Musculoskeletal System
Musculoskeletal System
The musculoskeletal system is composed of three different parts:
Bones
Joints
Muscles
Bones
Our bones are hard solid organ that forms part of the skeleton.
Our bodies can be broken down into 3 sections
Head
Trunk
Limbs
Bones
Bones are mostly made up of bone cells that are continuously renewed.
There are two types of bone
Spongy bone contains many small cavities
Compact bone is much more dense
Bones
Bones come in a variety of shapes and sizes.
Bones can be divided into 4 categories.
Long bones
Short bones
Flat bones
Irregular bones
Long Bones
Longer than they are wide
They have a long thin body, called the diaphysis, and two rounded extremities, called epiphyses.
They are mainly compact bone.
The center contains bone marrow, a soft, fatty substance and blood vessels.
These bones are mainly found in the limbs.
Long Bones
Short Bones
Generally cubic.
Mainly composed of spongy bone
Generally found in the wrists and heels
Short Bones
Flat Bones
Thin, flat and generally curved.
They’re made up of two layers of compact bones separated by a small layer of spongy tissue.
These are found in the skull, ribs, sternum and scapula (Shoulder blade)
Flat Bones
Irregular Bones
These bones do not fit into any other category
They have irregular shapes.
They are found mainly in the spine
Irregular Bones
Bones
Bones
Function of Bones
Support Bones form a rigid structure that makes up the framework of
our bodies. They also provide an anchor for organs and muscles.
Protection Bones protect our internal organs. Rib cage protects the lungs
and heart. Skull protects the brain.
Movement Bones act as levers during muscle movement.
Function
Storage
Internal cavities of the bones store fat. Bony tissue stores minerals, such as calcium and phosphorus.
Production of blood cells
The bone marrow found in the bones produces the formed elements of the blood
Red blood cells, white blood cells and platelets.
Joint
A joint is the junction between two or more bones.
Joints are essential as they allow movement.
Almost all bones have at least one joint.
Joints are lined with cartilage to minimize wear on the bones.
Types of Joints
There are 3 types of joints in our bodies
Fixed
These joints do not move. They are the type of joints which are in our skull.
Semi-movable
These are joints with only a small range of motion. The spine is a series of these joints.
Fixed Joints
Semi-Movable
Types of Joints
Freely movable joint
Some joints can only move in one direction
Ex Elbow and Knees
Some joints have a complete range of motion
Hips and Shoulders
Movable Joints
Movable Joints
Types of Joints
Muscles
Muscles have the ability to contract causing our bodies or our internal organs to move.
Muscles have 4 functions Movement
Posture maintenance
Joint stabilization
Heat release
Movement
Muscle movement can either be voluntary or involuntary.
Voluntary movements are movements as raising your arm or moving your legs.
Examples of involuntary movements are peristalsis and your heart beating.
Posture, Joints and Heat
When we aren’t moving, our muscles are still contracting and releasing to maintain our posture.
Muscles are also used to stabilize your joints. Some joints need muscles to stay in place.
Most (75%) of the energy used by muscles are transformed into heat. The heat lost helps maintain our body’s temperature.
Types of Muscles
There are 3 different types of muscles
Skeletal Muscles
Also known as striated)
Smooth muscles
Cardiac Muscles
Skeletal Muscles
Skeletal muscles are the only voluntary muscles in our bodies.
They are attached to bones.
As they contract, they move the bones.
Skeletal muscles have relatively low endurance and must rest after being exerted.
Skeletal Muscles
Skeletal muscles are made up of several muscle fibers gathered into bundles.
Muscles are held together with connective tissue and is connected to the bone through tendons.
Skeletal muscles also have antagonistic muscles.
This means that they pull in opposite directions to move a joint in opposite directions Ex Bicep and Tricep
Skeletal Muscles
Antagonistic Muscles
Smooth Muscles
Smooth muscles make up the walls of certain internal organs.
Ex Uterus, stomach, uterus
They move involuntarily.
They move much slower but tirelessly.
Smooth Muscles
Cardiac Muscle
Cardiac muscle is the muscle that makes up the heart.
It is an involuntary muscle with a structure more similar to skeletal muscle.
It has great strength and endurance.
This type of muscle is branched.
Cardiac Muscle
Bones
The adult human body has 206 bones.
The femur, or thighbone, is the longest and strongest bone of the human skeleton.
There are 26 bones in the human foot.
The human hand, including the wrist, contains 54 bones.
Bones
We’re going to learning about the bones in the arms, legs, head and trunk.
We won’t be learning all of the bones.
You will be given a diagram on the test where you’ll have to identify them.
Bones of the Skull
Bones of the Skull
For the skull, all you are responsible to know is:
The skull
Mandible (jaw)
The skull is composed of 22 different bones, but most fuse together by the age of 2.
Bones in the Spine
Bones of the Spine
The spine is composed of 33 bones in 5 sections
From top to bottom, the sections are:
Cervical
Thoracic
Lumbar
Sacrum
Coccyx
Bones of the Arm and Hand
Bones of the Arm and Hand
There are 3 bones in the arm
Humerus – Upper arm
Ulna – Bone from the elbow to pinky
Radius – Bone from the elbow to thumb
The wrist and hand are in 3 sections
Carpals
Metacarpals
Phalanges
Bones of the Leg and Foot
Bones of the Leg and Foot
The legs have 4 bones
Femur – Thigh bone Tibia – Shin bone Fibula – A bone in the lower leg Patella – Kneecap
The foot is similar to the hand
Tarsals Metatarsals Phalanges
The link between the femur and spine is the pelvis.
Ribs
Scapula
Ribs and Scapula
You have 12 sets of ribs Some individuals can have 11 or 13 ribs.
Ribs are classified into 3 categories True ribs are connected directly to the sternum.
False ribs are connected to the sternum through another rib
Floating ribs do not connect to the sternum
The sternum is the bone where the ribs meet.
The scapula is the shoulder blade.
Muscles
You are born with every muscle fiber that you’ll ever have.
If all of your muscles could pull in one direction, they would be capable of pulling 25 tons.
There are around 650 muscles in the body.
Muscles
Muscles
The muscles you will be responsible for are:
Bicep
Triceps
Deltoid
Pectoral
Quadriceps
Glutes
Anterior tibialis
Calves
Hamstrings
Obliques
Abdominals
Erector Spinae
Latissimus Dorsi
Trapezius
Muscles in the Arm
Shoulder and Chest
Leg Muscles
Core Muscles
Back Muscles
