Skeletal System

Allied Health Sciences I

4th block

Melissa Lewis, RN

Skeletal System

Makes up our bony framework of our bodies

Composed of 206 bones Some bones are hinged (movable) Some bones are fused (can not move)

Functions of Skeletal System

1. Supports body structures Provides shape to body

2. Protects inner organs (ex. skull protects brain, ribs protect heart & lungs)

3. Movement & anchorage of muscles 4. Mineral storage (bones store calcium &

phosphorus) 5. Hemopoiesis (RBC formation occurs in long

bones, sternum, and ilia)

Structure of Bones

Bones are made up of microscopic cells called osteocytes (mature bone cells)

Our bones are made up of: 35% organic material 65% inorganic material, mineral salts, & water

Organic material = protein call bone collagen The organic material gives the bone flexibility

Inorganic material = mineral salts like calcium, magnesium, sodium, etc. This inorganic material makes the bone very hard &

durable

Bone Creation

During embryo stage Osteoblasts (primitive embryonic cells)

secrete protein fiber Then cartilage is deposited in between fibers During 8th week of embryo development

ossification begins Ossification = when mineral matter starts to

replace cartilage and bone is created

Infant Bones

Very soft and pliable because is ossification is not complete

Soft spot on anterior fontanel Ossification continues throughout

childhood

Bone Types

1. Long bones (found in extremities) 2. Flat bones (skull and ribs) 3. Irregular bones (spinal column) 4. Short bones (ankles and wrists)

*****The degree of movement of a joint is determined by bone shape and joint structure

Structure of a Bone

Diaphysis = hollow cylinder of hard compact bone Makes bone hard and smooth yet light enough for

movement Medullary canal/cavity inside diaphysis

It contains marrow inside where WBC’s are formed

Epiphyses = ends of the diaphysis This is filled with yellow bone marrow (fat cells, blood

vessels, & cells which form into RBC’s) Hemopoiesis = blood cell formation occurs here

Structure of a Bone cont…

Endosteum = lining of marrow canal that keeps cavity intact

There are areas of dense/compact bone and some areas of spongy/porous bone Dense/compact = stronger bone

Structure of a Bone cont…

Periosteum = covering on the outside of bone Contains blood vessels, lymph vessels, &

nerves Periosteum is necessary for bone growth,

repair, and nutrition

Bone Growth

Bones grow in length from the middle outward Bones grow in circumference by adding more

bone to the outer surface of the diaphysis osteoblasts (they deposit new bone)

As the circumference increases, bone material from the center part of the diaphysis is dissolving making an internal cavity/canal

Osteoclasts are very large bone cells that secrete enzymes. They are responsible for the inner bone dissolving.

Bone Growth cont…

This canal/cavity fills with marrow and cells that eventually produce WBC & RBC

When epiphyseal cartilage ossifies growth stops If cartilage present = still growing No cartilage present = finished growing

Average growth for females continues to 18 years old, males 20-21years old

If bone is fractured, bones cells near break will become active and create new bone

Parts of the Skeletal System

1. Axial skeleton = skull, spinal column, ribs, sternum (breastbone), hyoid bone Hyoid bone is a u-shaped bone in neck to

which the tongue attaches 2. Appendicular skeleton = upper

extremities; should girdles, arms, wrists, hands and lower extremities; hip girdle, leg, ankles, and feet

Axial Skeleton Skull made up of cranium and facial bones Cranium protects brain

Cranial bones are thin and slightly curved During infancy bones are connected by

connective tissue called a suture (immovable joints)

Facial bones protect eyes, ear, nose, and mouth Some facial bones are bone & cartilage (ex. Top

of bridge of nose is bone, bottom is cartilage)

Axial Skeleton cont…

22 bones in skull 8 bones in cranium

1 Frontal (forehead) 2 parietal (roof & sides of skull) 2 temporal (ears) 1 occipital (base of skull which contains foramen

magnum) 1 ethmoid (located b/w eyes creates nasal

septum) 1 sphenoid (look like bat) other bones connect to

it

14 Facial Bones

5 nasal 2 nasal for bridge of nose 1 vomer (lower part) 2 inferior concha (side walls of nasal cavity)

2 maxilla – upper jaw 2 lacrimal – inner aspects of eyes (tear ducts) 2 zygomatic – cheek bones 2 palatine – hard palate of mouth 1 mandible – lower jaw (only movable bone

in face)

