8-2. Movement in humans

THE HUMANMUSCULOSKELETA

L SYSTEM

Created by Alfie Msk_A Biology teacher of GIS Junior High

• All body movements involve bones and muscles found in the body

• The human movement system consists of the skeleton and muscles

• The skeleton consists of bones

• Bones are the passive movement device, because they cannot move without the help of the muscles.

• The muscles are called the active movement device, because they can move the bones


The skeleton function

1. Shape the body2. Protect vital organs3. Attach the muscles4. Produce bone marrow5. Erect the body


BONES• The types of bones are classified into two, namely cartilage and hard

bones.1. Cartilage

During the embryo stage, the skeletons of humans and vertebrates are mostly composed of cartilage

In their development, the cartilage will develop into bones (hard bones)

However, some cartilage does not develop into bones.

The nose, earlobes, and larynx are some examples of cartilage which does not develop into bones

Contains many adhesive substances, such as protein and less calcium so the cartilages are more flexible


There are 3 types of cartilage, namely ;

a. Hyaline cartilage;is the cartilage that is composed of a similar substances. It is found in the trachea lining, the ends of the leg and arm bones, joints, and between the ribs and breastbone.

b. Elastic cartilage;is flexible and found in the nose and earlobes

c. Fibrous cartilage;is strong but less flexible compared to the other types of cartilage. It is found in the disks between the backbones.


2. HARD BONES

• The term “bones” is actually referring to the hard bones

• Bones are distinguished from the cartilage based on the constituent substances.

• The bones develop from cartilage, the development process of cartilage becoming bones is called ossification.

• Much of the intercellular space in the bone contains calcium (calcium carbonate or calcium phosphate), some adhesive substances, and protein.

• That’s why the bones are hard and not flexible.


• The hardening process in the bones is affected by vitamin D that increases the calcium absorption in the small intestine.

• That is the reason why people who lack vitamin D have fragile bones.

• The bones tissue structure ;

the outer part of the bone is covered with pliant connective tissues that called periosteum

layers of circles surround the haversian canal

inside the haversian canal there are blood vessels whose function is to provide nutrients to the bone cells, and nerves, in each layer



There are 2 types of bones according to the composing substance ;

1. Compact bones possess compact composing substances, ex. Long bones

2. Spongy bonespossess hollow composing substances, ex. Short bones, flat bones, the ends of the long bones



• The outer layers are hard (compact bones) and they surround the hollow space called the marrow space.

• Thus, the bones are not closely arranged, but they are hollow inside.

• If bones were not hollow inside, then our body would be very heavy and would be hard to move


Based on their form, bones are classified into 3 categories;

1. Long bones

Long bones are long and round like a pipe, both ends of these bones thicken like knobs and are composed of spongy bones, and called epiphysis

Between the knobs is the compact bone that is surrounded by the periosteum, and called diaphysis

The middle part of long bones contains yellow marrow and fat

Ex. Upper arm, thigh, toes, fingertips



2. Flat bones

flat bones are flat, with spongy –like hollows inside them

these bones contain red marrow as the production place of red blood cells

ex. Ilium bones, rib bones, breastbone, scapula, skull bones



3. Short bones

shorth bones are short, contain red marrow ex. Vertebrae, carpus, tarsus


Bone Marrow• Bone marrow fills the space inside the bones

• There are 2 types of marrow ; red marrow and yellow marrow

• Red marrow is where red blood cells are produced

• Yellow marrow is found in the bones of adults, it is composed of a mixture of connective tissues, like fat tissues and red marrow


Bone Growth• Bones are living tissues that are able to grow and repair

themselves.

• During the formation of long bones, the cartilage develops into bones, starting from the middle part of the bones.

• The process begins by the appearance of blood vessels in the cartilage and the bone cells (osteoblast) production of the bone tissue.

• Ossification starts when the fetus is still inside the womb.

• Other types of bones develop from bone cells, the bones grow bigger and longer.

• The increase in length of the bones takes place in the growing are near the end of the bones, called the epiphyseal disk Created by Alfie Msk_A Biology teacher of

GIS Junior High


The Structure of Human Skeleton

• The human skeleton consists of 206 bones.

• The bones that contructing the skeleton consist of 3 general categories;

1. the skull, 2. body skeleton,3. limbs.


Skull

The Cranial bones

1. Frontal bone: 12. Parietal bones : 23. Occipital bone : 14. Temporal bones : 25. Sphenoid bones : 26. Ethmoid bones : 2


Skull

The facial bones

1. Maxilla : 22. Mandible :

23. Palatine bones: 24. Nasal Bones : 25. Zygomatic bones :

26. Lacrimal bones :

27. Vomer bone : 1


Body Skeleton• The body skeleton is the group of bones that

forms the body.

