continually remodeled and strengthened into a permanent patch

Explain how this picture makes you feel and describe it using vocabulary you have learned about bones, tissues and integument.Axial Skeletonforms the longitudinal axis (skull, vertebral column, bony thorax)skullcraniumencloses/protects brainfrontal bone forehead/brows/superior orbitparietal bones superior and lateral cranium temporal bones inferior to parietal external auditory meatus ear canalstyloid process needle-like projection for neck muscle attachmentszygomatic process bridge that joins with zygomatic bone to form cheekbonesmastoid process contains air cavities and provides attachment site for neck musclesjugular foramen allows for passage of jugular veincarotid canal allows for passage of carotid arteriesoccipital bone floor and back wall of skullforamen magnum passage of spinal cord to the brainoccipital condyles rests the skull on the first vertebrasphenoid part of the floor of cranial cavity, part of the orbitethmoid bone irregular and anterior to sphenoid, forms roof of nasal cavity and medial orbit

facial bonesholds the eyes in positionattached to each other with sutures (except mandible)maxillae fuse to form upper jaw, carry teeth in alveolar marginpalatine process hard palatezygomatic bones lateral orbits, connect with temporal bones to form cheekboneslacrimal bones medial orbits, groove for tear ductsnasal bones bridge of the nosevomer bone median line in the nasal cavity that forms the septuminferior conchae thin curved bone projecting into the nasal cavitymandible strongest bone of the face, lower jawhyoid bonenot a part of the skull be closely related to the mandible and temporal boneonly bone not articulated with another bonesuspended midneck above the larynx by attachments to the styloid processserves as a movable base for the tongue and attachment site for neck musclesfetal skullregions 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

vertebral column (spine)made of 26 irregular bones (reinforced by ligaments), the sacrum, and coccyxseparated and cushioned by flexible intervertebral discssupports the skull and protects the spine all have 6 common features:body weight-bearing part, anterior sidevertebral arch formed from the joining of all extensionsvertebral foramen spinal cord canaltransverse processes 2 lateral projectionsspinous process posterior projectionsuperior articular processes projections allowing vertebra to articulate (join) together

cervical vertebrae (C1-C7)7 vertebrae in the neck regionfirst is the atlas (supports the skull and allows anterior/posterior movements)second is the axis (allows lateral movements)remaining 5 are smallest and lightestall have transverse foramen for vertebral arteries travelling to the brain thoracic vertebrae(T1-T12)next 12 vertebraefrom the most superior rib to the most inferior ribdesigned to articulate with the head of the ribs lumbar vertebrae (L1-L5)lower backmassive bodies to withstand heavy stresses sacrumfusion of 5 vertebraearticulates with L5 (superior), the coccyx (inferior), and the ilium (laterally) coccyx (tailbone)fusion of 3 to 5 small vertebraeremnant of mammalian tails

bony thorax (thoracic cage) thoracic vertebrae12 vertebrae that articulates with the ribssternum (breastbone)fusion of 3 bones (manubrium, body, and xiphoid process)contains hematopoietic tissue

ribs12 pairs that all articulate with the thoracic vertebraefirst 7 pairs are true ribs articulate with the sternum by costal cartilagenext 5 pairs are false ribs articulate indirectly to sternum or not at all(last 2 pair lack articulation and are floating ribs)

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

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

scapula is triangular not directly attached to the axial skeletonloosely held in place by trunk musclesglenoid 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

bones of the upper limbsarm 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)

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

bones of the lower limbscarry total body weight when standingbones are much thicker and stronger than the comparable bones of the upper limb femur only bone in the thighheaviest/strongest bone in the bodyhead articulates with the acetabulumneck is a common fracture siteslants 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

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

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

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

structural - fibrous, cartilaginous, and synovial jointsfibrous immovablecartilaginous bone ends connected by cartilageslightly movable (intevertebral joints)synovial surfaces enclosed by a capsule of tissue and ligamentsare freely movablemore flexibility than other joint types (flexibility varies slightly)

inflammatory disorders of jointsbursitis - inflammation of bursae or synovial membranesprain - ligaments / tendons are damaged by excessive stretching or torn away from the bonearthritis - over 100 different inflammatory or degenerative diseases that damage the jointsacute forms of arthritis usually result from bacterial invasion (treated with antibiotics)chronic forms of arthritisosteoarthritis - usually slow / irreversible, rarely cripplingrheumatoid 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