Chapter 23: The Skeletal System

Major bones

- The frontal bone forms the anterior portion of the cranium. It is also the forehead bone - Parietal bones form most of the top and sides of the skull - The occipital bone forms the back of the skull. The large hole at the base of the occipital bone is called the foramen magum. It allows the spinal cord to connect to the brain. Two bumps called occipital condyles are on either side of the foramen magnum. They sit on to of the first vertebra. When you nod your head, your occipital condyles are rocking back and forth on the first vertebra of the spinal cord. - Two temporal bones form the lower sides of the skull - A canal called the external auditory meatus (ear canal) runs through each temporal bone.

Major facial bones

- The mandible is the lower jaw bone and is the only movable bone in the skull. It attaches to the temporal bone in front of the external auditory meatus in an area known as the temporal mandibular joint (TMJ) (also known as the temporomandibular joint). The mandible anchors the lower teeth and forms the chin - The maxillae form the upper jaw of the facial skeleton to which the upper teeth anchor -The zygomatic bones are the cheekbones - Several thin nasal bones fuse together to form the bridge of the nose - Palatine bones form the hard palate, which is the roof of the mouth - The vomer is a thin bone that divides the nasal cavity mandible, maxillae, zygomatic bones, nasal bones, palatine bones, and the vomer

The bones of the hand include carpals, metacarpals, and phalanges:

-Carpals are wrist bones. Each wrist contains 8 marble-sized carpal bones - Metacarpals form the palms of the hands. Each hands has 5 metacarpals - Phalanges are the bones of the fingers. There are 14 phlanges in each hand- 3 for each finger and 2 per thumb - The joints between the phalangeal bones are the proximal and distal interphalangeal (PIP and DIP) joints - The joints that join the phalanges to the metacarpals are called the metacarpophalangeal (MCP) joints. Also known as knuckles.

Spinal Column

-Cervical vertebrae, located in the neck, are the smallest and lightest vertebrae. The first cervical vertebra is called the atlas and the second is called the axis. - Thoracic vertebrae are the prosterior attachment for the 12 pairs of ribs. - Lumbar vertebrae are very sturdy structure. They form the small of the back and bear the most weight of all the vertebrae - The sacrum is a triangular-shaped bone that consists of five fused vertebrae - The coccyx (tailbone) is a small, triangular-shaped bone made up of three to five fused vertebrae; it is considered nonessential in humans

Bone healthy lifestyle

A person with a bone-healthy lifestyle avoids smoking and alcohol. Smoking rids the body of calcium, which is necessay for bone growth. Alcohol prevents calcium aborption in the digestive tract. Smokers are almost twice as likely to develop osteoporosis as nonsmokers.

Bone Tests

Bone density tests and bone scans are currently the most useful tools in determining bone health. Bone density tests are painless procedures used to determine the density of a person's bones. Because osteoporosis shows no symptoms in early stages, it is important to have these tests done when your doctor recommends them. Bone scans help diagnose the causes of bone pain, arthritis, bone infections, and bone cancers. These scans use radioactive tracers that are injected into the patient and concentrate in bone tissue.

Intramembranous ossification

Bones begin as tough, fiberous membranes. Eventually, bone-forming cells called osteoblasts secrete bone matrix into the membrane, changing the membrane to bone. Except for the lower jaw bone, the bones of the skull are formed by intramembranous ossification.

Endochondal ossification

Bones start out as cartilage models. Eventually, the osteoblasts form a bone collar around the diaphysis of the cartilage model. Then bone is formed in the diaphysis of the bone. This area is called the primary ossification center. Later, the epiphyses turn to bone (secondary ossification centers), and the medullary cavity and spaces in cancellous bone are formed. The cells that form holes in bone are called osteoclasts.

Which of the following are very important for healthy bones?

Calcium Vitamin D

Ewing sarcoma family of tumors primarily affects those between the ages of 10 and 20 and which descent?

Caucasian

Osteoporosis is a common disorder that affects

Caucasians more than any other race. more women than men

Which of the following vertebrae are the smallest?

Cervical vertebrae

Which of the following male body structures is less movable than that of a female?

