24 The Skeletal System

Learning Outcomes (cont.) 24.1 Describe the structure of bone tissue. 24.2 Explain the functions of bones. 24.3 Compare intramembranous and endochondral ossification. 24.4 Describe the skeletal structures and one location of each structure.

Learning Outcomes (cont.) 24.5 Locate the bones of the skull. 24.6 Locate the bones of the spinal column. 24.7 Locate the bones of the rib cage. 24.8 Locate the bones of the shoulders, arms, and hands.

Learning Outcomes (cont.) 24.9 Locate the bones of the hips, legs, and feet. 24.10 Describe the three major types of joints and give examples of each. 24.11 Describe the common diseases and disorders of the skeletal system.

Introduction Bones provide structure and support 206 bones plus joints and connective tissue Divisions Axial ~ 80 bones Skull Vertebral column Rib cage Appendicular ~ 126 bones Arms and legs Pectoral girdle Pelvic girdle Learning Outcome: 24.1 Describe the structure of bone tissue. Hyoid bone – anchors the tongue; included in the axial skeleton. Pectoral girdle – attaches the arms to the axial skeleton. Pelvic girdle – attaches the legs to the axial skeleton.

Bone Structure Bones contain various kinds of tissues Osseous tissue Blood vessels Nerves Osseous tissue can appear compact or spongy Spongy (Cancellous) Bone Compact Bone Learning Outcome: 24.1 Describe the structure of bone tissue. Osseous tissue Spongy or cancellous bone has more spaces within it than compact bone does. Spongy bone looks a lot like a natural sea sponge with the spaces filled with red bone marrow. Compact bone looks solid like granite or marble.

Bone Structure (cont.) Structures within compact bone Osteons Bone matrix Lamella Lacunae Canaliculi All bones are made up of both compact and spongy bone Learning Outcome: 24.1 Describe the structure of bone tissue. Osteons (Haversian system) – elongated cylinders that run up and down the long axis of the bone. Each osteon has a central canal that contains blood vessels and nerves. Bone matrix – inorganic salts, collagen fibers, and proteins that exists between osteocytes(bone cells). The primary salt of the matrix is calcium phosphate, which makes bone matrix very hard. Lamella – layers of bone surrounding the canals of osteons. Lacunae – holes in the bone matrix that hold osteocytes. Canaliculi – tiny canals that connect lacunae to each other and allow osteocytes to spread nutrients to each other.

Bone Structure (cont.) Long bones Femur and humerus Parts Diaphysis Epiphysis Articular cartilage Medullary cavity Periosteum Endosteum Learning Outcome: 24.1 Describe the structure of bone tissue. Bones are classified according to their shape. Long bones Diaphysis – shaft of a long bone. Epiphysis – expanded end; consists of thin layer of compact bone surrounding cancellous bone. Articular cartilage – covers epiphyses of long bones. Medullary cavity – canal that runs through center of diaphysis; contains yellow bone marrow in adults. Periosteum – membrane surrounding the diaphysis. Endosteum – membrane lining the medullary cavity and the holes of cancellous bone.

Bone Structure (cont.) Short bones Flat bones Irregular bones Sesamoid bones Learning Outcome: 24.1 Describe the structure of bone tissue. Short bones – small bones located in the wrists and ankles. Examples – Carpals and Tarsals Flat bones – primarily located in the skull and rib cage. Examples include the ribs and frontal bone. Irregular bones include the vertebrae and the pelvic girdle bones. Sesamoid bones – small, rounded bones usually found next to joints or embedded in a tendon. An example is the patella.

Gender Differences in Skeletal Structure Male Skull Larger and heavier Forehead shorter Face less round Jaw larger Male pelvis Bones are heavier and thicker Cavity is narrower Learning Outcome: 24.1 Describe the structure of bone tissue. Refer to Table 24-1 Differences Between the Male and Female Skeletons.

Apply Your Knowledge C B D Very Good! A E Matching: Holes in the matrix that contain osteocytes Made of inorganic salts, collagen fibers, and proteins; between osteocytes Layers of bone surrounding the canals of the osteons Elongated cylinders that run the length of the bone Canals that connect lacunae to each other Osteons Bone matrix Lamella Lacunae Caniculi C ANSWER: B D Very Good! Learning Outcome: 24.1 Describe the structure of bone tissue. A E

Functions of Bones Give shape to body parts Support and protect soft structures Function in body movement Red bone marrow – hematopoiesis Store calcium Learning Outcome: 24.2 Explain the functions of bones.

