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Chapter 7
Skeletal System
Bone Classification
• Long Bones
• Short Bones
• Flat Bones
• Irregular Bones
• Sesamoid Bones
7-2
Parts of a Long Bone
• epiphysis- expanded end of long bone
• distal
• proximal
• diaphysis-shaft
• compact bone-outer surface
• spongy bone- cancellous bone, which contain bony plates called
trabeculae. Found at the epiphysis of long bone.
• medullary cavity -hollow space
found in the diaphysis and spaces of
spongy bone
• endosteum - thin membrane lining
the cavity-contains bone forming
cell.
• periosteum-tough,
vascular membrane
covering the outer
surface.
• marrowred
yellow
7-3
Major parts of long bone
Compact and Spongy Bone
7-4
Spongy bone
•
•
•
•
•
Location:
Flat bones, irregular bones, and end of long bones
Osteocytes- lie within the bony plates
No central canal
A layer of spongy sandwiched between plates of
compact bone
• In an adult, red marrow, is found in the spongy bone
of all flat bones.
• In an infant, red marrow occupies the cavities of
long bone. Yellow marrow stores fat and fills the
cavity in an adult.
Compact bone
• In compact bone, the osteocyte's lie concentrically
around a central canal. Each unit forms an osteon
cemented together to form compact bone.
• Central canals - contains blood vessels and nerve
fibers, which provide nutrients for bone cells.
• Transverse canals interconnect with the central
canals, allowing communication between each
osteon and the surface of bone.
• Collagen gives bone strength and inorganic salts
make it hard and resistant.
Microscopic Structure
of Compact Bone
• osteon
• central canal
• perforating canal
• osteocyte
• lacuna
• bone matrix
• canaliculus
7-5
Bone Development
Intramembranous Ossification
• bones originate within sheetlike layers of connective tissues
• broad, flat bones
• skull bones (except mandible)
• intramembranous bones
Endochondral Ossification
• bones begin as hyaline cartilage
• most bones of the skeleton
• endochondral bones
7-6
Endochondral Ossification
• hyaline cartilage model
• epiphyseal plate
• primary ossification center
• osteoblasts vs. osteoclasts
• secondary ossification centers
7-7
Growth at the Epiphyseal Plate
First layer of cells
• closest to the end of
epiphysis
• resting cells
• anchors epiphyseal
plate to epiphysis
Second layer of cells
• many rows of
young cells
• undergoing mitosis
7-8
Growth at the Epiphyseal Plate
Third layer of cells
• older cells
• left behind when new
cells appear
• cells enlarging and
becoming calcified
Fourth layer of cells
• thin
• dead cells
• calcified
intercellular
substance
7-9
Homeostasis of Bone Tissue
•Bone Resorption – action of osteoclasts and parathyroid
hormone
•Bone Deposition – action of osteoblasts and calcitonin
7-10
Factors Affecting Bone
Development, Growth, and
Repair
• Deficiency of Vitamin A – retards bone development
• Deficiency of Vitamin C – results in fragile bones
• Deficiency of Vitamin D – rickets, osteomalacia
• Insufficient Growth Hormone – dwarfism
• Excessive Growth Hormone – gigantism, acromegaly
• Insufficient Thyroid Hormone – delays bone growth
• Sex Hormones – promote bone formation; stimulate
ossification of epiphyseal plates
• Physical Stress – stimulates bone growth
7-11
Levers and Movement
7-14
Skeletal Organization
Axial Skeleton
• head
• neck
• trunk
Appendicular Skeleton
• upper limbs
• lower limbs
• pectoral girdle
• pelvic girdle
7-15
Skeletal Organization
7-16
Skull
Frontal (1)
