Skeletal System

Lesson 1– Skeletal System Skeletal system refers to the bones that form the framework of the body. An adult human has 206 bones. FUNCTIONS: Provides shape and support to the body Protects vital organs Acts as a set of levers, and together with muscles helps a person move Produces blood cells Stores calcium Skeletal System The skeletal system refers to the bones that form the framework of the body. An adult human has 206 bones. The skeletal system performs these functions: Provides shape and support to the body Protects vital organs Acts as a set of levers, and together with muscles helps a person move Produces blood cells Stores calcium

Lesson 1– Types of Bones Long bones Short bones Flat bones Irregular bones Types of Bones Bones vary in shape and size depending on where they are found in the body. Bones are classified by shape. Long bones are longer than they are wide. Bones of this type form the extremities, or arms and legs. Short bones have a similar length and width. Bones of this type can be found in the wrists and ankles. They have an outer layer of compact bone and an inner layer of bone with a latticework structure. Flat bones have a broad shape. Bones of this type can be found in the skull, shoulder blades, and pelvis. They cover organs to protect them or provide a surface for large areas of muscle. Irregular bones are specialized and do not fit the other types. Examples include the bones of the ear, face, and vertebrae.

Lesson 1– Parts of Long Bones Diaphysis Epiphysis Articular cartilage Periosteum Medullary canal Endosteum Parts of Long Bones The longest part of a long bone is called the diaphysis, or shaft. Each end of the shaft is called an epiphysis. A thin layer of articular cartilage covers the epiphysis to absorb shock where two bones meet to form a joint. The outer part of the bone is made of compact bone tissue, which does not bend easily. It is covered by the periosteum, which is a tough, fibrous tissue. This tissue contains blood vessels, lymph vessels, and osteoblasts for bone growth, repair, and nutrition. Inside the compact bone is spongy bone. The medullary canal is a cavity in the center of the shaft where marrow is stored. It is lined by the endosteum to keep the cavity intact.

Lesson 1– Bone Marrow Red marrow Yellow marrow Bone Marrow Present in long bones, marrow is important in making blood cells. Red marrow is found in epiphyses and in certain flat bones. It produces red blood cells, platelets, and some white blood cells. Children have red marrow throughout their bodies. As they become adults, most of it is replaced with yellow marrow. Yellow marrow, which is mostly made of fat cells, fills the medullary canal. This marrow serves as fat storage and contains blood vessels and some cells that form white blood cells.

Lesson 1– Sections of the Skeletal System Axial skeleton Appendicular skeleton Sections of the Skeletal System The skeletal system is divided into two sections, axial and appendicular. The axial skeleton forms the main trunk of the body. It includes the skull, spinal column, ribs, and breastbone. The appendicular skeleton forms the extremities. It includes the shoulder girdle, arm bones, pelvic girdle, and leg bones.

Lesson 1– Axial Skeleton: Skull The skull consists of the cranium and facial bones. Cranium- surrounds and protects the brain. 1 frontal 2 parietal 2 temporal 1 occipital 1 ethmoid 1 sphenoid The cranial bones join at points called sutures. Axial Skeleton: Skull The skull consists of the cranium and facial bones. The cranium surrounds and protects the brain. The cranial bones join at points called sutures. At birth, there are two openings in the cranium called fontanels, or “soft spots.” They give space for the skull to enlarge as the brain grows, and they usually close by 18-24 months of age. The 8 cranial bones include the following: 1 frontal 2 parietal 2 temporal 1 occipital 1 ethmoid 1 sphenoid

Lesson 1– Axial Skeleton: Skull (Continued) Facial bones 5 nasal 2 maxilla 2 lacrimal 2 zygomatic 2 palatine 1 mandible Sinuses Axial Skeleton: Skull (continued) Facial bones are also part of the skull. Facial bones guard and support the eyes, nose, mouth, and ears. Sinuses are air spaces in and around these bones. These spaces allow the voice to resonate to sound stronger. The 14 facial bones include the following: 5 nasal 2 maxilla, or upper jaw 2 lacrimal, or inner aspect of the eyes 2 zygomatic, or cheek 2 palatine, or roof of the mouth 1 mandible, or lower jaw The mandible is the only movable bone in the face. It contains the sockets for the lower teeth. The maxilliary bones contain the sockets for the upper teeth.

Lesson 1– Axial Skeleton: Spinal Column Vertebrae consists of 26 bones . It encloses and protects the spinal cord and supports the head and trunk It is divided as follows: Cervical (7)—neck Thoracic (12)—chest, attach to ribs Lumbar (5)—waist Sacrum (1)—back of pelvic girdle Coccyx (1)—tailbone Discs Pads of cartilage separating vertebrae Act as shock absorbers Permit bending and twisting movements Axial Skeleton: Spinal Column The spinal column consists of 26 bones called vertebrae. It is also known as the vertebral column. It encloses and protects the spinal cord and supports the head and trunk. Discs of cartilage tissue separate the vertebrae to cushion the bones and allow movement. The spinal column includes these vertebrae: 7 cervical, or neck 12 thoracic, or chest 5 lumbar, or middle back 1 sacrum 1 coccyx, or tailbone

Lesson 1– Axial Skeleton: Thorax Thorax or “ chest cavity” It helps to protect the heart and lungs. Ribs 12 pairs of long slender bones Attach to thoracic vertebrae True ribs—first 7 pairs; attach to sternum False ribs—last 5 pairs, do not attach to the sternum . Sternum Manubrium Gladiolus Xiphoid process Axial Skeleton: Thorax The thorax is also known as the chest cavity. It helps to protect the heart and lungs. There are 12 pairs of ribs, or costae: The first 7 pairs are called “true ribs” because they are attached to the sternum, or breastbone. The next 5 pairs are called “false ribs.” - The first 3 pairs of these ribs each attach to the cartilage of the rib above it. - The last 2 pairs have no attachment on the front of the body and are called “floating ribs.” The sternum includes 3 parts: The manubrium is the upper region. It is attached by ligaments on both sides to the clavicles, or collarbones. The gladiolus is the body. The xiphoid process is a small piece of cartilage at the bottom.

