UNIT 8 : Physiology of Human Body Systems
ASSIGNMENT
Learning aim A: Understand the impact of disorders of the musculoskeletal system and
their associated corrective treatments
General outline of the musculoskeletal system
The musculoskeletal system is comprised of the skeleton, muscles, cartilage, tendons,
ligaments, joints and other connective tissue that binds the body. The skeleton is the main
framework of the body comprised of 206 bones and divided into the axial skeleton and the
appendicular skeleton. The axial skeleton includes all the bones present in the torso and
head, it consists of 80 bones in six categories: the skull, the ossicles of the middle ear, the
hyoid bone, the rib cage, sternum and the vertebral column. The appendicular skeleton
includes all the bones present in the limbs, pectoral girdle, and pelvic girdle, it totals 126
bones of the human body.
Types of bone
The bones of the skeletal system are classified into 5 types: long, short, flat, irregular and
sesamoid. Long bones form the limbs and are cylinders of hard bone with marrow inside that
narrow in the middle and have ‘heads’ at each end. The wide ends provide more solidity,
increased movement and greater leverage to the joints, examples of long bones include the
humerus, femur and radius. Short bones are about as long as they are wide, they provide
stability and support as well as limited movement. They are only found in the wrist and ankle
joints in the form of the 8 carpal bones and 7 tarsal bones. Flat bones provide protection to
the internal organs and provide a large surface area for muscle attachment, they are formed
of two layers of hard bone with a spongy layer in between. Examples of flat bones include:
cranium, scapula, ribs and sternum which all protect the vital organs of the body. Irregular
bones have various forms and structures eg. they could be very dense or air filled, they also
aid in the protection of internal organs due to their unique shape and structure. Examples of
irregular bones include: the vertebrae, facial bones and bones of the hip, the vertebral bones
are small and dense in structure do to the weight bearing function and the protection of the
spinal cord, whereas the facial bones are very light due to being superficial and only
providing shape. Sesamoid bones are small bones in the tendons or located where there is a
lot of pressure eg- the patella, they protect the tendons from stress and wear. The patellas
main function is protection of the vulnerable knee joint beneath as the joint is stressed
everyday and especially vulnerable in sport activities.
Types of joint [2]
The joints of the skeletal system are classified
into 3 main types: fibrous, cartilaginous and
synovial. Fibrous joints connect bones with
fibrous tissue which means there is no joint
cavity and they are immovable or slightly
movable. Examples of these are the joints
between the bones of the skull called sutures.
Cartilaginous joints are found between
articulating bones are joined with cartilage,
have no joint capsule and are only slightly
moveable. An example of a cartilaginous joint are the symphyses, where articulating bones
are covered with hyaline cartilage and sandwiched between fibrous cartilage that is
,compressible and can act as a shock absorber eg- the intervertebral discs. The final type is
the synovial joint which is the most abundant of the three and found in the appendicular
skeleton. These joints are where the articulating surfaces of the bones are covered by
articular cartilage and separated by a fluid filled joint cavity. The joint cavity is a double
layered capsule that contains synovial fluid and hyaluronic acid to reduce friction at a moving
joint. Furthermore, there are 6 types of synovial joint:
Joint example Movement that occurs example
Ball and socket - Comprised of a ball-like end Shoulder
of one bone fitting into a Hip
complementary hollow of
another
- Allows the greatest range of
[1] movement at a joint
Hinge - comprised of one slightly Elbow
rounded end of a bone meeting Knee
the slightly hollowed end of
another, this allows one bone
to move whilst the other is
stationary
- it works like a lever allowing
movement of 180°
Condyloid - consists of an oval-shaped Wrist
end of one bone fitting into an fingers
oval-shaped hollow of another
bone
- allows angular movement
along two axes
saddle - made of concave and convex thumb
portions that fit together
- it allows angular movement
but with a greater range of
motion
pivot - consist of the rounded end of Atlas and axis in
one bone fitting into a ring the neck
formed by the other bone wrist
which allows one bone to
rotate around the other
- allows rotational movement
Gliding (plane) - have bones with articulating Wrist
surfaces that are flat or slightly Ankle
curved faces which allows one Vertebrae
bone to slide over another
- allows flexing and extending
but a limited range of
movement
Movement that occurs at joints
, Type of movement description example
Flexion Decreasing the angle of a When performing a bicep
joint curl
Bending the joint
Extension Increasing the angle of a joint
Straightening the joint
Abduction Moving away from the centre When star jumping
line of the body
Adduction Moving towards the centreline
of the body
Dorsiflexion Pointing of the toes upwards Pointing and flexing your
toes
Plantarflexion Pointing of the toes
downwards
Elevation Moving a body part in the Raising and lowering your
superior direction (upwards) shoulders
Depression Moving a body part in the
inferior direction (downwards)
Eversion Rotating the ankle so the sole When your ankles roll
is facing away from the other inwards/outwards when
walking on uneven ground
Inversion Rotating the ankle so the sole
is facing towards the other
Lateral rotation Rotating a limb away from the When you turn out your
centre line of the body knees
Medial rotation Rotating a limb towards the
centre line of the body
pronation Rotating forearm so the palm When you turn a doorknob
faces down
supination Rotating forearm so the palm
faces up
retraction Moving the shoulder back Doing a push up
protraction Moving the shoulder forward
Lateral flexion Bending the spine from side When you move your neck
to side away from the centre from side to side
line
circumduction Make a 360° movement Rolling your shoulder
Bone structure
Bone tissue consists of compact (cortical) bone and
spongy (cancellous) bone. Compact bone is made of
haversian systems which are structural units composed
