the skeletal system

how bones grow and develop

Early in the development of a human fetus, the skeleton is made entirely of cartilage. The relatively soft cartilage gradually changes to hard bone through ossification. This is a process in which mineral deposits replace cartilage in bone. At birth, several areas of cartilage remain, including the ends of the long bones in the arms and legs. This allows these bones to keep growing in length during childhood. By the late teens or early twenties, all of the cartilage has been replaced by bone. Bones cannot grow in length after this point has been reached. However, bones can continue to grow in width. They are stimulated to grow thicker when they are put under stress by muscles. Weight-bearing activities such as weight lifting can increase growth in bone width.

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bone structure

Bones are organs. Like other organs, they are made up of more than one kind of tissue. There are four different kinds of tissues in bones, as shown in Figure 16.11. From the outside of the bone to the center, the tissues are periosteum, compact bone, spongy bone, and bone marrow. Periosteum is a tough, fibrous membrane that covers and protects the outer surfaces of bone. Compact bone lies below periosteum. It is very dense and hard. Compact bone gives bones their strength. Spongy bone lies below compact bone. It is less dense than compact bone. Spongy bone contains many tiny holes, or pores, which provide spaces for blood vessels and bone marrow. Bone marrow is a soft connective tissue inside pores and cavities in spongy bone. Bone marrow makes blood cells.

textbook_image

bones

Some people think bones are like chalk: dead, dry, and brittle. In reality, bones are very much alive. They consist of living tissues and are supplied with blood and nerves.

functions of the skeletal system

Your skeletal system supports your body and gives it shape. What else does it do? The skeletal system makes blood cells. Most blood cells are produced inside certain types of bones. The skeletal system stores calcium and helps maintain normal levels of calcium in the blood. Bones take up and store calcium when blood levels of calcium are high. They release some of the stored calcium when blood levels of calcium are low. The skeletal system works with muscles to move the body. Try to walk without bending your knees and youll see how important the skeletal system is for movement. The skeletal system protects the soft organs of the body. For example, the skull surrounds and protects the brain. The ribs protect the heart and lungs.

components of the skeletal system

Bones are the main organs of the skeletal system. In adults, the skeleton consists of a whopping 206 bones, many of them in the hands and feet. You can see many of the bones of the human skeleton in Figure 16.10. The skeletal system also includes cartilage and ligaments. Cartilage is a tough, flexible connective tissue that contains the protein collagen. It covers the ends of bones where they meet. The gray tissue in Figure 16.10 is cartilage. A ligament is a band of fibrous connective tissue. Ligaments connect bones of the skeleton and hold them together.

skeletal system problems and how to prevent them

What you eat as a teen can affect how healthy your skeletal system is not only now but also in the future. Eating a diet with plenty of calcium and vitamin D can help keep your bones strong. If you dont get enough calcium and vitamin D in your diet as a teen, you will be more likely to develop osteoporosis when you are older.

sprains

Another type of skeletal system injury is a sprain. A sprain is a strain or tear in a ligament that has been twisted or stretched too far. Ankle sprains are a common type of sprain. Athletes often strain a ligament in the knee called the ACL. Warming up adequately and stretching before playing sports may reduce the risk of a sprain. Ligament injuries can take a long time to heal. Rest, ice, compression, and elevation of the sprained area may help the healing process.

osteoporosis

Osteoporosis is a disease in which the bones become porous and weak because they do not contain enough calcium. The graph in Figure 16.14 shows how the mass of calcium in bone peaks around age 30 and declines after that, especially in women. Maximizing the calcium in your bones while youre young will reduce your risk of developing osteoporosis later in of life.

fractures

People with osteoporosis have an increased risk of bone fractures. A bone fracture is a crack or break in bone. Even if you have healthy bones, you may fracture a bone if too much stress is placed on it. This could happen in a car crash or while playing a sport. Wearing a seatbelt when you ride in a motor vehicle and wearing safety gear when you play sports may help prevent bone fractures. Bone fractures heal naturally as new bone tissue forms at the site of the fracture. However, the bone may have to be placed in a cast or have rods or screws inserted into it to keep it correctly aligned until it heals. The healing process usually takes several weeks or even months.

