Bone
Function of Bone
Movement Can change the position of body parts
Protection  Hard cases that enclose organs (brain)
Support  Anchor muscles
Mineral Storage  Stores phosphate, and calcium
Blood cell formation  Bone marrow produces blood cells
Bone
Bone is the most rigid type of connective tissue
Living bone cells are called osteocytes,
which are made from collagen and elastin
Osteocytes, after being made, settle in the
open spaces (or cavities) in bone called lacunae
Compact Bone
•Forms on the outside of bones
•Densely packed with collagen
•Outside covering of the bone is called the periosteum
•Compact bone is organized as thin concentric circles called a
Haversian System (osteons)
•The channels in the osteons are used for the connection of
blood vessels and nerves; they are called Haversian Canals
•Osteocytes are connected together by small protrusions called
canaliculi
Osteocytes connected
together by canaliculi
Osteocyte 
Canaliculi 
Spongy Bone
Forms the interior portion of bones
Flat lattice fuses together to form a hard interior
Inside the spaces of spongy bone is red marrow and yellow
marrow
Red marrow  synthesizes red; white blood cells; especially in
hip and sternum
Yellow marrow  synthesizes fat
Development of Bones
Cartilage serves as starting point of bone growth
Periosteum covers newly forming osteoblasts and
osteocytes
The cartilage then begins to calcify
Each end of a bone is called an epiphysis
At the end of the epiphysis is the epiphyseal
plate, which contributes to bone growth
The growth of the epiphyseal plate is controlled
by growth hormone, which is released by
the pituitary gland
Bone Remodeling
Over time calcium and phosphate are added and
withdrawn from bone tissue
Osteoblasts deposit bone and osteoclasts
break it down
Most bones are cartilaginous during development
During development, bones grow from the
middle out
In adulthood, bones grow from either end
Each growing end of the bones is called an
ossification center
Calcium in Bone
Calcium is needed for lots of physiological processes,
including muscle contraction and nerve
communication
When calcium in blood decreases, parathyroid
hormone stimulates osteoclasts to release enzymes
that remove calcium from bone
When there is an abundance of calcium in the blood,
calcitonin stimulates osteoblasts to take in calcium
from the blood to synthesize new bone
Calcium in Bone
Remodeling also occurs in
response to exercise.
More exercise = increase calcitonin
Increase in Calcitonin = increase in
osteoblast formation
More osteoblasts = increase in bone density
As you age, bone is broken down
faster than it is renewed.
Calcium is not as readily absorbed
in older women
Loss of Calcium
in bones = Osteoperosis
Osteoporosis
Overview of Human Skeleton
Adult skeleton has 206 bones
Bone growth usually stops by age 20
adult skeleton
Appendicular Skeleton  Bones of the
pectoral and pelvic girdle
Axial skeleton  bones of the skull,
spine, sternum, and ribs
Infant skeleton
Appendicular Skeleton
Bones of the pectoral girdle are held together by ligaments
Bones of the Pectoral Girdle
Clavicle  Collarbone
Scapula  Shoulder Blade
Clavicle connects to the sternum in the anterior and the scapula in the posterior
Humerus  single long bone of the upper arm
The joint that connects the humerus to the scapula is very shallow, the
attachment is unstable, often results in dislocated shoulders
Ulna  small bone of the lower arm; prominent bone in the elbow
Radius  other small bone of the lower arm; visceral to the ulna (palm down)
Carpals (8)  bones of the wrist
Metacarpals (5)  bones of the medial hand
Phalanges (15)  Bones of the digits
Pectoral Girdle
Bones of the Pelvic Girdle
Coxal Bones (2)  Hip Bones
Coxal bones are wider in females than in males
Sacrum ->Lower spine
Coccyx  tailbone
Femur -> Thighbone (largest and strongest bone in the body (can withstand ~700
pounds of downward force)
Tibia  shin bone; larger of the 2 lower leg bones
Fibula smaller lower leg bone that reaches outer ankle
Tarsals (7)  Bones of the ankle; distributes weight to heels and balls of your feet
Metatarsals (5)  bones of the inner foot
Phalanges (14)  bones of the toes
Pelvic Girdle
Axial Skeleton
Bones of the Head and Face
Cranium protects the brain & consists of 8 tightly fitted
bones in adults
In infants, bones are not fit together tightly and are held
together by membranes called fontanels (gone by about
1 year of age)
Infant skull
Major Bones of the Cranium
Frontal (1)  Forehead
Parietal (2)  Sides of skull
Occipital (1)  posterior of skull to its base, leads to foramen
magnum (hole for spinal chord)
Temporal (2)  On sides of skull inferior to parietal bones
Sphenoid Bone (1)  Anterior to temporal bone
Ethmoid (1) Part of inner orbital wall
Facial Bones
Mandible  Lower jaw (only movable portion of the skull)
Maxillary Bones  Hold teeth and center nose
Palatine Bone . Make up the posterior portion of the hard
palate & floor of the nasal cavity
Zygomatic Bones  Cheekbones and bridge of nose
Lacrimal Bone  Lies between ethmoid and maxillary bone
Vomer  Flat bone which forms the nasal septum
Cranium Bones
Parietal
Facial Bones
Vertebral Column
Extends from skull to Pelvis
Intervertebral disks between the vertebrae act as padding.
Prevent vertebrae from grinding against one another
These disks allow for flexibility (bending forward and backward)
The 1st 7 disks (going from superior to inferior) are called the
cervical vertebrae
The next 12 disks are called the thoracic vertebrae
The lowest 5 vertebrae are called the lumbar vertebrae
Sacrum connects the lumbar vertebrae to the tailbone (coccyx)
Vertebral Column
Ligaments of the Knee (4)
LCL
ACL
meniscus
MCL
PCL
True Ribs, False Ribs, and
Floating Ribs
Joints
Joints  areas of contact between bones
Ends of bones are covered with cartilage to reduce friction
Synovial Joints  2 bones separated by a cavity
Ligaments connected the 2 bones together
The cavity is usually filled with fluid (synovial fluid) that lubricate the joint
Example—>The Knee
The knee is a unique synovial joint because it has lots of pieces of small cartilage
that hold the knee in place
The added pieces of cartilage are called menisci
Fluid filled sacs called bursa have extra fluid to reduce friction between ligaments
and tendons of the knee
Bursitis -> inflammation of the bursa sacs
Joints
Bursa sacs 
Joints
Hinge Joints  joints shaped like the hinges of a door
Elbow is an example of a hinge joint (moves in one direction)
Ball and Socket Joints  allow for rotation in all planes
Shoulder is an example of a ball and socket joint
Arthritis  The synovial membrane (which holds synovial fluid)
becomes inflamed and thickens (rheumatoid arthritis)
Osteoarthritis  Cartilage at the end of the bone breaks down
and wears away the bones
Joints
Elbow
Hinge Joint
Moves in 1 Direction
Hip
Ball & Socket Joint
Arthritis
Osteoarthritis
Rheumatoid arthritis