chapter 07 muscles and joints

Muscles and Joints

CHAPTER 7

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Muscles Overview

• Muscles support and maintain body posture through a low level of contraction

• Skeletal muscles produce a substantial amount of heat when they contract

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• Skeletal – Attaches to the bones of the skeleton– Voluntary/striated – Operates under conscious control

• Smooth – Called visceral muscle– Involuntary/not striated– Not under conscious control

Types of Muscles

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• Cardiac – Forms the wall of the heart– Involuntary

Types of Muscles

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Attachment of Muscles• Tendon

– Attaches muscles to bones• Point of origin

– Point of attachment of the muscle to the bone that is less movable

• Point of insertion– Point of attachment to the bone that it moves

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• Buccinator– Located in fleshy part of cheek

• Temporal– Located above and near the ear

• Masseter– Located at the angle of the jaw– Raises the mandible and closes the jaw

Muscles of the Head and Neck

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• Sternomastoid• Also called the sternocleidomastoid

– Extends from the sternum upward along the side of the neck to the mastoid process

Muscles of the Head and Neck

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• Trapezius– Triangular-shaped muscle – Extends across the back of the shoulder– Covers back of neck– Inserts on clavicle and scapula

Muscles of the Upper Extremities

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• Latissimus Dorsi– Originates from vertebrae of lower back– Crosses lower half of thoracic region– Passes between humerus and scapula – Inserts on anterior surface of humerus– Forms the posterior border of the armpit


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• Pectoralis Major– Large, fan-shaped muscle– Crosses the upper part of the front chest– Originates from sternum

• Crosses over to humerus

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• Deltoid – Covers the shoulder joint– Originates from clavicle and scapula

• Inserts on lateral side of the humerus

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• Biceps Brachii– Muscle has two heads– Originates from scapula

• Inserts on the radius

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• Triceps Brachii– Muscle has three heads – Originates from scapula and humerus– Inserts onto olecranon process of the ulna

• At the elbow

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• Gluteus Maximus– Forms most of the fleshy part of the buttock– Originates from ilium and inserts in the femur

• Gluteus Medius– Located above the upper outer quadrant of

the gluteus maximus muscle– Originates from posterior part of ilium – Inserts in greater trochanter of the femur

Muscles of the Lower Extremities

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• Quadriceps Femoris– Forms anterior part of the thigh– Help extend the thigh

• Hamstring Muscles– Located in posterior part of the thigh– Help flex leg on the thigh – Help extend the thigh


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• Gastrocnemius– Main muscle of the calf– Attaches to heel bone by way of Achilles

tendon– Used to plantar flex foot and flex toes

• Tibialis Anterior– Positioned on the front of the leg– Used to dorsiflex foot and turn foot inward


PATHOLOGICAL CONDITIONS

Muscles

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Muscular Dystrophy

• Pronounced– (MUSS-kew-lar DIS-troh-fee)

• Defined– Group of genetically transmitted disorders– Characterized by progressive weakness and

muscle fiber degeneration– No evidence of nerve involvement or

degeneration of nerve tissue

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Polymyositis

• Pronounced– (pol-ee-my-oh-SIGH-tis)

• Defined– Chronic, progressive disease affecting the

skeletal muscles– Characterized by muscle weakness and

degeneration – Atrophy

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Rotator Cuff Tear• Pronounced

– (ROH-tay-tor kuff TAIR)• Defined

– Tear in muscles that form a “cuff” over upper end of arm

• Rotator cuff helps to lift and rotate the arm • Also helps to hold head of humerus in place during

abduction of arm

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Rotator Cuff Tear

DIAGNOSTIC TECHNIQUES, TREATMENTS,

AND PROCEDURES

Muscles

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Diagnostic Techniques, Treatments, and Procedures

• Electromyography– Process of recording strength of contraction of

a muscle when stimulated by electric current• Muscle biopsy

– Extraction of a specimen of muscle tissue, through biopsy needle or incisional biopsy, for purpose of examining it under a microscope

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Joints Overview• Joint = articulation

– Point at which two individual bones connect– Joints determine degree of movement – Movement ranges from free to limited

• Suture = immovable joint– Purpose is to bind bones together

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Classification of Joints(Structural)

• Fibrous – Surfaces of bone fit closely together– Held together by fibrous connective tissue– Immovable joint

• Example: Suture between the skull bones

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• Cartilaginous – Bones are connected by cartilage– Limited movement joint

• Example: Symphysis– Joint between the pubic bones of the pelvis

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• Synovial – Space between the bones = joint cavity– Joint cavity lined with synovial membrane– Synovial membrane secretes synovial fluid– Bones are held together by ligaments– Free movement joint

