Chapter 6 The Skeletal System by linzhengnd


									Bones and Cartilage
          Provides framework
           that supports the

                body.


          Provides movement
          with the help of the
           skeletal muscles.

**Storage of calcium

          Produces blood cells
There are a total of 206 bones in
the human body.

The skeletal system contains both bone and
cartilage – 2 types of connective tissue.

The appearance and texture of bone
varies, depending on its location.
Compact Bone
Outer layer of bone, very hard and dense.

Organized in structural units called
Haversian systems.

Matrix is composed of Ca salts (Ca
carbonate and Ca phosphate)

Osteocytes – living bone cells that live in
Porous (Spongy) bone
       Located in the ends of long bones.

      Many spaces that are filled with red
      bone marrow which produces blood

       Trabeculae – needle-like threads of
     spongy bone that surround the spaces.
    Add strength to this portion of the bone.
Embryonic Bone Growth
 The skeleton is first
  made of cartilage and
  fibrous connective
  tissue. These are
  gradually replaced by
 Bone matrix is
  produced by
 “Calcification” begins
  at 8 weeks gestation.
Embryonic Bone Growth
 Process is not complete
  at birth.
   Areas of fibrous
    connective tissue
    remain between the
    bones of the skull =
   Purpose ?
            Factors that Affect Bone Growth and
            •genetic factors influence height.

            •Ca, (P), protein,
            •vit D to promote absorption of Ca and P by the gut,
Nutrition – •vitamins A and C to promote ossification.

            •growth hormone, thyroxine, parathyroid hormone and insulin help regulate cell division, protein
             synthesis, Ca metabolism and energy production.

            •“stress” – “bearing weight” causes bones to thicken. Without stress, bones will lose Ca faster than it
             is replaced. End result – osteoporosis.
        4 Types of Bones
 Long bones – bones of
  the arms and legs.
   Diaphysis – a hollow
    tube made of compact
    bone = shaft.
   Medullary cavity –
    hollow area inside the
    diaphysis of a bone;
    contains yellow bone
    marrow (fat).
        4 Types of Bones
 Long bones cont’d
   Epiphysis
      Composed of spongy bone which
       contains red bone marrow in
       children, replaced with yellow
       marrow in adults.
      Epiphyses are covered with compact
       bone which in turn is covered with
       articular (hyaline) cartilage.
   Periosteum – strong fibrous
    membrane covering a long bone
    except at the joints surfaces.
   Endosteum – fibrous membrane that
    lines the medullary cavity.
      4 Types of Bones