Spinal Column/Vertebra

Strong and flexible Supports head Provides attachment for ribs Spine encloses spinal cord of nervous system Spine is made up of small bones called vertebraes Each vertebrae is separated from the next vertebrae by

pads of cartilage called intervertebral disks These disks act like shock absorbers As we age these disks become thinner, thus height

shrinking

Vertebral Column

Divided into 5 sections named according to their body location 7 Cervical – neck area

Atlas –first cervical vertebrae, articulates with occipital bone in skull, allows us to nod our head (nod head “YES”)

Axis – second cervical vertebrae, Odontoid process – forms pivot point with atlas, allow us to turn our

heads (nod head “NO”) 5 lumbar – large vertebrae in back

Bears most of body weight Sacrum – (pelvic girdle) five fused bones, articulation point

for hips Coccyx (tailbone) four fused bones

Spinal Column/Vertebra cont…

Spinal nerves enter and leave spinal cord through openings (foramen) b/w vertebrae

Spine is curved to make it stronger than a straight one would be

Basic Vertebra Parts

Body – large, solid part Foramen – central opening for

spinal cord Processes – 2 wing-like bony

structures above foramen Spinous process (spine) Articular processes

Sternum

Thoracic area of body is protected and supported by thoracic vertebrae, ribs, & sternum

Sternum (breastbone) is divided into 3 parts Manubrium (upper region) The body Xiphoid process (lower cartilage part)

Clavicles (collar bones) are attached to upper sternum by ligaments

Ribs

We have 12 pairs of ribs True ribs – 1st 7 pairs (attach directly to

sternum) False ribs - next 3 pairs of ribs (attach to

7th rib instead of sternum) Floating ribs – last 2 pairs of ribs (don’t

connect to sternum or other ribs)

Appendicular Skeleton

Included bones from upper and lower extremities (126 bones)

1. Shoulder Girdle (made up of 4 bones) 2 curved clavicles (collar bones)

Attach scapulae to sternum Helps to brace shoulder and prevent excessive

forward motion 2 triangular scapulae (shoulder bones)

Arm attaches to torso here Muscles from arm attach here to allow for

movement

Appendicular Skeleton: Arm

Bones of arm = humerus, radius, and ulna Humerus = upper arm bone

Second largest bone in body Top of humerus articulates with scapulae

Radius and ulna = lower arm bones Radius = is bone that runs up thumb side of

forearm Ulna = largest bone is forearm Upper end of ulna = Olecranon process =

forms elbow (funny bone)

Appendicular Skeleton: Hand

Hand has 27 bones Wrist bones = carpals Hand made up of 2 parts

Palmer surface with 5 metacarpal bones 5 fingers with 14 phalanges

Each finger has 3 phalanges Thumb has only 2 phalanges (most

flexible finger)

Appendicular Skeleton: Pelvic Girdle

In youth pelvic girdle has 3 bones Ilium, ischium, & pubis

These bones eventually fuse together to form a bowl-shaped structure (pelvic girdle)

A joint is formed called symphysis pubis in front

A joint is formed called sacroiliac in back with sacrum

Appendicular Skeleton: Pelvic Girdle cont…

The pelvic girdle serves as attachment for bones and muscles of the leg

Also provides support for lower abdomen

The pelvis in a female is much wider than male (necessary for child-bearing)

Appendicular Skeleton: Upper Leg

The upper leg contains the femur (thigh bone) which is the largest and strongest bone in the body

The top of the femur has a smooth, round head that fits into the cavity of the ilium known as the acetabulum forming a ball and socket joint

Appendicular Skeleton: Lower Leg

Lower leg has 2 bones = tibia & fibula

Tibia is the largest of these 2 bones

The patella (kneecap) is found in front of the knee joint

Appendicular Skeleton: Ankle

The ankle bone = tarsus Tarsus contains 7 tarsal bones These tarsals connect the foot to the leg

bones The largest ankle bone is the heel bone

(calcaneus) The ankle allows the foot to extend and

flex when walking

Appendicular Skeleton: Foot The foot contains 5 metatarsal bones The metatarsal and tarsal bones join to

form 2 arches: Longitudinal &Perpendicular

These arches strengthen the foot and provide flexibility and springiness to stride

