Muscular System Types of muscles Types of muscles Functions Functions Properties of muscle tissue Properties of muscle tissue Neuromuscular System Neuromuscular System Structure of skeletal muscle Structure of skeletal muscle Origin and insertion Origin and insertion Muscles of the trunk Muscles of the trunk Muscles of the upper extremity Muscles of the upper extremity Muscles of the lower extremity Muscles of the lower extremity Types of muscles Types of muscles Functions Functions Properties of muscle tissue Properties of muscle tissue Neuromuscular System Neuromuscular System Structure of skeletal muscle Structure of skeletal muscle Origin and insertion Origin and insertion Muscles of the trunk Muscles of the trunk Muscles of the upper extremity Muscles of the upper extremity Muscles of the lower extremity Muscles of the lower extremity

There are over 600 muscles in the human body and they make up about 40-50% of the weight of the body

Types of Muscles Skeletal Muscles (Voluntary) Skeletal Muscles (Voluntary) Cardiac (or heart muscles) Cardiac (or heart muscles) Smooth (in the organs and blood vessels) Smooth (in the organs and blood vessels)

Functions Movement – occurs when skeletal muscles contract. They exert forces on tendons which then pull on the bones causing joint movement.Movement – occurs when skeletal muscles contract. They exert forces on tendons which then pull on the bones causing joint movement. They also move substances – smooth muscles help move food through the gastrointestinal track; cardiac muscle pumps blood; skeletal muscle helps return venous blood to the heart.They also move substances – smooth muscles help move food through the gastrointestinal track; cardiac muscle pumps blood; skeletal muscle helps return venous blood to the heart. Stabilize and maintain body position – muscles are contracted even if it seems that there is no movement (e.g. - neck)Stabilize and maintain body position – muscles are contracted even if it seems that there is no movement (e.g. - neck) When muscles contract (voluntary or involuntary – shivering) they can generate up to 85% of body heat.When muscles contract (voluntary or involuntary – shivering) they can generate up to 85% of body heat.

Muscles (list) Anterior deltoid, pectoralis, iliopsoas, quadriceps, tibialis anterior, abdominus rectus, external obliques and biceps brachii.deltoid, pectoralis, iliopsoas, quadriceps, tibialis anterior, abdominus rectus, external obliques and biceps brachii.Posterior trapezius, triceps brachii, latissimus dorsi, gluteus maximus, hamstrings, gastrocnemius & soleus, erector spinae.trapezius, triceps brachii, latissimus dorsi, gluteus maximus, hamstrings, gastrocnemius & soleus, erector spinae.

Origin & Insertion Origin: Origin: Usually the more proximal attachment (the end that is closest to the center of the body)Usually the more proximal attachment (the end that is closest to the center of the body) The fix or stationary boneThe fix or stationary bone Insertion: Insertion: Usually more distal attachment ( the end that is furthest away from the center of the body)Usually more distal attachment ( the end that is furthest away from the center of the body) The movable boneThe movable bone

Origin & Insertion The point where the muscle tendon attaches to the fixed or stationary bone is called the ORIGIN.The point where the muscle tendon attaches to the fixed or stationary bone is called the ORIGIN. The point where the muscle tendon attaches to the moving bone is called the INSERTION.The point where the muscle tendon attaches to the moving bone is called the INSERTION. When a muscle contracts the insertion moves towards the origin.When a muscle contracts the insertion moves towards the origin.

What happens (in terms of muscle contraction) when you lift a glass to drink some water?

Movements  Flexion  Extension  Adduction  Abduction  Pronation  Supination  Circumduction  Rotation  Dorsiflexion  Plantar flexion

Types of Motor Unit (muscle fibers) Types of Motor Unit (muscle fibers) 3 Types: Type I – Slow Twitch Muscle Fibers - Slow-oxidative fibers (red color) Type I – Slow Twitch Muscle Fibers - Slow-oxidative fibers (red color) Fairly slow nerve transmissions speed & small muscle forcesFairly slow nerve transmissions speed & small muscle forces Can maintain contractions for long time as they are fatigue resistantCan maintain contractions for long time as they are fatigue resistant

Types of Motor Unit (muscle fibers) Types of Motor Unit (muscle fibers) Type IIa – Fast Twitch Muscle Fibers - Fast-oxidative glycolytic fibers (red/white color) Intermediate fibersIntermediate fibers Fast nerve transmissions speed & stronger contraction forcesFast nerve transmissions speed & stronger contraction forces Also resistant to fatigue (moderate)Also resistant to fatigue (moderate)

Types of Motor Unit (muscle fibers) Types of Motor Unit (muscle fibers) Type IIb – Fast Twitch Muscle Fibers - Fast-glycolytic fibers The fastest nerve contractions times & largest forcesThe fastest nerve contractions times & largest forces Fatigue very fast and cannot maintain contractions for long periods of time.Fatigue very fast and cannot maintain contractions for long periods of time.

Types of Muscle Contraction & The Roles Muscle

Isometric Contraction  Muscle fibers maintain a constant length throughout the entire exercise  There is NO movement  Pressing one’s arm against the wall

ISOMETRIC Contractions occur when there is tension on the muscle but NO movement E.G static contractions occur when holding your weight in a stationary position HANDSTAND

Isotonic Contraction  The muscle fibers changes its length as it works and so movement occurs.  Shortening is called Concentric Contraction  lengthening under tension is called Eccentric Contraction - resistance to gravity creates EC

ISOTONIC - the muscle is moving while contracting, it can be divided into concentric and eccentric contractions CONCENTRIC - contractions involve the muscle shortening while contracting e.g biceps brachii in elbow flexion ECCENTRIC - contraction involves muscle lengthening whilst contracting e.g. bicep brachii in elbow extension Isotonic Contraction

MUSCLE SHORTENING MUSCLE LENGTHENING

Muscle Relaxation  There is no contraction (force = zero)

Agonist (or prime mover)  Muscle contracts concentrically  Segments of the body move towards each other  Muscle shortens & movement occurs  Force produced is grater than the resistance

Antagonist  The muscle that counteracts the agonist by lengthening when the agonist muscle contracts  Segments of the body move away from each other  It is relaxed

When you flex your elbow, (e.g. during a bicep curl) the biceps brachii is the agonist, and the triceps brachii is the antagonist.

Antagonist Pairs Elbow flexionBiceps brachiiTreicips brachii Shoulder rotationDeltoidLatissimus dorsi Medial shoulder rotationPectoralis majorinfraspinatus Knee extensionQuadricepsHamstrings Wrist flexionFlexor carpi radialisExtensor carpi radialis Dorsi flexionTibialis anteriorGastrocnemius Trunk flexionRectus abdominisErector spinae group Hip flexioniliopsoasGluteus maximus MovementAgonist (prime mover) Antagonist

Reciprocal Inhibition (reflex)  When the agonist motoneuron is stimulated, the motoneuron of the antagonist is inhibited, preventing it from contracting.  When the agonist contracts usually the antagonist relaxes. This means that the agonist is not being opposed by any other muscle.