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joints

A joint is a place where two or more bones of the skeleton meet. There are three different types of joints based on the degree to which they allow movement of the bones: immovable, partly movable, and movable joints. Immovable joints do not allow the bones to move at all. In these joints, the bones are fused together by very tough collagen. Examples of immovable joints include the joints between bones of the skull. You can see them in Figure 16.12. Partly movable joints allow very limited movement. In these joints, the bones are held together by cartilage, which is more flexible than collagen. Examples of partly moveable joints include the bones of the rib cage. Movable joints allow the greatest movement and are the most common. In these joints, the bones are connected by ligaments. The surfaces of the bones at the joints are covered with a smooth layer of cartilage. It reduces friction between the bones when they move. The space between the bones is also filled with a liquid called synovial fluid. It helps to cushion the bones. There are several different types of movable joints. You can see three of them in Figure 16.13. Move these three joints in your own skeleton to experience the range of motion each allows.

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instructional diagrams

description_image

This diagram depicts the human skeleton. The axial skeleton includes the skull, vertebral column, and thoracic cage. The skull consists of 28 bones: 8 cranial vault bones, 14 facial bones, and 6 auditory ossicles. From a lateral view, the parietal, temporal, and sphenoid bones can be seen. From a frontal view, the orbits and nasal cavity can be seen, as well as associated bones and structures, such as the frontal bone, zygomatic bone, maxilla, and mandible. The interior of the cranial vault contains three fossae with several foramina. Seen from below, the base of the skull reveals numerous foramina and other structures, such as processes for muscle attachment. The vertebral column contains 7 cervical, 12 thoracic, and 5 lumbar vertebrae, plus 1 sacral and 1 coccygeal bone. Each vertebra consists of a body, an arch, and processes. Regional differences in vertebrae are as follows: cervical vertebrae have transverse foramina; thoracic vertebrae have long spinous processes and attachment sites for the ribs; lumbar vertebrae have rectangular transverse and spinous processes, and the position of their facets limit rotation; the sacrum is a single, fused bone; the coccyx is four or fewer fused vertebrae. The thoracic cage consists of thoracic vertebrae, ribs, and sternum. There are 12 pairs of ribs: 7 true and 5 false (two of the false ribs are also called floating ribs). The sternum consists of the manubrium, body, and xiphoid process. The appendicular skeleton consists of the bones of the upper and lower limbs and their girdles. The pectoral girdle includes the scapula and clavicle. The upper limb consists of the arm (humerus), forearm (ulna and radius), wrist (eight carpal bones), and hand (five metacarpals, three phalanges in each finger, and two phalanges in the thumb). The pelvic girdle is made up of the sacrum and two coxae. Each coxa consists of an ilium, ischium, and pubis. The lower limb includes the thigh (femur), leg (tibia and fibula), ankle (seven tarsals), and foot (metatarsals and phalanges, similar to the bones in the hand).

description_image

The image below shows the Human Skeleton. The human skeleton is the internal framework of the body. It is composed of around 300 bones at birth, this total decreases to 206 bones by adulthood after some bones have fused together. The human skeleton performs six major functions; support, movement, protection, production of blood cells, storage of minerals and endocrine regulation. Bones are the main organs of the skeletal system. Some people think bones are like chalk: dead, dry, and brittle. In reality, bones are very much alive. They consist of living tissues and are supplied with blood and nerves.

description_image

This diagram shows some major bones of the human skeletal system. There are 206 bones in a normal human body. The hands and feet contain many those bones--the hand bones are called carpals, metacarpals, and phalanges. The foot bones are called tarsals, metatarsals, and phalanges. The skeletal system has several functions for humans. It gives the body structure and shape. It gives protection to vital organs--for example the skull protects the brain and the ribcage protects the heart and lungs. It helps with movement--muscles attach to the bones and together they help us move. The final function is blood production. Red and white blood cells are made in the bone marrow of the long bones.

questions

Components of the skeletal system include

a. bones.

b. cartilage.

c. ligaments.

