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 bonesForms on the outside of bones Densely packed with collagenDensely packed with collagen Outside covering of the bone is called the periosteumOutside covering of the bone is called the periosteum Compact bone is organized as thin concentric circles called a Haversian System (osteons)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 CanalsThe 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 canaliculiOsteocytes are connected together by small protrusions called canaliculi

Osteocytes connected together by canaliculi Canaliculi  Osteocyte 

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Bone Remodeling Over time calcium and phosphate are added and withdrawn from bone tissue Osteoblasts deposit bone and osteoclasts break it down Most bones are cartilaginous during development During development, bones grow from the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 Appendicular Skeleton  Bones of the pectoral and pelvic girdle Axial skeleton  bones of the skull, spine, sternum, and ribs Infant skeleton adult 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 MCL PCL meniscus

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