Chapter 5: The Skeletal System
Bones: An Overview – pg 116-124

Identify the subdivisions of the skeleton as axial or appendicular.
Axial – forming the longitudinal axis of the body
Appendicular – forming the limbs and girdles
http://www.nd.edu/~nsfbones/APPENDICULAR.pdf
(includes joints, cartilages and ligaments)

List at least three functions of the skeletal system.
Support, protection, movement, storage, blood cell formation
(hematopoiesis) in marrow

Name the four main kinds of bones (206).
Types: Compact or spongy bone
http://www.britannica.com/EBchecked/topic/72869/bone/41884/Fourtypes-of-cells-in-bone
http://eugraph.com/histology/crtbone/compbon.html
http://www.google.com/imgres?imgurl=http://silver.neep.wisc.edu/~lakes/B
oneSpongy.jpg&imgrefurl=http://silver.neep.wisc.edu/~lakes/BoneTrab.ht
ml&usg=__2Of_t7OAd2QN-dxlTqMQMtL8GA=&h=383&w=808&sz=30&hl=en&start=15&zoom=1&tbnid=0EzIESKay
mXxoM:&tbnh=68&tbnw=143&ei=ZrmMToWzL8G5tgfqqbigAw&prev=/sea
rch%3Fq%3Dcompact%2Bvs%2Bspongy%2Bbone%26hl%3Den%26safe
%3Dactive%26sa%3DX%26tbm%3Disch%26prmd%3Divns&itbs=1
Kinds: or http://www.bartleby.com/107/17.html or http://visual.merriamwebster.com/human-being/anatomy/skeleton/types-bones.php
Long (compact) – all the bones of limbs except wrist and ankles
Short (spongy) – wrist, ankle, sesamoid bones (form in tendons)
like the patella
Flat (two thin layers of compact sandwiching a layer of spongy
bone) – thin, flat and curved, like those
of the skull, ribs,
and sternum
Irregular bones – like vertebrae, hipbones

Identify the major anatomical areas of a long bone.
Diaphysis = shaft, compact bone
Periosteum or fibrous connective tissue membrane
Epiphysis = end consisting of thin compact bone enclosing spongy bone
Articular cartilage = covers the epiphysis, is hyaline cartilage, prvides
smooth slippery surface
Epiphyseal line in adults separating the epiphysis from the diaphysis;
Epiphyseal plate – a plate of hyaline cartilage in young growing bone
Medullary cavity, or yellow marrow = stores adipose tissue in adults, is red
marrow in infants. Red Marrow is in spongy cavities of flat bones and
epiphyses of some long bones in adults.
Bone markings – places where muscles, tendons, ligaments attach or
where blood vessels and nerves pass.
Projections (processes)
Depressions (cavities)
See table 5.1 pg 119
http://www.daviddarling.info/encyclopedia/L/long_bone.html

Explain the role of bone salts and the organic matrix in making bone both hard and
flexible.
Osteocytes are bone cells
Lacunae are cavities in the matrix were osteocytes are found
Lamellae are the concentric circles of lacunae
Haversian (central) canals are the centers of the lamellae; they carry blood vessels and
nerves
Canaliculi are tiny canals radiating outward from the central canals to all lacunae, they
transport nutrients to all osteocytes in the hard matrix
Volkmann’s (perforating) canals provide communication between the layers and center
of the bone, they are perpendicular to the length
Calcium salts in the matrix provide the hardness, the organic parts (collagen fibers)
provide flexibility and great tensile strength

Describe briefly the process of bone formation in the
fetus and summarize the events of bone remodeling throughout life.
Skeletons form from cartilage and bone,
Hyaline cartilage forms the skeleton in embryos; as small children, most of this is
replaced by bone. Cartilage only remains in limited areas, nose, ear, joints, part
of ribs.
Ossification – changing hyaline cartilage to bone. Osteoblasts change the matrix
on the outside, then the hyaline cartilage is absorbed and the medullary cavity
forms Appositional growth = diameter growth; controlled by growth and sex
hormones
Articular cartilages last a lifetime, continually being replaced, epiphyseal plates
provide longitudinal growth areas
Bones change throughout our lives as a result of changing calcium levels, and
gravity and stress. Hypercalcemia is elevated Ca levels, results in deposition of
Ca salts
Bones get remodeled according to stress. Fibroblasts create new matrix, get
entrapped, and become osteocytes. Atrophied bones result from inactivity.
Parathyroid hormone determines when bones form/deteriorate, while stresses
determine where bones form/deteriorate.

