Ch. 5 Lecture - Skeletal System (marieb).ppt (2022)

The Skeletal System

PowerPoint® Lecture Slide Presentation

by Patty Bostwick-Taylor,
Florence-Darlington Technical College

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PART A

5

  • Overview of the Skeletal System
  • Skeleton (Greek) = “dried up body”
  • Two subdivisions of the skeleton
    • Axial skeleton – longitudinal axis of body
    • Appendicular skeleton – limbs & girdles
  • Parts of the skeletal system:
    • Bones (skeleton)
    • Joints
    • Cartilages
    • Ligaments

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  • Functions of Bones
  • Support
    • Form internal framework: supports body & cradles soft organs
  • Protection
    • Ex: skull bones fused to enclose the brain
    • Ex: vertebrae surround spinal cord
    • Ex: rib cage encloses thoracic organs
  • Movement
    • Skeletal muscles attached to bone via tendons, move body and its parts
    • Results in full body locomotion, fine movements, internal movements

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Functions of Bones, continued…

  • Storage
    • Fat (marrow) in medullary cavities
    • Bones store minerals: calcium & phosphorus
      • Ca2+ needed for nervous impulses, muscle contraction, blood clotting
      • Hormones control movement of calcium to and from bones and blood
  • Blood cell formation
    • AKA hematopoesis
    • Within marrow/medullary cavities

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  • Classification of Bones
  • The adult skeleton has 206 bones
  • Two basic types of bone tissue:
    • Compact bone
      • Dense, smooth, homogeneous
    • Spongy bone
      • AKA cancellous bone
      • Small needle-like
        pieces of bone, called
        trabeculae
      • Many open spaces
        • Site of hematopoesis
        • Filled with red marrow

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Figure 5.2b

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Structure of Cancellous Bone

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Structure of Compact Bone

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Figure 5.1

Classification of Bones on the basis of Shape

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  • Classification of bones on the basis of shape
    • 4 shapes of bone: long, short, flat, irregular
    • Long bones
      • Longer than they are wide
      • Shaft with heads at both ends
      • Contain mostly compact bone
      • Example:
        • All the bones of the limbs (except patella, ankle & wrist)

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Classification of Bones, continued…

    • Short bones
      • Generally cube-shaped
      • Contain mostly cancellous bone
      • Examples:
        • Bones of the wrist (carpal) & ankle (tarsal)
        • Sesamoid bones – bones which form within tendons; e.g. patella

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Classification of Bones, continued…

    • Flat bones
      • Thin, flattened, and usually curved
      • Two thin layers of compact bone surround a layer of cancellous bone
      • Examples:
        • Skull
        • Ribs
        • Sternum

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Classification of Bones, continued…

    • Irregular bones
      • Irregular shape
      • Do not fit into other bone classification categories
      • Example:
        • Vertebrae
        • Pelvic bones
        • Facial bones

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Answer “Did You Get It?” Questions #1-2

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Classification of Bones

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Figure 5.1d

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  • Anatomy of a Long Bone

Gross Anatomy

  • Diaphysis/es
    • AKA shaft
    • Length of the bone
    • Composed of compact bone
  • Periosteum
    • Outside covering of the diaphysis
    • Fibrous connective tissue membrane

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Anatomy of a Long Bone, continued…

  • Perforating/Sharpey’s fibers
    • Connective tissue fibers
    • Secure periosteum to underlying bone
  • Epiphysis/es
    • Ends of the bone
    • Thin layer of compact bone enclosing cancellous bone

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Anatomy of a Long Bone, continued…

  • Articular cartilage
    • Covers the external surface of the epiphyses
    • Made of hyaline cartilage
    • Decreases friction at joint surfaces
  • Arteries
    • Supply bone cells with nutrients

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Anatomy of a Long Bone, continued…

  • Epiphyseal line
    • Remnant of the epiphyseal plate
    • Seen in adult bones
  • Epiphyseal plate
    • Flat plate of hyaline cartilage seen in young, growing bone
    • Hormones inhibit long bone growth by the end of puberty
    • Epiphyseal plate is replaced by bone, leaving epiphyseal line behind

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Proximal End of a Long Bone

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Epiphyseal Plate

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Anatomy of a Long Bone, continued…

  • Medullary cavity
    • Cavity inside of the shaft
    • Contains yellow marrow (mostly adipose tissue) in adults
    • In infants, contains red marrow (for blood cell formation)
    • In adults, red marrow is in cavities of cancellous bone (flat bones) and in epiphyses (long bones)

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Bone Markings

  • Surface features of bones
    • Sites of attachments for muscles, tendons, and ligaments
    • Passages for nerves and blood vessels
  • Categories of bone markings
    • Projections or processes—grow out from the bone surface
      • All begin with T
    • Depressions or cavities—indentations
      • All begin with F (except facet)

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Bone Markings

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Table 5.1 (1 of 2)

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Bone Markings

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Table 5.1 (2 of 2)

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Bone Markings – Major Features

  • Body/shaft/diaphysis
  • Head
    • Humerus, femur
  • Neck
    • Femoral neck
  • Condyle
    • Distal femur, posterior mandible, occipital condyles
  • Facet
    • Thoracic vertebral bodies
  • Crest
    • Sagittal crest

