Types of Bones
Classification of Bones
Function of Bone
Osteology – The Science of Bones
Bone are composed of: Cells, Fibers and a Matrix ( Ca2+)
The Matrix of the Bone is referred to as an
The Chemical Composition of the bone matrix is
(Ca2+)10(PO4)6 (OH)2 return
Bone is living tissue it grows and changes throughout your life.
You completely replace your entire skeleton
about every ten years.
Figure 07.01Structure of a
Two Types -
1. Intramembranous – Develops in the connective tissue membranes in the embryo called Mesenchyma – embryonic CT
2. Endochrondral Bone Formation – Bone forms in cartilage
A cartilage model of the skeleton is in place and the cartilage is removed and bone is laid down.
NOTE : Bone is NOT calcified cartilage
Formation of bone is called Ossification -
it starts in the embryo and continues to age 18 in females and 20 in males.
Within the cartilage skeleton model of the embryo are ossification centers.
This is where the cartilage is being destroyed and the bone is being made.
Ossification takes place in the middle of the bone shaft first and then at the ends. The bone develops moving very slowly toward the ends of the bone.
Two types of bone are produced :
Spongy Bone – Contains a lot of cavities this structure reduces weight and increases strength of the bone.
This is the region that is effected by osteoporosis the most.
Hemopoietic tissue (makes blood) fills the cavities of spongy bone.
Compact Bone - Dense strong bone that makes up the outer surface of the bone.
Compact bone is composed of millions of subunits called:
Haversian Systems or Osteons
Spongy Bone with Hemopoietic Tissue
Epiphyseal Plate or Growth Plate
Three types of Bone Cells
1. Osteoblasts – Makes new bone
2. Osteocytes – Maintain existing bone if damage occurs. Live inside calcified bone in lacuna (“little pond” in Latin)
3. Osteoclasts – Remove bone, act like white blood cells. They are triggered by parathormone from the thyroid to breakdown bone to increase calcium level in blood.
Their action can lead to osteoporosis – Loss of bone mass due to lack of calcium. Bones can become weak and brittle.
Haversian Canal Systems
or OsteonLamella of bone
Function of Bones
2. Motion – Muscle Attachment
3. Protection – Skull protects Brain
Ribs & Sternum protects Heart & Lungs
4. Calcium Storage – There is a constant exchange between bones and blood.
5. Bone Marrow – Process called Hemopoisis is the making of Red and White blood cells.
In the infant red marrow is found in most of the bones.
In the adult it is only found in 1. Sternum and Ribs
2. Hip Bones (iliac Crest) Take marrow samples here
3. Bodies of Vertebrae
4. Proximal end of Long Bonesreturn
Classification of Bones
1. Long Bones
Upper Extremities - Humerus
Radius & Ulna
Palm - Metacarpals
Fingers - Phalanges
Lower Extremities - Femur
Tibia & Fibula
Foot - Metatarsals and Phalanges
2. Short Bones - Wrist - Carpal bones or carpus
Ankle - Tarsals bones or Tarsus
3. Irregular Bones - Vertebrae & Skull
may be movable or immovable
contain many irregular bones
4. Flat Bones - Scapula – Shoulder blade
Clavicle – Collar bone
Skull - Frontal & Parietal bones of skull
5. Sesamoid Bones “seed” – small, nodular found within tendon ex: patella (knee cap)
Identifying Characteristics of Bones
1. Fossa – Depression in a bone
ex: TMJ (Temporal Mandibular Joint) forms a fossa
2. Sinus – Cavity in a bone
ex: maxillary sinus – cavity above upper jaw
3. Foramen – Hole in a bone
ex: Foramen Magnum – hole for spinal cord in skull
4. Meatus – Tubular structure in bone
ex: External auditory meatus let sound enter skull
5. Condyles – Large smooth curved surfaces that touches another bone.
ex: Distal end of femur
6. Trochanter – A large projection on a bone for muscle attachment
Axial Skeleton - Skull
Ossicles (ear bones)
Sternum & Ribs
Appendicular Skeleton - Upper Extremities
Pectoral Girdle - clavicle & scapula (attachment to axial skeleton)
Pelvic Girdle – ilium, ischium, pubic bone
SkullTwo major components –
1. Skull Cap - Calvarium or cranium contains 8 bones that enclose the brain.
2. Facial Bones – 14 bones that support muscles of the face.
Bones of the Calvarium –
1. Frontal – forehead – Anterior fossa of base of skull
2. Parietal – 2 – means “walls”- top of skull
3. Temporal – 2 – sides of skull
4. Occipital – posterior part of skull
Temporal Bone - Four Parts
1. Squamous – Flat/thin part of skull ( Don’t get hit here)
2. Mastoid Process – “breast” – contain sinus for middle ear.
3. Zygomatic Process – “bar” – posterior portion of cheek bone
4. Petrous portion – “hard” – houses the inner ear
Occipital Bone – Thick Bone
Contains the Foramen Magnum “Big Hole”
Articulates with first cervical vertebra - Atlas
Greek god Atlas Return
Sphenoid – Floor of skull – called the keystone of the skull keeps the other bones in place.