-->  d. all of the above

The adult skeleton consists of

a. 56 bones.

b. 76 bones.

c. 106 bones.

-->  d. 206 bones.

Functions of the skeletal system include

a. making blood cells.

b. storing calcium.

c. giving the body shape.

-->  d. all of the above

Cartilage is a tough, flexible tissue that contains the protein

a. keratin.

b. cuticle.

-->  c. collagen.

d. periosteum.

Blood cells are produced by

-->  a. bone marrow.

b. compact bone.

c. spongy bone.

d. cartilage.

Which type of tissue gives bones their strength?

a. periosteum

-->  b. compact bone

c. spongy bone

d. bone marrow

Immovable joints connect the bones of the

a. rib cage.

b. shoulder.

-->  c. skull.

d. none of the above

Why do the ends of long bones ossify later than other parts of the skeleton?

a. to cushion the ends of the bones

b. to prevent growing pains in the bones

c. to allow the bones to grow in width

-->  d. to allow the bones to grow in length

Partly movable joints are held together by

a. collagen.

b. keratin.

-->  c. cartilage.

d. ligaments.

Which bones are connected by partly movable joints?

a. bones of the skull

-->  b. bones of the ribcage

c. bones of the arms

d. bones of the legs

Which joint moves like the hinge on a door?

a. shoulder

b. elbow

-->  c. knee

d. back

Which statement about bone fractures is false?

a. Bone fractures naturally heal on their own.

b. Bone fractures are caused by excess stress on bone.

c. People with osteoporosis have an increased risk of bone fractures.

-->  d. none of the above

Bones release stored calcium to the blood as needed.

-->  a. true

b. false

Bones are like chalk: dead, dry, and brittle.

a. true

-->  b. false

Bones are organs made up of four types of bone tissues.

-->  a. true

b. false

Compact bone lies between spongy bone and periosteum.

-->  a. true

b. false

An example of a ball-and-socket joint is the elbow.

a. true

-->  b. false

Calcium and vitamin D are needed to keep bones strong.

-->  a. true

b. false

Blood cells are produced by compact bone.

a. true

-->  b. false

People with osteoporosis have an increased risk of bone fractures.

-->  a. true

b. false

By birth, the human skeleton consists entirely of bone.

a. true

-->  b. false

Bones grow thicker when they are put under stress by muscles.

-->  a. true

b. false

A sprain occurs when a bone bends but doesnt break.

a. true

-->  b. false

The adult skeletal system contains 206 bones.

-->  a. true

b. false

__type of bone tissue that contains many tiny pores

a. compact bone

b. ossification

c. cartilage

-->  d. spongy bone

e. periosteum

f. ligament

g. bone marrow

__tough, fibrous tissue that forms the outer layer of bone

a. compact bone

b. ossification

c. cartilage

d. spongy bone

-->  e. periosteum

f. ligament

g. bone marrow

__type of bone tissue that is very dense and hard

-->  a. compact bone

b. ossification

c. cartilage

d. spongy bone

e. periosteum

f. ligament

g. bone marrow

__band of fibrous tissue that holds bones together

a. compact bone

b. ossification

c. cartilage

d. spongy bone

e. periosteum

-->  f. ligament

g. bone marrow

__soft tissue inside spongy bone that makes blood cells

a. compact bone

b. ossification

c. cartilage

d. spongy bone

e. periosteum

f. ligament

-->  g. bone marrow

__tough, flexible connective tissue containing collagen

a. compact bone

b. ossification

-->  c. cartilage

d. spongy bone

e. periosteum

f. ligament

g. bone marrow

__process in which cartilage changes to bone

a. compact bone

-->  b. ossification

c. cartilage

d. spongy bone

e. periosteum

f. ligament

g. bone marrow

diagram questions

question_image

What is being represented by label M?

a. CLAVICLE

b. ULNA

-->  c. HUMERUS

d. SCAPULA

question_image

Which label shows the ribs?

a. X

-->  b. K

c. R

d. W

question_image

What is the function of X in the figure?

a. IT PROTECTS THE MUSCLES

b. IT PROTECTS THE HEART

-->  c. IT PROTECTS THE LUNGS

d. IT PROTECTS THE BRAIN

question_image

Which letter corresponds to the part that connects the femur to the tibia?

