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/Four-types-of-cells-in-bone

http://eugraph.com/histology/crtbone/compbon.html

http://www.google.com/imgres?imgurl=http://silver.neep.wisc.edu/~lakes/BoneSpongy.jpg&imgrefurl=http://silver.neep.wisc.edu/~lakes/BoneTrab.html&usg=__2Of_t7OAd2QN-dxlTqMQMtL8-GA=&h=383&w=808&sz=30&hl=en&start=15&zoom=1&tbnid=0EzIESKaymXxoM:&tbnh=68&tbnw=143&ei=ZrmMToWzL8G5tgfqqbigAw&prev=/search%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.merriam-webster.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 thefetus 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/axial/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, hamate, pisiform and troquetral;

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%20female%20pelvis.pdf

Female inlet is larger and more circular

Female pelvis is shallower and bones are lighter and thinnerFemale ilia flare more laterallyFemale sacrum is shorter and less curvedFemale ischial spines are shorter and farther apart; allowing larger outletFemale 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._wpU42Zr.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;