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Chapter 7

Chapter 7 . Skeletal System. Vocab. Osteoblast – bone-forming cells Osteoclast – cell that erodes bone Osteocyte – mature bone cell . 7.2 Bone Structure. Parts of a long bone: Epiphysis – expanded portion at the end of the bone, forming the joint (articulates) with another bone.

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Chapter 7

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  1. Chapter 7 Skeletal System

  2. Vocab • Osteoblast – bone-forming cells • Osteoclast – cell that erodes bone • Osteocyte – mature bone cell

  3. 7.2 Bone Structure • Parts of a long bone: • Epiphysis – expanded portion at the end of the bone, forming the joint (articulates) with another bone. • Articular Cartilage – cartilage coating the for the epiphysis • Diaphysis – the shaft of the bone • Periosteum – tissue that encloses the bone, helps form and repair bone tissue.

  4. 7.2 Bone Structure • Inside the long bone: • The wall of the diaphysis is mainly composed of tightly packed tissue called compact bone. • Compact bone– has a continuous matrix with no gaps. • Medullary cavity - semirigid tube with a hollow chamber; spongy bone lines it. • Endosteum – thin layer of cells line the cavity, marrow fills the cells. • Epiphyses is composed of spongy bone. • Spongy bone – consists of numerous branching bony plates.

  5. 7.2 Bone Structure (Microscopic) • Osteocytes (bone cells) are located in lacunae (small chambers) which form circles around Haversian canals (osteoniccanals aka) • The osteocytes communicate with other cells by cellular processes passing through canaliculi • Osteocytes clustered around a haversian canal form a Haversian system (aka osteon system) . • Many of these units cemented together form compact bone • Osteonic canals hold blood vessels and nerve fibers. They connect the larger cannals, Volkmann’s canals which hold larger blood vessels.

  6. 7.3 Bone Development and Growth • Bones begin developing within the first two weeks of prenatal development. • They form by replacing existing connective tissue in two ways: • Intramembranous bones originate between sheetlike layers of connective tissue • Endochondral bones begin as masses of cartilage that bone tissue later replaces.

  7. 7.3 Bone Development and Growth • Intramembranous Bones • The broad, flat bones of the skull • Membranelike layers of connective tissue are the site of future bones. • Primitive connective tissue cells enlarge and turn into bone-forming cells osteoblasts. • The osteoblasts become active within the membranes and deposit bony matrix • Eventually the cells give rise to periosteum and osteoblasts give rise to spongy bone.

  8. 7.3 Bone Development and Growth • Endochondral Bones • All other bones • Develop from masses of hyaline cartilage shaped like future bones • Primary ossification center =development of the shaft of the bone • Secondary ossification center = development of the ends of the bone. • Epiphyseal disks (growth plate)= keep the two ossification centers separate • Increases bone length as cells ossify • Cartilage becomes osteoblasts becomes osteocytes

  9. 7.3 Bone Development and Growth • Homeostasis of bone tissue • After bones are formed, they are continually remodeled by the osteoclasts and osteoblasts • Osteoclasts = resorb bone matrix (resorption) • Osteoblasts = replace it (deposition)

  10. Repair of a Bone Fracture • Read 136-137

  11. 7.4 Functions of Skeletal System • Bones are made of Osseous Tissue • Function of Skeletal System: • Support and protection • Body movement • Blood Cell formation (marrow) • Storage of inorganic materials • salt, calcium, potassium

  12. 7.5 Skeletal Organization • Two portions: • Axial skeleton: head, neck, and trunk • Appendicular skeleton: limbs

  13. 7.5 Skeletal Organization - Axial • Skull = cranium (brain case) and the facial bones • Hyoid bone = located between the lower jaw and larynx; helps move the tongue and aids in swallowing • Vertebral Column = consists of vertebrae, sacrum, coccyx • Thoracic cage = protects organs of the thoracic cavity and the upper abdominal cavity. Consists of ribs, sternum

  14. 7.5 Skeletal Organization – Appendicular • Pectoral girdle – scapula and a clavicle • Upper limbs – humerus, radius, ulna, carpals, metacarples, phalanges • Pelvic girdle – coxalbones (hip bones) pelvis (coxal + scarum + coccyx) • Lower limbs – femur, tibia, fibula, patella, tarsals, metatarsals, phalanges

  15. Skull Vocab • Foramen = any tiny opening, specifically for blood vessels or nerves supplying to the face • Suture = connection of large bones • Coronal – Frontal and parietal bone • Lambdoidal – occipital and parietal bone • Squamosal – temporal and parietal bone • Sagittal – between parietal bones • Fissure = any wide gap between bones

  16. 7.6 Skull • Contains 22 bones, 8 of which make up cranium, 13 form facial skeleton. • The mandible is the only bone that is not interlocked, and instead moves • The skull contains paranasal sinuses which reduce the skull’s weight and increase voice intensity. They are lined with mucous membranes • The 8 cranium bones are: • Frontal bone • Parietal bone (2) • Occipital bone • Temporal bone (2) • Sphenoid bone • Ethmoid bone

  17. 7.6 Skull – Cranium • Frontal bone – forms anterior portion of the skull above the eyes. Contains two frontal sinuses and the supraorbital foramen through which blood vessels and nerves pass • Parietal bone – one on each side of the skull just behind the frontal bone. The sagittal suture fuse the midline, and the coronal suture fuses the parietal with the frontal bone • Occipital bone – jones the parietal bones along the lambdoidal suture. The foramen magnum is a large opening which allows nerves to pass from the brain to the spinal cord.

