THE MUSCULAR SYSTEM

• Skeletal muscles

• Visceral muscles

• Cardiac muscles

• Skeletal muscles

• Visceral muscles

• Cardiac muscles

Classification of muscles by location

Skeletal muscles

– usually attached to bones

Visceral muscles

– in the walls of some organs

Cardiac muscles

– in the heart, myocardium

Skeletal

– striated, voluntary

Visceral

– nonstriated, involuntary

Cardiac

striated, involuntary

Skeletal muscles

• the red lean meat of the body, make up almost half of the body weight.

• usually controlled by the cerebrum.

Muscle fibers

– muscle cells

Fibrils or myofibrils

– many fine threadlike structures

Fascia

– a layer of connective tissue

Skeletal muscles

are usually attached at each to a bone, but some are attached to a cartilage, a ligament, another muscle or to the skin.

connective tissue

The attachment to bone is by ------------------, usually a tendon or aponeurosis, but sometimes directly to bone.

Origin

– of a muscle is its more fixed, less movable attachment, usually its proximal end.

Insertion

– of a muscle is its more movable end, usually its distal end.

Tendon

– sometimes called a sinew cord, or leader is a cordlike fibrous connective structure that extends from the end of a muscle to a bony attachment.

Aponeurosis

– is a sheet of fibrous connective tissue that is often attached at one end to a muscle, often flat muscle and by the other end to a bone, cartilage, ligament or other muscle.

A tendon sheath

– is a tunnel-like channel that surrounds a tendon.

Tenosynovitis

– is an inflammation of a tendon sheath

Bursa

– is a saclike structure lying between a muscle or tendon and an adjacent bony prominence over which the muscle tendon moves.

Bursitis

– is an inflammation of a bursa and it is frequently very painful.

Calcification

– the deposition of calcium, may occur in a bursa or tendon sheath.

Muscle Tone

– muscles do not completely relax when at rest, but remain partly contracted.

Contraction

– the main function of all muscles is to contract and cause movement of the body or a part of it.

proximal to that joint

Muscle that cross a joint to insert into a bone and cause movement are located

Prime Movers

– are muscles that initiate and carry out some movement.

Antagonists

– are muscles that perform some movement opposite to that caused by the prime movers.

Synergists

– are muscles that act with the prime movers to accomplish some movement but prevent unwanted movement.

Fixation muscles

– are those that hold the adjacent bones in a fixed position so that the prime movers may accomplish some certain movement.

Posture

– the maintenance of the upright position of the body consists of a balanced contraction of some muscle groups and the partial relaxation of opposing groups.

Muscle spasm

– is a contraction of muscles that may persist for a long period of time, without relaxation.

Paralysis of muscles

– follows injury to, or destruction of, the nerves supplying that muscle.

Poliomyelitis (infantile paralysis)

– may attack cells in the spinal cord that supply motor nerves to skeletal muscles.

Irritability

– is the property of being able to respond to stimuli.

Conductivity

– is the ability to conduct impulses from nerves, from electrical stimuli

Extensibility

– is the facility or stretching. This occurs by a lengthening of the fibrils of each muscle fibers.

Elasticity

– the ability to return to the original length following stretching.

Contractility

– is the ability to become shorter, and is due to a shortening with thickening of each fibril of each muscle fiber.

• Skeletal muscles contract and cause movement.

• They maintain position (posture) in the upright and other positions of the body.

• They give support to joints by maintaining a partial state contraction.

Functions of Muscles

• By Location

• By Shape

• By Direction of Fibers

• By Action

• Number of Parts

How Muscles Are Named

Diaphragm

Dome-shaped muscular partition that separates the thorax and abdomen.

• Aortic hiatus

• Esophageal hiatus

• Opening of the inferior vena cave

3 large openings

Pectoralis Major Muscle

Thick fan-shaped muscle that covers the upper anterior chest wall.

Psoas Major Muscle

Muscle lies lateral to the lumbar vertebrae in the posterior wall of the abdomen.

Intercostal muscles

Fill in the spaces between adjacent ribs, and their costal cartilages.

The Diaphragm and Radiography

O The tops of the dome lie well above the costal margins and may reach the -----

inspiration

The Diaphragm and Radiography

Following ----, they lie at a lower level than the following expiration.

higher

With the subject lying down the diaphragm lies at a ______ level than when upright.

highest possible

Air escaping from a hole in the wall of the stomach or intestine will rise to the ___ ____ level in the abdomen.

chest and abdomen radiography

The diaphragm must be included in both

O Sternomastoid muscle O Pectoralis minor muscle O Deltoid muscle O Biceps brachii O Brachialis muscle O Triceps brachii O Flexor digitorum profundus O Extensor digitorum O Trapezius muscle O Latissimus dorsi muscle O Sacrospinalis muscle O Psoas minor muscle O Gluteus maximus muscle O Quadriceps femoris muscle O Biceps femoris muscle O Gastrocnemius muscle

Other Examples of Skeletal Muscle

O Inguinal ligment O Patellar ligament O Ligamentum teres O Calcaneal tendon

Example of Ligaments and Tendons

O Umbilical Area O Inguinal Area O Femoral Area

Weak Abdominal Areas