Correct! Apply Your Knowledge Why is it important for the bones to store calcium? ANSWER: Every cell in the body needs calcium, so the body must have a large supply readily available. Correct! Learning Outcome: 24.2 Explain the functions of bones.

Bone Growth Ossification Intramembranous ossification Bones begin as tough, fibrous membrane Osteoblasts turn the membrane to bone Learning Outcome: 24.3 Compare intramembranous and endochondral ossification. Ossification – the process of bone growth Intramembranous ossification Bones begin as tough, fibrous membranes. Bone-forming cells called osteoblasts turn the membrane to bone. Except for the lower jaw bone, the bones of the skull are formed by intramembranous ossification.

Bone Growth (cont.) Endochondral ossification Bones begin as cartilage models Diaphysis ~ primary ossification center Diaphysis Learning Outcome: 24.3 Compare intramembranous and endochondral ossification. Endochondral ossification Osteoblasts form a bone collar around the diaphysis of the cartilage model. Bone is formed in the diaphysis of the bone.

Bone Growth (cont.) Endochondral ossification Epiphysis ~ secondary ossification center Epiphyseal disc ~ cartilage between epiphysis and diaphysis Diaphysis Learning Outcome: 24.3 Compare intramembranous and endochondral ossification. Endochondral ossification Epiphyses turn to bone. Medullary cavity and spaces in cancellous bone are formed. The cells that form holes in bone are called osteoclasts Bone will continue to grow in length as long as there is some cartilage between an epiphysis and the diaphysis This plate of cartilage is called an epiphyseal disk or growth plate. Once the cartilage is gone, bone growth stops

Building Better Bones Bone – healthy diet Bone-healthy exercises Vitamin D Calcium Bone-healthy exercises Weight-bearing Strength-training Learning Outcome: 24.3 Compare intramembranous and endochondral ossification. Many factors influence bone health. Patients improve or maintain their bone health learning about behaviors that will support bone health. Bone-Healthy Diet Calcium and vitamin D are particularly important for healthy bones. Without vitamin D, the bloodstream cannot absorb calcium. Without calcium, bone tissue will slowly wear away. Bone-building nutrients are found in dairy products, broccoli, kale, spinach, salmon, sardines, egg yolks, whole grains, and fruits, especially bananas and oranges. Bone-Healthy Exercises Weight-bearing and strength-training exercises. When your muscles contract, they pull on your bones. This tension stimulates bones to thicken and strengthen. Lifting weights is an effective way to increase the tension on bones.

Building Better Bones (cont.) Bone-healthy lifestyle – avoid smoking and alcohol Bone tests Bone density tests Bone scan Learning Outcome: 24.3 Compare intramembranous and endochondral ossification. Bone-Healthy Lifestyle Avoid smoking and alcohol. Smoking rids the body of calcium, which is necessary for bone growth. Alcohol prevents calcium absorption in the digestive tract. Bone Tests Bone density tests are painless procedures used to determine the density of a person’s bones. Bone scans help diagnose the causes of bone pain, arthritis, bone infections, and bone cancers.

Good Job! Apply Your Knowledge What are the two types of bone growth? ANSWER: Intramembranous ossification, in which bones begin as tough membrane and are turned to bone by osteoblasts, and endochondral ossification, in which primary ossification occurs in the diaphysis of the bone and secondary ossification occurs in the epiphysis. Learning Outcome: 24.3 Compare intramembranous and endochondral ossification. Good Job!

Bony Structures Bones are designed with Projections and processes Depressions and hollows at articulations Openings for blood vessels and nerves Learning Outcome: 24.4 Describe the skeletal structures and one location of each structure. Bones have projections and processes for muscle and ligament attachment. Joints or articulations have depressions and hollows for bones to come together

Bony Structures (cont.) Term Definition Condyle A rounded process that usually articulates with another bone Crest A narrow, ridge-like projection Epicondyle A projection situated above a condyle Foramen An opening through a bone that is usually a passageway for blood vessels, nerves, or ligaments Fossa A relatively deep pit or depression Learning Outcome: 24.4 Describe the skeletal structures and one location of each structure. Table 24-2 Terms Used to Describe Skeletal Structures.