a. X

b. K

-->  c. V

d. E

question_image

What is the part of the human skeleton represented with the letter A?

a. HUMERUS

-->  b. PHALANGES

c. FEMUR

d. ULNA

question_image

What label refers to the femur?

a. E

b. U

-->  c. S

d. W

question_image

This part protects the brain.

a. E

-->  b. U

c. F

d. J

question_image

Which letter represents the skull?

a. J

b. V

c. FU

-->  d. U

question_image

Which letter represents phalanges?

a. E

b. V

c. S

-->  d. A

question_image

Which represents the bone that protects the brain?

a. F

b. D

-->  c. U

d. E

question_image

Which letter represents the Femur?

a. T

b. H

-->  c. A

d. K

question_image

Identify the ribs in the diagram.

a. X

b. W

-->  c. M

d. E

question_image

Identify the femur

a. C

b. J

-->  c. U

d. W

question_image

Identify the sacrum

a. T

b. U

c. D

-->  d. Y

question_image

Which represents the bone that protects the brain?

a. T

b. N

c. F

-->  d. D

question_image

Which label refers to the phalanges?

a. E

b. X

-->  c. Y

d. H

question_image

Which label shows the clavicle?

-->  a. W

b. C

c. X

d. A

question_image

Identify the strongest and longest bone in the body.

a. H

b. V

c. E

-->  d. F

question_image

Which bone connects the radius and the scapula?

a. THE TIBIA

b. THE ULNA

c. THE FEMUR

-->  d. THE HUMERUS

question_image

Which bone is represented by the letter R?

a. PATELLA

-->  b. CALCANEUS

c. METATARSALS

d. WORMIAN BONES

question_image

Select the mandible.

-->  a. X

b. W

c. E

d. D

question_image

Which label refers to the ribs?

a. X

-->  b. T

c. D

d. J

question_image

In the image below which label shows the Tibia?

a. V

-->  b. M

c. X

d. Y

question_image

Which letter represents the skull?

a. X

-->  b. D

c. M

d. J

question_image

Where is the insertion of the temporalis muscle?

-->  a. D

b. X

c. J

d. N

question_image

Which small bone is directly below the femur?

a. S

b. V

-->  c. E

d. N

question_image

Which label shows the femur?

a. W

b. E

-->  c. A

d. J

question_image

Which letter indicates the clavicle?

a. L

b. E

-->  c. F

d. V

question_image

Which is a bone located in the forearm?

a. humerus

b. tibia

-->  c. radius

d. fibula

question_image

Which bones connect to the phalanges in the hand?

-->  a. Metacarpals

b. Carpals

c. Metatarsals

d. Tarsals

question_image

How many types of bones are in the human arm and hand?

-->  a. 6

b. 3

c. 5

d. 7

question_image

How many major bones does our body have?

a. 30

b. 26

-->  c. 23

d. 21

question_image

What bone protects the brain?

a. Sternum

-->  b. Cranium

c. Ribs

d. Mandible

question_image

The heart is protected by which bone(s)?

a. skull

b. femur

c. sacrum

-->  d. Rib cage

question_image

Which bones connect the skull to the rest of the body?

a. sternum

b. clavicle

-->  c. 7 cervical vertebrae

d. scapula

question_image

Which bones connect to the skull?

-->  a. Cervical vertebrae

b. Radius

c. Femur

d. Rib cage

question_image

How many parts of the skeletal system are marked in the diagram?

a. 18

b. 19

c. 21

-->  d. 20

question_image

How many thoracic vertebrae are there?

a. 10

b. 15

c. 20

-->  d. 12

question_image

What is a bony structure that forms the head of the skeleton in most vertebrates?

a. Ulna

-->  b. Skull

c. Sternum

d. Pelvis

question_image

What is the human bone that sits highest in the human body?

a. sternum

b. humerus

c. femur

-->  d. skull

question_image

What bone is below the clavicle?

a. Vertebra

b. Humerus

-->  c. Scapula

d. Ribs

question_image

Which part of the skeletal system is at the topmost and houses the brain?

a. Ribs

b. Ulna

c. Femur

-->  d. Skull

question_image

How many femora are present in human body?

