Chapter 1: Musculoskeletal System
What is the musculoskeletal system?
The musculoskeletal system is a combination of the muscular system and the human skeleton, portraying
aspects of bones, cartilage, ligaments, joints, tendons, and other connective tissues. Together the features
support your body's weight and help you with movement and posture. The muscles, joints, and Skeleton
all work together to allow the body to have the flexibility and therefore allow our body to perform certain
movements. However, adaptations like more elastin can lead to anomalies with disorders such as
hypermobility. However, these benefits the musculoskeletal system acquires, eventually start to
deteriorate due to medical conditions and aging which can then lead to complications for the joint
movements and other practice of the connective tissues.
Bones
A bone is composed of rigid organs that make up the body's Skeletal system. These bones support your
body through protecting vital organs and tissues from exterior damage, store calcium, fat and produce
blood cells. These can be categorized into long bones, short bones, flat bones, irregular bones, and
sesamoid bones. They work with muscles, tendons, ligaments, and other connective tissues to support the
movement of the body. (Hartley et al.2016)
Muscles
Muscles are composed of thousands of elasticated fibers that support your body to contract and retract
your muscles. These contractions act upon electrical impulses that travel to the sight of muscle fibers
through nerve cells. An organism's muscles control the basic movement required for day-day activities.
These fibers that make up muscles are associated with allowing an organism to do activities that may
require strength by contracting and retracting. (Hartley et al., 2016)
Cartilages
Cartilage is an important structural part of the body. Although it is represented as firm it may be identified
to be softer and flexible than bones, making them stronger and less likely to break. These connective
tissues can be found in joints between bones, end of ribs, between the vertebrae in the spine, ears and nose
and bronchial tubes or airways. (Hartley et al., 2016)
Ligaments
Ligaments are bands of tissues that help connect bones to other bones. They provide structural support
while allowing movement to the joints and body. Ligaments are collagen that provides us with tensile
strength. Elastin present in the ligaments provides flexibility. (Hartley et al., 2016)
Tendons
Tendons are fibrous connective tissue that attaches skeletal muscle to bone. This can be characterized as a
cord of strong flexible tissues. Tendons allow movement with muscle contraction. Tendons are made of
dense connective tissues made of collagen which gives the tendons tensile strength. Unlike ligaments,
tendons have less elastin which limits the flexibility of the connective tissues. (Hartley et al., 2016)
,Joints
Joints, also known as articulations, are the base where two bones meet and move together to allow certain
movements to be performed. The joints provide motion where the intensity of the range of motion is
based on the type of movement. The three major types of joints are:
- Fibrous
Fibrous bones are joined together by dense fibrous tissues, and the gaps filled with tissues are either
wide or narrow unlike other joints where there is a cavity present. Again, unlike other types of joints
like Cartilaginous and synovial joints, the fibrous joints tend to be slightly or immovable in terms of
movements.
- Cartilaginous
Articulating bones are joined together by large amount of cartilage, again there no dense cavity so
therefore, it has a narrow/wide interior to where the tissues meet. These cartilaginous joints allow
more movement than the fibrous joints but less movement than the synovial joints.
- Synovial
The synovial joint has articulating surfaces of bones that have been covered u with dense articular
cartilage and separated by a fluid filled cavity, The joint can be freely moved in any direction around
the axis of the cavity. The synovial joints have double layered capsules the outer tough flexile fibrous
coat and an inner synovial membrane.
Different types of movements at joints
• Flexion/extension
Flexion is bending the joint inwards; this usually occurs when the angle at which the movement is
performed on the joint decreases. An example of flexion would be performing a bicep curl as the angle at
the elbow decreases from 180°. Extension is straightening the joint. This is the opposite of flexion as this
occurs when the angle at which the movement is performed on the joint increases. An example would be
the process from going down during a bicep curl as it goes back to 180°(Types of joint movement - Skeletal
system - OCR - GCSE Physical Education Revision - OCR - BBC Bitesize, 2022).
• Adduction/abduction
Abduction is the movement which pushes you away from the midline. A prime example could be the hip
and shoulder joint heading away from the torso during a jumping jack movement. Adduction again is the
opposite of abduction as the joints move towards the midline of the body. This could be doing the resting
position of a jumping jack movement (Types of joint movement - Skeletal system - OCR - GCSE Physical
Education Revision - OCR - BBC Bitesize, 2022).
• Internal/external
External movement is like abduction as it’s where the joints rotate away the midline but for internal
there’s a vertical movement instead of horizontal. Similarly internal movement is also similar to
adduction as the body movement of the joint is towards the body with only difference being the internal
movement is vertical and not horizontal (Anatomical Movements of the Human Body | Geeky Medics, 2022).
, • Rotation
Rotational movement is where limbs turn around its long axis, like a screwdriver. This can be visualized
during a rational shot in golf as the hips rotate and face a different direction during the movement (Types
of joint movement - Skeletal system - OCR - GCSE Physical Education Revision - OCR - BBC Bitesize, 2022).
• Circumduction
Circumduction movements are when a limb, hand or even fingers move in a circular pattern on an axis,
using a combination of flexion, adduction, extension, and abduction motion. This allows you to swing
your arms around with circular movement at the shoulders (Betts et al., 2022).
Some types of Joints in our body
The 6 major joints in our body include the shoulder, elbow, wrist, hip, knee, and ankle joints. These
following joints all work together with muscles, tendons, ligaments and bones to allow the human body to
perform activities such as movement.
1. Shoulder
The shoulder joint, which is a type of synovial joint, is formed at the articulation of the humerus head and
the glenoid cavity of the scapula. As most synovial joints do, the surfaces are covered with hyaline
cartilage and so do the shoulder joints. This therefore gives the head of the humerus a vast range of
motion. The ligaments in the shoulder joints include many ligaments which work together to give the
shoulder stability and support to prevent it from dislocating. This combination of ligaments allows the
shoulder to perform movements such as, Extension/flexion, abduction/adduction, internal/external
rotation, and circumduction. In addition, the bicep tendon also helps with the mobility and stability of the
joint (Jones, 2019).
2. Elbow
The elbow joint, which is a type of synovial joint, is formed at the articulation between the head of the
radius and the notch of the ulna with the humerus. The synovial fluid that surrounds the articulation
allows the elbow to be flexible and strong. These ligaments work with the bicep tendon that allows the
elbow to perform movements such as flexion/extension (McAdams, 2006).
3. Wrist
The wrist joints, a type of synovial joint is formed from the articulation between the radius and lunate.
The synovial joint in this case is capsulated with dual layers with the fibrous outer layer attaching the
radius, ulna and other crap bones, and the internal layer compromised of synovial membrane, secreted by
synovial fluid which lubricates the joint to allow smooth movements and flexibility. This joint works with
ligaments and wrist tendon allowing movements such as flexion/extension and abduction/adduction
(Carroll, 2009).
4. Hip
The hip joint, which is another example of ball and socket synovial joint, is formed from the articulation
between the pelvis and head of the femur. The joint is formed with ligaments from the intracapsular and
extracapsular groups. The primary function of the hip joint is to stabilize the human body and is often
known as the most weight-bearing joint. The acetabulum is formed to decrease the chances of the head
slipping causing a dislocation. The hip joint works with ligaments and tendons of the femur, which allows
