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The Skeletal System By: Alaa Alshaibani and Alexis Samuelson System Structures and location link to video: http://www.youtube.com/watch?v=gp4SBFiP4-Y The Skull • Made up of the cranium and the facial bones • It is located at the top of the body, the head of the body • Made up of roughly 22 bones: Cranial Bones: • Frontal bones • Parietal bones • Occipital bone • Temporal bone • Sphenoid bone • Ethmoid bone Facial bones: • Mandible • Maxillae • Palatine bones • Zygomatic bones • Lacrimal bones • Nasal bones • Vomer bone • Inferior nasal conchae Vertebral Column • Begins at the base of the skull and ends at the pelvis. • Composed of vertebrae that are separated by intervebral discs • The column is divided into three parts • The final five is what creates the lumbar vertebrae • The sacrum forms the bottom of the lumbar vertebrae, the tip being the coccyx Vertebral Column Cervical Vertebrae • The first seven vertebrae • The first two are the atlas and axis and they help to rotate the head • The vertebrae are special in that they have transverse foramina and their spinous processes are bifid. Thoracic Vertebrae • The next 12 bones of the vertebral column • Long pointed spinous process, the bodies increase in size as you go down • Connects to the ribs Lumbar Vertebrae • The final five vertebrae • The sacrum forms the bottom of the lumbar vertebrae, the tip being the coccyx Thoracic Cage • Made up of: • The ribs • Thoracic vertebrae • Sternum • Costal cartilages • 24 ribs total which attach to each of the thoracic vertebrae • The sternum is made up of the manubrium, body, and xiphone together are the breast bone Pectoral Girdle • Located at the shoulder • Made up of the clavicles (collarbones) and scapulae (shoulder blades) Upper Limb Upper Limb • Bones form framework for arm, forearm, and hand • Provide attachments for muscles, function in levers • Bones include: humerus, radius, ulna, carpals, metacarpals, and phalanges Upper Limb - Humerus • Extends from the scapula to the elbow • Greater and lesser tubercles provide attachments for muscles • Deltoid tuberosity provides attachment for deltoid muscle that raises the upper limb horizontally to the side • Coronoid fossa receives a process of the ulna when the elbow bends • Olecranon fossa receives ulnar process when upper limb straightens at elbow • The capitulum helps the humerus articulate with the radius Upper Limb - Humerus Upper Limb - Radius • Located on thumb side of forearm; extends from elbow to wrist and crosses over ulna when palm faces backward • Head at upper end of radius articulates with humerus and a notch of the ulna • Allows radius to rotate freely Upper Limb - Ulna • Longer than radius; overlaps the end of the humerus posteriorly • Trochlear notch articulates with the humerus • Olecranon process and coronoid process provide attachments for muscles • Head articulates laterally with a notch of the radius Upper Limb – Radius and Ulna Upper Limb - Hand • Made up of the wrist, palm, and fingers • Eight small carpal bones that are bound in two rows of four bones • Five metacarpal bones form framework of the palm • Each finger has three phalanges (proximal, middle, and distal phalanx), except for thumb Upper Limb - Hand Pelvic Girdle • Consists of two coxae which articulate with each other anteriorly and with the sacrum posteriorly • Sacrum, coccyx, and pelvic girdle form pelvis • Girdle supports trunk of the body, provides attachments for lower limbs, protects the urinary bladder and reproductive organs • Each coxa develops from an ilium, an ischium, and a pubis Pelvic Girdle Pelvic Girdle Lower Limb Lower Limb • Bones form frameworks of the thigh, leg, and foot • Includes femur, tibia, fibula, tarsals, metatarsals, and phalanges Lower Limb - Femur • Extends from hip to knee • Large, rounded head projects medially into acetabulum of the coxa • Patella (kneecap) articulates with femur • Lateral and medial condyles articulate with tibia Lower Limb - Femur Lower Limb - Tibia • Larger of the two leg bones, located on medial side • Medial and lateral condyles articulate with condyles of the femur • Tibial tuberosity provides an attachment for patellar ligament • Inferior surface of tibia’s distal end articulates with the talus of the ankle Lower Limb - Fibula • Long, slender bone on lateral side of the tibia • Head