Forensic Anthropology “The Skeletal System”

Osteology The study of bones. The branch of anatomy that deals with the structure and function of bones. Anthropology— the science that deals with the origins, physical and cultural development, biological characteristics, and social customs and beliefs of humankind; the study of human remains. Physical Anthropology —studies human differences Forensic Anthropology— studies these identifying characteristics on the remains of an individual

Historical Development 1800s—scientists begin studying skulls 1897—sausage maker’s wife murdered; bone fragments found in his factory 1932—the FBI opens the first crime lab Smithsonian Institution partners with FBI 1939—William Krogman publishes Guide to the Identification of Human Skeletal Material Soldiers killed in World War II are identified using anthropologic techniques DNA—new tool to analyze skeletons

What are the 5 Functions of the Skeletal System? 1. Movement: Skeletal system provides points of attachment for muscles. Your legs and arms move when the muscles pull on the bones. 2. Support: The backbone is the main support center for the upper body. It holds your head up and protects your spinal cord. Muscle attached to bones!!

What are the 5 Functions of the Skeletal System? 3. Protection: The bones of your skull protect your brain. Your ribs protect your lungs and heart from injury. 4. Makes Blood: Red and white blood cells are formed by tissue called marrow, which is in the center of the bone.

What are the 5 Functions of the Skeletal System? 5. Storage: Bones store minerals, such as calcium and phosphorus, for use by the body

What are the Two Major Skeletal System Parts? Axial Skeleton: The axial skeleton includes the skull, spine, ribs and sternum. Appendicular Skeleton: The appendicular skeleton includes the appendages of the body, which are the shoulders, arms, hips, and legs.

The Skeletal System Parts of the skeletal system include: Bones (skeleton) Joints Cartilages Ligaments Divided into two divisions: Axial skeleton (skull, ribs and vertebra) Appendicular skeleton (pelvis, extremities)

The Skeletal System

Functions of Bones Support of the body Protection of soft organs Movement due to attached skeletal muscles Storage of minerals and fats Blood cell formation

Bones of the Human Body The adult skeleton has 206 bones Two basic types of bone tissue Compact bone Homogeneous Spongy bone Small needle-like pieces of bone Many open spaces Figure 5.2b

Classification of Bones on the Basis of Shape Figure 5.1

Classification of Bones Long bones Typically longer than wide Have a shaft with heads at both ends Contain mostly compact bone Examples: Femur, Humerus Short bones Generally cube-shape Contain mostly spongy bone Examples: Carpals, tarsals

Classification of Bones Flat bones Thin and flattened, usually curved Thin layers of compact bone around a layer of spongy bone Examples: Skull, ribs, sternum Irregular bones Irregular in shape Do not fit into other bone classification categories Example: Vertebrae and hip

Gross Anatomy of a Long Bone Diaphysis Shaft Composed of compact bone Epiphysis Ends of the bone Composed mostly of spongy bone

Structures of a Long Bone Periosteum Outside covering of the diaphysis Fibrous connective tissue membrane Sharpey’s fibers Secure periosteum to underlying bone Arteries Supply bone cells with nutrients Figure 5.2c

Bone Markings Surface features of bones Projections and Processes – grow out from the bone surface Depressions or Cavities – indentations Sites of attachments for muscles, tendons, and ligaments Passages for nerves and blood vessels

Microscopic Anatomy of Bone Osteon (Haversian System) A unit of bone Central (Haversian) canal Carries blood vessels and nerves Perforating (Volkman’s) canal Canal perpendicular to the central canal

Changes in the Human Skeleton In embryos, the skeleton is primarily hyaline cartilage During development, much of this cartilage is replaced by bone Cartilage remains in isolated areas Bridge of the nose Parts of ribs Joints

Bone Growth Epiphyseal plates allow for growth of long bone during childhood New cartilage is continuously formed Older cartilage becomes ossified Cartilage is broken down Bone replaces cartilage

Bone Growth Bones are remodeled and lengthened until growth stops Bones change shape somewhat Bones grow in width

Long Bone Formation and Growth

Types of Bone Cells Osteocytes Osteoblasts Osteoclasts Mature bone cells Osteoblasts Bone-forming cells Osteoclasts Bone-destroying cells Break down bone matrix for remodeling and release of calcium Bone remodeling is a process by both osteoblasts and osteoclasts