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  • Process
    • Mastoid process (temporal), styloid process (distal radius & ulna)
  • Tubercle/tuberosity
    • Tubercle: greater & lesser tubercle on humerus, conoid tubercle (inferior edge of lateral clavicle)
    • Tuberosity: radial tuberosity, tibial tuberosity, deltoid tuberosity (humerus)
  • Trochanter
    • Greater & lesser trochanters on proximal femur
  • Epicondyle
    • Lateral epicondyle of humerus

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Bone Markings – Major Features

  • Foramen/foramina
    • Mental foramen (lateral mandible)
  • Canal/meatus
    • Canal: carotid canal (base of skull)
    • Meatus: external auditory meatus
  • Fissure
    • Superior orbital fissure, inferior orbital fissure
  • Sinus
    • Frontal sinus
  • Fossa
    • Olecranon fossa (posterior, distal humerus)
      • Fovea capitus on femoral head (fovea smaller than fossa)

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Microscopic Anatomy of Bone

  • Osteocytes – mature bone cells
  • Lacunae – tiny cavities housing osteocytes
  • Lamellae – concentric circles (layers) of lacunae & matrix
  • Central (Haversian) canals – passageway for blood vessels & nerves

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Microscopic Anatomy of Bone

  • Canaliculi – tiny canals
    • Radiate from the central canal to lacunae
    • Form a transport system connecting all bone cells to nutrient supply
  • Perforating (Volkman’s) canals
    • Canal perpendicular to the central canal
    • Carries blood vessels and nerves

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Microscopic Anatomy of Bone

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Microscopic Anatomy of Bone

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Figure 5.3b–c

Answer “Did You Get It?” Questions #3-4

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  • Bone Formation, Growth, and Remodeling
  • 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 starting
to replace
cartilage

Epiphyseal
plate
cartilage

Articular
cartilage

Spongy
bone

In a child

In a fetus

In an embryo

New bone
forming

Growth
in bone
width

Growth
in bone
length

Epiphyseal
plate cartilage

New bone
forming

Blood
vessels

Hyaline
cartilage

New center of
bone growth

Medullary
cavity

Bone collar

Hyaline
cartilage
model

(a)

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Bone Growth (Ossification)

    • Ossification = process of bone formation
      • Flat bones form on fibrous membranes
      • Other bones develop from hyaline cartilage models
    • Two phases:
      • Hyaline cartilage model covered with bone matrix
        • Done by osteoblasts = bone-forming cells
      • Hyaline cartilage model digested away, forming a medullary cavity
        • Two locations remain as cartilage after birth: articular cartilages (covering ends of bones) and epiphyseal plates

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Long Bone Formation and Growth

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Figure 5.4a

Bone starting
to replace
cartilage

Epiphyseal
plate
cartilage

Articular
cartilage

Spongy
bone

In a child

In a fetus

In an embryo

New bone
forming

Growth
in bone
width

Growth
in bone
length

Epiphyseal
plate cartilage

New bone
forming

Blood
vessels

Hyaline
cartilage

New center of
bone growth

Medullary
cavity

Bone collar

Hyaline
cartilage
model

(a)

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Bone Growth (Ossification)

    • Growth in Bone Length
      • New cartilage is continuously formed on external surface of articular cartilage and epiphyseal plate
      • Older cartilage becomes ossified
        • Cartilage is broken down
        • Enclosed cartilage is digested away, opening up a medullary cavity
        • Bone replaces cartilage through the action of osteoblasts

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Bone Growth (Ossification)

    • Growth in Bone Width; AKA appositional growth
      • Osteoblasts (from periosteum) add bone to outside of diaphysis
      • Osteoclasts (in endosteum) remove bone from inside of diaphysis
      • Both occur at approximately the same rate, resulting in larger diameter
      • Long-bone growth controlled by hormones; ends in puberty
        • Growth hormone
        • Sex hormones

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Bone Growth (Ossification)

    • Bones are continually remodeled in response to two factors
      • Blood calcium levels
      • Pull of gravity and muscles on the skeleton

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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 in response to parathyroid hormone
  • Bone remodeling is performed by both osteoblasts & osteoclasts

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Bone & Calcium Homeostasis

  • Parathyroid hormone (PTH): releases Ca2+ in blood
    • ↑’s blood Ca2+ by ↑’g osteoclast activity
    • ↑ Ca resorption from urine in kidney back into blood
    • Stimulates vitamin D production
    • Stimulated by ↓ blood Ca2+
  • Calcitonin – stores Ca2+ in bone
    • Hypercalcemia = high blood calcium, decreases osteoclast activity
    • ↓’s Ca2+ by ↓’g osteoclast activity
    • Stimulated by ↑ Ca2+

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Bone Remodeling

  • Bone Remodeling = depositing new bone matrix in a mature bone
    • In order to retain normal proportions & strength during long-bone growth
    • In order to form projections where muscles attach
    • Atrophy in bedridden or physically inactive people

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  • Homeostatic Imbalances

Growth & Development

    • Giantism: abnormally increased size, excessive endochondral growth @ epiphyseal plates
    • Dwarfism: person is abnormally small, improper growth @ epiphyseal plates
    • Osteogenesis imperfecta: (bone + production + imperfect) – genetic disorders causing brittle bones with insufficient collagen; easily fractured, especially in fetus; poor healing/misalignment
    • Rickets
      • Failure of bones to calcify
      • Softening & bowing of bones
      • Children with lack of calcium or Vitamin D in diet