• The body skeleton is further classified into smaller groups that consist of the ;

1. Backbones 2. Sternum (breastbone)3. Ribs 4. Shoulder girdle5. Pelvic girdle


1. Backbone

1. Cervical vertebrae : 7

2. Thoracic vertebrae : 12

3. Lumbar vertebrae: 54. Sacral vertebrae : 55. Coccygeal vertebrae :

4


2. Sternum (breastbone)

1. The upper part (manubrium): 1

2. The body of the sternum (gladiolus): 1

3. The xiphoid process: 1


3. Ribs

1. True ribs : 7 setsattached to backbone and sternum

2. False ribs : 3 setsthe ends are attached to the backbone, while the front parts are attached to the ribs above

3. Floating ribs : 2 setsthe ends are attached to the backbone, while the front part are floating


4. Shoulder girdle• The shoulder girdle is

located on the left and the right side of the body, each consist of :

1. clavicles : 22. scapulas : 2

• the clavicles are located at the front, and each connects the girdle with the sternum

• The scapulas are located at the back and are attached to the ribs


5. Pelvic girdle

1. The ilium : 22. The pubis : 23. The ischium

: 2

• The 3 bones join into one


The Limbs

• The limbs consist of the upper limbs (arms) and the lower limbs (legs)

• The upper limbs are connected to the shoulder girdle

• The lower limbs are connected to the pelvic girdle


The bones of the upper limb consist of ;

1. Humerus : 2(upper arms)

2. Radius : 23. Ulna : 2

(lower arms)4. Carpals : 2 x

85. Metacarpals : 2 x

56. Phalanges : 2 x 14



The bones of the lower limbs consist of ;

1. Femurs : 22. Patellae : 23. Tibias : 24. Fibulas : 25. Tarsal bones : 2 x 76. Metatarsal bones : 2 x 57. Phalanges : 2 x 14


JOINTS

• The location where two or more bones are connected is called a joint.

• Base on their movement ability, the joints are classified into 3 types as follows ;

1. Synarthrosis2. Amphiarthrosis3. Diarthrosis


1. Synarthrosis •A synarthrosis is a joint

which permits no movement.

•The connector in this joint are connective fibers.

•Ex. Joints in the skull (called sutures), in the bone connection that forms the pelvic girdle


2. Amphiarthrosis • An amphiarthrosis is a

joint which permits slight movement.

• The connector in this joint is the cartilage tissue.

• Ex. The connection between backbones , between the ribs and the breastbone.


3. Diarthrosis • A diarthrosis is a joint which permits free

movement.• At both ends of the bones that are connected

to this joint, a space is formed containing synovial fluid.

• There are 4 types of diarthrosis ;a.hinge jointsb.pivot jointsc. saddle jointsd.ball and socket joint


a. Hinge joints

• The hinge joints are the joints which only allow movement in one direction.

• These joints are similar to a door hinge which can only open to one side

• Ex. The knee and the elbow joints, the joints between the phalanges


b. Pivot joints• The pivot joints are the

joints which allow bone to rotate around another bone.

• Ex. Between the atlas and axis neckbone which enables you to turn your head.


c. Saddle joints

• The saddle joints are the joints which resemble a saddle.

• Ex. The thumb, between the metacarpal and carpal


d. Ball and socket joints • The ball and socket joints

are the joints which enable move in all direction.

• Loose joints often happen in these types of joints.

• Ex. Between the humerus and the shoulder girdle, between the femur and the pelvic girdle.


MUSCLES• Muscles bring about the body movement,

therefore the muscles are called the active movement devices.

• Based on the shape and working procedures, muscles are classified into 3 types ;

1. smooth muscle2. striated muscle3. cardiac muscle


1. Smooth muscles

• Smooth muscles are also called the visceral muscles, because they are located in the visceral tracts such as digestive tracts, blood vessels, reproductory tracts, and the uterine wall.

• Smooth muscles are also called involuntary muscles because they work involuntary, without the coordination from the brain.

• These muscles are affected by the autonomousnerves, namely the sympathetic and parasympathetic nerves


The characteristics of smooth muscles are ;

• The cell has one nucleus.

• The cells are spindle-like with sharp ends.

• The muscles work involuntary, slowly, regularly, and do not wear out easily.


2. Striated muscles• Striated muscles are also called the skeletal

muscles, because these muscles attach and cover the bones that form the body skeleton.