• forehead
• roof of nasal cavity
• roofs of orbits
• frontal sinuses
• supraorbital foramen
• coronal suture
7-17
Skull
Parietal (2)
• side walls of cranium
• roof of cranium
• sagittal suture
7-18
Skull
Temporal (2)
• wall of cranium
• floor of cranium
• floors and sides of orbits
• squamosal suture
• external acoustic meatus
• mandibular fossa
• mastoid process
• styloid process
• zygomatic process
7-19
Skull
Occipital (1)
• back of skull
• base of cranium
• foramen magnum
• occipital condyles
• lambdoidal suture
7-20
Skull
Sphenoid (1)
• base of cranium
• sides of skull
• floors and sides of orbits
• sella turcica
• sphenoidal sinuses
7-21
Skull
Ethmoid (1)
• roof and walls of nasal cavity
• floor of cranium
• wall of orbits
• cribiform plates
• perpendicular plate
• superior and middle nasal conchae
• ethmoidal sinuses
• crista gallis
7-22
Facial Skeleton
Maxillary (2)
• upper jaw
• anterior roof of mouth
• floors of orbits
• sides of nasal cavity
• floors of nasal cavity
• alveolar processes
• maxillary sinuses
• palatine process
7-23
Facial Skeleton
Palatine (2)
• posterior roof of mouth
• floor of nasal cavity
• lateral walls of nasal cavity
7-24
Facial Skeleton
Zygomatic (2)
• prominences of cheeks
• lateral walls of orbits
• floors of orbits
• temporal process
7-25
Facial Skeleton
Lacrimal (2)
• medial walls of orbits
• groove from orbit to nasal
cavity
Nasal (2)
• bridge of nose
7-26
Facial Skeleton
Vomer (1)
• inferior portion of nasal
septum
7-27
Facial Skeleton
Inferior Nasal Conchae (2)
• extend from lateral walls of
nasal cavity
7-28
Facial Skeleton
Mandible (1)
• lower jaw
• body
• ramus
• mandibular condyle
• coronoid process
• alveolar process
• mandibular foramen
• mental foramen
7-29
Vertebral Column
c
• cervical vertebrae C1— 7
• thoracic vertebrae T1-T12
• lumbar vertebrae L1-L5
• sacrum S1-S5
• coccyx 5-fused
7-31
Vertebral Column
• cervical curvature
• thoracic curvature
• lumbar curvature
• pelvic curvature
• rib facets
• vertebra prominens
• intervertebral discs
• intervertebral foramina
7-32
Cervical Vertebrae
• Atlas – 1st; supports head
• Axis – 2nd; dens pivots to
turn head
• transverse foramina
• bifid spinous processes
• vertebral prominens –
useful landmark
7-33
Thoracic Vertebrae
• long spinous processes
• rib facets
7-34
Lumbar Vertebrae
• large bodies
• thick, short spinous
processes
7-35
Sacrum
• five fused
vertebrae
• median sacral
crest
• dorsal sacral
foramina
• posterior wall of
pelvic cavity
• sacral promontory
7-36
Coccyx
• tailbone
• four fused vertebrae
7-37
Thoracic Cage
• Ribs
• Sternum
• Thoracic vertebrae
• Costal cartilages
• Supports shoulder girdle
• Protects viscera
• Role in breathing
7-38
Ribs
• True ribs (7)
• False ribs (5)
• floating (2)
7-39
Rib Structure
• Shaft
• Head – posterior end;
articulates with vertebrae
• Tubercle – articulates with
vertebrae
• Costal cartilage – hyaline
cartilage
7-40
Sternum
• Manubrium
• Body
• Xiphoid process
7-41
Pectoral Girdle
• shoulder girdle
• clavicles
• scapulae
• supports upper limbs
7-42
Clavicles
• articulate with manubrium
• articulate with scapulae
(acromion process)
7-43
Scapulae
• spine
• supraspinous fossa
• infraspinous fossa
• acromion process
• coracoid process
• glenoid cavity
7-44
Upper Limb
• Humerus
• Radius
• Ulna
• Carpals
• Metacarpals
• Phalanges
7-45
Humerus
• head
• greater tubercle
• lesser tubercle
• anatomical neck
• surgical neck
• deltoid tuberosity
• capitulum
• trochlea
• coronoid fossa
• olecranon fossa
