The Muscular System

Support Systems

Unit 2

Functions of the Muscular System• Heat Production (thermogenesis)

– Breaking of ATP during muscle contraction

• Movement Facilitation– Muscles pull on the skeletal levers

• Structure (postural support)– Muscles hold parts of the skeleton in place

• Protection of Internal Organs – The abdominal muscles are thick and

protect the abdominal and pelvic cavity organs

Types of Contractibility

• Voluntary- contractions controlled by conscious thought or will

• Involuntary- contract due to unconscious impulses sent by the autonomic nervous system or certain specialized cells or hormones

Muscle Appearance

• Striated- stripes, muscles that on a microscopic level have cross fiber stripes

• Non-striated- Not having stripes, muscles cells that microscopically have a smooth appearance

Cardiac Muscle

• Forms the bulk of heart wall (Myocardium)

• Striated• Involuntary (typically)• Cardiac fibers typically have a

centrally located nucleus• Intercalated discs

– Strengthens cardiac muscle tissue– Allows for special wringing muscle

contraction

Cardiac Muscle Tissue

Smooth Muscle• Located in walls of hollow internal

surfaces such as:– blood vessels - stomach– urinary bladder - intestines

• Non-striated in appearance• Involuntary (typically)• Contractions usually move things

along, from point A to point B (peristalsis)

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Skeletal Muscle• Attached to bones • Striated appearance under a

microscope• Voluntary control (conscious

control)• Allow for postural support and

movement of body parts, both axial and appendicular

Skeletal Muscle Tissue

Connecting Tissues

Tendon – muscle to bone Ligament- bone to bone

Motions• Peristalsis- a wave like motion by

smooth muscle to advance substances • Abduction- movement away from

midline• Adduction- movement towards

midline• Flexion- decreasing a joint angle

• Extension- increasing a joint angle

• Hyperextension- extension past normal extension, or past anatomical position

Motions

• Plantarflexion- specific to ankle motion, pointing the toes

• Dorsiflexion- specific to ankle motion, pulling the toes towards the shin

• Supination- turning palm up

• Pronation- turning palm down

• Rotation- movement around an axis

Location and Function of Skeletal Muscles

• Biceps brachii- anterior surface of arm between the shoulder and elbow, flexes the elbow

• Triceps brachii- posterior aspect of arm between the shoulder and elbow, extends the elbow

• Trapezius- attaches to the spine from the occiput through the thoracic region and to the spine of the scapula, extends or hyperextends the head and neck, (also helps with shoulder retraction and elevation and depression)

• Deltoid- covers the cap of the shoulder, abducts the arm

• Diaphragm- connects to the lower ribs and runs through the entire body, deflects the diaphragm inferiorly increasing volume of the thoracic cavity

Location and Function of Skeletal Muscles

• Pectoralis major- attaches to the upper ribs along the sternum and to the humerus, adducts the arm

• Latissimus dorsi- attaches along mid to lower spine and pelvic and to the humerus, extends a flexed arm or hyperextends the arm from the anatomical position

• Rectus abdominus- attaches to the lower ribs and to the pelvic anteriorly, flexes the lumbar spine

• Gastrocnemius-attaches to the tibia and lower femur and uses the achilles tendon to attach to the calcaneous (heel bone), plantar flexes the ankle when the knee is in extension

Location and Function of Skeletal Muscles

• Soleus- attached deep to the gastrocnemius on the tibia and uses the achilles tendon to attach to the calcaneous, plantarflexes the ankle when the knee is bent

• Hamstrings- posterior thigh between the hip and knee, flexes the knee

• Quadriceps- anterior thigh between the hip and knee, extends the knee

• Gluteus maximus- posterior pelvis, extends a flexed thigh or hyperextends the thigh from the anatomical position

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Diseases and Disorders of the

Muscular System

Tendonitis

• Tendonitis is characterized by Inflammation of the tendons due to overuse or age-related changes of the tendon.

• It is common in individuals who begin a new exercise or increase their level of exercise.

• Age-related tendonitis is due to the loss of elasticity and the ability of the tendon to glide smoothly.

• Treatment includes: rest, ice, compression, and elevation (RICE).

Sprain• A sprain is an injury to a ligament,

which is the fibrous tissue that connects bones to other bones.

• There are three grades of sprains:– 1st Degree Sprain = stretching of ligaments

– 2nd Degree Sprain = partial tearing of ligaments

– 3rd Degree Sprain = complete tear of ligaments

Three Degrees of Sprains

Strains

• Muscle strain or muscle pull or even a muscle tear implies damage to a muscle or its attaching tendons.

• This can occur due to excessive pressure on muscles during the course of normal daily activities, with sudden, quick heavy lifting, during sports, or while performing work tasks.

Degrees of Muscle Strains

• First degree strain - a mild strain when only a few muscle fibers are stretched or torn. The injured muscle is tender and painful, but has normal strength.

• Second degree strain - a moderate strain with a greater number of injured fibers. There is more severe muscle pain and tenderness. There is also mild swelling, some loss of strength, and a bruise may develop.

• Third degree strain - this strain tears the muscle all the way through. There is a total loss of muscle function.

Careers• Orthopedic Surgeon• Certified Athletic Trainer• Medical Illustrator• Massage Therapist

Orthopedic Surgeon• Medical Doctor who specializes in

musculoskeletal ailments including acute, chronic, traumatic and overuse injuries

• Performs surgeries on musculoskeletal disorders such as ACL tears, Knee replacements, Scoliosis surgery

• Attends 4 year undergrad + 4 year medical school + 5 year orthopedic residency program + 1 year fellowship

• Salary- $300,000++• Arthroscopic surgery

Certified Athletic Trainer• Responsible for prevention,

recognition, evaluation, immediate care and rehabilitation of injuries

• Work at high schools, universities, professional sports, gyms, industry, military, hospitals and clinics

• Bachelors Degree• $35,000 + • Athletic Training- Smooth Professio

nal

Medical Illustrator• Artists who have detailed knowledge of the

human body• Create graphic representations of medical or

biological subjects for textbooks, pamphlets, exhibits, films, legal procedures, teaching models

• Pre-med/ Art Major• Masters of Medical Illustrating• Salary - $33,000-60,000• Job outlook is small and competitive, BUT

growing because of technology

Massage Therapist• Manipulate patients body with pressure, tension or

vibration manually or with mechanical aids• Work in hospitals, nursing homes, sports and fitness

centers, spas, beauty salons, cruise ships, private offices

• Graduate from accredited Massage school (8 months to 12 months)and pass License exam

• Can specialize in pediatric massage, sports massage….• Salary varies widely

• Where do MT work and how much do they make

• Sports Massage

Vocabulary- word parts• My/o- muscle (myofibril is a muscle fiber)

• Ab- prefix, away (abduction)• Ad- prefix, towards (adduction)• Bi- prefix, two (biceps)• Tri- prefix, three (triceps)• Quad- prefix, four (quadriceps)• Contra- prefix, opposite or against

(contralateral- pertaining to the other side)• Dys- prefix, bad, difficult, or painful (dysphagia-

difficulty swallowing)

• -algia- suffix, pain (myalgia- muscle pain)

Vocabulary• Ligament- connective tissue that holds bone to

bone• Tendon- connective tissue that hold muscle to

bone• Tendonitis- inflammation of a tendon• Sprain- stretch or tear of a ligament• Strain- stretch or tear of a muscle or tendon• Myocardium- heart muscle• Thermogenesis- heat production• Striations- stripes

• MRI- Magnetic Resonance imaging