Name and describe the various types of fractures.
Closed/simple fractures – clean breaks that don’t penetrate skin
Open/compound fractures – penetrate the skin
Comminuted – breaks into many fragments
Compression – bone is crushed
Depressed – broken bone presses inward (skull)
Impacted – broken ends are forced into each other
Spiral – ragged due to twisting forces
Greenstick – incomplete breaks
Reduction – realignment of bone ends
Closed reduction – try to fit the pieces together by hand
Open reduction – bones are secured with pins/wires in
surgery
6-8 weeks for healing after casting/traction, more for large bones or
in the elderly
Repairs – hematoma or blood filled swelling depriving osteocytes of
nutrients; new capillaries form granulation tissue in the clotted
blood; phagocytes dispose of dead tissue; connective tissue cells
form
Fibro cartilage callus containing cartilage matrix, bony matrix
and collagen fibers
Bony callus forms as cartilage changes to bone (when
fibroblasts and osteoclasts migrate
into the area
Bony callus transforms, depending on the stress applied to
the fracture area
Axial Skeleton
http://www.getbodysmart.com/ap/skeletalsystem/skeleton/menu/menu.html

On a skull or diagram, identify and name the bones of the skull.
Cranium - - 8 flat bones:
Frontal bone (forehead)
Parietal bones (top and sides of head) meet at the sagittal
suture and coronal sutures;
Temporal bones (above ears) join to parietals by squamous
sutures; contain the following markings:
External auditory meatus (canal to inner ear),
styloid process (neck muscles attach),
zygomatic arch (bridge to cheekbone),
Mastoid process (behind ear, contains mastoid
sinuses, neck muscles attach),
Jugular foramen (inside, jugular vein passes) and
Carotid canal (inside, internal carotid artery passes);
occipital bone (back of head and floor of brain cavity) joins
parietals via the lambdoid
suture;
Contains the foramen magnum (where brain stem and
spinal cord pass)
occipital condyles (where first vertebra rests),
sphenoid bone (butterfly bone forming the floor of cranial
cavity) contains the sella
turcica(Turk’s saddle –
holds the pituitary gland) and the foramen ovale (cranial
nerve V passes to the chewing muscles of the lower jaw)
forms part of the orbit and lateral part of skull, centrally filled
with sphenoid sinuses;
ethmoid bone – irregular, anterior to sphenoid, forms roof of
nasal cavity, part of medial orbital walls; has the crista galli
(cock’s comb where brain covering attaches) and cribriform
plates or holey areas where nerve fibers carry impulses to
olfactory receptors of the nose)
Facial bones (14)
Maxillae (maxillary bones) = upper jaw, carry upper teeth in
the alveolar margin; have palatine processes or anterior part
of hard palate, paranasal sinuses
(http://www.getbodysmart.com/ap/skeletalsystem/skeleton/a
xial/skull/facialbones/maxilla/tutorial.html)
Palatine bones – posterior to palatine processes, posterior
part of hard palate (failure to
fuse results in cleft palate)
Zygomatic Bones - cheekbones; form part of lateral orbital
walls,
Lacrimal bones – medial walls of orbits, groove serves as
tear passage
Nasal bones = nose bridge
Vomer bone = median line at the bottom of the nasal cavity
(plow), forms nasal septum
Inferior conchae = thin curved bones projecting from the
lateral walls of the nasal cavity (superior and middle
conchae are part of the ethmoid bone)
Mandible = lower jaw, rami are the upward parts, alveoli
contain teeth
Hyoid bone = only bone that doesn’t articulate, midneck
above larynx anchoring to styloid processes serves as a
movable base for the tongue and attachment for neck
muscles that move the larynx.