Lesson 1– Appendicular Skeleton: Shoulder Girdle 2 clavicles 2 scapulas. Appendicular Skeleton: Shoulder Girdle The shoulder girdle is also known as the pectoral girdle. It includes 4 bones: 2 clavicles, or collarbones 2 scapulas, or shoulder bones The clavicles help brace the shoulders and prevent a person from having too much forward motion. The scapulas provide a place for the arms to be attached, and together with muscles they assist with arm movement.

Lesson 1– Appendicular Skeleton: Arms and Hands Arm bones: Humerus Ulna Radius Hand bones: 8 carpals 5 metacarpals 14 phalanges Appendicular Skeleton: Arms and Hands The bones of each arm include the following: Humerus, or upper arm bone. Ulna, or the lower arm bone whose upper end forms the elbow. Radius, or the lower arm bone on the thumb side. The bones of each hand include the following: 8 carpals, which form the wrist. 5 metacarpals, which form the palm of the hand. 14 phalanges, which form the fingers.

Lesson 1– Appendicular Skeleton: Pelvic Girdle Pelvic girdle is made of 2 hip bones, which connect at the symphysis pubis. Each hip bone is composed of 3 sections: Illium Ischium Pubis Appendicular Skeleton: Pelvic Girdle The pelvic girdle includes 2 os coxae, or hip bones. They attach to the sacrum in addition to connecting to each other at a joint called the symphysis pubis. Each os coxae consists of these 3 fused sections: Illium Ischium Pubis The pelvic girdle supports the trunk of the body, in particular the lower soft abdominal organs. It also provides a place for the legs to be attached.

Lesson 1– Appendicular Skeleton: Legs and Feet Leg bones: Femur Patella Tibia Fibula Foot bones: 7 tarsals 5 metatarsals 14 phalanges Appendicular Skeleton: Legs and Feet The bones of each leg include the following: Femur, or the thigh bone in the upper leg. It is the longest bone in the body. Patella, or kneecap. Tibia, or the shin in the lower leg. Fibula, which is also in the lower leg. The bones of each foot include the following: 7 tarsals, which form the ankle. A large tarsal bone called the calcaneous forms the heel. 5 metatarsals, which form the instep of the foot. 14 phalanges, which form the toes.

Lesson 1– Joints Joints are areas where two or more bones connect Ligaments Bands of connective tissue help hold bones together at joints Joints are classified by movement: Diarthrosis– movable Amphiarthrosis– partially movable Synarthrosis– not movable Joints Joints are areas where two or more bones connect. Bands of connective tissue called ligaments help hold bones together at joints. Joints are classified by movement. A diarthrosis joint is movable. An amphiarthrosis joint is partially movable. A synarthrosis joint is not movable.

Lesson 2– Diseases and Disorders of the Skeletal System Arthritis Rheumatoid arthritis Osteoarthritis Sprain Dislocation Fracture Abnormal curvature of spine Kyphosis Scoliosis Lordosis Diseases and Disorders of the Skeletal System Arthritis refers to a group of disorders where one or more joints are inflamed. In many cases, the cause is not known, but some causes may include joint disease, infection, or trauma. The two most common types of arthritis are rheumatoid arthritis and osteoarthritis. With rheumatoid arthritis, the body’s immune system attacks its own tissue at the joints. Osteoarthritis is also known as degenerative joint disease and usually occurs with aging. Symptoms of arthritis include pain, swollen joints, and stiffness during motion. There is no cure. Treatment is geared toward relieving discomfort. This may involve rest, application of heat and cold, pain and anti-inflammatory medications, and steroid injections. When severe damage has occurred, surgery may be performed to replace joints. A sprain is when a twisting action tears the ligaments at a joint. It may be caused by a sudden or unusual motion. Symptoms include pain, swelling, and limited movement of the joint. Treatment involves rest, elevation, immobilization with a bandage or splint, anti-inflammatory medication, and alternating application of heat and cold. A dislocation is when a bone is displaced from a joint. It is typically caused by trauma, but it may also be inherited. It often occurs in shoulders, fingers, knees, and hips. Treatment involves reduction, or the return of the bone to its proper position, immobilization with a splint or cast, and rest. A fracture is a crack or break in the bone caused by trauma. Symptoms include pain, swelling, and bruising. Treatment involves resetting the bone and immobilization with a cast or traction. Common types of fractures are described below: Greenstick: The bone is bent and split, but does not completely break. Simple or closed: The bone completely breaks but does not pierce through the skin. Compound or open: The bone breaks and pierces through the skin, which can lead to infection. Comminuted: The bone splinters into more than two pieces, which can become embedded in the surrounding tissue.