Introduction to Movement and Locomotion

Movement is one of the things that differentiates a living thing from a

non- living thing. When we speak about locomotion and movement,

we often use one for the other. But, it is important to understand the

difference between the two in relation to living things.

Locomotion and Movement

Movement is when the living organism moves a body part or parts to

bring without a change in the position of the organisms. Locomotion

is when the movement of a part of the body leads to change in the

position and location of the organism. Both of these are brought about

by the joint efforts of the skeletal and muscular systems. Movement is

seen in both vertebrates and invertebrates.

Browse more Topics under Locomotion And Movement

● Muscle

● Skeletal System

● Joints

● Disorders of Muscular and Skeletal System

Types of Movements

When we talk about locomotion and movement, there are three types

of movements:

● Amoeboid movement is brought about by pseudopodia which

are appendages which moves with movement of protoplasm

within a cell.

● Ciliary movement is brought about by appendages called as

cilia which hair-like extensions of the epithelium. Both these

kinds of movements are seen with cells of the lymphatic

system.

● Muscular movement is a more complex movement which is

brought about by the musculoskeletal system. This type of

movement is seen in the higher vertebrates. To understand

more about the movements brought about by the

musculoskeletal system, we need to understand the types of

muscles, and joints.

Types of Muscles

Muscles found in higher vertebrates are of three types:

● Striated or skeletal muscles

● Unstriated or smooth muscles

● Cardiac muscles

(Source: Blogspot)

Striated or Skeletal Muscles

These muscles are voluntary in nature which means their movement is

under the control of our will. They are mainly responsible for bringing

about the movement of posture and location of the organism. They are

called striated muscles due to the presence of striations present on

them when seen under the microscope.

Unstriated or Smooth Muscles

These muscles are involuntary in nature which means their movement

is not under the control of our will. When seen under the microscope,

they do not have any striations on them. These muscles are found in

the digestive tract and reproductive system.

Cardiac Muscles

These muscles are specialized muscles that are found only in the heart.

They are involuntary muscles which have striations on them. They

have the property to contract and relax in a rhythmic manner.

Skeletal System

The skeletal system is made up of bones and cartilages. There are a

total of 206 bones in the body. They are divided into the Axial

skeleton and the appendicular skeleton.

The axial skeleton consists of bones that are found towards the center

of the body including the skull, the vertebrae, and the sternum. The

appendicular skeleton consists of bones that are found in the

extremities.

Joints

They form an integral portion of the locomotive apparatus. A joint is a

name given to two or more bones that articulate with each other to

bring about a movement. Depending on the type of movement they

allow, joints can be of three types: Fixed, slightly moveable and

moveable joints.

Solved Example for You

Q: What kind of muscles are found in the reproductive system?

a. Cardiac Muscles

b. Striated Muscles

c. Skeletal Muscles

d. Smooth Muscles

Sol: Correct answer is (d) Smooth muscles

Reproductive system has smooth or involuntary muscles that are not

under the control of our will.

Muscle

The muscular system along with the skeletal system forms the

skeletomuscular system that is responsible for the movement and

locomotion in vertebrates. The unit of the muscular system is called a

muscle. Muscles are made up of proteins and fibres and form the

major component of the body weight.

General Structure of a Muscle

(Source: SEER Training)

Each muscle (mainly skeletal) has an outer covering called the

perimysium. It covers and protects the muscle fibres. Around the

entire structure lies the fibrous layer of the epimysium which protects

the entire muscle. Each bundle of fibre is known as a ‘fascicle’. And

each fibre is covered by the endomysium.

Browse more Topics under Locomotion And Movement

● Introduction to Locomotion and Movement

● Skeletal System

● Joints

● Disorders of Muscular and Skeletal System

Types of Muscles

Skeletal Muscles

These are found throughout the body where conscious movements are

performed. They are attached to bones through a structure called as

the tendon. We find them around joints so that they bring about

movements in that part of the body. For this reason, skeletal muscles

are also known as voluntary muscles.

The skeletal muscles are very specialized in their structure and

function. Each is made up of many fibres. Each skeletal muscle fibre

is made up myofibrils which are made up of smaller units called as the

sarcomere. The cell membrane of these fibres is known as the

sarcolemma. These muscles are also rich in mitochondria which are

required to help each muscle fibre cell perform the activity of the

muscle. From the sarcolemma, there are tubular extensions known as

the T- tubules which conduct electrochemical impulses from the outer

membranes to the centre of the muscles. Muscles are made up of

proteins- actin, myosin, and troponin.

Skeletal muscles are named in different ways: Some are named

depending on their location, some depending on their origin or

insertion, some based on the number of origins of a single muscle and

others on basis of their direction and function.