Bony Structures (cont.) Term Definition Head An enlargement on the end of a bone Process A prominent projection on a bone Suture An interlocking line of union between bones Trochanter A relatively large process Tubercle A small, knoblike process Tuberosity A knoblike process, usually larger than a tubercle Learning Outcome: 24.4 Describe the skeletal structures and one location of each structure.

Apply Your Knowledge GREAT! ANSWER: Match the following: ___ Epicondyle A. A relatively deep pit or depression ___ Fontanels B. An interlocking line of union between bones ___ Fossa C. “Soft spots” felt on an infant’s skull ___ Process D. A knoblike process, usually larger than a tubercle ___ Suture E. A projection situated above a condyle ___ Tuberosity F. A prominent projection on a bone E C A F Learning Outcome: 24.4 Describe the skeletal structures and one location of each structure. B D

The Skull Two bone types – cranial and facial Infant skulls Bones not completely formed Fontanels – tough membranes Sutures Learning Outcomes: 24.5 Locate the bones of the skull. Cranial bones form the top, sides, and back of the skull. Facial bones form the face. Skull bones of an infant Fontanels, which are tough membranes that connect the incompletely developed bones. They allow the infant’s skull to be somewhat moldable to assist with delivery through the birth canal. As the fontanels close, the sutures of the skull are formed.

The Skull (cont.) Cranial bones Frontal Parietal Occipital Temporal External auditory meatus Sphenoid and ethmoid bones Ear ossicles Malleus Incus Stapes Learning Outcomes: 24.5 Locate the bones of the skull. Frontal bone – the anterior portion of the cranium, the forehead bone. Parietal bones – most of the top and sides of the skull. Occipital bone – the back of the skull Foramen magnum – allows the spinal cord to connect to the brain. Occipital condyles sit on top of the first vertebra. Two temporal bones form the lower sides of the skull. External auditory meatus – commonly called the ear canal Runs through each temporal bone. The mastoid process – where major neck muscles attach to your skull. Sphenoid bone Forms part of the floor of the cranium Shaped like a butterfly. Sella turcica – deep depression containing the pituitary gland. Ethmoid bones – between the sphenoid bone and the nasal bones; form part of the floor of the cranium. Ear ossicles – The body’s smallest bones – the malleus, incus, and stapes Located in the middle ear cavities of the temporal bones. Click to see Skull

The Skull (cont.) Facial bones Mandible ~ lower jaw Maxillae ~ upper jaw Zygomatic Cheekbones Fused nasal bones form bridge of nose Palatine ~ hard palate Vomer ~ divides nasal cavity Learning Outcomes: 24.5 Locate the bones of the skull. Mandible Lower jaw bone; the only moveable bone in the skull. It attaches to the temporal bone in front of the external auditory meatus at the temporal mandibular joint (TMJ). The mandible anchors the lower teeth and forms the chin. Maxillae Form the upper jaw bone. Anchors the upper teeth. Zygomatic bones Cheekbones Several thin nasal bones fuse together to form the bridge of the nose. Palatine bones – hard palate; the roof of the mouth. Vomer – thin bone that divides the nasal cavity. Click to see Skull

The Skull (cont.) Back Sphenoid bone Vomer bone Frontal bone Parietal bone Ethmoid bone Nasal bone Sphenoid bone Temporal bone Occipital bone Zygomatic bone Learning Outcomes: 24.5 Locate the bones of the skull. External auditory meatus Maxillae Mandible Back

Very Good! Apply Your Knowledge ANSWER: Match the bones of the skull: ___ Occipital A. Form the upper jawbone ___ Sphenoid B. A thin bone that divides the nasal cavity ___ Mandible C. Part of the floor of the skull ___ Maxillae D. Form the prominence of the cheeks ___ Zygomatic E. Back of skull ___ Vomer F. Lower jawbone E C F A Learning Outcomes: 24.5 Locate the bones of the skull. D Very Good! B

The Spinal Column 7 cervical vertebrae 12 thoracic vertebrae 5 lumbar vertebrae Sacrum Coccyx Learning Outcome: 24.6 Locate the bones of the spinal column.