Coccyx

Axial skeleton

Contains 80 bones, including the bones of the skull, vertebral column, and rib cage. It supports the head, neck, and trunk, and it protects the brain, spinal cord, and organs in the thorax. The hyoid bone, which anchors the tongue, is also included in the axial skeleton.

Osteoarthritis is also known as

Degenerative Joint Disease (DJD)

Treatment for scoliosis includes

Different types of back braces, surgery to correct spinal curves, and physical therapy to strengthen the muscles of the back and abdomen.

Which of the following is a group of tumors that affect different tissue types?

Ewing sarcoma family of tumors

Which of the following are classified as long bones?

Femur Humerus

Types of joints

Fibrous joints are connected together with short fibers. So the bones of this type of joint do not normally move against each other. Most fibrous joints are found between cranial and facial bones. Fibrous joints in the skull are called sutures. Cartilgainous joints are connected together with a disc of cartilage. This type of joint is slightly movable. The joints between vertebrae are cartilaginous joints. Synovial joints are covered with hyaline cartilage and are held together by a fibrous joint capsule. The joint capsule is lined with a synovial membrane, which secretes a slippery fluid called synovial fluid. This fluid allows the bones to move easily against each other. Bones are also held together through tough, cord-like structures called ligaments. Synovial joints are freely movable. Examples are the knees, elbows, shoulders, and knuckles.

Which of the following is an opening through a bone that is usually a passageway for blood vessels, nerves, or ligaments?

Foramen

Bone-Healthy Diet

Good nutrition is essential for proper bone growth during childhood and the teen years. It is equally important in adulthood in order to maintain healthy bones. Bone-building nutrients are found in dairy products, broccoli, kale, spinach, salmon, sardines, egg yolks, whole grains, and fruits-especially bananas and oranges. Calcium and vitamin D are particulary important for healthy bones. WIthout vitamin D, the bloodstream cannot absorb calcium from the digestive tract.

Bones give shape to which of the following body parts?

Head, legs, arms, and trunk

Which of the following is a frequent cause of lordosis?

High heels

Which of the following forms the lower part of the coxal bone?

Ischium

To diagnose gout what type of fluid is aspirated for testing?

Joint fluid

Which of the following is known as the lower jaw bone?

Mandible

What cell replaces bone when there is excess calcium in the blood

Osteoblast

Which of the following cells breaks down bone when the body needs more calcium in the blood?

Osteoclasts

Which condition is most commonly called brittle-bone disease?

Osteogenesis imperfecta

In which of the following conditions do bones become thin over time?

Osteoporosis

Which of the following is a function of bones?

Protect soft structures Provide support to the body Give shape to the body

Which of the following bones is triangular-shaped?

Scapula

Which of the following is the abnormal lateral curvature of the thoracic or lumbar spine?

Scoliosis. Treament includes different types of back braces, surgery, and physical therapy

Types of Bones

Short, flat, irregular, and sesamoid Long bones Sesamoid bones Flat bones

The Skull

Skull bones are divided into two types: cranial and facial bones. Cranial bones form the top, sides, and back of the skull. Facial bones form the face. The skull bones of an infant are not completely formed. The "soft spots" felt on an infant's skull are actually fontanels, which are tough membranes that connect the incompletely developed bones. These structures 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.

Differences Between the Male and Female Skeletons

Skull- Is much heavier and larger Pelvis- Male pelvic bones are heavier, thicker, and have more obvious muscular attachments Pelvic cavity- Narrower in all diameters and is longer, less roomy, and more funnel-shaped. Sacrum- Male sacrum is narrower, sacral promontory projects foward to a greater degree, and sacral curvature is bent less sharply posteriosly than in a female Coccyx- less movable than a female

Appendicular skeletion

The body's other 126 bones include the bones of the arms, legs, pectoral girdle, and pelvic girdle. The pectoral girdle attaches the arms to the axial skeleton and the pelvic girdle attaches the legs to the axial skeleton.

Bones of the Shoulders, Arms and Hands

The clavicles, or collarbones, are slender in shape. Each joins with the sternum and a scapula. Scapulae (shoulder blades) are 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.