Describe how the skull of a newborn infant (or fetus) differs from that of an adult, and
explain the function of fontanels.
Fetal skull – ossifies after 22-24 months; fontanels are fibrous
membranes connecting cranial bones
(anterior and posterior)
Sutures, interlocking immovable joints, except the mandible, join all

Name the parts of a typical vertebra and explain in general how the cervical, thoracic,
and lumbar vertebrae differ from one another.
26 irregular bones connected by ligaments
All have body or centrum (disclike, weightbearing), vertebral arch (formed from
posterior extensions, laminae (bridge to spinous process) and pedicles (bridge to
centrum)), vertebral foramen (for spinal cord), transverse processes, spinous
process (fused laminae) and superior and inferior articular processes
33 vertebrae before birth; 9 fuse to form the sacrum (5) and the coccyx (4)
7 cervical vertebrae – C1 thru C7 – C1 = atlas (no body; superior depressions
receive occipital condyles of skull), C2 = axis (point of rotation, odontoid process
or dens is upright process acts as pivot point; C3-C7 are small, light, short
spinous processes, have transverse foramina housing the vertebral arteries
going to the brain, these help identify cervical vertebrae
12 thoracic vertebrae – T1-T12 – heart shaped centra, two costal demifacets
(articulating surfaces) on each side, receive heads of ribs, long spinous process,
hooks downward
5 lumbar vertebrae – L1-L5 – massive blocklike body, short hatchet like spinous
processes, very sturdy http://en.wikipedia.org/wiki/File:Gray430.png (interesting but not
helpful!)
http://healthguide.howstuffworks.com/lumbar-vertebrae-picture-b.htm
http://www.lumbarspine.net/photos.html
http://www.aafp.org/afp/980415ap/alvarez.html
http://emedicine.medscape.com/article/1264191-overview
Sacrum – 5 fused vertebrae, alae or wings articulate with hip bones, forming
sacroiliac joints, median sacral crest is fused spinous processes, dorsal sacral
foramina are holes lateral to sacral crest, sacral canal = vertebral foramen
Coccyx – 4 fused vertebrae, tailbone

Discuss the importance of the intervertebral discs and spinal curvatures.
26 irregular bones connected by ligaments, separated by fibro cartilaginous
intervertebral discs, which cushion and absorb shocks; water content decreases
with age, hardening them, decreasing their compressibility (herniation)
primary curvatures = curves that exist at birth prevent shock, maintain flexibility
(cervical curvature)

Explain how the abnormal spinal curvatures (scoliosis, lordosis, and kyphosis) differ
from one another.
secondary curvatures develop over time or may be either congenital or disease
inflicted = lumbar curvature (when you learn to walk), scoliosis (lateral shift),
kyphosis, ( exaggerated thoracic curve) and lordosis (exaggerated lumbar curve)
Appendicular Skeleton (126 bones)
http://facstaff.gpc.edu/~jaliff/appendsk.htm
http://www.getbodysmart.com/ap/skeletalsystem/skeleton/menu/menu.html
http://wps.aw.com/bc_marieb_ehap_9/79/20308/5198960.cw/index.html

