300 baby bones
206 adult bones
>1/2 are in hands
& feet
The giraffe has the same number of bones in its neck as a human: seven in total.
Longest bone= femur
Smallest bone= inner ear
(hammer, anvil, stirrup)

 Bone is made of the same type of minerals as limestone.

The long horned ram can take a head butt at 25 mph. The human skull will fracture at 5mph.

The only bone in the human body not connected to another is the hyoid, a V-shaped bone located at the base of the tongue

Enamel is the hardest substance in the human body

The strongest bone in the body is hollow and it is stronger than concrete - femur

• Support
• Protection
• Movement
• Hematopoiesis
• Reservoir for minerals and adipose tissue

Inner ear - 3
Upper limb – 30
Shoulder girdle - 2
Skull – 22 bones
Cranium – 8
Facial - 14
Vertebral
Column - 32
Thorax - 27
Iliac crest
80 bones
Lower limb – 29
Pelvic girdle – 6
126 bones

Lordosis Kyphosis Scoliosis

“keystone of cranium” Foramen – For nerves and vessels
Ethmoid
Ethmoid

Suture - Fibrous joint
Process - projection that contacts adjacent bone

closes at 8 wks
closes at 9-18 mths
Fontanel – space between infant skull bones

Sinus: air-filled space

canaliculi

Long
Arms
Legs
Phalanges
Flat
Scapula
Sternum
Ribs
Skull
Short
Wrist
Ankle
Irregular
Vertebrate
Hip
Patella

Structural and functional unit of bone
• Haversion Canal
– Allows passage of blood vessels, lymphatic vessels, and nerve fibers
• Lamella
– Concentric rings of collagen fibers around haversion canal
– Allows bone to withstand force
• Lacunae
– Small cavities occupied by osteocytes that join lamella
• Canaliculi
– Hairlike canals that join lacunae to each other and the central canal
– Allow osteocytes to exchange nutrients, wastes, and chemical signals via gap junctions

• Osteoblast
– Build bone cells
– Synthesize and secrete organic components of bone matrix
– Initiate calcification
– Found in periosteum and endosteum
• Osteocytes
– Mature bone cells
– Formed when osteoblasts get trapped in matrix
– Do not secrete matrix
– Maintain bone tissue
• Osteoclasts
– Bone resorption (digest/break down matrix): part of normal bone growth, development, maintenance and repair
– Found in endosteum

• Organic components (1/3)
– Collagen fibers
• Provide resilience against stretching and twisting
• Inorganic components (2/3)
– Mg, F, Na
– Salts that interact to form hydroxyapatite
• Calcium phosphate
• Calcium hydroxide
– Provide hardness and resist compression

• Connective
– Osseous
– Dense fibrous
– Adipose
– Vascular
– Lymphatic
• Nervous

• Red = hematopoietic tissue
– Bone cell forming tissue
– Everywhere in infant
• Yellow = fatty tissue
– Young to middle age develop in shafts
– Does NOT produce blood

I love anatomy!!!!!

• Osteogenesis (ossification) – bone tissue formation
– Embryo: leads to skeleton
• Intramembranous ossification
– Fibrous membrane replaced with bone
• Endochondral ossification
– Hyaline cartilage replaced with bone
– Most bones develop this way
– More complicated (hyaline cartilage broken down first)
– Children: leads to bone growth
– Adults: leads to bone remodeling and repair

• Osteoblasts permit calcification
• Some osteoblasts trapped in ossification center (now considered osteocytes)
• Growth is outward from ossification center
• Osteoblasts require oxygen and nutrients, so blood vessels are trapped in bone
• Fibrous membranes→spongy bone→compact bone
• Outer fibrous membrane becomes periosteum

•Chondrocytes in center of shaft increase in size and calcify
•Deprived of nutrients and die
•Vessels grow into perichondrium
•Inner layer turns to osteoblasts
•Perichondrium now periosteum
•Thin layer of bone formed around shaft
•Bone collar provides support
•Calcified cartilage breaks down
•Osteoblasts replace with spongy bone
•1° oss. center- bone dev and spreads toward epiphysis

•1° oss. center enlarges
•Osteoclasts break down spongy bone
•Medullary cavity now open
•Osteoblasts move to epiphysis

• Length
– Primary ossification center
• center of diaphysis
• Thickness
– Secondary ossification center
• center of epiphysis

•
Growth Hormone (GH)
– Produced by pituitary gland
– Stimulates protein synthesis and cell growth
• Thyroxine
– Produced by thyroid gland
– Stimulates cell metabolism and increases osteoblast activity
•
Sex Hormones at Puberty
– Cause osteoblasts to produce bone faster than epiphyseal cartilage can divide
• Growth spurt
•
Epipyseal plate closure
– Estrogens (female)
• Cause faster closure of plate than androgens
– Androgens (male)
•
Parathyroid Hormone
– Increases blood calcium level (decreases bone calcium)
– Inhibits osteoblast; Stimulates osteoclast
• Calcitonin
– “tones down” blood calcium level (increases bone calcium)
– Inhibits osteoclast; stimulates osteoblast

• Calcium and phosphate salts
– Hormone calcitriol and Vit D allow absorption
• Vitamins A, C, K, B12

• Simple - the bone is broken, but the skin is not lacerated
• Compound - skin is pierced by the bone or by a blow that breaks the skin at the time of the fracture
•
Greenstick - fracture on one side of the bone, causing a bend on the other side of the bone.
• Spiral – fracture wraps around bound in spiral manner
• Comminuted - results in three or more bone fragments.
• Transverse - fracture is at right angles to the long axis of the bone
• Compression – occurs in vertebrate
• Lisfranc - one or all of the metatarsal bones are displaced from the tarsus

(Fracture
Hematoma)
Bony

• Osteomalacia
– “soft bones”
– Lacking minerals (ie. Calcium, vit D)
– Rickets
• Child form of osteomalacia
• More detrimental since bones are still growing
• Signs: bowed legs; deformities of pelvis, ribs and skull
• Osteomyelitis
– “bone marrow inflammation”
– Caused by pus-forming bacteria that enter via wound or nearby infection
• Osteoporosis
– Bone degradation occurs faster than bone can be deposited
– Decrease in bone mass
– Porous bones
– Fractures in the vertebrate and femur are common
– Most common postmenopause: rapid decline in estrogen (stimulates osteoblasts and inhibits osteoclasts

• Giantism
– Childhood hypersecretion of GH
– Excessive growth
• Osteogenesis Imperfecta
– Osteogenesis imperfecta (OI) is a genetic disorder characterized by bones that break easily, often from little or no apparent cause. There ae
9 different types.
• Pituitary Dwarfism
– Childhood deficiency of GH
– Short long bones; max height is 4 ft.
• Paget’s Neoplasms
– Bone remodeling process disturbed
– Bones are abnormal, enlarged, not as dense, brittle, and prone to fracture
– Affects older adults