7-46
Radius
• lateral forearm bone
• head
• radial tuberosity
• styloid process
7-47
Ulna
• medial forearm bone
• trochlear notch
• olecranon process
• coronoid process
• styloid process
7-48
Wrist and Hand
• Carpals (16)
• trapezium
• trapezoid
• capitate
• scaphoid
• pisiform
• triquetrum
• hamate
• lunate
• Metacarpals (10)
• Phalanges (28)
• proximal phalanx
• middle phalanx
• distal phalanx
7-49
Pelvic Girdle
• Coxae (2)
• supports trunk of body
• protects viscera
7-50
Coxae
• hip bones
• ilium
• iliac crest
• iliac spines
• greater sciatic notch
• ischium
• ischial spines
• lesser sciatic notch
• ischial tuberosity
• pubis
• obturator foramen
• acetabulum
7-51
Greater and Lesser Pelvis
Greater Pelvis
• lumbar vertebrae
posteriorly
• iliac bones laterally
• abdominal wall
anteriorly
Lesser Pelvis
• sacrum and coccyx
posteriorly
• lower ilium, ischium, and
pubis bones laterally and
anteriorly
7-52
Male and Female Pelvis
Female
• iliac bones more flared
• broader hips
• pubic arch angle greater
• more distance between
ischial spine and ischial
tuberosity
• sacral curvature shorter and
flatter
• lighter bones
7-53
Lower Limb
• Femur
• Patella
• Tibia
• Fibula
• Tarsals
• Metatarsals
• Phalanges
7-54
Femur
• longest bone of body
• head
• fovea capitis
• neck
• greater trochanter
• lesser trochanter
• linea aspera
• condyles
• epicondyles
7-55
Patella
• kneecap
• anterior surface of knee
• flat sesmoid bone located
in a tendon
7-56
Tibia
• shin bone
• medial to fibula
• condyles
• tibial tuberosity
• anterior crest
• medial malleolus
7-57
Fibula
• lateral to tibia
• long, slender
• head
• lateral malleolus
• does not bear any
body weight
Insert figure 7.54
7-58
Ankle and Foot
• Tarsals (14)
• calcaneus
• talus
• navicular
• cuboid
• lateral cuneiform
• intermediate cuneiform
• medial cuneiform
• Metatarsals (10)
• Phalanges (28)
• proximal
• middle
• distal
7-59
Ankle and Foot
7-60
Clinical Application
Types of Fractures
• green stick
• fissured
• comminuted
• transverse
• oblique
• spiral
7-62
Bone-Fractures
• Classification-type-location-direction of the
fracture
• Open/compound- broken through the skin
– Complication-infection-osteomyelitis-delayed
union
Closed-not open to the outside of the skin
Degree of the fracture-partial or complete breakeg. Greenstick, seen in children, until age 10.
Comminuted has more than two pieces and
compression fracture, involves two bones
compressed together.
Impacted-fragments are wedged together-often
breaks of the humerus
Bone Fractures
• Pattern-The direction of the injury produces a
pattern of fracture.
• Transverse- angular forces
• Spiral- results from a twisting motion
• Location- Long bones, neck or head,
proximal/distal
• Grouped according to their etiology
sudden trauma- most common
stress trauma- wear and tear on a bone
pathologic fractures- weakened by disease
Bone Healing
• Hematoma- Clot forms during the first
48/72 hrs after a fracture
• Cellular proliferation- Involves all three
layers• Granulation tissue replace the clot
• New capillary buds and fibroblast
• Fibrocartilaginous callus forms distal to
fracture- forming a bridge between the
fragments
Bone healing
• Callus formation- cartilage forms at the site
– 3/4 weeks mineral salts are deposited
• Ossification
– Mature bone cells replace the callus, osteoclast
resorb the callus-cast removed at this point
• Remodeling- resorbition of excess callus
fracture site becomes thicker and stronger in
relation to function