Identify on a skeleton or diagram the bones of the shoulder and pelvic girdles and their
attached limbs.
Shoulder (pectoral) girdle = clavicle and scapula
Clavicle = collarbone; doubly curved; attaches to manubrium of sternum and
scapula; acts as a brace;
Scapula = shoulder blades
Has a flattened body; acromium = enlarged end = connections with
clavicle at the acromioclavicular joint; coracoid process = anchors some of
the arm’s muscles; suprascapular notch = nerve passageway; held by
trunk muscles; has three borders (superior, inferior or vertebral and lateral
or axillary); has the angles (superior or medial, the part that sticks out,
inferior and lateral or below the joint) the glenoid cavity = socket receiving
the head of the humerus laterally.
Flexibility results from the attachment to the axial skeleton at the
sternoclavicular joint, slides back and forth against the thorax and glenoid
cavity is shallow with few ligaments; is easily dislocated
Arm (30 bones each)
Humerus – proximal head connects to the scapula
2 bony projections – greater and lesser tubercles are muscle attachments
deltoid tuberosity = ridge in the middle anteriorly, running laterally
radial groove – oblique on the posterior side, where the radial nerve runs
medial trochlea and capitulum (ball-like) articulation areas with the radius and
ulna
coronoid fossa – proximal to trochlea = depression on anterior side
olecranon = depression in posterior surface
medial and lateral epicondyles allow ulna to rotate freely when the elbow is bent
Radius is lateral on the thumb side
Radioulnar joints both distally and proximally
Connected with ulna via flexible interosseous membranes
Disc head of radius rides at the capitulum
Styloid process distally
Ulna = medial on the little finger side;
coronoid process (anterior side) rides in groove of humerus;
Olecranon process = posterior; these grip the trochlear notch
Hand: 8 carpals of the wrist:
lunate, scaphoid, trapezium, trapezoid, capitate,
and troquetral;
hamate, pisiform
4 metacarpals of the palm and
14 phalanges numbered 1-5 starting with the thumb
Pelvic Girdle – two coxal bones (ossa coxae) or hip bones; combine with sacrum and
coccyx to form the bony pelvis
Large heavy bones attached securely to the axial skeleton
Sockets receive femur and are deep and heavily reinforced with ligaments;
designed for weight bearing; total weight of upper body rests on pelvis; reproductive
organs, urinary tract and large intestine are protected within.
Hip bones are fused from the ilium (connects posteriorly with the sacrum at the
sacroiliac joint; the alae are the winglike parts of the ilia, the iliac crest is the upper part,
ends anteriorly at the anterior superior spine and posteriorly at the posteriur superior
spine, followed by smaller inferior spines), ischium (most inferior part; ischial tuberosity
- thick part - receives weight while sitting; ischial spine is superior to the tuberosity,
greater sciatic notch where blood vessels and sciatic nerve pass from the pelvis
posteriorly into thigh) and pubis (most anterior part, fuses the rami of pubic bone
anteriorly and ischium posteriorly enclosing the obturator foramen, or opening where
blood vessels and nerves pass into the anterior part of the thigh; fuse anteriorly forming
the pubic symphysis; the fusion of the three form the acetabulum receiving the head of
the femur
False pelvis – between the wings of the ilium;
True pelvis – the interior circle within the pelvic girdle; the outlet and inlet of
which are carefully measured for childbirth
Femur – proximal end has greater and lesser trochanters separated by the
intertrochanteric line and posteriorly by the intertrochanteric crest; along with gluteal
tuberosity on the shaft are muscle attachment sites; the head articulates with the
acetabulum of the hip; the neck is commonly fractured; slants medial; distal end has
lateral and medial condyles, articulating with the tibia; posteriorly these are separated
by the intercondylar notch; anteriorly the smooth spot is the patellar surface.
Tibia – connected to fibula by interosseous membrane; shinbone; medial and lateral
condyles separated by intercondylar eminence, articulate with femur; patellar ligament
attaches to tibial tuberosity; the medial malleolus at the distal end forms the inner bulge
of the ankle; the sharp ridge down the middle anteriorly is the anterior crest, unprotected
by muscles;
Fibula – articulates with tibia proximally and distally; does not form the knee joint; the
distal end has the lateral malleolus, the outer part of the ankle;
Foot = tarsals, metatarsals and phalanges; provides support and serves as a lever to
propel us forward
Tarsals – posterior; 7 tarsal bones; the largest is the calcaneus
(http://orthoinfo.aaos.org/topic.cfm?topic=A00524)
or heelbone and the talus lies between the tibia and the calcaneus; 5 metatarsals form
the sole, and 14 phalanges form the toes
Three arches: medial and lateral longitudinal arches and transverse arch.
Ligaments bind the foot bones together; tendons help hold the bones in the arched
position;

