A&P Chapter 5 Skeletal System and Articulations
1. List the skeletal system functions.
---support, protection, movement, storage, and blood cell
formation
2. Outline the divisions of the skeleton.
---axial skeleton consists of bones that form the longitudinal
axis of the body (skull, bones associated with skull,
thoracic cage, and vertebral column)
---appendicular skeleton includes all the bones of the limbs
and the pectoral and pelvic girdles that attach limbs to the
trunk
3. Summarize bone functions.
---support: bones form internal framework that supports and
anchors all soft organs; steel girders and reinforcing
concrete of the body
---protection: bones protect soft body organs
---movement: skeletal muscles attached to bones by tendons
use bones as levers to move body and its parts
---storage: bones used to store fat and minerals (calcium
and phosphorus most important)
---blood cell formation (hematopoiesis): occurs within marrow
cavities of certain bones
4. Outline the storage function of bones.
---bones store fat in internal cavities
---also store calcium, phosphorus, and other minerals
---bone is continually being built up and torn down depending
on needs of body
--under control of hormones
5. Outline the classification of bones.
---two basic types of osseous or bone tissue
--compact bone is dense and looks smooth and homogeneous
--spongy bone composed of small needlelike pieces of bone and
lots of open spaces
---bones are classified according to SHAPE
---Long bones typically longer than they are wide
--have shaft with heads at both ends
--mostly compact bone
--all bones of limbs (except wrist & ankle bones)
---Short bones generally cube-shaped and contain mostly
spongy bone
--bones of wrist and ankle are short bones
---Flat bones are thin, flattened, and usually curved
--have two layers of compact bone sandwiching layer of
spongy bone between
--most bones of skull, ribs, and sternum are flat bones
---Irregular bones are those that do NOT fit one of categories
discussed above
--vertebrae and hip bones are irregular bones
6. Describe the gross anatomy of long bone: Diaphysis,
periosteum, epiphyses, articular cartilage, epiphyseal plate,
epiphyseal line, and medullary cavity.
---diaphysis (or shaft) makes up most of long bone’s length and
is composed of compact bone
---periosteum is fibrous connective tissue membrane that covers
and protects the diaphysis
--100s of connective tissue fibers (Sharpey’s fibers) secure
periosteum to underlying bone
---epiphyses are the ends of the long bone
--each epiphysis consists of layer of compact bone enclosing
area filled with spongy bone
---articular cartilage covers external surface of the epiphysis
(instead of the periosteum that covers the shaft)
--articular cartilage is glassy hyaline cartilage, provides
smooth, slippery surface that decreases friction at joint
surfaces
---epiphyseal plate is flat plate of hyaline cartilage seen
in young, growing bone
--cause the lengthwise growth of a long bone
--by end of puberty, hormones stop long bone growth and
epiphyseal plates have been completely replaced by bone
---epiphyseal line is thin line of bony tissue spanning the
epiphysis and appears quite different from rest of bone there
--epiphyseal line is remnant of epiphyseal plate
--epiphyseal line marks previous location of epiphyseal plate
---medullary cavity is cavity of the shaft of long bones
--also called yellow marrow cavity
--in adults, primarily storage area for adipose (fat) tissue
7. Discuss the locations of red marrow.
---medullary cavity of long bones of infants contains “red
marrow” and blood cells are formed there
---in adults, red marrow confined to cavities of spongy
bone of flat bones and the epiphysis of some long bones
8. Describe the microscopic anatomy of hard bone: Osteon,
Haversian Canal, lamellae, osteocytes, lacunae, canaliculi, and
Volkmann’s Canals.
---compact bone (hard bone) riddled with passageways carrying
nerves and blood vessels which provide living bone cells
with nutrients and route for waste disposal
---osteon is complex of central canal and matrix rings (also
called Haversian system)
---osteocytes are mature bone cells
---lacunae are tiny cavities within the matrix that contain
osteocytes
---lamellae is term given the concentric circles around
Haversian Canal containing the lacunae
---Haversian Canal is another name from ‘central canal”
--central canals run lengthwise through bony matrix carrying
blood vessels and nerves to all areas of bone
---canaliculi are tiny canals that radiate outward from the
central canal to all lacunae
--form transport system that connects all bone cells to
nutrient supply through hard bone matrix
---Volkmann’s canals (perforating canals) run into compact bone
at right angles to the shaft
--part of communication pathway from outside of bone to
its interior
9. Using a flow chart, describe circulation in a bone.
---observe and discuss overhead # 5.3
10. Discuss ossification: Two types and the function of
osteoblasts.