The downward pressure and weight of the body slowly flattens these arches over time (called “fallen arches or flatfeet”)

Appendicular Skeleton: Foot cont…

Sx of “flatfeet or fallen arches” = pain & fatigue

Factors that lead to “flatfeet” = improper poor nutrition, fatigue, overweight, poor posture, and improperly fitting shoes

All toes have 3 phalanges in each except the big toes which only has 2 phalanges

Each foot has 14 phalanges

Joints & Related Structures Joints/articulations = points of contact b/w 2

bones These joints are classified into 3 main types

according to their degree of movement 1. Diathroses (movable joints) 2. Amphiarthroses (partially movable joints) 3. Synarthroses (immovable joints)

Diathroses Joints

Most of our joints are diathroses They have 3 main parts: cartilage, bursa, & synovial

cavity The 2 movable bones meet at a joint but do not touch The 2 surfaces are covered with smooth, slippery cartilage This cartilage acts like a shock absorber and prevents

friction Synovial membrane secretes synovial fluid (a lubricant) into

the synovial cavity (area between the two cartilages) Synovial fluid decreases friction of joint movement Bursa sacs are located b/w muscles, tendons, ligaments,

and bones Inflammation of these areas = bursitis

Types of Diarthroses Joints:

1. Ball and Socket joints Allow for the greatest amount of movement Examples = shoulders and hip joints

2. Hinge joints Move in only one direction Exampes = knees and elbows

3. Pivot joints Rotation joints Examples = radius and ulna, atlas and axis joint

4. Gliding joints Flat surfaces glide across each other Examples = vertebrae of spine

Amphiarthroses Joints

Partially movable joints Have cartilage b/w articular

surfaces Examples = attachment of ribs to

spine and symphysis pubis (joint b/w 2 pelvic bones

Synarthroses Joints

Immovable jointsFound in cranium

Types of Motion: Define from book

Flexion Extension Abduction Adduction

Circumduction Rotation Pronation Supination

Common Skeletal Disorders

Fracture = broken bone 1. Closed reduction – cast or splint is

applied to immobilize joint 2. Open reduction – surgery (wires,

metal plates, or screws used to hold bones in place) and cast or splint applied

3. Traction – pulling force is used to hold bones in alignment

Common Types of Fractures

1. Closed/simple – broken bones that do not pierce through skin

2. Open/compound – most serious type of fracture, bones pierce through skin, worry about infection

3. Greenstick – simplest type of fracture, bone is partially bent but never completely separates

4. Comminuted – bone is splintered or broken into many pieces that embed in surrounding tissues

Bone or Joint Injuries

1. DislocationBone is displaced from proper

position in a jointTearing and stretching of

ligaments can occur

Bone or Joint Injuries

Sprain Injury to a joint caused

by any sudden or unusual motion such as turning an ankle

Ligaments are torn from their attachment or torn across

Joint is not dislocated

Strain

Diseases of the Bone

1. Arthritis – inflammatory condition of one or more joints accompanied by pain and often changes in bone position Types of arthritis:

Rheumatoid – chronic autoimmune (when body’s own immune system attacks tissues) disease, affects more women than men

Osteoarthritis – degenerative joint disease, occurs with aging,

Diseases of the Bone cont…

2. Gout – increase of uric acid in bloodstream, these crystals build up in joints and kidneys, common site = great toe, lots of pain

3. Rickets – usually found in children, caused by lack of vitamin D, caused bone deformities (bowlegs and pigeon chest) Prevention = calcium, vit D, and sunlight

Diseases of the Bone cont…

4. Slipped (herniated disc) – disc ruptures or protrudes out of place Places pressure on spinal nerves

5. Whiplash injury – trauma to cervical vertebra

Abnormal Curvatures of Spine

1. Kyphosis (hunchback) = humped curvature in thoracic spine area

2. Lordosis (swayback) = exaggerated inward curvature in lumbar spine area

3. Scoliosis = side-to-side or lateral curvature of spine

Other Disorders

1. Osteoporosis Affects mainly women Mineral density in bones is greatly reduced With aging you lose calcium and phosphorus,

thus bones more porous (less strong) 2. Osteomyelitis = bone infection

Occurs most in children from injuries or systemic infection

3. Osteosarcoma = bone cancer

THE END!!!Next unit is Muscular System