MOVEMENT AND LOCOMOTION

Movement is a process by which a part or parts of an organism move

without an organism changing its position. Movement includes change in

shape, size and direction of the body parts or part in relation to the body

axis

Locomotion is the movement of the whole body of an organism from one

location or place to another. This means that all forms of locomotion entail

movement, but not all movements are locomotion.

Skeleton is a structure in animals that provide mechanical support to the

body and protects the internal body organs.

Types of skeletons

There are three types of skeletons, namely;

❖ Exoskeleton is a hard covering on the outer side of the body of

arthropods such as insects, crustaceans and arachnids. It is made of

a tough polysaccharide called chitin and it is usually covered by a

water proof outer covering of wax.

❖ Hydrostatic skeleton is a type of skeleton which is provided by

fluid filled cavity under pressure. It acts as skeleton for muscle

movement and hence termed hydrostatic skeleton.

❖ Endoskeleton is the type of skeleton in vertebrates made of a very

hard tissue called bones. Bones are made up of widely spread

living cells into which mineral salts are deposited. The main

mineral salts are calcium phosphate, calcium carbonate and trace

amounts of magnesium phosphate.

Human skeleton

Human skeleton is a rigid frame work of cartilage and bones to which

softer tissues, organs and muscles are attached.

Components of human skeleton

❖ Tendons

These are tough connective tissues which attach muscles to bones.

The tendons are inelastic tissue that firmly holds the muscles to the

bones. Tendon may also attach muscles to body structures such as the

eye ball.

The function of the following component of human skeleton

(i)

Skull is the bone frame work of the head. Skull consists of two

parts namely cranium and visceral skeleton. The cranium is made

up of flat bones joined tightly together to form immovable joints.

It has the following function;

❖ Protects the brain

❖ Protects the olfactory organs

❖ Protects the eyes, middle and inner ear

❖ The cranium possesses a special occipital bone with occipital

condyles which articulate with atlas vertebra to form a joint.

This joint permits the nodding and other movement of the

head

(ii)

Ribs are thin, flat curved bones that form the protective cage

around the organs of the upper. It has the following functions;

❖ They give the chest its shape

❖ They protect the heart, lungs, spleen and kidneys against

injuries and shock.

❖ They help in breathing by expanding to let air in and

contracting to let air out.

(iii)

Vertebral column is the series of 33 bones called vertebrae. It has

the following functions;

❖ It allows human beings to stand upright and maintain

their balance

❖ It supports the head and arms

❖ Protects the spinal cord which mainly controls most

body functions

❖ It provides the site for attachment for the ribs and

many muscles.

Vertebral column has five types of vertebrae.

(i)

The cervical vertebrae these are short bones that are found in

the neck region. There are seven vertebrae that make the

skeleton of the neck region. The first two cervical vertebrae

are called atlas and axis respectively

Adaptation of cervical vertebrae

❖ The cervical vertebrae are branched to increase surface

area for muscle attachment.

❖ They have spinal canal which houses and protects the

spinal cord and nerves.

Functions of cervical vertebrae

❖ Supports the skull or weight of the head

❖ They allow free rotation/nodding of the skull on vertebral

column

❖ They provide attachment for neck muscles

Figure; cervical vertebrae

(ii)

The thoracic vertebrae the twelve thoracic vertebrae

together with the ribs and sternum form the thoracic cage

which protect the heart, lungs and some blood vessels against

injuries. In addition, the thoracic vertebrae play a major role in

breathing which is enhanced by movement of the intercostal

muscles.

Figure; 7.1: the thoracic vertebrae

Adaptation of thoracic vertebrae

❖ They have long neural spine that increases surface area for

muscle attachment.

❖ They also have spinal canal for the passage of spinal cord

❖ They possess facets which facilitate articulation of bones.

Facets are small rounded surfaces on the thoracic vertebrae

on which the ribs are attached.

(iii)

The lumbar vertebrae these are found in the lumbar or abdominal

region. Lumbar region is the lower back region of the vertebral

column. There are five bones in humans that make lumbar

vertebrae. They allow bending movements and rotation of the

trunk. In order to allow this movement large number of muscles

are attached in this region.

Adaptations of lumbar vertebrae

❖ They have long transverse processes that increase surface

area for abdominal muscles attachment

❖ They also have extra processes which increase surface area

for attachment of muscles, the neural spine bone which is

short and broader for muscle attachment and support. They

also have large and thick centrum for support.

Figure; 7.2: the lumbar vertebrae

(iv)

The sacral vertebrae. These are the vertebrae that are found

in the sacral region or pelvic region of the vertebral column.

They are fussed together to form a broader structure called

sacrum. Sacrum provides large surface area for muscle

attachment

Figure; sacral vertebrae

Adaptation of sacral vertebrae

❖ They have a sacrum which gives support and transmits the

weight of the stationary state to the rest of the body.

❖ They also have numerous posterior foramens or canals

which facilitate the passage of spine nerves.

❖ Their base is broader in order to provides large surface area

for muscle attachment.

(v)

Caudal vertebrae, these are the vertebrae found in the tail

region. Depending on the length of the tail, the caudal

vertebrae bone varies greatly from one mammal to another.

(vi)

Scapula is a flat triangular bone which covers a number of

anterior ribs. At one end, the scapula has concave depression

known as glenoid cavity which articulates with the head of

humerus to form a ball and socket joint

Adaptation of scapula to their function

❖ They have long spine projections called acromion and

metacromion. These projections are used in the

attachment of muscles

❖ Also it has a broad and a flattened surface. These two

surfaces provide large surface area for muscle

attachment and allow the upper limbs to move in many

planes and angles

Figure; 7.3 Scapula

Function of Scapula

❖ Provide site for attachment of muscles that move the arms

Clavicles are collar bones.

Functions of Clavicles

❖ They provide sites for muscle attachment

❖ They aid in movement of the arm

The humerus is the skeleton in the upper arm. It’s rounded which

articulates with the glenoid cavity.

Figure; 7.4: the humerus

Function of humerus

❖ Attachments of biceps and triceps muscles

Adaptations of the humerus to its function include

❖ The presence of rounded head that fits into the glenoid cavity of

the scapula. This allows for greater flexibility of movement of the

arm. Humerus articulates with the fore arm at the elbow joint.

❖ It has trochlea at the lower ends which articulates with forearm(at

the ulna bone) that allows movement in one plane.

❖ Also, it has capitulum which articulates with the head of the

radius.

❖ The humerus is long to provide large surface area for attachment of

biceps and triceps muscles.

Radius and ulna, these are bone found in the fore arm. Radius is on the

side of the thumb while ulna is on the side of small finger

Function of Radius and ulna

❖ Supports the carpals, metacarpals and phalanges

❖ They provide site for attachment of forearm

Pectoral girdle (shoulder girdle) this is a set of bones in the appendicular

skeleton that connect to the arm on each side. It consists of two dorsal

shoulder blades, the scapulae (singular: scapula) and a pair of ventral

collar bones called clavicles. They are not fussed to axial skeleton but are

flexible and attached to the vertebral column by ligaments and muscles.

This arrangement enables the girdle