---ossification is the process of bone formation
---there are two major forms (types) of ossification
--intermembranous where bone develops from mesenchyme
or fibrous connective tissue (roofing bones of skull,
mandible, and clavicle
--endochondral occurs when bone replaces existing cartilage
---except for flat bones which form on fibrous membranes, most
bones develop using hyaline cartilage structures as their
models
---endochondral ossification involves two major steps
---first, hyaline cartilage model is completely covered with
bone matrix by bone forming cells called osteoblasts
---then, enclosed hyaline cartilage model is digested away
--opens up medullary cavity within newly formed bone
11. Discuss bone destruction: Osteoclasts, related hormones, and
relation to blood calcium.
---bones are continually remodeled in response to changes in two
factors
--calcium levels in the blood
--pull of gravity and muscles on the skeleton
---if blood levels of calcium drop below homeostatic levels,
parathyroid glands release parathyroid hormone (PTH) into
blood
---PTH activates osteoclasts (giant bone-destroying cells in
bones) to break down bone matrix and release the calcium ions
into the blood
---hypercalcemia (too much calcium in blood) results in calcium
being deposited in bone matrix as hard calcium salts
---bone remodeling essential if bones are to retain normal
proportions and strength during maturation process
--bones become thicker and form large projections in areas
where bulky muscles are attached
---at such sites, osteoblasts deposit new matrix and become
trapped, differentiate into osteocytes (mature bone cells)
---**PTH determines when or if bone is to be broken down or
formed in response to need for more or fewer calcium ions
in the blood
---**stresses of muscle pull and gravity acting on skeleton
determine where bone matrix is to be broken down or formed
12. Summarize the steps in fracture repair.
---repair of bone fractures (breaks) involves four major events
---(1) blood vessels are ruptured when the bone breaks resulting
in blood-filled swelling called a hematoma
--bone cells deprived of nutrition die
---(2) new capillaries (granulation tissue) grow into clotted
blood at site of damage
--connective tissue cells of all types form mass of repair
tissue called fibrocartilage callus (cartilage matrix, some
bony matrix, and collagen fibers), which acts to “split”
the broken bone, closing the gap
---(3) bony callus formed as more osteoblasts and osteoclasts
migrate into area and multiply
--fibrocartilage gradually replaced by bony callus (callus
made of spongy bone)
---(4) bony callus remodeled in response to mechanical stresses
placed upon it
--forms a strong permanent patch at fracture site
13. Distinguish the synarthroses, amphiarthroses, and
diarthroses.
---joints are classified in two major ways: functionally
and structurally
---functional classification focuses on amount of movement
allowed by the joint
---synarthroses are immovable joints (between bones of skull)
---amphiarthroses are slightly moveable joints (between adjacent
vertebrae at intervertebral disc)
---diarthroses are freely moveable joints (shoulder/elbow/ankle)
---freely moveable joints predominate in the limbs
---immovable and slightly moveable joints restricted to
axial skeleton where firm attachments and protection
of internal organs are priorities
14. Describe the general diarthrotic joint: Articular cartilage,
capsule, cavity, and reinforcing ligaments.
---as general rule, synovial joints (joint cavity) are freely
moveable (diarthrotic)
---synovial joints are joints in which articulating bone ends
are separated by joint cavity containing synovial fluid
---articular (hyaline) cartilage covers the ends of the bones
forming the joint
---fibrous articular capsule: joint surfaces enclosed in sleeve
or capsule of fibrous connection tissue and capsule is lined
with smooth synovial membrane
---joint cavity: articular capsule encloses a cavity (joint
cavity) which contains lubricating synovial fluid
---reinforcing ligaments: fibrous capsule reinforced with
ligaments
--bursae (fluid-filled synovial membrane sacs) often cushion
tendons where they cross bone
15. Distinguish osteoarthritis, rheumatoid arthritis, and gouty
arthritis.