articulates with tibia just below the lateral condyle, but does not enter into the knee joint Lower Limb – Tibia and Fibula Lower Limb - Foot • Made up of the ankle, the instep, and the toes • Ankle is composed of seven tarsal bones (largest is calcaneus) • Instep is made up of five elongated metatarsal bones that articulate with the tarsus • Phalanges align and articulate with the metatarsals; each toe has three phalanges except for the great toe (no middle phalanx) Lower Limb - Foot Skeletal System Information Function of Skeleton • The skeleton serves to: • • • • Protect vital organs Support the body Create blood cells Help to stabilize and shape the body Bones, Tendons, Ligaments • Bones: the organs of the skeletal system made up of cartilage, bone tissue, dense connective tissue, and nervous tissue • Tendons: white fibrous connective tissue that attaches muscle to bone • Ligaments: connective tissue that ties together two or more bones at a joint Structures of a long bone • Epiphysial plates, articular cartilage, compact bone, medullary cavity, yellow marrow, periosteum, proximal epiphyses, diaphysis, distal epiphysis, endosteum Bone growth • Endochondral bones begin as a cartilaginous model. As it grows the diaphysis in the middle, with the help of osteoblasts replace the cartilage with spongy bone—the primary ossification center, and form a thin layer of compact bone around it. • Secondary ossification centers form in the epiphyses, an epiphyseal plate separates the two ossification centers, which expands, causing the bone to lengthen. • The extracellular matrix calcifies, osteoclasts break it down, osteoblasts release new bone tissue to replace it. • The bone continues to lengthen, only stopping once the diaphysis and epiphysis ossification centers meet. Joints Joints • Bind parts of skeletal system, allow bones to grow, permit the skeleton to change shape during childbirth, and let the body respond to skeletal muscle contractions • Can be immovable, slightly movable, or freely movable • Vary in structure and function Classification of Joints by Tissue Classification - Fibrous • Lie between bones that closely contact one another • Formed by thin layer of dense connective tissue • Doesn’t allow much movement • Examples: • Sutures between pairs of flat bones of the skull • Articulations of teeth in jaw bones (gomphosis) Classification Cartilaginous • Hyaline cartilage (fibrocartilage), makes for slight flexibility • Helps to absorb shock and equalize pressure • Examples: • Intervertebral discs are composed of a band of fibrocartilage surrounding gelatinous core • Symphysis pubis Classification - Synovial • Allow free movement, make up a majority of joints within skeletal system • Articular ends of bones in synovial joints are covered with hyaline cartilage and a surrounding capsule of dense connective tissue • This + an outer layer of ligaments + inner lining of synovial membrane = joint capsule Classification - Synovial • Menisci – flattened, shock-absorbing pads of fibrocartilage between articulating surfaces of bones • Bursae – fluid-filled sacs lined with synovial membrane • Commonly located between tendons and bony prominences (patella, elbow, etc.) 6 Types of Synovial Joints Ball-and-Socket Joint • Consists of a bone with a ball-shaped head that articulates with the cup-shaped cavity of another bone • Allows widest range of motion and movements in all planes, in addition to rotational movement • Example: • Shoulder and hip joints Condyloid Joint • Oval-shaped condyle of one bone fits into elliptical cavity of another • Permits a variety of movement in different planes, but not rotational movement • Example: • Joints between metacarpals and phalanges Gliding Joints • Articulating surfaces are nearly flat or slightly curved • Allow sliding and twisting movements • Examples: • Most joints within the wrist and ankles • Sacroiliac joints and joints formed between ribs 2-7 that connect with the sternum Hinge Joint • Convex surface of one bone fits into concave surface of another • Resembles the hinge of a door • Permits movement in one plane only • Examples: • Elbow • Joints of phalanges Pivot Joint • Cylindrical surface of one bone rotates within a ring formed of bone and ligament • Movement limited to rotation around central axis • Example: • Joint between proximal ends of the radius and the ulna Saddle Joint • Forms between bones whose articulating surfaces have both concave and convex regions • Surface of one bone fits the complementary surface of the other • Permits variety of movements • Example: • Joint between carpal (trapezium) and metacarpal bones of thumb Types of Joint Movement Joint Movements • One end of muscle is attached to a relatively immovable part on one side of joint, other end fastened to movable part • When muscle contracts, the fibers pull the insertion (movable end) towards the origin (fixed end) Joint Movements • Flexion: Bending parts at a joint so the parts come closer together (angle between decreases) • Extension: Straightening parts so that they move further apart (angle between widens) • Dorsiflexion: Bending the foot at the ankle upwards • Plantar flexion: Bending the foot downwards Joint Movements • Hyperextension: Excess extension of the parts at a joint beyond anatomical position • Abduction: Moving a part away from the midline • Adduction: Moving a part towards the midline • Rotation: Moving a part around an axis • Circumduction: Moving a part in a circular motion Joint Movements • Pronation: Turning the hand so that the palm is facing downwards • Supination: Turning the hand so the palm is facing upward • Eversion: Turning the foot so that the sole faces laterally • Inversion: Turning the foot so that the sole faces medially Joint Movements • Retraction: Moving a part backward • Protraction: Moving a part forward • Elevation: Raising a part • Depression: Lowering a part Distinguish Between the Appendicular and Axial Skeletons Axial Skeleton • Consists of the bony and cartilaginous parts that support and protect the organs of the head, neck, and trunk 1. Skull – Composed of the cranium and facial bones 2. Hyoid bone – Located between lower jaw and larynx; supports the tongue and is an attachment for muscles that move the tongue Axial Skeleton 3. Vertebral column – Consists of many vertebrae separated by cartilaginous intervertebral discs, the sacrum, and the coccyx 4. Thoracic cage – Protects the organs of the thoracic cavity and upper abdominal cavity; composed of 12 pairs of ribs, and the sternum Appendicular Skeleton • Consists of the bones of the upper and lower limbs and the bones that anchor the limbs to the axial skeleton 1. Pectoral girdle – Scapula and clavicle form the pectoral girdle on both sides of body; connects bones of upper limbs and aids in movement 2. Upper limbs – Each consists of a humerus, radius, and ulna, which articulate with each other at the elbow joint. At the distal end are carpals, metacarpals, and phalanges. Appendicular Skeleton 3. Pelvic girdle – Two coxae connect the bones of the lower limbs to the axial skeleton; form the pelvis with the sacrum and coccyx 4. Lower limbs – Each consists of femur, tibia, fibula, and a foot. The patella covers the anterior surface of the knee joint. The foot consists of tarsals, metatarsals, and phalanges. Diseases/Disorders Osteogenisis Imperfecta • Literally translated to mean: “bone that is imperfectly made from the beginning of life.” • A genetic bone disorder, caused by a mutation that prevents the creation of collagen, resulting in extremely brittle bones, bones break easily Hemarthrosis • When there is bleeding in a joint, due to joint pain/ swelling Rickets • Caused by a lack of either Vitamin D, Phosphate, or calcium • Bones become weakened and curve Osteochondritis Dissecans • Occurs when a fragment of bone in a joint separates from the rest of the bone because its blood supply was not sufficient • The joint will become inflamed and painful, and can catch or lock during movements • Most common in the knee, but can also occur in other joints, such as the hip or ankle • Can be caused by repeated stress on the joint, inherited faulty genes, or ischemia, which restricts a bone’s blood supply Osteochondritis Dissecans Osteoid Osteoma • A benign bone tumor that has a center of growing cells surrounded by a shell of thickened bone • Most common in long bones, but can occur in any bone of the body • Occurs primarily in males of 4-25 years of age • Can sometimes disappear on its own, or be treated surgically Osteoid Osteoma Epiphysiolysis • The loosening or separation of the epiphysis from the shaft of the bone • Some treatments include physical therapy or prosthetic implants • Occurs often in hip and leg bones Epiphysiolysis