The Spinal Column (cont.) Cervical vertebrae Smallest and lightest Located in the neck Atlas Axis Thoracic vertebrae Posterior attachment for ribs Lumbar vertebrae Small of the back Bear most weight Learning Outcome: 24.6 Locate the bones of the spinal column. Cervical vertebrae Located in the neck Smallest and lightest vertebrae The first cervical vertebra – atlas The second – axis When turning your head from side to side, the atlas pivots around the axis. Thoracic vertebrae Posterior attachment for the 12 pairs of ribs. They have long, sharp, spinous processes. Lumbar vertebrae Very sturdy structures. Form the small of the back. Bear the most weight of all the vertebrae.

The Spinal Column (cont.) Sacrum A triangular-shaped bone Five fused vertebrae Coccyx A small, triangular-shaped bone 3 to 5 fused vertebrae Learning Outcome: 24.6 Locate the bones of the spinal column. The coccyx The tailbone Small, triangular-shaped bone made up of three-to-five fused vertebrae Considered unnecessary

Right! Apply Your Knowledge ANSWER: Cervical – 7 Identify the sections of the spinal column and give the number of vertebrae for each. Thoracic – 12 Learning Outcome: 24.6 Locate the bones of the spinal column. Lumbar – 5 Right! Sacrum – 5 fused Coccyx – 3 to 5 fused

The Rib Cage Sternum Breastplate Joins with the clavicles and most ribs Xiphoid process Learning Outcome: 24.7 Locate the bones of the rib cage. The rib cage is made of 12 pairs of ribs and the sternum or the breastplate. The sternum forms the front, middle portion of the rib cage. The xiphoid process is the cartilaginous tip of the sternum. The sternum joins with the clavicles and most ribs. To ribcage

The Rib Cage (cont.) Ribs All are attached posteriorly to thoracic vertebrae True – 1st 7 pairs False – pairs 8, 9, and 10 Floating – pairs Learning Outcome: 24.7 Locate the bones of the rib cage. All 12 pairs of ribs are attached posteriorly to thoracic vertebrae. The ribs are classified in three groups based on their anterior attachment. True ribs The first seven pairs of ribs. Attach directly to the sternum by costal cartilage. False ribs Rib pairs 8, 9, and 10. Do not attach directly to the sternum, but instead attach to the costal cartilage of rib pair number 7. Floating ribs Rib pairs 11 and 12 Do not attach anteriorly to any structure. To ribcage

The Rib Cage (cont.) Back Learning Outcome: 24.7 Locate the bones of the rib cage. Back

Apply Your Knowledge BRAVO! ANSWER: T F F T F True or False: ___ The sternum forms the front middle portion of the rib cage. ___ The xiphoid process is a boney tip of the sternum. ___ The true ribs are the first five pairs of ribs. ___ False ribs attach to the costal cartilage of rib pair seven. ___ Floating ribs attach to the xiphoid process. T F cartilaginous F seven T Learning Outcome: 24.7 Locate the bones of the rib cage. F do not attach anteriorly to any structure.

Bones of the Shoulders, Arms, and Hands Clavicles ~ collar bones Scapulae ~ shoulder blade Arm bones Humerus Radius Ulna Learning Outcome: 24.8 Locate the bones of the shoulders, arms, and hands. The bones of the shoulders are called the pectoral girdle. They function to attach the arms to the axial skeleton. The clavicles – slender in shape. Each joins with the sternum and a scapula. Scapulae – thin, triangular-shaped flat bones located on the dorsal surface of the rib cage. Each scapula joins with the head of a humerus and a clavicle. The arm bones include the humerus, radius, and ulna. Humerus – upper part of the arm. Its proximal end joins with the scapula, and its distal end attaches at the radius and the ulna. Radius – lateral bone of the forearm. It is on the same side of the arm as the thumb. Proximally, it joins with the humerus and the ulna, and distally with the carpal bones. Ulna – medial bone of the lower arm. The proximal end of the ulna joins with the humerus to form the elbow joint. Distally, it also joins with the radius and some of the carpal bones.

Bones of the Shoulders, Arms, and Hands (cont.) Carpals ~ 8 Metacarpals ~ 5 Phalanges ~ 14 3 per finger 2 per thumb Learning Outcome: 24.8 Locate the bones of the shoulders, arms, and hands. The bones of the hand include carpals, metacarpals, and phalange. Carpals are wrist bones. Each wrist contains eight marble-sized carpal bones. Metacarpals form the palms of the hands. Each hand has five metacarpals. Phalanges – the bones of the fingers 14 phalanges per hand – three for each finger and two per thumb. The joints between the phalangeal bones are the proximal and distal interphalangeal joints. The joints that join the phalanges to the metacarpals are called the metacarpophalangeal joints or knuckles.