Bones of the Hips, Legs, and Feet

The hip bones, also called coxal bones, attach the legs to the axial skeleton. They also protect pelvic organs. Each coxal bone has three parts: the illium, the ischium, and the pubis. - The ilium is the most superior part of a coxal bone. When you put your hands on your hips, you are touching the part of the ilium called the iliac crest - The ischium forms the lower part of a coxal bone and the pubis forms the front - The pubis bones of each coxal bone join together to form the sympysis pubis These three bones also are referred to as the pelvic girdle

The Rib Cage

The rib cage is made of 12 pairs of ribs and the sternum which is often called the breastplate that forms the front middle portion of the rib cage. The cartilaginous tip of the sternum is known as the xiphoid process. The sternum joins with the clavicles and most ribs. All 12 pairs of ribs are attached posteriorly to thoracic vertebrae. The ribs themselves are classified into three groups based on their anterior attachment: -True. the first seven pairs of ribs are true ribs. They attach directly to the sternum through pieces of cartilage called costal cartilage. -False ribs do not attach directly to the sternum by individual cartilage but instead attach to the costal cartilage of rib pair 7 - Floating rib pairs are called floating ribs because they do not attach anteriorly to the sternum or to any other structure

Pelvic girdle

The structure that attaches the legs to the axial skeleton

Bone-Healthy Exercises

Weight-bearing and strength-training exercises are best for bone health. When your muscles contract, they pull on your bones. This tension stimulates bones to thicken and strenghten. Lefting weights is an effective way to increase the tension on bones. Other activities such as jogging, walking briskly, or playing a sport regularly will also stimulate your bones to increase in density.

Gout

also known as gouty arthritis, is a type of arthritis that usually occurs more frequently with age. It is caused by deposits of uric acid crystals in the joints. To diagnose goit, a specimen of joint fluid is aspirated from the affected joint and tested for urate crystals. Blood tests for high levels of uric acid and creatinine also may be prefomed. The most common treatments are pain medications and changes to the patient's diet.

Which of the following is a long bone?

are located in the wrists and ankles. Examples include the femur (thighbone), and the humerus (upper arm bone). Long bones have the following parts: Diaphysis- the shaft of a long bone. It is tubular and consists of a thick collar of compact bone that surrounds the central medullary cavity. Epiphysis- the expanded end of a long bone. It consists of a thin layer of compact bone surrounding cancellous bone movements.

Bones come together at joints, also called

articulations

Examples of short bones are:

carpals and tarsals which are the wrists and ankles.

The joints between the phalangeal bones are the proximal and ______ interphalangeal joints.

distal

Bones start out as cartilage models in

endochondral ossification.

Joints can be classified as

fibrous, cartilaginous, or synovial

Which of the following do not attach anteriorly to the sternum or to any other structures?

floating ribs

Rheumatoid arthritis normally affects the

hands. feet.

Osteogenesis Imperfecta (OI)

is more commonly called brittle bone disease. People with this disease have decreased amounts of collagen in their bones, which leads to very fragile bones. There are 8 types of this disease: Type 1. The mildest form of OI which occurs more than the others Type 2. The most severe form of OI, normally fatal within a few weeks of birth Type 3. A severe type of OI; however, infants usually live longer than those with type 2 Type 4. a moderate form of OI that is usually diagnosed later in childhood Type 5. similar to Type 4 except that large callouses form around bone fractures. This type accounts for only 5% of OI cases Type 6. an extremely rare, moderate form of OI characterized by a defect in mineralization of the bone Type 7. A moderate form caused by inheritance of a recessive gene mutation. Moderately abnormal bone growth occurs in this type of OI Type 8. Similar to Type 2 and 3, and growth deficiency is severe; however, the sclera is white in Type 9

Lordosis is the exaggerated inward curvature of the ______ spine.

lumbar

The pelvic cavity of a ______ is narrower in all diameters, is longer, and is less roomy.

male

Bones contain various kinds of tissues, including

osseous tissue, blood vessels, and nerves. Osseous tissue can be compact or spongy. At the microscopic level, spongy, or cancellous, bone has more spaces within it than compact bone does.

Cells that form holes in bone are called

osteoclasts.

Ossification

process of bone growth from creating bone from either fibrous membranes or cartilage. There are two types of ossification called intramembranous and endochondral ossification.

The rib cage is made of 12 pairs of ribs and the

sternum

Hematopoiesis

the red marrow within cancellous bone produces new blood cells