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  • Homeostatic Imbalance

Bacterial Infection

    • Osteomyelitis: bone marrow inflammation, can be caused by Stapholococcus (type of bacterium) through wounds or tuberculosis

Bone tumor

Decalcification

      • Osteomalacia: (bone softness) – due to calcium depletion from bones; pregnancy or “Adult Rickets” from vitamin D deficiency

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  • Bone Fractures – Homeostatic Imbalance
  • Fracture — 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 broken bone ends
    • Closed reduction: bones realigned via external means
    • Open reduction: bones realigned via internal surgery and secured with pins/wires/plates

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Common Types of Fractures

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Table 5.2

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More on Fractures

complete – two bone fragments are separate

incomplete – two bone fragments are not separated

comminuted - > 2 fragments

impacted – 1 fragment pushed into cancellous portion of another fragment

oblique/spiral – at an angle other than perpendicular

greenstick – partly broken and partly bent

linear – parallel to long axis of bone

transverse – perpendicular to long axis

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More Fracture Pics…

  • Incomplete/Greenstick
  • Transverse
  • Oblique
  • Longitudinal
  • Spiral
  • Complete
  • Dislocation

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A Few More Notes on Fractures…

  • Note: joint immobilization during mid-late bone healing results in 3x decrease in strength
    • Muscles lose mass (atrophy)
    • Bone not subject to the stresses that helps it form
      • Solution = walking cast

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  • Repair of Bone Fractures
    • Hematoma (blood-filled swelling) forms
      • Blood vessels rupture when bone breaks
      • Bone cells die due to lack of nutrition
    • Break is splinted by fibrocartilage to form a callus
      • New capillaries grow into clot
      • Phagocytes remove dead tissue
      • Fibrocartilage callus forms; contains cartilage matrix, bony matrix, collagen fibers
      • Callus “splints” the bone

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  • Repair of Bone Fractures
    • Fibrocartilage callus is replaced by a bony callus
      • Osteoclasts remove fibrocartilage callus
      • Osteoblasts build bony callus
    • Bony callus is remodeled to form a permanent patch
      • Done in response to mechanical stresses
      • Occurs over next few weeks-months

Answer “Did You Get It?” Questions #5-8

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Stages in the Healing of a Bone Fracture

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Figure 5.5

Hematoma

External
callus

Bony
callus of
spongy
bone

Healed
fracture

New
blood
vessels

Internal
callus
(fibrous
tissue and
cartilage)

Spongy
bone
trabecula

Hematoma
formation

Fibrocartilage
callus formation

Bony callus
formation

Bone remodeling

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  • The Axial Skeleton
  • Forms the longitudinal axis of the body
  • Divided into three parts
    • Skull
    • Vertebral column
    • Bony thorax

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Axial Skeleton

  • Skull (28 bones including auditory ossicles)
  • Hyoid bone (1 bone)
  • Vertebral column (26 bones)
    • Cervical (7 vertebrae)
    • Thoracic (12 vertebrae)
    • Lumbar (5 vertebrae)
    • Sacrum (1 – 5 fused vertebrae)
    • Coccyx (1 -~4 fused vertebrae)
  • Thoracic Cage (25 bones)
  • Ribs (24)
  • Sternum (1 – 3 parts)

80 total bones in axial skeleton

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  • The Skull
    • Two sets of bones: cranium & facial bones
    • Bones are joined by sutures: interlocking, immovable joints
    • Only the mandible is attached by a freely movable joint
    • Braincase – encloses cranial cavity
    • Surrounds & protects brain
      • 6 bones, 8 when paired
  • Facial bones – forms facial structure
      • 8 bones, 14 when paired
  • Auditory ossicles – form the middle ear
    • These bones transmit vibration to eardrum
      • Malleus, incus, & stapes

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Braincase bones – 8 bones

  • 2 parietals
  • 2 temporals
  • 1 frontal
  • 1 occipital
  • 1 sphenoid
  • 1 ethmoid

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The Skull, continued…

    • Cranium: encloses & protects brain
      • Frontal bone
      • Parietal bones (wall) – sagittal & coronal sutures
        • Most of sides & roof of cranial cavity
        • Joined to temporal by squamous suture (scale-like)
        • Joined to frontal by coronal suture (crown)
        • Joined to occipital by lambdoid suture (λ)
        • Sagittal suture joins two parietals

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The Skull, continued…

      • Temporal bones (time) – squamous sutures
    • Inferior part of cranium & part of cranial floor
    • Joined to occipital and parietal by squamous suture
        • External acoustic (auditory) meatus – sound waves travel through to eardrum
        • Styloid process– muscle attachment for tongue, hyoid, & pharynx movement
        • Zygomatic process– articulates with zygomatic
        • Mastoid process– neck muscle attachment for head rotation
        • Jugular foramen
        • Internal acoustic meatus
        • Carotid canal
    • Other landmarks:
      • Mandibular Fossa – articulates with mandible

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The Skull, continued…

      • Occipital bone (back of the head)
        • Lambdoid suture - joined to parietals by lambdoid suture
        • Foramen magnum– passage of spinal cord (connects to brain)
        • Occipital condyles– articulate with vertebral column
        • Posterior part & prominent portion of the base of the cranium

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The Skull, continued…

      • Sphenoid bone (wedge-shaped)
        • Sella turcica – contains pituitary gland
        • Foramen ovale
        • Optic canal
        • Superior orbital fissure
        • Sphenoid sinuses
    • Connects to all other cranial bones

