The Skeletal System PDF/PPT

 


The Skeletal System

       Skeleton comes from a Greek word
meaning dried up body.

       Bone appears dead and dried up, but
it is not!

       Bone is living tissue

       Newborn human has 350 bones

       Adult human has 206 bones

       Parts of the skeletal system

       Bones (skeleton)

       Joints

       Cartilages

       Ligaments (bone to bone)(tendon=bone
to muscle)

Functions of Bones

  • Support of the body (framework)

  • Protection of soft organs

  • Serve as levers (with help from
    muscles)

  • Storage of minerals and fats
    (calcium)

  • Blood cell formation

Bones of the Human Body

Two basic
types of bone tissue

    • Compact bone

      • Dense/hard

    • Spongy bone

      • (Cancellous)

      • Many open spaces

        • Decrease wt of bone/contain
          red bone marrow

Classification of Bones on the Basis of Shape

  • Long bones

    • Typically longer than wide

    • Have a shaft with heads at
      both ends

    • Contain mostly compact bone

    • Found in legs and arms

         
Examples:
Femur, humerus

  • Short bones

    • Generally cube-shape and small

    • Contain mostly spongy bone

    • Found in wrist, ankles, and toes

         
Examples:
Carpals, tarsals

  • Flat bones

    • Thin and flattened

    • Usually curved

    • Cover organs/provide surface
      for lg. muscle

    • Thin layers of compact bone
      around a layer of spongy bone

         
Examples:
Skull, ribs, sternum

  • Irregular bones

    • Irregular shape

    • Do not fit into other bone
      classification categories

         
Example:
Vertebrae and hip

Gross Anatomy of a Bone

  • Diaphysis

§ 
Shaft

§ 
Composed
of compact bone

  • Epiphysis

§ 
Ends
of the bone

§ 
Composed
mostly of spongy bone

  • Periosteum

§ 
Outside
covering of the diaphysis

§ 
Fibrous
connective tissue membrane

§ 
Serves
as an attachment for muscle

  • Arteries

§ 
Supply
bone cells with nutrients

·        
Articular cartilage

§ 
Covers
the external surface of the epiphyses

§ 
Made
of hyaline cartilage

§ 
Decreases
friction at joint surfaces

·        
Medullary cavity

§ 
Cavity
of the shaft

§ 
Contains
yellow marrow (mostly fat) in adults

§ 
Contains
red marrow (for blood cell formation) in infants

Changes in the Human Skeleton

  • In embryos, the skeleton is
    primarily hyaline cartilage

  • During development, much of
    this cartilage is replaced by bone

  • Cartilage remains in isolated
    areas

    • Bridge of the nose

    • Parts of ribs

    • Joints

Bone Growth

  • Epiphyseal plates allow for growth of long bone during childhood

    • New cartilage is continuously
      formed

    • Older cartilage becomes
      ossified

      • Cartilage is broken down

      • Bone replaces cartilage

  • Bones are remodeled and lengthened until growth stops

    • Grow longitudinally for height

    • Bones grow in width to support
      weight

Epiphyseal Disc

       Growth plate

       The cartilage near the epiphyseal
disc multiplies and eventually becomes ossified (turns to bone)

       As long as new cartilage continues
to form the bone continues to lengthen.

       When the growth plate hardens and
becomes ossified, growth stops

       Hormones play a big part in this

       Growth hormone stimulates growth

       Sex hormones stop growth

Bone Width

       Long after longitudinal bone growth
has stopped, bones continue to grow in thickness and width.

       Bones are continuously being
reshaped

Types of Bone Cells

  • Osteocytes

    • Mature bone cells

  • Osteoblasts

    • Bone-forming cells

  • Osteoclasts

    • Bone-destroying cells

    • Break down bone matrix for
      remodeling and release of calcium

  • Bone remodeling is a process by both osteoblasts and osteoclasts

Bone Remodeling

       A combined action of osteoblasts
(bone forming cells) and osteoclasts (bone destroying cells)

       Osteoblasts deposit bone on the
external bone surface

       Osteoclasts break down bone from the
inside

Bone Fractures

  • A break in a bone

  • Types of bone fractures

    • Closed (simple) fracture –
      break that does not penetrate the skin

    • Open (compound) fracture –
      broken bone penetrates through the skin

  • Bone fractures are treated  by reduction and immobilization

    • Realignment of the bone

Dislocation of joint

       Displacement of bones at the joint

       Often caused by impact trauma to
that joint

       Can be more damaging and painful
than a fracture

       Damage to the joint capsule and
surrounding ligaments and tendons often takes much longer to heal than bone
tissue.

Repair of Bone Fractures

  • Hematoma (blood-filled
    swelling) is formed

  • Break is splinted by
    fibrocartilage to form a soft callus

    • Blood vessels grow into the
      hematoma

  • Fibrocartilage callus is
    replaced by a bony callus

  • Bony callus is remodeled to
    form a permanent patch

Skeletal System

Divided into two divisions

Axial skeleton ~ bones of the cranium, face, vertebral column,
and bony thorax.

