4 Musculoskeletal System

Muscular System at a Glance Functions of muscular system Hold body erect and produce movement Move body fluids through the ducts and tubes of other systems Move food through digestive system Produce body heat – 85% of our heat comes from muscle activity

Muscular System at a Glance Organs of muscular system Muscles – made up of long slender cells bound together by connective tissue – body has >600 muscles Fascia – is the connective tissue binding or separating muscle or muscle groups Tendons – narrow band of non-elastic, dense fibrous connective tissue, attaching muscle to a bone by inserting into periosteum

Types of Muscles Skeletal muscle Smooth muscle Cardiac muscle

Types of Muscles Voluntary muscles Consciously choose to contract the muscle Skeletal muscles are voluntary muscles Involuntary muscles Under control of subconscious brain Smooth, or visceral muscles and cardiac muscles

Produce voluntary movement of skeleton Skeletal Muscles Attached to bones Produce voluntary movement of skeleton Also referred to as striated muscle Looks striped under microscope

Skeletal Muscles

Smooth muscle Associated with internal organs Also called visceral muscle Stomach Respiratory airways Blood vessels Called smooth because has no microscopic stripes Produces involuntary movement of these organs

Smooth Muscles

Also called the myocardium Makes up the walls of the heart Involuntary Cardiac muscle Also called the myocardium Makes up the walls of the heart Involuntary

Cardiac Muscle

Characteristics of the three types of muscles.

Muscle innervation The stimulation of a muscle by an impulse transmitted by a motor nerve Neuromuscular- the relationship between a nerve and a muscle (neur/o+muscul+ar)

Antagonistic- working in opposition of each other Antagonistic pairs Antagonistic- working in opposition of each other Pair of muscles arranged around a joint Produce opposite actions While one contracts the other relaxes agonist-muscle that is contracting Antagonist-muscle that is relaxing

Contrasting muscle motion Abduction-movement away from the midline Adduction-movement towards the midline Flexion- decreasing the angle between two bones Extension- increasing the angle between two bones Rotation- circular movement around an axis Supination- rotating the arm in forward or upward position Pronation- rotating the arm in a downward or backward position Dorsiflexion- bending the foot in a upward position Plantar flexion- bending the foot in a downward position Inversion- movement of the foot in a inward position Eversion-movement of the foot in a outward position

Figure 4.4, p 104 Abduction and adduction of the shoulder joint.

Figure 4.5 Flexion and extension of the elbow joint.

Figure 4.8 Dorsiflexion (A) and plantar flexion (B) of the ankle joint.

Eversion and inversion of the foot.

Pronation and supination of the forearm.

Pathology of the muscular system Fibers, fascia & tendons Fasciitis – inflammation of the fascia Fibromyalgia – chronic condition – bone or muscle pain, fatigue, causing progressive weakness Tenosynovitis - inflammation of the sheath around a tendon Tendinitis/tendonitis – inflammation of a tendon caused by over-use of a joint Chronic fatigue syndrome – generalized, debilitating disorder not relieved by bed rest

Pathology of the muscular system Muscle Disorders Adhesion – fibrous tissue band holding structures together abnormally Atrophy – muscle wasting Myalgia – muscle pain

Pathology of the muscular system Muscle movement Ataxia – shaky unsteady movement due to lack of coordination Contracture – permanent tightening of the muscle, fascia, tendons, ligaments or skin due to connective tissue changes – ie scarring Intermittent claudication – pain in leg muscles during exercise, relieved by rest – due to poor circulation (associated with PVD) Spasm – sudden involuntary contraction of a muscle Cramp – painful localized spasm

Pathology of the muscular system Muscular dystrophy Group of more than 30 genetic disorders characterized by progressive weakness and atrophy of muscles controlling movement Two most common: Duchenne muscular dystrophy – most common form in kids, boys more than girls, onset 3-5 yrs, rapid progression to 12 yrs Becker muscular dystrophy – less severe form of duchenne

Problems of the muscular system Carpel tunnel syndrome- repetitive motion disorder; compression of finger tendons and median nerve as they pass through carpal tunnel of the wrist ganglion cyst- cyst on tendon sheath; usually on hand, wrist, or ankle Epicodylitis- inflammation of the tissues surrounding the elbow Plantar fasicitis- inflammation of the plantar fascia Strain- injury to a specific tendon Shin splint- injury to the tibialis anterior.