Notes: Naming Muscles

Types of Muscles  Prime mover – muscle with the major responsibility for a certain movement  Antagonist – muscle that opposes or reverses a prime mover  Synergist – muscle that aids a prime mover in a movement and helps prevent rotation  Fixator – stabilizes the origin of a prime mover

Naming of Skeletal Muscles  Direction of muscle fibers  Example: rectus (straight)  Relative size of the muscle  Example: maximus (largest)

Naming of Skeletal Muscles  Location of the muscle  Example: many muscles are named for bones (e.g., temporalis)  Number of origins  Example: triceps (three heads)

Naming of Skeletal Muscles  Location of the muscle’s origin and insertion  Example: sterno (on the sternum)  Shape of the muscle  Example: deltoid (triangular)  Action of the muscle  Example: flexor and extensor (flexes or extends a bone)

Types of Movements (terminology) Origin - where a muscle begins Insertion - where a muscle ends Action - motion produced

Flexion - joint angle gets smaller

Extension - joint angle gets larger

hyperextension - movement beyond 180 o of joint motion

abduction - movement away from midline of body

adduction - movement toward midline of body

Identifying Muscles

Face Muscles  Temporalis- temporal Bone  Closes jaws (chewing)  Masseter- side of jaw  Closes jaws (chewing)  Frontalis- frontal bone  Raises eyebrows and wrinkles forehead horizontally

Face Muscles  Orbicularis Oculi- encircles eye  Closes eye  Orbicularis Oris- encircles mouth  Draws lips together  Mentalis-chin  Raises and protrudes lower lip

Neck Muscles  Sternocleidomastoid- attaches to sternum, clavicle, and mastoid process  Turns the head and bows the head

Head and Neck Muscles

Anterior Trunk Muscles  Pectoralis Major- upper chest  Pulls upper arm forward and across the chest  Rectus Abdominus-connects pubic bones to ribs and sternum  Compresses contents of abdominal cavity  Flexes spinal column (sit-ups)

Anterior Trunk Muscles  External Oblique- slant downward from lower ribs to pelvic girdle  Tenses abdominal wall

Posterior Trunk Muscles  Trapezius- triangular muscle extends from the base of skull, cervical & thoracic vertebrae to the shoulder  Rotates the scapula (shoulder blade)  Latissimus Dorsi- from lower back, around side, to armpit  Adducts arm, pulls arm back in swimming, climbing, and rowing

Trunk Muscles

Deep Trunk and Arm Muscles

Arm Muscles  Deltoid- covers shoulder joint, connects clavicle and scapula to the humerus  Abducts the upper arm (lifts arm)  Biceps brachii- in upper arm, connects scapula to radius  Flexes upper arm at the elbow, rotates the hand laterally

Arm Muscles  Brachialis- beneath the biceps brachii, connects the shaft of humerus to the ulna  Strongest flexor of the elbow  Brachioradialis- connects the humerus to the radius  Aids in flexing the elbow

Arm Muscles  Triceps brachii- 3 heads, back of upper arm connects humerus and scapula to ulna  Extensor of the elbow

Arm Muscles

Upper Leg Muscles  Gluteus Maximus- muscle of the hip that forms most of the butt  Extends leg at hip, for climbing and jumping  Gluteus Medius- from hip to femur and is under the gluteus maximus  Steadies the pelvis during walking  Good site for intramuscular injections (shots)

Butt Muscles Gluteus Minimus Gluteus Maximus Gluteus Medius

Upper Leg Muscles  Rectus Femoris- one of the quadriceps  Extends the knee (like when kicking a ball) and can flex the hip  Vastus Lateralis- one of the quadriceps (on the outside of leg)  Extends the knee

Upper Leg Muscles  Vastus Medialis – one of the quadriceps (toward the inside of body)  Extends the knee  Sartorius- thin and straplike and the most superficial  Synergist to help cross legs

Upper Leg Muscles  Biceps Femoris- part of the hamstring group  Prime movers of thigh extension and knee flexion.

Muscles of the Pelvis, Hip, and Thigh

Lower Leg Muscles  Tibialis Anterior- From upper tibia to tarsals  Acts to dorsiflex and invert the foot  Gastrocnemius- a two bellied muscle that form the curve of the calf  Plantar flexion of the foot. Needed to lift the heel during walking.

Muscles of the Lower Leg

Superficial Muscles: Anterior

Superficial Muscles: Posterior

Diseases of the Muscular System

Muscular Dystrophy  Congenital muscle-destroying disease affect specific muscle groups  Muscle fibers degenerate & atrophy due to an absence of dystrophin, a protein that helps keep muscle cells intact  Most common & serious—Duchenne’s M.D.  Mostly in males (diagnosed between2-6 yrs)  Survival is rare beyond early 30’s  X-linked recessive

Myasthenia gravis  Rare adult disease caused by antibodies to acetylcholine receptors at the neuromuscular junction which prevents the muscle contraction from occurring  Drooping upper eyelids, difficulty swallowing & talking, muscle weakness & fatigue  Death occurs when respiratory muscles cease to function

Disorder of Muscle Tissue Cramps & Spasms - an “over contraction” – can be due to electrolyte imbalance, fatigue, overuse

Hernia - a tear in wall of muscle – can be congenital, or from severe strain

ABDOMINAL HERNIA

Muscle Tear - aka: “pulled” muscle or strained muscle – caused by overstretching of muscle during activity muscle fibers actually tear apart Torn Pectoralis Major

Hamstring Muscle Tear

Hypertrophy - increase in the size of muscle fibers

Atrophy - decrease in size of muscle fiber

Problems with Tendons Tendonitis  Inflammation of tendons and of tendon-muscle attachments Tenosynovitis  Inflammation of a tendon sheath.  Causes include trauma, tendon stress, bacterial disease  shoulder capsule, hip capsule, hamstring muscles, and Achilles tendon.  Tendon sheaths become inflamed and painful, and accumulate fluid.