Appendicular skeleton ~ includes the bones of the pelvic
girdles, the upper extremities and lower extremities.

The Axial Skeleton

 

  • Forms the longitudinal part of
    the body

  • Divided into three parts

    • Skull

    • Vertebral column

    • Bony thorax

The Skull (28 bones) (18 names!)

  • Sits on top of the vertebral
    column

  • Two sets of bones

    • Cranium (8 bones)

    • Facial bones (14 bones)

  • Bones are joined by sutures

  • Only the mandible is attached
    by a freely movable joint

The
Cranium

       Bony structure that encases and
protects the brain.

       8 bones

       Frontal
Bone
~ forehead/upper
part of the bony structure surrounding the eyes.

       Parietal Bone (2) ~ upper sides of the head and
the roof of the cranial cavity (top of the head)

       Temporal Bones (2) ~ sides of the head, close to
ears.

       Commonly called the temples

       Includes the external auditory
meatus

      
Opening
for the ear

       Includes the zygomatic process

      
Part
of the cheekbone

       Occipital Bone ~ back and base of the cranium

       Includes the foramen magnum

      
Foramen
means hole

      
Large
hole for the brainstem/spinal cord

       Sphenoid Bone ~ forms sides of cranium and parts
of orbits of the eyes

       Butterfly shaped

       Includes Sella Turcica (Turk’s
Saddle)

      
Where
pituitary gland sits

       Ethmoid Bone ~ irregularly shaped bone located
between the eye orbits

       Major supporting bone of the nasal
cavity

       That’s it!  No more cranium bones!

       206 bones – 8 bones = 198 bones to
go…

Facial
Bones

       14 bones

       Most of these bones come in pairs

       Only the mandible and vomer are
single bones

       Mandible ~ the lower jaw bone

       Carries the lower teeth

       The anterior portion forms the chin

       Only freely movable joint in the
skull

       Maxilla (2) ~ Upper jaw

       Two bones fused together

       Roof of the mouth

       Also form parts of the nasal cavity
and eye orbits

       Palantine Bones (2) ~ form the posterior part of the hard
palate and the floor of the nasal cavity.

       Failure of the palatine and/or
maxillary bones to fuse causes a cleft palate.

       Zygomatic Bones (2) ~ the cheekbones

       Also forms a part of the orbits of
the eyes

       Other Facial Bones

                      Lacrimal Bones (2) ~ inner wall
of eye sockets

                      Nasal Bones (2) ~ bridge of nose

                      Vomer ~ nasal septum

                      Inferior Nasal Conchae (2)

       That’s it!  No more facial bones!

       198 bones – 14 bones = 184 bones to
go…

Paranasal Sinuses

  • Functions of paranasal sinuses

  • Air filled cavities

    • Lighten the skull

    • Give resonance and
      amplification to voice

The Fetal Skull

  • The fetal skull is large
    compared to the infants total body length

  • Fontanelles – fibrous membranes
    connecting the cranial bones

    • Allow the brain
      to grow

    • Convert to bone within 24
      months after birth

The Hyoid Bone

  • U shaped

  • Found in the upper neck

  • The only bone that does not
    articulate with another bone

  • Serves as a moveable base for
    the tongue

Middle
Ear

       3 Tiny bones ~ transmit vibrations

       All derived from Latin words

       Malleus (hammer)

       Incus (anvil)

       Stapes (stirrup)

       Smallest bone in the body

Middle
Ear and Hyoid Bones

       That’s it!

       184 bones – 4 bones = 180 bones to
go…

The Vertebral Column

       The backbone or spine

       Consists of 26 bones called
vertebrae

       Vertebrae separated by
intervertebral discs (act as shock absorbers)

       The spine has a normal curvature

       Each vertebrae is given a name
according to its location

       C1-C7 ~ in the neck region

       7 cervical vertebrae

       T1-T12 ~ located in the chest region

       12 thoracic vertebrae

       L1-L5 ~ located in the lower back

       5 lumbar vertebrae

       Sacrum ~ curved bone of the lower
back (posterior wall of the pelvis)

       fused sacral vertebrae

       5 vertebrae at birth

       Coccyx ~ the tailbone

       4 vertebrae at birth

       The vertebrae become larger as the
vertebral column descends…..WHY?

       Vertebral foramen ~ opening for
spinal cord.

       What is the opening for the spinal
cord in the skull called?

       180 bones – 26 vertebral column
bones = 154 bones to go!

The Bony Thorax (Thoracic Cage)

  • The chest region

  • Forms a cage to protect major
    organs

  • Composed of sternum, ribs and
    thoracic vertebrae.

  • Sternum ~ breastbone.