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The Skull, continued…

      • Ethmoid bone
        • Crista galli
        • Cribriform plate
        • Superior nasal concha & middle nasal concha form lateral walls of nasal cavity
    • Light, spongy bone that increases surface area of nasal cavity
      • Moistens & warms inhaled air
    • Anterior floor of the cranium between the orbits
    • Composes much of nasal cavity & part of nasal septum
      • Perpendicular Plate – part of nasal septum (with vomer)

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Human Skull, Lateral View

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Figure 5.7

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Human Skull, Superior View

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Figure 5.8

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Human Skull, Inferior View

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Figure 5.9

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Human Skull, Anterior View

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Figure 5.11

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The Skull, continued…

    • Facial bones: holds eyes & support facial muscles
      • Maxillae/maxilla
        • Maxillary bones
        • Alveolar margin
        • Palatine processes
        • Paranasal sinuses
        • Hollow portions of bones surrounding the nasal cavity
        • Functions of paranasal sinuses
          • Lighten the skull
          • Give resonance and amplification to voice

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Facial Bones, continued…

      • Palatine bones
      • Zygomatic bones
      • Lacrimal bones
      • Nasal bones
      • Vomer bone
      • Inferior nasal conchae
      • Mandible
        • Body
        • Ramus/rami
        • Alveoli
        • Alveolar margin

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Paranasal Sinuses

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Figure 5.10a

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Paranasal Sinuses

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Figure 5.10b

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  • The Hyoid Bone
      • Not really part of the skull
      • The only bone that does not articulate with another bone
      • Serves as a moveable base for the tongue
      • Attachment point for neck muscles that raise/lower the larynx during swallowing and speech

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  • The Fetal Skull
      • Infant’s face is very small compared to cranium size
      • Fetal skull is large compared to the infant’s total body length
      • Fontanels — fibrous membranes connecting the cranial bones; AKA soft spots
        • Allow skull to be compressed during child birth
        • Allow the brain to grow during latter pregnancy and early infancy
        • Convert to bone within 22-24 months after birth

Answer “Did You Get It?” Questions #9-13

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The Fetal Skull

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Figure 5.13a

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The Fetal Skull

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Figure 5.13b

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  • The Vertebral Column (Spine)

Functions:

    • Axial support for the body
    • Extends from skull (support) to pelvis (transmits body weight to lower limbs)
    • Surrounds and protects the spinal cord
    • Allows spinal nerves to exit spinal cord
    • Site for muscle attachment
    • Permits head & trunk movement

Composition:

    • Composed of 26 irregular bones, connected by ligaments, creating a flexible and curved structure

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The Vertebral Column (Spine)

    • 33 vertebrae before birth
      • 9 fuse to become the sacrum and coccyx
    • 24 vertebral bones
      • Neck: 7 cervical vertebrae
      • Chest/thorax: 12 thoracic vertebrae
      • Lower back: 5 lumbar vertebrae
    • Intervertebral discs: pads of fibrocartilage in between vertebrae
      • Absorb shock
      • Provide flexibility
      • Loses function with age

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The Vertebral Column

    • Homeostatic Imbalance: Herniated (slipped) discs
      • Caused by:
        • Drying of discs
        • Weakening of ligaments of vertebral column
        • Exceptional twisting forces
      • If disc presses on spinal cord or spinal nerves, can cause numbness and pain

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Vertebral Column Damage

  • “Broken Tailbone”
    • Fractured coccyx
    • Can occur during childbirth and from falls

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The Vertebral Column

    • Spinal curvatures
      • S-shaped curve
      • Functions:
        • Prevents shock to head
        • Make body trunk flexible
      • Primary curvatures are the spinal curvatures of the thoracic and sacral regions
        • Present from birth
        • Produce C-shape in newborns’ spine

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The Vertebral Column

      • Secondary curvatures are the spinal curvatures of the cervical and lumbar regions
        • Develop after birth
        • Lumbar curvature provides ability to center body weight on lower limbs; develops as a baby begins to walk
        • Cervical curvature develops as a baby begins to raise its head

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The Vertebral Column

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Figure 5.16

    • Homeostatic Imbalance: Abnormal Spine Curvatures
        • Scoliosis: abnormal lateral curvature
  • Kyphosis: abnormal posterior curvature
    • Usually upper thoracic
    • Hunchback
  • Lordosis: abnormal anterior curvature
    • Lumbar
    • Swayback
  • Causes: congenital, due to disease, poor posture, unequal muscle pull on spine

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Vertebral Column Defects

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  • Vertebral Anatomy
  • Body/centrum – bears weight; faces anteriorly
  • Vertebral arch – created by posterior extensions; forms vertebral foramen
    • Lamina – extend from transverse process to spinous process
    • Pedicle – extend from body to transverse process (feet)
  • Vertebral foramen – houses spinal cord
  • Transverse process – extend laterally from the vertebral arch between pedicle & lamina

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  • Spinous process- project dorsally from laminae; can feel externally
  • Articular processes – area of vertebral articulation
    • Superior and inferior
    • Lateral to vertebral foramen
  • Articular facet – smooth surface articulates with ribs
  • Intervertebral foramina- notches formed by adjacent vertebrae; spinal nerves exit here
  • Vertebral canal – formed by all vertebral foramina; spinal cord passage/protection