-->  a. 2

b. 3

c. 1

d. 4

question_image

How many humerus bones does a person have?

a. 3

b. 6

-->  c. 2

d. 1

question_image

What is the topmost part of the skeletal system?

-->  a. skull

b. pelvis

c. clavicle

d. femur

question_image

What two bones create a hinge joint?

a. pelvis & vertebra

b. humerus & clavicle

c. ulna & radius

-->  d. femur & fibula

question_image

What is the topmost part of the skeletal system?

-->  a. cranium

b. femur

c. pelvis

d. radius

question_image

Which bone is also known as the collarbone?

-->  a. Clavicle

b. Scapula

c. Sternum

d. Patella

question_image

Which bones are slender curved articulated in pairs to the spine?

a. clavicle

b. mandible

c. humerus

-->  d. ribs

question_image

What is the bone over the brain called?

a. Mandible

-->  b. Cranium

c. Ribs

d. Sternum

question_image

How many patellae can be seen in the picture?

-->  a. 2

b. 3

c. 1

d. 4

question_image

What is the lower jawbone in mammals and fishes?

a. Cranium

-->  b. Mandible

c. Clavicle

d. Sternum

question_image

What is the upper leg bone called?

a. Tibia

b. Fibia

c. Patella

-->  d. Femur

question_image

What connects the femur to the fibia and tibia?

a. Carpals

-->  b. Patella

c. Tarsals

d. Skull

question_image

What is the bone touching the fibia?

a. Zygomatic arch

b. The clavical

-->  c. The tibia

d. Humerus

question_image

How many kinds of bones are below the knee cap?

a. 13

b. 6

c. 9

-->  d. 5

question_image

How many parts of the human skeleton are from the knee below?

a. 5

b. 4

c. 10

-->  d. 6

question_image

This bone protects the brain.

a. Sternum

b. Zygomatic arch

-->  c. Skull

d. Humerus

question_image

What is the topmost part of the skeletal system?

a. coccyx

b. carpals

-->  c. skull

d. pelvis

question_image

From the diagram, what connects the femur to the tarsals?

-->  a. Tibia

b. Fibula

c. Metatarsals

d. Palvis

question_image

What bones are located in the fingers?

a. Radius

-->  b. Phalanges

c. Tibia

d. Humerus

question_image

How many bones are in the lower leg?

a. 3

b. 4

-->  c. 2

d. 1

question_image

How many kinds of bones can be found below the patella?

-->  a. 4

b. 5

c. 2

d. 3

question_image

What circular bone structure are the legs connected to?

a. Humerus

b. Ribs

-->  c. Pelvis

d. Carpals

question_image

What is the topmost part of the skeletal system?

-->  a. cranium

b. patella

c. ribs

d. pelvis

question_image

Which of these bones are you born without?

a. maxilla

b. scapula

c. ulna

-->  d. patella

question_image

Which is not a bone in the face or head?

a. Nasal Bone

-->  b. ilium

c. Maxilla

d. Frontal

question_image

How many bones make up the leg?

a. 2

b. 5

c. 3

-->  d. 4

question_image

How many phalanxes are there?

a. 5

b. 4

-->  c. 3

d. 2

question_image

What connects the femur and tibia?

a. ulna

b. ischium

c. ilium

-->  d. patella

question_image

Which of the following is not a bone in the leg?

a. Femur

-->  b. Ulna

c. Patella

d. Tibia

question_image

Which bones protect the heart and lungs?

-->  a. ribs

b. pelvic girdle

c. humerus

d. clavicle

question_image

What lies between the pelvic girdle and tibia?

a. Skull

-->  b. Femur

c. Scapula

d. Ribs

question_image

How many objects are labeled in the first image?

a. 17

-->  b. 19

c. 18

d. 21

question_image

How many patellas are in the human body?

a. 3

b. 4

-->  c. 2

d. 1

question_image

What is a bony structure that forms the head of the skeleton in most vertebrates?