  • Dagger-shaped bone located
    along the midline of the anterior chest.

  • Ribs ~ 12 pairs of ribs attach
    posteriorly to the thoracic vertebrae

  • True ribs ~ first 7 pair

  • False ribs ~ last 5 pairs

That is it for the axial skeleton!

       154 bones – 24 ribs -1 sternum = 129
bones to go!!!

 

The Appendicular Skeleton

  • Limbs (appendages)

  • Pectoral (shoulder) girdle

  • Pelvic girdle

The Pectoral (Shoulder) Girdle

  • Composed of two bones

    • Clavicle – collarbone

    • Scapula – shoulder blade

  • These bones allow the upper
    limb to have exceptionally free movement

Bones of the Upper Limb

  • The arm is formed by a single
    bone

    • Humerus

    • Head of humerus allows for
      rotation

  • The forearm has two bones

    • Ulna

    • Radius

Radius

       Radius ~ locate
on the lateral or thumb side when the palm of the hand is facing forward.

Ulna

       Ulna~ the longer of the two forearm bones.

       Located on the medial or little
finger side of the forearm.

Bones of the Upper Limb

  • The hand

    • Carpals – wrist

    • Metacarpals – palm

    • Phalanges – fingers

Bones of the Pelvic Girdle

  • Composed of two coxal bones
    (hip bones)

    • Composed of three pair of
      fused bones

      • Ilium

      • Ischium

      • Pubis

  • The total weight of the upper
    body rests on the pelvis

  • Protects several organs

    • Reproductive organs

    • Urinary bladder

    • Part of the large intestine

Bones of the Lower Limbs

  • The thigh has one bone

    • Femur – thigh bone

  • Patella ~ knee cap

  • Triangular bone located within
    a tendon that passes over the knee.

  • The leg has two bones

    • Tibia ~ shin bone

      • larger

    • Fibula

      • Long and thin

  • The foot

    • Tarsal (7)– ankle

    • Metatarsals (5)– sole/instep

    • Phalanges (14) – toes

Joints

  • Articulations of bones

  • Functions of joints

    • Hold bones together

    • Provide flexibility

  • Ways joints are classified

    • By their function

    • By their structure

Functional Classification of Joints

  • Synarthroses – immovable joints

  • Amphiarthroses – slightly
    moveable joints

  • Diarthroses – freely moveable
    joints

Structural Classification of Joints

  • Fibrous joints

    • Generally immovable

  • Cartilaginous joints

    • Immovable or slightly moveable

  • Synovial joints

    • Freely moveable

Fibrous Joints

  • Bones united by fibrous tissue
    – synarthrosis or largely immovable.

Cartilaginous Joints – mostly amphiarthrosis

  • Bones connected by cartilage

  • Examples

    • Pubic
      symphysis

    • Intervertebral
      joints

Synovial Joints

  • Articulating bones are
    separated by a joint cavity

  • Synovial fluid is found in the
    joint cavity

  • Reinforced by ligaments

  • 6 Types of Synovial Joints

Hinge
joint

·        
Movement
is like two boards joined together by a hinge

·        
Movement
in one direction

·        
Elbow,
knees, fingers

Ball and
Socket Joint

·        
When
ball-shaped end of one bone fits into the cup-shaped socket of another

·        
Bones
can move in many directions

·        
Shoulder,
hip

Pivot
Joint

·        
Allows
for rotation around the length of a bone.

·        
Allows
only for rotation

·        
Head
(side to side “no” action)

·        
Forearm
joints (palms) supination/pronation

Saddle
Joint

·        
When
the surfaces of both articulation bones are saddle-shaped              

·        
Concave/convex

·        
Thumb

·        
Wide
range of motion

Gliding
Joint

·        
Interaction
of flat surfaces of articulating bones

·        
Limited
but complex movement

·        
Wrist,
ankle

Condyloid
Joint

·        
Oval-shaped
articular surface of one bone fits into the oval-shaped depression of another

·        
Mandible,
knuckles

Inflammatory Conditions Associated with Joints

  • Bursitis – inflammation of a
    bursa usually caused by a blow or friction

  • Tendonitis – inflammation of
    tendon sheaths

  • Arthritis – inflammatory or degenerative
    diseases of joints

    • Over 100 different types

    • The most widespread crippling
      disease in the United States

Clinical Forms of Arthritis

  • Osteoarthritis

    • Most common chronic arthritis

    • Probably related to normal
      aging processes

  • Rheumatoid arthritis

    • An autoimmune disease – the immune
      system attacks the joints

    • Symptoms begin with bilateral
      inflammation of certain joints

    • Often leads to deformities

  • Gouty Arthritis

    • Inflammation of joints is
      caused by a deposition of urate crystals from the blood

    • Can usually be controlled with
      diet

      • Red meat and wine are high in
        uric acid.

 The Skeletal System PDF

The Skeletal System PPT


 

 

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