• Example = shoulder

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Classification of Joints(Functional)

• Hinge – Allows a back and forth type motion– Example = elbow

• Ball-and-Socket – Allows movement in many directions around

a central point– Example = shoulder joint and hip joint

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Classification of Joints(Functional)

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Movements of Joints• Flexion

– Bending motion– Decreases angle between two bones

• Extension– Straightening motion– Increases angle between two bones

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Movements of Joints• Abduction

– Movement of a bone away from midline of the body

• Adduction– Movement of a bone toward midline of the

body

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Movements of Joints• Supination

– Act of turning the palm up or forward• Pronation

– Act of turning the palm down or backward

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• Dorsiflexion– Narrows the angle between the leg and the

top of the foot– Foot is bent backward, or upward, at the ankle

Movements of Joints

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• Plantar Flexion– Increases angle between the leg and the top

of the foot– Foot is bent downward at the ankle– Toes pointing downward, as in ballet dancing

Movements of Joints

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Movements of Joints• Rotation

– Turning of a bone on its own axis• Circumduction

– Movement of an extremity around in a circular motion

– Can be performed with ball-and-socket joints

PATHOLOGICAL CONDITIONS

Joints

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Adhesive Capsulitis• Pronounced

– (add-HE-sive cap-sool-EYE-tis)• Defined

– Shoulder condition characterized by a stiffness of the shoulder, limited shoulder movement, and pain

– Also known as “frozen shoulder”

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Arthritis• Pronounced

– (ar-THRY- tis)• Defined

– Inflammation of joints

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Ankylosing Spondylitis

• Pronounced– (ang-kih-LOH-sing spon-dil-EYE-tis)

• Defined– Type of arthritis that affects the vertebral

column– Causes deformities of the spine

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Bunion (Hallux Valgus)• Pronounced

– (BUN-yun) (HAL-uks VAL-gus)• Defined

– Abnormal enlargement of the joint at the base of the great toe

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Dislocation• Pronounced

– (diss-loh-KAY-shun)• Defined

– Displacement of a bone from its normal location within a joint

– Causes loss of function of the joint

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Ganglion• Pronounced

– (GANG-lee-on)• Defined

– Cystic tumor developing on a tendon– Sometimes occurs on back of wrist

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Gout• Pronounced

– (GOWT)• Defined

– Acute arthritis that is characterized by inflammation of the first metatarsal joint of the great toe

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Herniated Disk• Pronounced

– (HER-nee-ay-ted disk)• Defined

– Rupture of the central portion of the vertebral disk through the disk wall and into the spinal canal

– Also called a ruptured disk or a slipped disk

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Herniated Disk

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Lyme Disease• Pronounced

– (LYME dih-ZEEZ)• Defined

– Acute, recurrent inflammatory infection, transmitted through the bite of an infected deer tick

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Osteoarthritis• Pronounced

– (oss-tee-oh-ar-THRY-tis)• Defined

– Most common form of arthritis• Results from wear and tear on the joints, especially

weight-bearing joints such as hips and knees– Also known as degenerative joint disease

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Osteoarthritis

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Rheumatoid Arthritis• Pronounced

– (ROO-mah-toyd ar-THRY-tis)• Defined

– Chronic, systemic, inflammatory disease that affects multiple joints of the body

– Mainly the small peripheral joints

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Sprains• Pronounced

– (SPRAYN)• Defined

– Injury involving ligaments that surround and support a joint

• Caused by a wrenching or twisting motion

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Systemic Lupus Erythematosus

• Pronounced– (sis-TEM-ic LOO-pus er-ih-them-ah-TOH-

sis)• Defined

– Chronic, inflammatory connective tissue disease affecting the skin, joints, nervous system, kidneys, lungs, and other organs

– Characteristic “butterfly rash” appears on the face

DIAGNOSTIC TECHNIQUES, TREATMENTS

AND PROCEDURES

Joints

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• Arthrocentesis– Surgical puncture of a joint with a needle for

the purpose of withdrawing fluid for analysis• Arthrography

– Process of X-raying the inside of a joint, after injecting the joint with a contrast medium

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• Arthroplasty– Surgical repair of a joint

• Arthroscopy– Visualization of the interior of a joint using an

endoscope

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• Erythrocyte Sedimentation (sed) Rate– Blood test that measures the rate at which

erythrocytes settle to the bottom of a test tube filled with unclotted blood


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• Rheumatoid factor– Blood test that measures the presence of

unusual antibodies that develop in a number of connective tissue diseases, such as rheumatoid arthritis


chapter 07 muscles and joints

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