Smooth Muscles

These are also called as involuntary muscles as they are not under the

control of our will. They are found in the visceral organs and so are

also known as visceral muscles. They do not have striations when

viewed under the microscope like the skeletal muscles and so they are

called as smooth muscles. Smooth muscles are found in the digestive

system, reproductive system, urinary system and are also found in the

blood vessels.

Cardiac Muscles

These are striated involuntary muscles that are specialized to perform

rhythmic contraction and relaxation and are found only in the heart.

The cells of the cardiac muscles are branched and connected to

adjacent cells via connections known as the intercalated disc. This

branching along with the striations make these muscles strong and

resilient to withstand demanding activity from the entire body. The

branching also helps in quick transmission of signals to enable the

heart to respond fast.

Solved Example for You

Q: What is the covering of the individual muscle fibrils called?

a. Endomysium

b. Epimysium

c. Fascia

d. Perimysium

Sol: The correct answer is (a) Endomysium

Endomysium covers the individual muscle fibres. Epimysium covers

the entire muscle while the perimysium covers the muscle fibre

bundles.

Skeletal System

Did you know that newborn babies have around 305 bones! A baby’s

skeleton is mostly made up of cartilage. As it grows older cartilage

undergoes ossification to form a complete skeletal system, having 206

bones. Let us learn about a human skeletal system.

Parts of the Skeletal System

(Source: Britannica)

The skeletal system is made up of bones and cartilage. There are two

types of connective tissues called tendons and ligaments that are also

considered a part of the system. Ligaments connect bones to bones

whereas tendons connect bones to muscles.

The two main parts of the skeletal system, as mentioned above, are

bones and cartilage.

Bones

There are 206 bones in the body which form more than 200 joints with

each other. They are classified into two broad categories based on

location:

● Axial skeleton: These bones are found towards the midline of

the body and include the skull, the rib cage, and the vertebral

column.

● The appendicular skeleton: These bones are found in the

appendages such as arms, legs fingers, and toes.

Bones can be classified into four types based on their shape:

● Long Bones -They are long and slender bones found generally

in the limbs. ex. humerus, femur.

● Short Bones: They are short bones which are smaller in size

and are found in the carpals and tarsals.

● Flat Bones: they are thin and flat in nature and not all of them

are completely flat. They provide surface area for muscle

attachment. Ex: scapula, sternum

● Irregular Bones: These bones do not have specific shapes and

therefore cannot be put into any other group. Ex: vertebrae

Structure of a Bone

Lets now see what the structure of an individual bone looks like.

(Source: http://lyceum.algonquincollege.com/)

Each bone tissue is made up of two types of osseous tissue: compact

bone and spongy bone.

Compact bone is hard and compact in nature and always found

towards the outside of the bone whereas the spongy bone which is

softer and more porous is found towards the centre. The function of

each bone determines the ratio in which these two types of tissues

exist within it.

The connective tissue that is found on the outside of the bone is

known as the periosteum. The periosteum is made up of cellular and

fibrous tissue and plays a crucial role in the attachment to muscles and

joints as it is this layer which contains tendon and ligament

attachments. The endosteum is the connective tissue layer which lines

the marrow cavity.

Browse more Topics under Locomotion And Movement

● Introduction to Locomotion and Movement

● Muscle

● Skeletal System

● Joints

● Disorders of Muscular and Skeletal System

The shaft of a bone is known as the diaphysis and the swollen end is

called the epiphysis. The epiphyseal line demarcates the two parts. It

is the diaphysis which houses the marrow cavity which is majorly

composed of loose connective tissue and is responsible for producing

blood cells.

The cells that form bone matrix are known as osteoblasts and the

mature cells of the bone are called osteocytes. There is a special type

of cells that help remove bone matrix and are found during bone

remodelling known as osteoclasts. These are gigantic cells and are

always found on the side of the bone where the matrix is being eaten

away during growth and remodelling.

The matrix in a bone tissue is made up of two components: the organic

part that contains fibres whereas the inorganic part consists of the

minerals(hydroxyapatite).

Learn more about Disorders of Muscular and Skeletal Systems.

Cartilage

Cartilage is the second component of the skeletal system. It is made up

of fibres that are embedded in connective tissue or ground substance.

Cartilage consists of two types of fibres: Collagen and elastin fibres.

The cells that form cartilage are known as chondroblasts and the

mature cells of the cartilage are known as chondrocytes.

The chondrocytes lie in lacunae in the matrix. The outer layer of a

cartilage is known as the perichondrium. Unlike the bone, cartilage is

avascular which means that it contains no blood supply. However, the

perichondrium contains blood supply. There are 3 types of cartilages

namely Hyaline cartilage, elastic cartilage, and fibrocartilage.

● Hyaline cartilage– the most abundant of the three cartilages and

functions to help surfaces slide over one another. Example:

found in the respiratory system.