Apply Your Knowledge Excellent! A B B C A B C C ANSWER: Match the following: ___ Clavicle A. Pectoral girdle ___ Radius B. Arm bones ___ Humerus C. Hands ___ Carpals ___ Scapula ___ Ulna ___ Phalanges ___ Metacarpals A B B Excellent! C A Learning Outcome: 24.8 Locate the bones of the shoulders, arms, and hands. B C C

Bones of the Hips, Legs, and Feet Hip bones Coxal bones Ilium Ischium Pubis Learning Outcome: 24.9 Locate the bones of the hips, legs, and feet. Coxal bones, attach the legs to the axial skeleton and protect pelvic organs. Iilium – most superior part of a coxal bone. When you put your hands on your hips, you are touching the iliac crest. Ischium – the lower part of a coxal bone and the pubis forms the front. Pubis bones – join to form the pubic symphysis or pelvic girdle

Bones of the Hips, Legs, and Feet (cont.) Bones of leg Femur Patella Tibia Fibula Learning Outcome: 24.9 Locate the bones of the hips, legs, and feet. Femur Thigh bone and the largest bone in the body. Its proximal end joins with the hip bone at the acetabulum (or hip socket). Ligaments and muscles hold it in place. Patella (kneecap) Attached the distal end of the femur and to the tibia Sesamoid bone – a small, rounded bone in front of the knee joint Tibia (or shinbone) Medial bone of the lower leg. Its proximal end joins with the femur and fibula, and distally to the ankle bones. Fibula The lateral bone of the lower leg. Much thinner than the tibia. It joins with the ankle bones at its distal end.

Bones of the Hips, Legs, and Feet (cont.) Bones of the foot Tarsals ~ 7 Metatarsals ~ 5 Phalanges ~ 14 3 per toe 2 per each big toe Learning Outcome: 24.9 Locate the bones of the hips, legs, and feet. Tarsal bones Form the back of the foot. The calcaneus, or heel bone, is the largest tarsal bone. Seven per foot. Metatarsals Form the front of the foot. Five per foot. Phalanges The bones of the toes Each foot contains 14 – two per big toe and three per other toes. Interphalangeal joints - between these ‘lower’ phalanges Metatarsophalangeal joints –join the toes to the foot

Super! Apply Your Knowledge ANSWERS: Match the following: A. Coxal bones B. Leg bones C. Foot bones ___ Tibia ___ Patella ___ Ilium ___ Ischium ___ Femur ___ Metatarsals ___ Pubis ___ Fibula ___ Calcaneus ___ Tarsals B B A A B C A Learning Outcome: 24.9 Locate the bones of the hips, legs, and feet. B C C Super!

Joints Junctions between bones Fibrous joints Connected together with short fibers Between cranial bones and facial bones Sutures Learning Outcome: 24.10 Describe the three major types of joints and give examples of each. Joints are the junctions between bones and are classified by structure. Fibrous joints Bones are connected together with short fibers. The bones do not normally move against each other. Found between cranial bones and facial bones. Fibrous joints in the skull are called sutures.

Joints (cont.) Cartilaginous joints Disc of cartilage Slightly moveable Between vertebrae Learning Outcome: 24.10 Describe the three major types of joints and give examples of each. The bones of cartilaginous joints are connected together with a disc of cartilage. This type of joint is slightly moveable. The joints between vertebrae are cartilaginous joints.

Joints (cont.) Synovial joints Covered with hyaline cartilage Fibrous joint capsule  Freely movable Ligaments hold bones together Learning Outcome: 24.10 Describe the three major types of joints and give examples of each. Synovial joints Bones are covered with hyaline cartilage and held together by a fibrous joint capsule. The joint capsule is lined with a synovial membrane. The synovial membrane secretes synovial fluid which allows the bones to move easily against each other. Ligaments – tough, cord-like structures. Freely moveable. Examples of synovial joints are the elbows, knees, shoulders, and knuckles.