Describe important differences between a male and female pelvis.
http://www.srcf.ucam.org/~ja297/The%20difference%20between%20the%20male%20and%20fe
male%20pelvis.pdf
Female inlet is larger and more circular
Female pelvis is shallower and bones are lighter and thinner
Female ilia flare more laterally
Female sacrum is shorter and less curved
Female ischial spines are shorter and farther apart; allowing larger
outlet
Female pubic arch is more rounded because the angle of the pubic arch is
greater
Joints
http://www.wisc-online.com/Objects/ViewObject.aspx?ID=mea304
http://education.yahoo.com/reference/gray/subjects/subject/70;_ylt=Ah._wpU42Z
r.9ZOu_MfLu5BtHokC

Name the three major categories of joints and compare the amount of movement
allowed by each.
Joints are articulations; they hold bones together and give the skeleton mobility
Classified functionally and structurally;
Functional classification depends on amount of motion:
synarthroses or immobile joints;
amphiarthroses or slightly movable joints (predominantly axial) and
diarthroses or freely movable joints (predominantly appendicular)
Structurally: http://www.shockfamily.net/skeleton/JOINTS.HTML
Fibrous – fibrous tissue joins them; tend to be immobile; examples are
skull sutures; irregular edges interlock. Syndesmoses, the connecting fibers
are longer than those of sutures, providing more give, like the joint connecting
the distal ends of the tibia and fibula.
Cartilaginous – cartilaginous tissue connects bone ends; most are
amphiarthrotic; examples: pubic symphysis, intervertebral joints, epiphyseal
plates of growing long bones, cartilaginous joints between first ribs and sternum
are synarthrotic examples
Synovial joints – joint cavities contain synovial fluid; tend to be freely
mobile;
Articular cartilage – hyaline covers the ends;
Fibrous articular capsule a sleeve or capsule of fibrous connective
tissue enclosing the joint surfaces; the capsule is lined with a smooth synovial
membrane
Joint cavity – the articular capsule encloses a cavity containing
synovial fluid
Reinforcing ligaments – the fibrous capsule is usually reinforced
with ligaments
Bursae and tendon sheaths are found closely associated with synovial joints;
they are bags of lubricant; reducing friction; bursae are flattened fibrous sacs
lined with synovial membrane and fluid; found where ligaments, muscles, skin,
tendons or bones rub together; tendon sheath, is an elongated bursa wrapping
around a tendon subjected to friction.
Types of joints; http://www.shockfamily.net/skeleton/JOINTS.HTML
Plane joint – articular surfaces are flat; slip or glide across; nonaxial
movement; intercarpal joints
Hinge joint – cylindrical end of one bone fits into a trough of another;
angular movement in one plane, elbow, ankle, phalanges; are uniaxial or
movement in one direction
Pivot joint – rounded end of one bone fits into sleeve or ring of another;
turning along bone axis; uniaxial joints; proximal radioulnar joint, atlas and dens
of axis
Condyloid joint –
Saddle joint –
Ball and socket joint -
Developmental Aspects of the Skeleton

Identify some of the causes of bone and joint problems throughout life.
What’s missing:
information on the sternum
Flat bone; fusion of three bones: manubrium, body and xiphoid process; attached to 7 pairs of
ribs; has 3 landmarks: jugular notch, clavicular notch; sternal angle and transverse ridge at the
level of the 2nd ribs; and the xiphisternal joint or fusion of body and xiphoid process around the
9th thoracic verterbra
Sternal punctures are made to obtain blood samples for blood diseases from the sternal
marrow.
Information on ribs:
Twelve pairs of ribs; all articulate with vertebral column; true ribs (first 7 pairs) articulate with
sternum by costal cartilage; false ribs (5 pr) attach indirectly or are not attached to sternum;
floating ribs (last 2 pr of false ribs) lack sternal attachments;