The Skeletal System (B)

The Axial Skeleton Forms the longitudinal part of the body Divided into three parts Skull Vertebral column Bony thorax The Axial Skeleton

The Axial Skeleton Figure 5.6

The Skull Two sets of bones Bones are joined by sutures Cranium Facial bones Bones are joined by sutures Only the mandible is attached by a freely movable joint The Skull

The Skull Figure 5.7

Bones of the Skull Figure 5.11

Human Skull, Superior View Figure 5.8

Human Skull, Inferior View Figure 5.9

What are the Basic Bone Shapes? Four basic bone shapes: 1. Long- arms, legs and fingers 2. Short- wrist and ankles 3. Flat- skull and sternum 4. Irregular- spine

What is the Structure of Bone? Typical Four Layers: Periosteum: Covers Bones Compact Bone: Lies beneath the periosteum Spongy Bone: Lies beneath the compact bone Bone Marrow: Fills the gaps between the spongy bone

What is the Structure of Bone? Bones are complex living structures that undergo growth and development. A thin tough outer membrane covers the bone. Beneath the outer membrane is a layer of compact bone (hard and dense, but not solid – it is filled with holes and has small canals for blood vessels and nerves). What is the Structure of Bone?

What is the Structure of Bone? Inside the compact bone is a layer of spongy bone. It has many small spaces, is light weight, but strong. Spongy bone is also found at the ends of bones.

What is the Structure of Bone? In the spaces of many bones there is a soft connective tissue called marrow. Two types of Marrow: Red Yellow Red Marrow produces most of the body’s blood cells. Yellow Marrow stores fat that can serve as an energy reserve.

How Strong are Bones? The structure of bones make it both strong and light weight. 20 % of an adults body weight is bone. Bone is made up of 2 minerals: Calcium Phosphorus

As an infant, most of your skeleton is cartilage. Cartilage is a strong flexible tissue. Over time the cartilage is replaced by solid bone, usually complete by the time you stop growing. Not all cartilage is replaced in adults. Many joints contain cartilage, protecting the ends of bones (ears and the end of the nose is also cartilage). How Do Bones Develop?

Clavicle or Collarbone The clavicle, or collar bone, holds the shoulder joint away from the rest of the upper body and is only as thick as your little finger. Clavicle or Collarbone

The scapula is located on the back side of the ribcage and helps provide part of the shoulder joint and movement for the arms. Scapula

Vertebral Column or Spinal Cord 1) The cervical region (neck bones)    2) The thorasic region (what the ribs attach to) 3) The lumbar region (the lower part of the back)  Vertebral Column or Spinal Cord

Coccyx and Sacrum

Humerus (Upper Arm Bone)

Radius on Top Ulna on Bottom Radius and Ulna

Carpals or (Wrist Bones)

Metacarpals (Top of Hands)

Phalanges (Little Fingers)

Rib Cage

Sternum (Breastbone)

Pelvis

Femur (Largest Bone in the Body)

The Tibia and Fibula

Tarsals

Metatarsals

Phalanges

What are Joints? A joint is a place where two bones come together. Joints allow the bones to move in different ways. Two types of joints: Immovable Movable

What are Immovable Joints? A joint that allows little or no movement

What are Movable Joints? Most of the joint are movable joints. Allow the body to move in a wide range of movements. Bones in movable joints are held together by strong connective tissue called ligaments. Four types of movable joints: Hinge Ball-and-socket Pivot Gliding What are Movable Joints?

What is a Ball-and-Socket Joint? Round end of bone fitting snuggly within another bone. Ex. Shoulder and Hip Allows the greatest range of motion. The ball-and-socket joint allows you to swing your arm freely in a circle. What is a Ball-and-Socket Joint?

What is a Hinge Joint? Ex. Knee and Elbow Movement in one direction like a door. Ex. Knee and Elbow Allows forward or backward motion.

Bone resting atop another bone permitting free movement. Ex. Neck, Wrist and Ankles Allows one bone to rotate around another. Allows you to turn your head What is a Pivot Joint?

Allows one bone to slide over another. Ex. Knuckles, wrist, ankle Allows your to bend and flex as well as make limited side to side motions. What is a Gliding Joint?

Connects bone to bone. What is a Ligament?

Attaches muscles to bones. What is a Tendon?