Apply Your Knowledge Yippee! A C B C A ANSWER: Match the following: A. Fibrous joints B. Cartilaginous joints C. Synovial joints ____ Between cranial bones and facial bones ____ Covered with hyaline cartilage ____ Between vertebrae ____ Freely movable ____ Sutures in the skull C B Yippee! C Learning Outcome: 24.10 Describe the three major types of joints and give examples of each. A

Common Diseases and Disorders of the Skeletal System Arthritis Osteoarthritis Degenerative joint disease (DJD) Weight-bearing joints Rheumatoid arthritis Chronic systemic inflammatory disease Smaller joints and surrounding tissues Learning Outcome: 24.11 Describe the common diseases and disorders of the skeletal system. Arthritis is a general term meaning joint inflammation. The most common types are: Osteoarthritis – inflammatory processes or metabolic disorders as the etiology of DJD. Rheumatoid arthritis (RA) – A chronic systemic inflammatory disease. Attacks the smaller joints, typically of the hands and feet, as well as the surrounding tissues of those joints.   Patients experience attacks of pain and inflammation followed by periods of remission. Believed to be an autoimmune disease, triggering joint inflammation. Refer to CONNECT to see an animation about Osteoarthritis vs. Rheumatoid Arthritis .

Common Diseases and Disorders of the Skeletal System (cont.) Bursitis – inflammation of the bursa Ewing sarcoma family of tumors (ESFT) Primarily affect bone Usually lower extremities Gout – deposits of uric acid crystals in joints Learning Outcome: 24.11 Describe the common diseases and disorders of the skeletal system. Bursitis  Bursa – a fluid-filled sac that cushions tendons Due to overuse of, and trauma to joints; bacterial infections   Ewing sarcoma family of tumors (ESFT)   Affects Caucasians between 10 and 20 years old Causes are not clear Gout A type of arthritis that usually occurs more frequently with age. Diet changes – eliminate foods that cause the formation of uric acid (meats, fish, beer, or wine)

Common Diseases and Disorders of the Skeletal System (cont.) Kyphosis – humpback Lordosis –swayback Osteogenesis imperfecta – brittle-bone disease Osteoporosis – thin, porous bones Learning Outcome: 24.11 Describe the common diseases and disorders of the skeletal system. Kyphosis  An abnormal curvature of the spine, most often at the thoracic level. Adolescent kyphosis – growth retardation or improper development of the epiphyses The adult form – aging and degenerative disc disease of the intervertebral discs and vertebral fracture from underlying osteoporosis. Lordosis An exaggerated inward curvature of the lumbar spine; swayback.   Wearing high heels is a frequent cause. Osteogenesis imperfecta (OI) Brittle-bone disease Decreased amounts of collagen in bones; very fragile bones   Eight types Hereditary Osteoporosis  Bones thin over time due to hypocalcemia – bone is broken down to release calcium and bone density decreases. Hormone deficiencies; sedentary lifestyle; lack of calcium and vitamin D in the diet; bone cancers; corticosteroids; smoking; alcohol consumption; and steroid use.

Common Diseases and Disorders of the Skeletal System (cont.) Osteosarcoma – bone cancer from osteoblasts Paget’s disease – bones enlarge, become deformed, and weak Scoliosis – an abnormal S-shaped curvature of the spine Learning Outcome: 24.11 Describe the common diseases and disorders of the skeletal system. Osteosarcoma  A type of bone cancer usually affecting the leg bones that originates from osteoblasts   It occurs most often in children, teens, and young adults and more often in males than females. The etiology of this type of cancer is unclear. Paget’s disease   Causes bones to enlarge and become deformed and weak. It usually affects people older than the age of 40.   This disease may be caused by a virus or various hereditary factors. Scoliosis  An abnormal, S-shaped, lateral curvature of the thoracic or lumbar spine. Can develop prenatally when vertebrae do not fuse together. It can also result from diseases that cause weakness of the muscles that hold vertebrae together. Other causes of scoliosis are unknown but they may be genetic.

Nice Work! Apply Your Knowledge What is the difference between osteoarthritis and rheumatoid arthritis? Osteoarthritis is a degenerative joint disease that primarily affects weight-bearing joints. Rheumatoid arthritis chronic systemic inflammatory disease of smaller joints and surrounding tissues; it is thought to be an autoimmune disease. Learning Outcome: 24.11 Describe the common diseases and disorders of the skeletal system. Nice Work!