• The striated or skeletal muscles are also called meat.

• Skeletal muscle cells form muscle fibers.

• The muscle fibers form bundles of muscles.

• The bundles of muscles join to form the muscles or meat.


• Muscle cells muscle fibers muscle bundles muscle/meat

• At the end of the striated muscles are the tendons.

• Tendons are the connective tissues that connect the bones and muscles.

• Tendons that are attached to a moving bone are called insertions, while a tendon that are attach to a non-moving bone are called origos


The characteristics of striated muscles are ;

• The cells have many nuclei.

• The cells are cylindrical or tube-like with light and dark areas (striated). The cells are striated because of the existence of muscle proteins called actin and myosin.

• Work voluntary or by the coordination from the brain.


3. Cardiac muscles• The cardiac muscles are special.

• The cardiac muscles have astructure similar to the striated muscles, but their working procedure is similar to the smooth muscles.

• The cardiac muscles that construct the heart wall work for a human lifetime.

• When we are working, taking a rest, sleeping, or even when we pass out the cardiac muscles keep on working


The characteristics of cardiac muscles are ;

•The cells are striated with many branches, they have one nuclei located in the middle of the cells

•The cardiac muscles work involuntary, but are controlled by the autonomous nerves (sympathetic and parasympathetic nerves)


How Muscles Work• Muscles will contract if they receive stimuli from the

nerves.

• Contracted muscles will appear to be bigger, shorter, and harder.

• If muscles contract, the bones where the muscles are joined will be pulled by the muscles so the joints move.

• In conclusion, body movement involves muscles, bones, joints, and nerves.


•To bend the lower arm and straighten it back, we need 2 muscles, the muscle to bend and the muscle to straighten it.

•The muscles that bend the joints are called the flexors, while the muscles that straighten the joints are called extensors.

•Muscles can not continuously contract, they also need relaxation.

•When 2 or more muscles are involved in bone movement, they can work antagonistically or synergically.


a. Antagonist Muscles•Two or more muscles that work in opposition to one

another are saidnto be antagonist.

•ex. Biceps and triceps that found in the upper arms.

•We need 2 muscles to move the lower arms up and down.

• If the biceps contract, the triceps will extend so the lower arm is lifted.

•On the other hand, if the triceps contract, the biceps will extend so the lower arm will extend.



b. Synergist Muscles

• Two muscles that work in the same way, namely to contract or extend together while moving the bones, are called synergist muscles.

• Ex. Pronator muscles in the lower arms.

• The lower arm consists of 2 pronator muscles, the pronator teres and the pronator quadratus, that work synergistically to lift palm up or down.



BONE AND MUSCLE DISORDERS1. BONE DISORDERS

a. Bone Fractures and Fissures usually happen because of accident

If the broken bone is exposed through the skin, it is called an open fracture.

If the broken bone is still inside the skin and muscles, it is called a closed fracture.

Bone fractures and fissures in children are easier to cure than in adults, because children’s bones are still growing and their bones still contain much periosteum.



b. Rickets Rickets is the leg bones disorder, which leg bones

bend into an O or X shape. This occurs due to vitamin D and calsium

deficiency in food which causes imperfect bone growth and formation.


c. Rheumatoid Arthritis This disease can occur at any age. It is marked by hardened connective tissue that

grows inside the joints. As a consequence, the bones in the joints will

join so they can not be moved.


d. Scoliosis, Lordosis, and Kyphosis

poor sitting posture can cause a bent backbone. if the backbone is curved from side to side, it is

called scoliosis. if the backbone is curved too much at the front is

called lordosis. if the backbone is curved too much at the back is

called kyphosis. in order to prevent backbone disorders, we must

sit with a correct body posture



Posture Comparising


2. Muscle Disorders

a. Cramp Cramps are caused by muscle contraction. Cramps can occur in cold weather or because

the muscles are overused. Cramps can also be a symptom of water and

ion imbalance in tje body.


b. Muscle Pain

commonly among elder people. this diseases may be caused by muscle swelling

in connective tissue. the swollen tissue compreses nerve endings and

blood vessels. as a consequence, the blood flow is blocked and

the pain appears. muscle pain usually recurs during cold weather

and can be overcome by massaging the muscle and self-warming.


c. Polio caused by viral infection in the nerves that

control the movement of the skeleton. people with polio usually become paralyzed.Polio can be prevented by polio immunization for

children under the age of 5.


d. Sprain sprains occur in the joints and ligaments.muscles or tendons can be damaged due to a

strong and sudden pull.


Education

8-2. Movement in humans