Vertebral Anatomy, continued…

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Differences in Vertebrae

    • Cervical (7: C1-C7)
      • Atlas (C1)
        • No body
        • Large articular facets that articulate with occipital condyles (holds head up)
        • Nod “yes”
      • Axis (C2)
        • Pivot for rotation of atlas & skull
        • Dens – large upright process
        • Shake your head “no”

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Differences in Vertebrae

Cervical Vertebrae, continued…

      • Smallest, lightest vertebrae
      • Short spinous processes; some have branched spinous processes
      • Transverse processes contain foramina for vertebral arteries going to brain; only present in cervical vertebrae
      • Small bodies (except atlas)

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Differences in Vertebrae

    • Thoracic (12: T1-T12)
      • Only vertebrae that articulate with the ribs
      • ~Heart-shaped body
      • 2 lateral articular facets for rib articulation
      • Transverse processes articulate with rib tubercles
      • Long, thick spinous processes hooks sharply down: giraffe head

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Differences in Vertebrae

    • Lumbar (5: L1-L5)
      • Large, thick bodies
      • Heavy, rectangular spinous process; moose head
      • Medially facing superior articular facets (“locks” vertebrae together for stability)

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A Typical Vertebrae, Superior View

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Figure 5.17

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  • Sacrum
      • 5 fused vertebrae
      • Articulates with L5 superiorly and coccyx inferiorly
      • Alae articulate with ilia (hip bones) laterally at the sacroiliac (SI) joint
      • Forms posterior wall of pelvis
      • Median sacral crest – fused spinous processes of the sacral vertebrae
      • Sacral foramina: posterior & anterior
      • Sacral canal – continuation of vertebral canal
      • Sacral hiatus – large inferior opening
        • Site of anesthetic injection prior to childbirth
      • Sacral promontory – bulge in anterior edge of body of 1st vertebra in sacrum
        • Palpated before childbirth to determine pelvic opening size

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  • Coccyx
      • Formed from the fusion of three to five vertebrae
      • “Tailbone,” or remnant of a tail that other vertebrates have
      • Reduced vertebral bodies
      • No foramina or processes

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  • The Bony Thorax
    • Consists of three parts:
      • Sternum
      • Ribs
      • Thoracic vertebrae
    • AKA thoracic cage
    • Forms a cage to protect heart, lungs, and major vessels

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The Bony Thorax, continued…

    • Sternum, AKA breastbone
      • Fusion of manubrium, body, and xiphoid (sword) process
      • Attached to 1st 7 pair of ribs
        • Jugular notch – concave superior border of manubrium; @ T3
        • Sternal angle – junction of manubrium & body; @ 2nd intercostal space (heart valve auscaultation @ heart’s apex)
        • Xiphisternal joint – junction of body & xiphoid process; @ T9

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The Bony Thorax, continued…

    • Ribs
      • 12 pair form walls of bony thorax
      • Articulate posteriorly with vertebrae, then curve downward anteriorly
        • True ribs: pairs 1-7; attach to sternum via costal cartilages
        • False ribs: pairs 8–12; attach indirectly to sternum or not at all
        • Floating ribs: pairs 11–12; no sternal attachment
      • Intercostal spaces – spaces between ribs are filled with muscles that air in breathing

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Answer “Did You Get It?” #14-17

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  • The Appendicular Skeleton
  • Composed of 126 bones
    • Pectoral girdle
    • Limbs (appendages)
    • Pelvic girdle

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Appendicular = “to hang something on”

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  • The Pectoral (Shoulder) Girdle
    • Composed of two bones
      • Clavicle—collarbone
      • Scapula—shoulder blade
    • Clavicle
      • Doubly curved
      • Articulates with the manubrium medially an with the scapula laterally
      • Forms shoulder joint with scapula
      • Braces arm away from top of thorax

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Pectoral Girdle

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Bones of the Shoulder Girdle, continued…

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Figure 5.21c–d

    • Scapulae
      • Acromion process: enlarged end of scapula’s spine
        • Connects with clavicle laterally at acromioclavicular joint
      • Coracoid process: beaklike
        • Points over top of shoulder; anchors some arm muscles
      • Suprascapular notch: nerve passageway

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Bones of the Shoulder Girdle, continued…

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Scapulae, continued…

      • Scapula not attached directly to skeleton
        • Held in place by trunk muscles
      • 3 borders:
        • Superior, medial (vertebral), and lateral (axillary)
      • Glenoid cavity: receives head of humerus (forms lateral angle)

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Bones of the Shoulder Girdle, continued…

    • Shoulder girdle is light and provides free movement:
      • One attachment point to axial skeleton at sternoclavicular joint
      • Scapula slides back and forth over the thorax
      • Glenoid cavity is shallow and shoulder is poorly reinforced by ligaments
      • BUT, shoulder is easily dislocated

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Bones of the Upper Limbs, continued…

    • Arm
      • Humerus (makes up arm)
        • Head of humerus articulates with glenoid cavity of scapula
        • Anatomical neck: slight constriction of humerus
        • Intertubercular sulcus lies between greater and lesser tubercles: sites of muscle attachment
        • Surgical neck: distal to tubercles; commonly fractured
        • Deltoid tuberosity: roughened area of attachment of deltoid muscle

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Bones of the Upper Limbs, continued…