Holds the Pituitary Gland in the “Turkish Saddle” formed by the four Clinoid processes.
Ethmoid Bone – “sieve” contains holes for olfactory nerves to pass through. This is called the Cribriform Plate.
Looking down into skull
Pituitary would be here
V shape of Occipital is called a
The immovable joints between the bones of the skull are called
Infant Skull – Contains areas of connective tissue called
Allows the skull to move during birth and accommodates rapid growth of brain.
There are two of each of the facial bones
1. Maxilla – Upper Jaw called keystone of face all facial bone touch the maxilla except mandible.
2. Zygomatic Process – Anterior roof of mouth formed by maxilla
3. Nasal Bones – Forms bridge of nose
4. Lacrimal Bones – Inferior medial orbit
5. Zygomatic Bones – Middle of cheek
6. Palatine Bones – Posterior portion of the roof of the mouth
7. Vomer – Bone of lower septum of nasal cavityReturn
The Cheek is made up of :
Zygomatic Process - Maxilla
Zygomatic Process - Temporal
The roof of the mouth is called the Hard Palate
It is composed of the: Maxilla - Anterior
Palatine - Posterior
Lateral Nose - Two inferior Conchae in the Inferior lateral nasal cavity
Medial Nose - Vomer – medial nasal cavity (called the Septum)
Mandible – Jaw bone only moveable joint of skull
Part of TM Joint
Teeth—Humans have a heterodont dentition ( Different Teeth)
Ribs attach to all the Thoracic Vertebrae
Laminectomy – Cut through this part of the vertebra to get to the spinal cord
Spinal cord found here
Thoracic is area most common for tumors
Largest bodies in Lumbar region due to carrying all of the body’s weight
Longest spinous processes in Thoracic region
C1 – Atlas
C2 – Axis
Odontoid Process “tooth” connects these two together allows you to rotate your head
Vertebral Column –
Abnormal Curves –
Kyphosis – Hunchback – Accentuated Thoracic Curve
Lordosis – Swayback – Accentuated Lumbar Curve
Scoliosis – Lateral curve in Thoracic region more common in females begins during puberty.
Intervertebral Discs –
Rings of Fibrocartilage between the vertebrae
Stiff cartilage ring Nucleus Pulposus –
Soft gelatinous center
Slipped Disc -
When someone has a slipped disc the disc doesn’t really move. The Annulus tears and the soft gelatinous center gets squeezed out. Sort of like putting pressure on a jelly donut the jelly squeezes out.
Best cure is bed rest and to let the ring heal and the center to regenerate.
Humerus – Bone of Arm
Figure 07.30For muscle attachment, you can see how active person is by looking at this area of a bone.
Common fracture siteFemur
Patella in tendon found here
Figure 07.31Articulates with femur
Articulates with Talus Bumps on side of ankle
Box Figure 07.01aBone
Repair of Bone Fracture
1. Severe Bleeding
2. Blood clot forms in the bone
3. Cells from the Periosteum produce Osteoblasts that produce new bone.
4. New bone fragment + Blood clot form a Callus
5. Bone forms between fracture ends called a Bony Collar
6. Osteoclasts remove excess bone
Box Figure 07.01b
Arthrology – Science of Joints
1. Fibrous Joints – Contain very little connective tissue between the bones.
ex: sutures of the skull
2. Cartilaginous Joints – Fibrocartilage between bones – strong joints
ex: Intervertebral Discs, Pubic Symphysis
3. Synovial Joints – Connections between bones of appendicular skeleton “ with egg white” ex: Humerous & Glenoid fossa, Femur & Acetabulum
Synovial Fluid is there to reduce friction in the joint and to moisten and nourish the cartilage. Cartilage doesn’t have blood vessels so the cartilage celled get nourish by synovial fluid.
A Bursa is a bag of synovial fluid attached to a joint that is there to reduce friction. Inflammation of the bursa is called Bursitis.
Produces Synovial Fluid
Made of Hyaline Cartilage
Types of Joints
Movement of a Joint
Flexion - Decrease an angle
Extension - Increase an angle
Adduction - Bring limb toward the midline
Abduction - Move limb away from midline
Circumduction - Circular motion
Dorsiflexion – Lift foot toward shin
Supination / Pronation- rotate hand palm up or palm down
Rheumatoid Arthritis – “discharge” of synovial fluid. Disorder of the immune system, joints swell with stiffness and pain due to excess of synovial.
Osteoarthritis – Breakdown of articular cartilage so bone grind on bone with pain and reduced movement
Osteoporosis - Loss of bone mass more frequent in women. Return