In Summary 24.1 Bones consist of the following substances: osteons or Haversian systems; bone matrix between osteocytes (bone cells); collagen fibers and proteins; the lamella; and canaliculi. The skeleton consists of long bone, short bones, flat bones and irregular bones The diaphysis is the shaft of the long bone. The epiphysis is an end of a long bone. Articular cartilage covers the end of the long bones. The endosteum lines the medullary cavity. The periosteum is the membrane surrounding the diaphysis. 24.1 Bones consist of the following substances: osteons or Haversian systems, bone matrix between osteocytes (bone cells), collagen fibers and proteins, the lamella, and canaliculi. Long bones include the femur and humerus; short bones include the carpals and tarsals; flat bones include the ribs and the frontal bone; irregular bones include the vertebrae and bones of the pelvic girdle. The diaphysis is the shaft of the long bone. The epiphysis is an end of a long bone. Articular cartilage covers the end of the long bones. The endosteum lines the medullary cavity. The periosteum is the membrane surrounding the diaphysis.

In Summary 24.2 Bone functions include giving shape to body parts, protecting soft structures of the body, and assisting in movement. The red bone marrow is responsible for hematopoiesis. Bones also store calcium. 24.3 Bones grow through the two types of ossification: intramembranous ossification and endochondral ossification. The cartilage plate between the diaphysis and the epiphysis allows for growth of the long bone.

In Summary (cont.) 24.4 Skeletal structures include the following: condyles, crests, epicondyles, foramina, fossae, heads, processes, sutures, trochanters, tubercles, and tuberosities. 24.5 The major bones of the skull are the frontal, parietal, temporal, and occipital bones. The skull also contains the fontanels, the mastoid processes, sphenoid,ethmoid, and ear ossicles. The facial bones include the mandible, maxillae, zygomatics, nasal and palatine bones, and the vomer. 24.5 The major bones of the skull are the frontal, parietal, temporal, and occipital bones. The fontanels are the membranous structures that connect the incompletely developed cranial bones. Within the skull are the mastoid processes, sphenoid, ethmoid, and ear ossicles. The facial bones include the mandible, maxillae, zygomatics, nasal and palatine bones, and the vomer. Locations shown in fi gures 24-6 and 24-7.

In Summary (cont.) 24.6 The spinal column includes cervical, thoracic, and lumbar vertebrae; the sacrum; and the coccyx. 24.7 There are 12 pairs of ribs, a sternum, and the xiphoid process. 24.8 Each upper extremity includes the clavicle, scapula, humerus, radius, ulna, carpals, metacarpals, and phalanges.. 24.6 The spinal column includes cervical, thoracic, and lumbar vertebrae; the sacrum; and the coccyx. Locations shown in figure 24-8 . 24.7 There are 12 pairs of ribs, a sternum, and the xiphoid process. Locations shown in figure 24-8 . 24.8 Each upper extremity includes the clavicle, scapula, humerus, radius, ulna, carpals, metacarpals, and phalanges. Locations shown in figure 24-10 .

In Summary (cont.) 24.9 The bones of the hip, leg, and foot include the coxal bones, the femur, patella, tibia, fibula, metatarsals, tarsals, and phalanges. 24.10 The three joint types are fibrous joints, cartilaginous joints, and synovial joints. A synovial joint consists of hyaline-covered bones held together by a fibrous joint capsule, which is lined by a synovial membrane that secretes synovial fluid. Ligaments hold the bones of these joints together. 24.9 The bones of the hip, leg, and foot include the coxal bones, the femur, patella, tibia, fibula, metatarsals, tarsals, and phalanges. Locations shown in figures 24-11 and 24-12. 24.10 The three joint types are fibrous joints (for example, sutures of the skull), cartilaginous joints (for example, the joints between vertebrae), and synovial joints (for example, the elbow). A synovial joint consists of hyaline-covered bones held together by a fibrous joint capsule, which is lined by a synovial membrane that secretes synovial fluid. Ligaments hold the bones of these joints together.

In Summary (cont.) 24.11 There are many common diseases and disorders of the bones and the skeletal system with varied signs, symptoms, and treatments. Examples include arthritis, bursitis, EFT, gout, kyphosis, lordosis, and scoliosis, as well as osteoporosis and osteosarcoma..

End of Chapter 24 Rigid, the skeleton of habit alone upholds the human frame. ~ Virginia Woolf