Arm, continued…

        • Radial groove: runs obliquely down posterior aspect of diaphysis; site of radial nerve
        • Trochlea: spool-like structure on the medial aspect of distal end of humerus; articulates with forearm (medial condyle)
        • Capitulum: ball-like structure on lateral aspect of distal end of humerus; articulates with forearm (lateral condyle)
        • Coronoid fossa: depression superior to trochlea on anterior surface; articulates with ulna
        • Olecranon fossa: depression superior to trochlea on posterior surface; articulates with ulna
        • Medial and lateral epicondyles: lie superior to condyles

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Bones of the Upper Limbs, continued…

    • Forearm
      • Radius
        • Lateral bone in anatomical position (thumb side)
        • Articulates with ulna at radioulnar joint proximally and distally
        • Connected to ulna via interosseous membrane along the lengths of the bones
        • Styloid process at distal end
        • Articulates with capitulum of humerus with disc-shaped head
        • Radial tuberosity: site of attachment of biceps muscle

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Bones of the Upper Limbs, continued…

Forearm, continued…

      • Ulna
        • Medial bone in anatomical position (little finger side)
        • Coronoid process on anterior surface of proximal end; articulates with trochlea of humerus (coronoid fossa)
        • Olecranon process on posterior surface of proximal end; articulates with trochlea of humerus (olecranon fossa)
        • Trochlear notch separates coronoid and olecranon processes

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Elbow Bone Landmarks

*

*

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Bones of the Upper Limbs, continued…

    • Hand
      • Carpals — AKA wrist
        • 8 bones arranged in 2 irregular rows of 4 bones each
        • Form the carpus (wrist)
        • Ligaments bind carpals together and limit movement
        • Scaphoid, lunate, triquetrum, pisiform, hamate, capitate, trapezoid, trapezium

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Bones of the Upper Limbs, continued…

Hand, continued…

      • Metacarpals — AKA palm
        • Numbered 1-5 from thumb toward pinky
        • Heads of metacarpals form knuckles
      • Digit – one finger or thumb, composed of 2-3 phalanges
        • Numbered 1-5 from thumb
      • Phalanges — bones of the fingers
        • 14 phalanges per hand
        • 3 phalanges per finger; 2 phalanges per thumb
          • Distal, middle, & proximal phalanx
          • Thumb lacks the middle phalanx

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Answer “Did You Get It?” Questions # 18-21

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  • Bones of the Pelvic Girdle
    • Formed by two coxal (ossa coxae) bones, AKA hip bones
    • Bony pelvis = coxal bones, sacrum, coccyx
    • Pelvic girdle = coxal bones
    • Large, heavy bones
    • Strong attachments to axial skeleton (@ SI joint)
    • Femur firmly attached to pelvic girdle by ligaments

*

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Bones of the Pelvic Girdle, continued…

    • Functions:
      • Total weight of the upper body rests on the pelvis
      • It protects several organs:
      • Reproductive organs
      • Urinary bladder
      • Part of the large intestine
    • Composed of three pairs of fused bones
      • Ilium
      • Ischium
      • Pubis

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Bones of the Pelvic Girdle, continued…

    • Ilium: large, flaring bone; forms most of hip bone
      • Connects posteriorly to the sacrum at the sacroiliac joint
      • Alae: wing-like portion of the ilia
      • Iliac crest: upper edge of the ala
      • Anterior superior iliac spine: anterior edge of iliac crest
      • Posterior superior iliac spine: posterior edge of iliac crest

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Bones of the Pelvic Girdle, continued…

    • Ischium: “sit down” bone
      • Most posterior part of coxal bone
      • Ischial tuberosity: origin of your hamstring muscles; receives body weight in sitting position
      • Ischial spine: superior to ischial tuberosity; narrow portion of pelvic outlet (birth canal)
      • Greater sciatic notch: passageway for blood vessels and sciatic nerve from posterior pelvis to thigh; avoid injections

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Bones of the Pelvic Girdle, continued…

    • Pubis/Pubic Bone
      • Most anterior part of coxal bone
      • Obturator foramen: formed by fusion of pubis rami anteriorly and ischium posteriorly
        • Passageway for blood vessels and nerves toward anterior thigh
      • Pubic symphysis: anterior cartilaginous (fibrocartilage) joint between pubic bones

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Bones of the Pelvic Girdle, continued…

    • Acetabulum
      • AKA “vinegar cup”
      • Fusion of ilium, ischium, and pubis
      • Deep socket which receives head of femur

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Bones of the Pelvic Girdle, continued…

    • False pelvis – superior to true pelvis; area medial to alae
    • True pelvis – inferior to alae and pelvic brim; forms birth canal
      • Pelvic outlet: inferior opening between ischial spines
      • Pelvic inlet: superior opening between left & right sides of pelvic brim

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  • Gender Differences of the Pelvis
      • Female inlet is larger and more circular
      • Female pelvis is shallower; bones are lighter and thinner
      • Female ilia flare more laterally

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Gender Differences of the Pelvis, continued…

      • Female sacrum is shorter and less curved
      • Female ischial spines are shorter and farther apart; thus the outlet is larger
      • Female pubic arch is more rounded because the angle of the pubic arch is greater

Answer “Did You Get It?” Questions #22-23

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  • Bones of the Lower Limbs
    • Carry total body weight
    • Lower limb bones much thicker and stronger than upper limb bones

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Bones of the Lower Limbs, continued…