---arthritis term given over 100 different inflammatory or
degenerative diseases that damage the joints
---osteoarthritis is most common form of arthritis; chronic
degenerative condition that typically affects the aged
---also called “wear and tear” arthritis
---over years, cartilage softens, frays, and breakdowns and
and exposed bone thickens; extra bone tissue (bone spurs)
grows around margins of eroded cartilage
---bone spurs protrude into joint cavity, restricting movement
---most commonly affects fingers, cervical/lumbar joints of
spine, and knees and hips
---progression slow, and rarely crippling
---aspirin, exercise, and rest
---rheumatoid arthritis is chronic inflammatory disorder that
is an autoimmune disease
--usually occurs between ages of 40 and 50
--affects 3x as many women as men
--fingers, wrists, ankles, and feet usually affected
--course varies with remissions and flareups
---begins with inflammation of synovial membranes
--joints swell as fluid accumulates
--WBCs enter joint and produce pannus (abnormal tissue
that clings to and erodes articular cartilages)
--cartilage destroyed and scar tissue forms and connects
bone ends
--scar tissue ossifies and bone ends become firmly fused
(ankylosis) and often deformed
---aspirin, exercise, cold packs, heat, methotrexate and
cyclosporin (anti-inflammatory drugs), and joint
replacement
---gouty arthritis (gout)is disease in which urea acid deposited
as needle-shaped crystals in soft tissues of joints
---very painful and very destructive
--bones ends fuse and joint becomes immobilized
--treated with colchicine and other drugs
---patients advised to lose weight, restrict intake of liver
kidneys, and sardines (rich in nucleic acids) and avoid
alcohol (inhibits secretion of uric acid by kidneys)
16. Describe rickets.
---rickets is disease of children when bones fail to calcify
---bones soften and bow where weight-bearing (legs)
---usually due to lack of calcium in diet or lack of vitamin
D which is need to absorb calcium into bloodstream
---not very common in US but still problem in some parts of
world
17. Describe osteoporosis.
---osteoporosis is a loss of bone mass leading to thin, fragile
bones
--especially in spine and neck of femur
---estrogen deficiency at menopause strongly implicated
---diet poor in calcium, lack of vitamin D, smoking, and
insufficient weight-bearing exercise to stress bones also
factors
18. Locate the following cranial bones: Frontal, parietals,
temporal, and occipital.
---observe and study overhead 5.7
19. Locate the following facial bones: Mandible, maxillae,
zygomatic, and lacrimal.
---observe and study overhead 5.11
20. Define fontanels.
---fontanels are the fibrous membranes connecting the cranial
bones of a newborn
--anterior, posterior, mastoid, and sphenoidal
--allow fetal skull to be compressed during delivery
--flexible so allow infant’s brain to grow during later
part of pregnancy and early infancy
--converted to bone during early part of infancy
-no longer can be felt 22 to 24 months after birth
21. Distinguish scoliosis, kyphosis, and lordosis.
---several abnormal distortions of spinal curvature may
appear during childhood and adolescence
---scoliosis is an abnormal lateral curvature
---kyphosis is an exaggerated thoracic curvature
---lordosis is an exaggerated lumbar curvature
22. Name the five regions of the vertebral column.
---cervical (7), thoracic (12), lumbar (5), sacrum
(5 fused), and coccyx (4 fused)
---observe and study overhead 5.14
23. Name the three bones of the sternum.
---sternum (breastbone) is typical flat bone resulting
from fusion of three bones
---manubrium, body, and xiphoid process
---sternum attached to first seven pairs of ribs
---observe and study overhead 5.19
24. Distinguish true, false, and floating ribs.
---twelve pairs of ribs form walls of thoracic cage
---all ribs articulate with vertebral column posteriorly
---true ribs are first seven pairs which attach directly to
sternum by costal cartilages
---false ribs are next five pairs which either attach
indirectly to sternum or are NOT attached to sternum
---floating ribs are last two pairs of false ribs
--lack sternal attachments
---intercostal spaces (spaces between ribs) filled with
intercostal muscles that aid in breathing
---observe and study overhead 5.19
25. Locate the clavicle and scapula.
---observe and study overhead 5.20
26. Locate the humerus, radius, ulna, carpals, metacarpals, and
phalanges.
---observe and study overhead 5.6
---observe and study overhead 7.1 A & B
27. Locate the sacrum, ilium, ischium, and pubis.
---observe and study overheads 5.23 A, B, & C
28. Distinguish the male pelvis from the female pelvis.
---female inlet is larger and more circular
---female pelvis is shallower and bones are lighter and thinner
---female ilia flare more laterally
---female sacrum shorter and less curved
---female ischial spines shorter and further apart thus
outlet is larger
---female pubic arch more rounded because angle of pubic arch
is greater (> 90o)
29. Locate the femur, tibia, fibula, tarsals, calcaneus,
metatarsals, and phalanges.
---observe and study overhead 5.6
---observe and study overhead 7.1 A & B
---calcaneus (heel bone) is largest of the tarsal bones
and is not visible in the available overheads
30. Distinguish the various types of articulations on the basis
of degree of movement.
---restatement of IO #13
31. List one example of each type of articulation.
---restatement of IO #13
32. and 33. Already covered in IO’s 14, 15, 16, & 17