VCE Physical Education Unit TwoThe Musculoskeletal System Traralgon College
Skeletal System Overview• A newborn baby has 305 bones.• As a human develops to the age of 25, some bones fuse together to obtain maximum strength.• The average human skeleton has 206 bones.• Largest bones – Thigh (Femur) and the Upper Arm (Humerus).• Smallest bones – Middle Ear (Maleus, Incus and Stapes).• All bones are living organs, which contain living (cells) and non-living (mineral) materials.
Functions of Bones• Bones have 5 major functions: Support – Provide support for tendons and ligaments and the framework for body shape. Protection – The cranium protects your brain, the ribs and sternum protect your internal organs such as heart and lungs. Movement – Bones work with muscles to produce movement. Muscles are attached to the skeleton and work by contracting (shortening) and pulling on bones. Storage – Bones are the site for storage and release of excess minerals. These are released as the body requires. Blood production – Some bones (ribs, vertebrae, humerus and femur) contain red bone marrow. This makes red cells, white cells and platelets for blood.
Bone Classifications – Long Bones• Long bones consist of a long shaft covered by hard bone around a hollow centre which contains yellow marrow.• The two ends contain spongy bone and red marrow.• These bones are light but very strong, and are major weight-bearing bones of the body.
Bone Classifications – Short Bones• Short bones are chunky, compact bones that are strong and reinforced by thickening of the bone tissue.• They contain spongy bone and allow a variety of movements at joints.
Bone Classifications – Flat Bones• Flat bones are made up of two strong layers of compact bone, joined by a layer of spongy bone.• These bones give protection to organs beneath them and allow for large areas of muscle attachment.
Bone Classifications – Irregular Bones • Irregular bones are made up of a thin layer of compact bone containing a mass of spongy bone. • Irregular bones are reinforced where extra strength is needed.
Division of the Skeleton• The skeleton has two main parts: – Axial Skeleton and the Appendicular Skeleton.• The Axial Skeleton includes the skull, the vertebral column (spine, sacrum, and coccyx), the sternum, and the ribs. Its components are aligned along the long axis of the body.• The Appendicular Skeleton includes the bones of the upper extremities (arms, forearms, and hands), the pectoral (shoulder) girdle, the pelvic (hip) girdle, and the bones of the lower extremities (thigh, knee, leg, and foot). Its components are outside the body main axis.
Muscular System Overview• There are over 600 muscles in the human body.• There size ranges from one that make the hairs on your arms stand up to the large muscles in your upper leg.• Without muscles our hearts wouldn’t beat, we couldn’t breathe, digest food, walk, talk or reproduce.
Functions of Muscles• Muscles have 3 major functions: Movement – Most of our muscles are under voluntary control such as skeletal muscles responsible for moving our bones. Some muscles we do not consciously control such as muscles of the eye and heart. Posture – Muscles make continuous changes to our posture allowing for the constant pull (gravity) placed on our body. Body Heat – The energy muscles require to contract produces movement and releases heat that helps maintain body temperature.
Types of Muscles• There are 3 types of muscles tissue in our body: Skeletal Muscle – Muscles attached to our bones under voluntary control. Smooth Muscle – Muscles found internally in blood vessels and walls of the intestine and stomach under involuntary control. Cardiac Muscle – Muscles that make up the walls of the heart which are under involuntary control.