-->  a. Skull

b. Humerus

c. Radius

d. Ribs

question_image

What is the topmost part of the skeletal system?

a. sternum

b. ulna

-->  c. skull

d. radius

question_image

What is a long flat bone shaped like a necktie located in the center of the chest and connects to the ribs via cartilage?

-->  a. Sternum

b. Humerous

c. Cranium

d. Clavicle

question_image

How many bones are in the lower arm?

a. 1

b. 4

c. 3

-->  d. 2

question_image

How many types of bones are labeled in the diagram of the skeletal system?

a. 22

-->  b. 21

c. 20

d. 19

question_image

What is the portion of the skull enclosing the brain?

a. 11

b. 13

-->  c. 10

d. 12

question_image

What is the topmost part of the skeletal system?

a. sternum

b. ribs

c. humerous

-->  d. cranium

question_image

What bones connect the cranium with the rest of the body?

-->  a. Cervical Vertebrae

b. Ulna

c. Iliac Crest

d. Sacrum

question_image

Which is not a bone in the arm?

-->  a. Femur

b. Radius

c. Ulna

d. Humerous

question_image

How many bones are there in the leg area?

-->  a. 4

b. 5

c. 7

d. 6

question_image

What is the bone that connects the humerus (upper arm bone) with the clavicle (collar bone)?

a. Rib

b. Ulna

c. Radius

-->  d. Scapula

question_image

Which bone does the humerus connect to?

a. Ribs

b. Sacrum

c. Skull

-->  d. Ulna

question_image

Which part of the skeletal system is found in the spinal column?

a. Patella

-->  b. Lumbar Vertebrae

c. Carpals

d. Mandible

question_image

How many bones make up the arm?

a. Five

b. One

-->  c. Three

d. Two

question_image

How many femur bones are in the diagram?

a. 3

b. 4

-->  c. 2

d. 1

question_image

What is the topmost part of the skeletal system?

-->  a. cranium

b. sacrum

c. ulna

d. humerus

question_image

Which bone is responsible for the protection of the cardiovascular box?

a. Cranium

-->  b. Ribs

c. Scapula

d. Humerus

question_image

The patella is attached to the what?

a. tarsals

b. femur

c. tibia

-->  d. fibula

question_image

Which bones are not in the leg?

a. Tibia

-->  b. Ulna

c. Patella

d. Femur

question_image

How many bones are in the human leg?

a. 3

b. 5

-->  c. 4

d. 2

question_image

How many parts of the human skeleton are from the knee below?

-->  a. 5

b. 6

c. 7

d. 4

question_image

If an adult human started weight-lifting what would be a likely outcome on bone morphology?

a. A thinning of weight bearing bones

b. A shortening of the leg bones

c. A lengthening of weight bearing bones

-->  d. A thickening of the weight bearing bones

question_image

What is the topmost part of the skeletal system?

-->  a. cranium

b. ribs

c. ulna

d. radius

question_image

Which bone is positioned as the upper arm?

-->  a. Humerus

b. Skull

c. Ribs

d. Clavicle

question_image

What connects the pelvic girdle to the ribs?

-->  a. vertebral column

b. femur

c. scapula

d. clavicle

question_image

What connects the skull to the pelvis?

a. humerus

b. ribs

-->  c. vertebral column

d. sternum

question_image

How many femurs are in the human skeletal system?

a. 3

b. 1

-->  c. 2

d. 6

question_image

How many scapulars are in the human body?

-->  a. 2

b. 1

c. 3

d. 4

question_image

What is a long bone that serves as a strut between the shoulder blade and the sternum or breastbone?

-->  a. Clavicle

b. Sternum

c. Humerus

d. Skull

question_image

Which is the bone that extends from the forearm to the wrist?

a. Radius

-->  b. Ulna

c. Femur.

d. Carpals

question_image

What bone protects your vital organs?

a. humerus

b. Pelvis

-->  c. ribs

d. scapula

question_image

What protects your brain

a. femur

-->  b. cranium

c. Cervical vertebrae

d. radius

question_image

What bone is located on the upper arm?

a. radius

b. Scapula

c. cranium

-->  d. humerous