skeletal system

• skeletal system components:

  1. cartilage: forerunner for bone tissue covers most joints in adults
  2. ligaments: hold bone together at joints (articulations)
  3. bone: mineralized connective tissue, blood, bone marrow, cartilage, adipose, nervous and fibrous connective tissues
• skeletal cartilages

  1. hyaline cartilage: articular, costal, respiratory, nasal (pre-existing skeletal model for enchondral ossification)
  2. elastic cartilage: ears epiglottis (high elasticity)
  3. fibrocartilage: vertebral discs, knee menisci (highly compressible, high tensile strength)
• there are 206 bones on average
• The skeleton is broken up into the axial skeleton and appendicular skeleton
• axial skeleton (80 total + 7 associated)

  • skull (22)
  • auditory ossicles (6)
  • hyoid bone (1)
  • vertebral column (33)
  • thoracic cage (25)
• appendicular skeleton

  • pectoral girdles (4)
  • upper limbs (60)
  • hip bones (2)
  • lower limbs (60)
• new borns have 270 bones that fuse once you get older
• sesamoid bones: bones that form within tendons in response to strain

  wormian (sutural) bones: extra bones in the skull
• bone markings:

  1. depressions: space for nerves and blood vessels shaped for articulation
  2. openings: enclose delicate structures allow passage to marrow
  3. projections: sites for ligament or tendon attachment shaped for articulations
• depression bone markings:

  1. facet (rib)
  2. fossa (fossa)
  3. fovea (fovea)
  4. groove (groove)
• openings bone markings:

  1. canal (temporal bone)
  2. fissure (sphenoid bone)
  3. foremen (frontal bone)
• projections bone markings:

  1. condyle (mandible)
  2. crest (ilium)
  3. head (humerus head)
  4. epicondyle (humerus deltoid tuberosity)
  5. tubercle & tuberosity (humerus medial epicondyle)
  6. process (scapula process)
  7. protuberance (occipital bone)
  8. trochanter (femur greater trochanter)
  9. line (lines aspera)
• label

  A) cranial vault

  B) cranial base

  C) posterior cranial fossa

  D) middle cranial fossa

  E) anterior cranial fossa

  
• label

  A) cranial cavity

  B) orbits

  C) paranasal sinuses

  D) nasal cavity

  E) oral cavity

  
• cranial bones:

  1. parietal
  2. ethmoid
  3. sphenoid
  4. temporal
  5. occipital
  6. frontal
• facial bones:

  1. vomer
  2. inferior nasal choncha
  3. nasal
  4. mandible
  5. maxilla
  6. palatine
  7. zygomatic
  8. lacrimal
• orbital bones:

  1. ethmoid
  2. sphenoid
  3. frontal
  4. lacrimal
  5. maxilla
  6. palatine
• paranasal sinus bones:

  1. frontal
  2. ethmoid
  3. sphenoid
  4. maxilla
• label

  A) coronal suture

  B) parietal bone

  C) temporal bone

  D) squamous suture

  E) zygomatic arch

  F) lambdoid suture

  G) external acoustic meatus

  H) occipital bone

  I) mastoid process

  J) styloid process

  K) mandibular condyle

  L) mandibular notch

  M) mandibular ramus

  N) coronoid process

  O) frontal bone

  P) sphenoid bone

  Q) ethmoid bone

  R) lacrimal bone

  S) lacrimal fossa

  T) nasal bone

  U) zygomatic bone

  V) anterior nasal spine

  W) maxilla

  X) alveolar processes

  Y) mental foreman

  Z) mandible

  
• fontanels: skull areas where intramembranous ossification is not yet complete
• unfused sutures: skill lines between or within developing bones, where intramembranous ossification is not yet complete
• hyoid bone helps you speak
• vertebral column:

  • 7 cervical vertebrae (C1-C7)
  • 12 thoracic vertebrae (T1-T12)
  • 5 lumbar (L1-L5)
  • 5 sacral vertebrae (sacrum)
  • 3-5 coccygeal vertebrae (C1-C5)
• scoliosis: abnormal lateral curvatures in vertebral column

  lordosis: exaggerated cervical and lumbar curvatures

  kyphosis: exaggeration of thoracic curvature resulting in hunchback appearance
• intervertebral discs: fibrocartilage pad between bodies of adjacent vertebrae; absorbs shock and binds vertebral column together; each disc has following components:

  • nucleus pulposus: soft, inner jelly-like substance; resilient shock absorber
  • anulus fibrosis: outer ring of fibrocartilage; contains nucleus pulpous, joins adjacent vertebrae
• label thoracic cage

  A) manubrium

  B) body

  C) xiphoid process

  D) floating ribs (11-12)

  E) vertobrochondral ribs (8-10)

  F) true ribs (1-7)

  
• bone remodeling

  1. bone deposition: secrete collagen fibers, proteoglycans and glycoproteins calcium ion vesicles
  2. bone resorption: secrete hydrogen ion, enzymes
• remodeling occurs under periosteum and endosteum