 Short bones     Flat bones –   Irregular
– carpels and    skull bones.    bones –
tarsals (wrist                  vertebrae.
 and ankle).
Divisions of the Skeleton
 Axial Skeleton – bones of the skull, spine, chest and
  the hyoid bone.
    Skull – 8 bones that form the cranium, 14 that form the
     face and 6 in the middle ears.
      Frontal – forehead bone, also forms upper part of eye
      Parietal – top/upper sides of the cranium behind the
       frontal bone
      Temporal – forms the lower sides of the cranium;
       contains middle and inner ear structures, external
       auditory canal, and mastoid process (behind the ear).
Divisions of the Skeleton
 Axial skull
   Cranium
      Occipital bone - forms the back of the skull, large hole
       (foramen magnum) allows entry of spinal cord.
      Sphenoid – forms central part of the floor of the cranium;
       pituitary gland is located in a depression called the sella
       turcica (Turkish sadle).
      Ethmoid bone – helps form floor of cranium, side walls
       and roof of nose.
      Nasal bones form upper bridge of nose.
Divisions of the Skeleton
 Axial - skull
    Face
      Maxilla – upper jawbones
      Zygomatic bones – cheek bones; help form eye orbit.
      Mandible – lower jawbone.
      Lacrimal bones – form medial wall of the eye socket and
       side of nasal cavity.
      Palatine – forms back part of the roof of the mouth, part
       of the orbit.
      Vomer – forms lower, back part of nasal septum.
Divisions of the Skeleton
 Axial - skull
    Ear bones – from the outside in..
       Malleus – hammer
       Incus – anvil
       Stapes – stirrup
    Sinuses – spaces or cavities inside the cranium
    Sutures – Immovable joints that join skull bones together
         Lamboidal – between the parietal and occipital
         Squamous – between the parietal and temporal
         Coronal – between parietal and frontal
         Sagittal – between parietal bones
    **Fontanels – usually ossify by 2 years of age
Divisions of the Skeleton
 Vertebral column consists of a series of separate
  bones or vertebrae connected such that they form a
  flexible curved rod.
   7 Cervical vertebrae - Atlas and axis are first two
   12 Thoracic
   5 Lumbar
   Sacrum
   Coccyx
Divisions of the Skeletal
 Axial – Vertebral column
   Vertebral column has 4 curves that support the weight
    of the body and help with balance.
        Cervical curvature – curves anteriorly
        Thoracic curvature curve posteriorly
        Lumbar curvature – anteriorly
        Sacral – posteriorly
Divisions of the Skeletal
 Axial – Vertebral column
   Abnormal curves
      Kyphosis (thoracic) = exagerated curve = “humpback”.
      Lodosis (lumbar) = exagerated curve = “swayback”.
      Scoliosis – lateral curve.
Divisions of the Skeletal
 Axial – Thorax
   Includes manubrium, sternum, thoracic vertebrae and
    the ribs.
   All 12 ribs are all attached posteriorly to the vertebrae:
      “True ribs” - 1st 7 pair are attached to the sternum by the
       costal cartilage beginning at the manubrium (upper part
       of the sternum).
      False ribs – ribs 8, 9, and 10 are attached to the cartilage
       of the 7th ribs.
      Floating ribs – last 2 pairs are not attached at the anterior
Divisions of the Skeletal
 Appendicular skeleton – bones of the upper and
  lower extremities and their girdles.
 Upper extremity
   Scapula – shoulder blade
   Clavicle – collar bone
   Humerus – long bone of the upper arm; 2nd longest
    bone in the body. The humerus is attached to the
    scapula proximally and articulates with the radius and
    ulna distally to form the elbow joint.
Divisions of the Skeletal
 Appendicular skeleton - Upper Extremity cont’d
   Radius and ulna – bones of the lower arm, articulate
    with each other distally and with the carpals.
   Carpals – 8 wrist bones
   Metacarpals – palm of hand
   Phalanges – 14 finger bones, 3 in each finger and 2 in
    each thumb.
Divisions of the Skeletal
 Appendicular skeleton - Lower extremity
   Pelvic (hip) girdle connects legs to the trunk. Consists
    of 2 large os coxae one on each side of the pelvis. Each
    os coxae consists of 3 separate bones in the infant:
      Ilium
      Ischium
      Pubis
             These grow together in the adult.
Divisions of the Skeletal
 Appendicular skeleton – Lower extremity
   Femur – thigh bone, longest bone in the body. The
    femur fits into the cup-shaped “socket” = acetabulum
    – in the pelvic girdle. Distally the femur articulates
    with the patella (knee cap) and the…
   Tibia (lower leg - shinbone).
   Medial malleolus – inner anklebone, protuberance of
    the tibia.
   Fibula – long slender, non-weight bearing bone
    located along the lateral border of the lower leg.
Divisions of the Skeletal
 Appendicular skeleton – Lower extremity
   Lateral Malleolus – rounded projection at the lower
    end of the fibula (outer anklebone)
   Tarsals – 7 ankle bones; the talus articulates with the
    tibia and the calcaneous, the heel bone.
   Metatarsals – 5 long bones of the foot.
   Phalanges - toe bones, two in the “big” toe and 3 in
    each of the other toes.
      Joints =Articulations
Three types of joints      Synarthroses –       Amphiarthroses –

• – synarthroses,       • immovable joints     • slightly moveable
  amphiarthroses          in which bones are     joints in which
  and diarthroses         joined by fibrous      bones are joined by
                          connective tissue.     cartilage. Ex –
                          Ex - bones of the      symphysis pubis
                          skull.                 (join 2 pelvic
                                                 bones) and the
                                                 vertebral discs that
                                                 join the vertebrae
Joints =Articulations
                                 All have a joint capsule, a joint
                                 cavity and a layer of cartilage

                                 over the ends of the adjoining

                                                                     Joint Capsule – made of tough
Synovial membrane – secretes a                                        fibrous connective tissue and
  lubricating fluid (synovial                                        lined with the smooth slippery
   fluid) that allows easier                                          synovial membrane; fits over
 movement with less friction.         Diarthroses                      the ends of the bones like a
                                        – freely

             Articular cartilage – layer of           Ligaments – cords or bands of
             cartilage over the end of the             fibrous connective tissue that
                        bones.                        hold the bones together firmly.
         Joints =Articulations

                               Types of Diarthroses

Ball and Socket –                    Hinge –                      Pivot –

  ball like head on one bone
                                   allow movements in only       small projection of one
      fits into a socket of
                                   2 directions – flexion and   bone pivots in an arch of
   another. Ex – shoulder
                                     extension. Ex – elbow       another. Ex – atlas and
  and hip. Widest range of
                                       and knee, fingers.                 axis.
Joints = Articulations

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