  18. 7.6 Skull – Cranium • Temporal bones – joins the parietal bone along a squamosal suture, helps articulate the mandible • Mastoid process = attachment for certain muscles of the neck • Styloid process = anchors muscles associated with the tongue and pharynx • Sphenoid bone – wedged between several other bones, contains spenoidal sinuses • Ethmoid bone – consists of two masses that make the roof of the nasal cavity.

  19. 7.6 Skull – Facial • Thirteen immovable and one movable bone • Maxillae – forms the upper jaw, comprise the anterior roof of the mouth, floors of the orbits, sides and floor of nasal cavity, sockets of upper teeth. • Palatine bones– L-shaped behind the maxillae • Zygomaticbones – cheek bones • Lacrimal bones – thin, scalelike structure located in the medial wall of each orbital • Nasal bones – long, thin, retangular, bridges of the nose • Vomer bones – thin, flat • Inferior nasal conchae – support mucous membranes within the nasal cavity • Mandible

  20. 7.7 Vertebral Column • Composed of vertebrae and those are separated by intervertebral disks. • Supports head and trunk and protects spinal cord • Three parts of the column • Cervical vertebrae = neck • Atlas – supports the head • Axis – allows head to turn side to side because of dens • Thoracic vertebrae = middle back • Larger than cervical, long pointed spinous process, facets on the sides of its body to articulate ribs • Lumbar vertebrae = lower back • Smallest of the vertebrae • Sacrum = composed of five fused vertebrae and forms base of column • Coccyx = lowest part of the vertebral column, four fused vertebrae

  21. 7.7 Vertebral Column • Parts of an individual vertebra: • Body = thick, anterior portion, supports the weight • Pedicles = 2 short stalks • Laminae = 2 fuse in the back • Be able to tell the difference between the three parts of the column

  22. 7.8 Thoracic Cage • Includes: ribs, thoracic vertebrae, sternum, costal cartilage that attach the ribs to the sternum • Ribs: • 12 ribs (usually) one pair attached to each thoracic vertebra • True ribs = first 7 join the sternum directly by costal cartilage • False ribs = remaining 5 their cartilage does not reach the sternum, 3 join the other 7’s cartilage and 2 are “floating ribs” • Sternum • Has three parts: manubrium (articulates with the clavicle), body (mid-section), xiphoid process (pointy part)

  23. 7.9 Pectoral Girdle • Includes: two clavicles and two scapulae • Clavicles • S-shaped bones that brace the freely movable scapulae, helping to hold shoulder in place • Attachment site for muscles of upper limbs, chest, and back • Scapulae • Spine divides the posterior surface of each scapula • Spine has two processes: • Acromion – tip of shoulder • Coracoid – curves to clavicle • Glenoid Cavity = depression that articulates with the head of the arm bone

  24. 7.13 Joints ***Table 7.4*** • Joints = a functional junction between bones • Classified according to the degree of movement they make possible. (Immovable, slightly movable, freely movable) • Classified by the type of tissue (fibrous, cartilaginous, synovial)

  25. 7.13 Joints • Fibrous Joints • Lie between bones that closely contact one another • Limited to no movement • Dense connective tissue • Ex: suture between a pair of flat bones of the skull • Cartilaginous Joints • Fibrocartilage or hyaline cartilage connect bones of this type of joint • Limited movement • Ex: joints that separate the vertebrae

  26. Joints • Synovial Joints • Most common type of joint • Free movement • Hyaline cartilage cover the ends of the bones, and dense connective tissue holds them together. • Joint capsule = composed of outer layer of ligaments and an inner lining of synovial membrane, (secretes synovial fluid which lubricates the joint) • Figure 7.34

  27. Joints • Types of synovial joints: • Ball and socket joint = ball shaped head articulates with a cup-shaped cavity of another bone. • Full range of motion • Ex: shoulder, hip • Condyloid joint = oval-shaped condyle of one bone fits into a elliptical cavity of another bone • Lots of movement except rotational • Ex: metacarples and phalanges • Gliding joint = articulating surfaces are nearly flat • Sliding or twisting movement • Ex: wrist and ankle • Hinge joint = convex surface of one bone, fits into the convex surface of another (door) • Elbow • Pivot joint = cylindrical surface of one bone rotates within a ring formed of bone or ligament • Rotation around a center axis only • Radius and ulna • Saddle = surface of one bone fits the complementary surface of another • Variety of movements • Ex: = carpal and metacarpal of the thumb

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