Skeletal_System.ppt by linzhengnd


									The Skeletal System
Animal skeletons function in support, movement,
    and protection

• There are three main types of skeletons
       –Hydrostatic skeleton


• Hydrostatic skeleton
  – Consists of fluid held under pressure in a closed
    body compartment

  – Provides body shape, which can be changed by
    contracting muscles in the body wall
  – Earthworms, hydras, and jellies have hydrostatic
• Exoskeleton
 – Rigid external skeleton
 – It can be hard or leathery
                                Shell (exoskeleton)

 – The shells of
   mollusks are
   exoskeletons made
   of calcium carbonate

  – The exoskeleton of
    arthropods is made
    of chitin
• Endoskeleton
  – Consists of hard or
    leathery supporting
    elements situated among
    the soft tissues
  – Most echinoderms,
    including sea stars and
    sea urchins, have an
    endoskeleton of hard
    plates beneath their skin
– Vertebrate endoskeletons consist of cartilage or
  a combination of cartilage and bone
• Human skeletons have five major functions
  – Support
  – Movement
  – Protection of internal organs
  – Blood formation
  – Mineral reservoir
Functions of Minerals Stored in Bones

• Calcium is needed for communication between
  neurons, muscle contraction, and blood clotting
• Phosphorus is a component of
  – DNA and RNA (genetic material)
  – ATP (molecule with stored energy)
  – cell membranes (phospholipids)
The human skeleton is a unique variation on an
     ancient theme
• All vertebrates have an axial skeleton
  – Supports the axis, or trunk, of the body
  – Consists of the skull, backbone, and, in most
    vertebrates, a rib cage
• Most vertebrates also have an appendicular
  – Supports the paired appendages
  – Consists of bones of the shoulder girdle, upper
    limbs, pelvic girdle, and lower limbs in humans
Bones of the Skeleton
                        • Axial skeleton
                           – Skull
                           – Vertebral Column
                           – Thoracic cage

                        • Appendicular skeleton
                           – Pectoral girdle
                           – Upper limbs
                           – Pelvic girdle
                           – Lower limbs
I. Bones of the Skeleton
       A. Axial Skeleton
            1. Skull
                  a. Cranial Bones – including:
                         i. Frontal
                         ii. Parietal
                         iii. Temporal
                         iv. Occipital
                  b. Facial – including:
                         i. Maxilla
                         ii. Zygomatic
                         iii. Nasal
                         iv. Mandible
Cranial Bones
Temporomandibular Joint (TMJ)

                                • TMJ
Occipital Bone

• Rear & much of base of skull
• Foramen magnum holds spinal
The Skull in Infancy & Childhood

                   • Spaces between unfused skull bones
                     called fontanels
                      – filled with fibrous membrane
                      – allow shifting of bones during
                        birth & growth of brain in
                      – fuse by 2 years of age
                   • 2 frontal bones fuse by age six
                   • Skull reaches adult size by 8 or 9
                     causing heads of children to be
                     larger in proportion to trunk
FYI: Locations of Paranasal Sinuses

Facial Bones
I. Bones of the Skeleton
       A. Axial Skeleton
            2. Vertebral Column
                  a. 7 cervical vertebrae in the neck
                         i. 1st is atlas – supports skull
                         ii. 2nd is axis – rotates head
                  b. 12 thoracic vertebrae in the chest
                  c. 5 lumbar vertebrae in the lower
                  d. 1 sacrum (5 bones fused into 1)
                  e. 1 coccyx ( 4 bones fused into 1)
General Features of the Vertebral Column

         • Single, small, triangular bone
            – 4 small vertebrae fused by age of

         • Provides attachment site for
           muscles of pelvic floor
I. Bones of the Skeleton
       A. Axial Skeleton
            3. Thoracic cage
                  a. ribs – 12 pairs:
                         i. True – pairs 1-7
                         ii. False – pairs 8-10
                         iii. Floating – pairs 11-12
                  b. sternum (3 bones fused into 1)
                         i. xiphoid process – where
                            diaphragm attaches
Thoracic Cage

                • Consists of thoracic
                  vertebrae, sternum & ribs
                • Attachment site for
                  pectoral girdle and many
                  limb muscles
                • Protects organs
                • Rhythmically expanded by
                  respiratory muscles to
                  draw air into the lungs
True and False Ribs

                      • True ribs (1 to 7) attach
                        to sternum with cartilage

                      • False ribs (8-10) (attach
                        to cartilage of 7th rib)

                      • 11-12 are floating and
                        not attached to sternum
I. Bones of the Skeleton
     B. Appendicular Skeleton
            1. Pectoral girdle – attaches arms
                  a. clavicle – 2
                  b. scapula - 2
I. Bones of the Skeleton
     B. Appendicular Skeleton
            2. Upper limbs - 30 Bones per Limb:
                  a. humerus –1
                  b. radius (thumb side) – 1
                  c. ulna – 1
                  d. carpals (wrist) - 8 small bones
                  e. metacarpals in the palm – 5
                  f. phalanges in the fingers - 14
Metacarpals and Phalanges

                        • Phalanges are bones of
                          the fingers

                        • Metacarpals are bones of
                          the palm
I. Bones of the Skeleton
     B. Appendicular Skeleton
            3. Pelvic girdle – attaches legs
                  a. Coxal bones – right and left each with
                         3 fused parts:
                         i. Ilium – crest of hip bone
                         ii. Ischium – what you sit on
                         iii. Pubis – protects reproductive

Each coxal bone is joined
to the vertebral column
Coxal Bone (Hip Bone)
Each side composed of 3 areas:
• Ilium is superior portion

• Pubis is anterior portion

• Ischium is posterolateral portion
   – bears body weight if sitting
I. Bones of the Skeleton
     B. Appendicular Skeleton
            4. Lower limbs:
                  a. femur - 1
                b. patella (knee cap) - 1
                c. tibia (shin) - 1
                d. fibula - 1
                e. tarsals (ankle) – 7
                f. metatarsals - 5
                g. phalanges (toes) – 14
                h. calcaneous (heel) -1
Femur       Patella and Tibia

The Foot

           • Bones of foot are similar in name &
             arrangement to the hand

           • Phalanges

           • Metatarsals
The Ankle

  • 7 tarsal bones are shaped & arranged
    differently from carpal bones due to
    load-bearing role of the ankle
  • Calcaneus forms heel (where achilles
    tendon attaches)
Bones are complex living organs

• Bones consist of several kinds of living tissues
  – A sheet of fibrous connective tissue covers
  – Cartilage at the end of bones cushions joints

• Bone tissues are served by blood vessels and
• A human
            contains red
            bone marrow in which stem cells produce blood cells

            Compact bone

            Central cavity

            bone marrow


Articulations =
• Movable joints provide flexibility
    – Kinds found in the vertebrate skeleton:

Head of
humerus                          Humerus


                               Ulna                   Ulna

     1 Ball-and-socket joint          2 Hinge joint          3 Pivot joint
meniscus – cartilage between femur and tibia
            “torn cartilage, runners knee”
ACL – anterior cruciate ligament

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