    • Thigh (1 bone only)
      • Femur
        • Heaviest, strongest bone in the body
        • Proximal epiphysis:
          • Ball-like head
          • Neck (commonly fractured)
          • Sites of muscle attachment:
          • Greater and Lesser trochanters
          • Intertrochanteric line
          • Intertrochanteric crest
          • Gluteal tuberosity
        • Slants medially toward knee; more so in women with wider pelvis

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Bones of the Lower Limbs, continued…

Femur, continued…

        • Lateral and medial condyles on distal epiphysis articulate with tibia
        • Intercondylar fossa separates the condyles
        • Patellar surface on anterior aspect of distal epiphysis; forms joint with patella

*

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Bones of the Lower Limbs, continued…

    • Leg
      • Tibia and fibula connected along their lengths by interosseous membrane

Composition:

      • Tibia
        • AKA Shinbone
        • Larger and medially oriented
        • Medial and lateral condyles at proximal epiphysis; articulate with femoral condyles to form knee joint
        • Intercondylar eminence separates condyles

*

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Bones of the Lower Limbs, continued…

Tibia, continued…

        • Tibial tuberosity: site of attachment for patellar ligament
        • Medial malleolus on medial aspect of distal epiphysis; forms inner ankle bulge
        • Anterior border: sharp ridge on anterior surface; unprotected by muscles

*

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Bones of the Lower Limbs, continued…

      • Fibula
        • Lateral to tibia
        • Forms joints with tibia proximally and distally
        • Thin, stick-like
        • Not involved with knee joint
        • Lateral malleolus on lateral aspect of distal epiphysis forms outer ankle bulge

*

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Bones of the Lower Limbs, continued…

    • Foot

Functions:

      • Support body weight
      • Act as lever to propel body forward during locomotion

Composition:

      • Tarsals
        • Posterior half of foot
        • 7 tarsal bones
          • Calcaneus, talus, navicular, cuboid, lateral cuneiform, intermediate cuneiform, medial cuneiform
        • Most weight carried by calcaneus and talus; talus articulates with tibia

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Bones of the Lower Limbs, continued…

Foot, continued…

      • Metatarsals (5)
        • Form the sole
      • Phalanges (14)
        • Form the toes
        • 3 phalanges per toe; great toe has 2 phalanges
        • Distal, middle, and proximal phalanx

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      • Arches of the Foot
        • Bones are arranged to form three arches
          • 2 longitudinal: medial and lateral
          • 1 transverse
        • Ligaments and tendons keep bones in place while allowing springiness
        • “Fallen arches” or “flat feet” are caused by weak arches

Answer “Did You Get It?” Question #’s 24-26

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Bones of the Lower Limbs, continued…

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  • Joints
  • Articulation/joint = point where two bones meet
  • Functions of joints:
    • Hold bones together
    • Allow for mobility
  • Ways joints are classified:
    • Functionally – based an amount of movement
    • Structurally – based on type of tissue between the bones

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Functional Classification of Joints

    • Synarthroses
      • Immovable joints
        • Axial skeleton
      • Some cartilaginous & fibrous joints
    • Amphiarthroses
      • Slightly moveable joints
        • Axial skeleton
      • Cartilaginous & some fibrous joints
    • Diarthroses
      • Freely moveable joints
        • Common in the limbs
      • Synovial joints

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Structural Classification of Joints

    • Fibrous joints
      • Generally immovable
    • Cartilaginous joints
      • Immovable or slightly moveable
    • Synovial joints
      • Freely moveable

*

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  • Fibrous Joints
    • Bones united by fibrous tissue
    • Examples:
      • Sutures:
        • Connective tissue fibers binding skull bones
      • Syndesmoses:
        • Allows more movement than sutures
        • Distal end of tibia and fibula

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  • Cartilaginous Joints
    • Bone ends covered by cartilage
    • Amphiarthrotic Examples (slightly movable):
      • Pubic symphysis (fibrocartilage)
      • Intervertebral joints (fibrocartilage discs between)
    • Synarthrotic Examples (immovable):
      • Epiphyseal plates (hyaline cartilage) of long bones
      • Costal cartilages between first ribs and sternum (hyaline)

*

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  • Synovial Joints
    • Articulating bones are separated by a joint cavity filled with synovial fluid
    • All the joints of the limbs

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    • Features of synovial joints:
      • Articular cartilage (hyaline) covers the ends of bones
      • A fibrous articular capsule encloses joint surfaces; lined with synovial membrane
      • Joint cavity is filled with synovial fluid
      • Ligaments reinforce the joint

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Synovial Joints, continued…

      • Structures Associated with the Synovial Joint
      • Bursae (AKA purses) – flattened fibrous sacs
        • Act like ball bearings by reducing friction
        • Lined with synovial membranes
        • Filled with synovial fluid
        • Not actually part of the joint
        • Common where ligaments, muscles, skin, tendons, or bones rub together
      • Tendon sheath
        • Elongated bursa that wraps around a tendon

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Summary of Joint Classes

[Insert Table 5.3 here]

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Table 5.3

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Homeostatic Imbalance

  • Dislocation – bone forced out of normal position in the joint cavity
  • Reduction – process of returning the bone to its proper position