The Muscular System TableLetter Colour Common Name Scientific Name Location Action (Where it is on the body) (What is does) A Delts Deltoid Shoulder Lifts arm B Pecs Pectorals Chest Pulls shoulders forward C Traps Trapezius Between neck and shoulder Lifts (shrugs) shoulders D Biceps Biceps Front of upper arm Bends elbow E Triceps Triceps Back of upper arm Straighten elbow F Rhomboids Rhomboids Between shoulders Pulls shoulders back G Abs Rectus Abdominis Stomach Bends trunk forward H Glutes Gluteus Maximus Buttocks Straightens hip I Sartorius Sartorius Thigh Rotate leg J Hamstrings Biceps Femoris Back of thigh Bends knee K Soleus Soleus Front of leg Flexes ankle L Lats Latissimus Dorsi Underarms Pulls shoulders down M Quads Quadriceps Front of thigh Straightens knee N Calf Gastrocnemius Behind shin Straightens ankle O Sternomastoid Sternomastoid Neck Turns head
Anatomical Terms• To avoid confusion when describing various body movements and positions of the musculoskeletal system, standard anatomical terminology is used.• Medial Direction – toward the midline of the body• Lateral Direction – toward the side of the body.
Anatomical Terms• Superficial Direction – close to the surface of the body.• Deep Position – any feature that is further away from the surface of the body. Example – the ribs are “Superficial” and the heart is “deep”.• Proximal and Distal Positions – refers to the limbs. Proximal means “closer” to where the limb is attached. Distal means further from the point of attachment – the fingers are distal to the shoulder.• Superior – a position towards the head.• Inferior – a position away from the head.
Types of Joints• Joints occur when 2 or more bones meet. They are held by ligaments (thick cords of stringy tissue).• Joints are essential for movement, as muscles need to pass over them for contraction to occur.• The type of joint will determine how moveable the bones are. There are three main types of joints:• Fibrous – immovable.• Cartilaginous – partially moveable.• Synovial – freely moveable.• Copy table 11.1 on page 268.
Types of Movement• Flexion – the angle of the joint is decreased.• Extension – the angle of the joint is increased.• Adduction – a body part is moved towards the middle of the body.• Abduction – a body part is moved from the midline of the body.• Rotation – a body part is moved either outwards or inwards around its long axis.• Circumduction – a body part is moved in a cone shape.
Types of Movement• Supination – a rotation of the forearm which causes the palm of the hand to face upwards.• Pronation – a rotation of the forearm which causes the palm of the hand to face downwards.• Eversion – a rotation of the sole of the foot outwards.• Inversion – a rotation of the sole of the foot inwards.• Refer to Figure 11.22 to 11.26 on page 270 and 271.
Types of Muscle Fibres• Skeletal muscle is made up of two basic fibre types:• Slow-twitch Fibres (Type 1) and• Fast-twitch Fibres (Type 2).
Slow-twitch Muscle Fibres• Colour = Red• Contract slowly over a longer period of time.• Best suited to aerobic and endurance activities.• Exerts less force and can contract repeatedly.
Fast-twitch Muscle Fibres• Colour = White• Contract rapidly over a shorter period of time.• Best suited to anaerobic and high intensity activities.• Exerts great force in bursts of power and speed.
Athletic Comparisons Sport % slow twitch % fast twitchDistance runners 60-90 10-40Track sprinters 25-45 55-75 Weight lifters 45-55 45-55 Shot putters 25-40 60-75 Non-athletes 47-53 47-53 Figure 11.31 and 11.32 on Page 274 and 275
Types of Muscle Contractions• There are three types of muscle contractions (listed in order of most common to least common):• Isotonic Contraction,• Isometric Contraction, and• Isokenitic Contraction.
Isotonic Contraction• Most common muscle contraction.• Occurs when the muscle length changes as tension is developed.• Example – when a shot-putter pick up the shot-put and raises it to his or her neck.
Isometric Contraction• Occurs when the muscle contracts but do not produce any movement.• Example – if you were to hold out your arm, palm up and a weight is placed on your hand. Your arm muscles would develop tension but not change in length.
Isokinetic Contraction• Occur when tension in a muscle is maximal throughout the range of motion.• This type of contraction exercises the muscle most effectively.• Specialised gym equipment assist with these contractions.• The harder you push or pull, the greater the resistance offered by the machine.
Summary• What you should know – page 280-281.• Test your knowledge – page 281.• SAC 1 - Preparation Sheet