● Fibrocartilage– This cartilage is tough and its main function is

to provide support and strength to structures. Example: found

in healing tissue during bone repair(callus)

● Elastic cartilage– This cartilage is abundant in elastic fibres and

functions to maintain the shape of the area it is present in.

Example: found in the middle ear.

Functions of the Skeletal System

● The main function of the skeletal system is that it provides a

framework to the body and provides shape.

● Along with the muscular system, the skeletal system helps in

the movement of the body parts of the body and locomotion of

the body.

● The skeletal system is hard and so forms a protective layer for

the softer, more delicate organs from any form of injury. The

rib cage protects the heart, lungs and visceral organs, the brain

is protected by the skull etc.

● It is the growth and development of bones that provides the

height and width of an individual.

● The centre of the bone consists of the bone marrow which

produces blood cells and therefore hemopoietic in nature.

Solved Example for You

Q: The connective tissue on the outer surface of a bone is called as?

a. Endosteum

b. Epiosteum

c. Perichondrium

d. Periosteum

Sol: The correct answer is (d) Periosteum

The connective tissue layer on the outer surface of a bone is known as

the periosteum. The connective tissue layer that is found lining the

marrow cavity in a bone is known as the endosteum. Perichondrium is

the outer layer of a cartilage. Epiosteum is not a structure found in

either cartilage or bone.

Joints

Joints aka articular surface can be defined as a point where two or

more bones are connected in a human skeletal system. Cartilage is a

type of tissue which keeps two adjacent bones to come in contact (or

articulate) with each other. 3 Types of joints are Synovial Joints,

Fibrous Joints, and Cartilaginous Joints. Joints help in bringing about

movements in different parts of the body. Let us see the classification

of joints and anatomy of different types of joints. 

Classification of Joints

Joints can be classified in different ways depending on:

a. The amount of mobility permitted by the joints

b. Type of tissue connecting the bones

Each of these types can be further subdivided. Let’s look at each

classification individually.

A] The amount of mobility permitted by the joint

(Source: TeachPE.com)

Depending on the degree of mobility permitted by the joint, we can

classify them as:

● Fixed Joint or Synarthroses– The word ‘syn-‘ tells us that the

bones are fused and therefore permit minimal or no movement.

These joints are fibrous joints which means that the binding

tissue between two bones is ‘fibrous’ in nature. Example of a

fixed joint is the sutures between skull bones.

● Slightly Movable Joint or Amphiarthroses– This joint permits

slight mobility that is more than what is seen in a fixed joint.

The binding tissue in this type of joint is cartilaginous in

nature. Example of a slightly moveable joint is those found

between intervertebral discs.

● Freely Moveable Joint or Synovial Joints– These joints permit

maximum movement between the bones involved. They are

also called as ‘diarthroses’ and are further classified into 6

types depending on the kind of movements possible.

Types of Synovial Joints

(Source: opencurriculum.org)

● Ball and socket joint– This kind of joint involves two bones.

One of the bone has a large rounded end which fits into a

cup-like socket of the other bone. This kind of joint is generally

found in large bones such as the shoulder joint and hip joint. A

ball and socket joint provides the greatest degree of movement

among different kinds of joints including rotation, flexion,

extension, abduction, and adduction.

● Hinge joint-This joint is said to be a very simple joint that

allows movement only in one axis. It allows only two kinds of

movements- flexion and extension. Example of this joint is the

joints found between in the elbow and knee.

● Pivot joint– This type of joint allows rotation along one axis

only. A common example of this type of joint is the

atlantooccipital joint in the neck.

● Ellipsoid/gliding joint– This joint is very similar to the ball and

socket joint but without rotation. It allows movements only in

two axes. Example of this is the wrist joint.

● Saddle joint– It is similar to an ellipsoid joint which involves

two bones- one of the bones has a convex surface while the

other has a concave surface. The convex surface of one bone

articulates with the concave of the other to allow limited

rotational movement. A very classic example of this kind of a

joint is the carpo-metacarpal joint in the thumb.

B] Type of Tissue Connecting the Bones

Based on the type of tissue connecting the bones, we can classify

joints as:

● Fibrous– The tissue connecting the two bones is fibrous in

nature

● Cartilaginous– Cartilage forms the connecting tissue between

two or more bones

● Synovial– The two bones form a synovial cavity with synovial

fluid which forms the connecting tissue

Apart from movement and locomotion, joints also help stabilize the

different parts of the body.

Solved Example for You

Q: What kind of a joint is in the wrist?

a. Saddle Joint

b. Pivot Joint

c. Gliding Joint

d. Ball and Socket Joint

Sol: The correct answer is (c) Gliding Joint

This joint allows movement only in two axes and is found in the wrist

joint between the radius, scaphoid and lunate bones.