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  • Types of Synovial Joints
  • Plane Joint
    • Flat articular surfaces
    • Short slipping or gliding movements
    • Nonaxial movements
    • Intercarpal joints of wrist
  • Hinge Joint
    • Cylindrical end of one bone fits into trough-shaped surface of another bone
    • Angular movement in one plane (hinge)
    • Uniaxial (one axis)
    • Elbow, ankle, phalanges

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Types of Synovial Joints

  • Pivot Joint
    • Rounded end of one bone fits into sleeve or ring of bone
    • Uniaxial – one long axis
    • Proximal radioulnar joint and joint between atlas and dens of axis
  • Condyloid Joint
    • AKA knuckle-like
    • Egg-shaped surface of one bone fits into oval concavity of another bone
    • Allow moving bone to travel
      • Side to side, or
      • Back and forth
    • Biaxial = movement around two axes; but, not around long axis
    • Knuckle (metacarpophalangeal) joints

*

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Types of Synovial Joints

  • Saddle Joint
    • Articular surfaces have convex and concave surfaces
    • Biaxial – similar movements as condyloid joints
    • Carpometacarpal joints in thumb
  • Ball-and-Socket Joint
    • Spherical head of one bone fits into round socket of another
    • Multiaxial joint – movement in all axes, including rotation
    • Most freely moving synovial joints
    • Shoulder and hip

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Figure 5.30d–f

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  • Homeostatic Imbalances of Joints
    • Bursitis (AKA “water on the knee”): inflammation of a bursa or synovial membrane usually caused by a blow or friction
    • Sprains: ligaments or tendons of joint are damaged by excessive stretching or are torn from bone
      • Heal slowly due to poor vascular supply
      • Tendonitis – inflammation of tendon sheaths

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Homeostatic Imbalances of Joints, continued…

    • Arthritis: inflammatory or degenerative diseases of joints
      • arth = joint; itis = inflammation
      • Over 100 different types; most widespread crippling disease in the United States
      • Pain, stiffness, swelling of joint
      • Acute arthritis caused by bacterial infection; treated with antibiotics
      • Chronic arthritis: osteoarthritis, rheumatoid arthritis, gouty arthritis

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Homeostatic Imbalances of Joints, continued…

    • Chronic forms of arthritis
      • Osteoarthritis (OA)
        • Most common chronic arthritis
        • Chronic degenerative condition related to normal aging processes
        • Erosion of articular cartilages, formation of bone spurs, restricts joint movement, crepitus, painful
      • Rheumatoid arthritis (RA)
        • Chronic inflammatory disorder occurring between the ages of 40-50; affects more women than men
        • Mostly in hand, wrist, foot, and ankle joints (symmetrical)
        • An autoimmune disease—the immune system attacks the joints
        • Symptoms begin with inflammation of synovial membranes, accumulation of synovial fluid; inflammatory cells destroy tissues
        • Often leads to deformities

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Homeostatic Imbalances of Joints, continued…

      • Gouty arthritis (AKA Gout)
        • Inflammation of joints is caused by a deposition of uric acid crystals from the blood
        • Extremely painful
        • Typically affects a single joint, such as the great toe
        • More common in men; after age of 30; probably genetic
        • Can usually be controlled with diet

Answer “Did You Get It?” Question #’s 27-30

*

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  • Developmental Aspects of the Skeletal System
  • Fetal Changes
    • First long bones made of hyaline cartilage
    • Earliest flat bones are fibrous membranes
    • During fetal development both are converted to bone
    • Fontanels remain upon birth to allow for brain growth, but ossify by 2 years of age

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12-week old fetus

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  • Skeletal Changes Throughout Life
    • Adolescence
      • Epiphyseal plates become ossified and long bone growth ends
    • Size of cranium in relationship to body
      • 2 years old—skull is ¾ of adult size
      • 8 or 9 years old—skull is near adult size and proportion
      • Between ages 6 and 11, the face grows out from the skull
        • Jaws increase in size
        • Cheekbones & nose become prominent
        • Respiratory passages expand
        • Permanent teeth develop

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Skeletal Changes Throughout Life, continued…

    • Curvatures of the spine
      • Primary curvatures are present at birth and are convex posteriorly
      • Secondary curvatures are convex anteriorly and are associated with a child’s later development
        • Result from reshaping of the intervertebral disks
      • Abnormal spinal curvatures (scoliosis and lordosis) are often congenital, but can result from injuries

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Skeletal Changes Throughout Life, continued…

    • Skeletal growth changes body proportions
      • Birth—head & trunk = 1.5x longer than lower limbs
      • Lower limbs grow faster than trunk; reach ~= length as head & trunk by age of 10
      • Puberty—female pelvis broadens; male skeleton becomes more robust

*

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Skeletal Changes Throughout Life, continued…

    • Osteoporosis
      • Bone-thinning disease afflicting
        • 50% of women over age 65
        • 20% of men over age 70
      • Disease makes bones fragile and bones can easily fracture
        • Especially vertebrae and neck of femur
      • Vertebral collapse results in kyphosis (AKA dowager’s hump)

*

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Skeletal Changes Throughout Life, continued…

      • Estrogen aids in health and normal density of a female skeleton after menopause
      • Other contributing factors: diet low in calcium and protein, low vitamin D, smoking, insufficient weight-bearing exercise
      • Elderly often suffer from pathologic fractures by avoiding doing anything too physical
      • Osteoarthritis also occurs in weight-bearing joints

Answer “Did You Get It?” Question #’s 31-34

*

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