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The Muscular System

The Muscular System A&P Chapter 8

Striations Visible bands of light and dark patches in a muscle cell.
Intercalated Disks Membranes that appear as dark lines between cells in cardiac muscle that allow electrical impulses to travel across and through them rapidly.
Muscle Tone A steady partial contraction of muscle that keeps the body in position.
Fascicles Individual muscle fibers that are arranged in bundles and held together by fibrous connective tissue.
Endomysium Layer of connective tissue found around the individual muscle fibers in the fascicles.
Perimysium Layer of connective tissue found around each fascicle.
Epimysium The sheath of tough connective tissue that encases the entire muscle.
Deep Fascia Fibrous bands or sheets that supports, covers, separates, and protects skeletal muscle.
Tendon Band of connective tissue that attaches a muscle to a bone.
Motor Impulses Nerve impulses that travel away from the central nervous system
Motor Neurons The name of the neuron that carries the nerve impulses away from the central nervous system.
Motor Unit Group consisting of a single neuron and all the muscle fibers it stimulates.
Neuromuscular Junction The point at which a nerve fiber contacts a muscle cell.
Neurotransmitter Chemical that is released from the neuron to stimulate a muscle fiber.
Acetylcholine Abbreviated ACh and is the name of the particular neurotransmitter released at a neuromuscular junction.
Synapse A point of communication between cells; junction between two neurons or between a neuron and an effector.
Synaptic Cleft Tiny space between cells across which the neurotransmitter must travel.
Receptors Proteins that are embedded in the muscle cell membrane
Motor End Plate Region of a muscle cell membrane that receives nervous stimulation
Excitability In cells, the ability to transmit an electrical current along the plasma membrane.
Action Potential Sudden change in the electrical charge on a cell membrane, which then spreads along the membrane; nerve impulse.
Contractility A muscle fiber’s capacity to undergo shortening and to change its shape, becoming thicker.
Actin One of the two contractile proteins in muscle cells, they are light and thin filaments found in muscle cells.
Myosin one of the two contractile proteins in muscle cells, they are dark and thick filaments found in muscle cells.
Filaments The threads that make up skeletal muscle and are composed of the proteins actin and myosin which gives skeletal muscle its striated appearance.
Sarcomere A contracting subunit of skeletal muscle, it consists of a band of myosin filaments and the actin filaments on each side.
Myosin Heads Paddlelike extensions which aid in movement between the myosin and actin filaments and forms attachments between the two filaments known as cross-bridges.
Troponin Protein that works with tropomyosin the regulate contraction in skeletal muscle.
Tropomyosin Protein that works with troponin to regulate contraction in skeletal muscle.
Sarcoplasmic Reticulum (SR) Intracellular membrane in muscle cells that is equivalent to the endoplasmic reticulum in other cells; stores calcium needed for muscle contraction.
Myoglobin Compound that stores oxygen in muscle cells.
Glycogen Compound built from glucose a molecule that is stored for energy in liver and muscles.
Creatine Phosphate Compound in muscle tissue that stores energy in high energy bonds.
Lactic Acid Organic acid that accumulates in muscle cells functioning without oxygen and causes the muscles to fatigue.
Oxygen Debt Amount of oxygen needed to reverse the effects produced in muscle functioning without oxygen.
Period of Recovery Oxygen Consumption Time after strenuous exercise during which extra oxygen is needed to slow down breathing and heart rate, and to replenish the glycogen, myoglobin, and creatine phosphate that are stored in cells
Stretching Muscles are able to contract more forcefully, as the internal filaments can interact over a greater length and also helps with balance and promotes flexibility at the joints.
Aerobics Exercise that increases oxygen consumption, such as running, biking, or swimming and leads to improved endurance.
Resistance Training Causes muscle cells to increase in size, an example is weight lifting.
Hypertrophy Enlargement or swelling of the muscles
Cross-Training A varied exercise program that includes stretching, aerobic exercise, and resistance training with periods of warm-up and cool-down before and after working out.
Interval Training Same method as cross-training just another name for it
Vasodilatation Increase in a blood vessel’s diameter
Tonus Partially contracted state of muscle; also, tone.
Isotonic Contractions Muscle contraction in which the tone within the muscle remains the same but the muscle shortens to produce movement.
Isometric Contractions Muscle contraction in which there is no change in muscle length but an increase in muscle tension, as in pushing against an immovable force.
Aponeurosis A broad sheet of fibrous connective tissue that attaches muscle to bone or to other muscle.
Origin Source; beginning; muscle attachment connected to a nonmovable part.
Insertion Muscle attachment connected to a movable part
Prime Mover Muscle that performs a given movement; agonist.
Antagonist Muscle that has an action opposite that of a give movement; substance that opposes the action of another substance.
Synergists Substance or structure that enhances the work of another. A muscle that works with a prime mover to produce a given movement.
Fulcrum Pivot point in a lever system; joint in the skeletal system
Effort Force in a lever system
Resistance The weight or load in a lever system
First-Class Lever The fulcrum is located between the resistance and the effort, examples are a see-saw or a pair of scissors.
Second-Class Lever The resistance is located between the fulcrum and the effort, examples are a wheelbarrow or a mattress lifted at one end
Third-Class Lever The effort is between the resistance and the fulcrum, examples are forceps and a pair of tweezers.
Mastication Act of chewing
Orbicularis Muscles Muscles of facial expression include ring-shaped ones around the eyes and the lips, named because of their shape.
Orbicularis Oculi The name of the muscle that surrounds each eye
Orbicularis Oris The name of the muscle that surrounds the lips
Levator Palpebra Superioris Lifter of the upper eyelid is the antagonist muscle for the orbicularis oculi.
Buccinator One of the largest muscles of expression that forms the fleshy part of the cheek.
Trumpeter’s Muscle Another name for the Buccinator so named because it is used in whistling or blowing.
Antagonists of the Orbicularis Oris Muscles that can produce a smile, a sneer, or a grimace
Scalp Muscles A number of muscles that lift the eyebrows or draw them together into a frown.
Mastication Muscles Four pairs of muscles all of which insert on the mandible
Temporalis Largest of the mastication muscles which is located above and near the ear and its function is to close the jaw.
Masseter Another mastication muscle which is located at the angle of the jaw and its function is to close the jaw.
Intrinsic Muscles Group of muscles that is located entirely within the tongue
Extrinsic Muscles Group of muscles that originates outside the tongue
Neck Muscles Ribbonlike muscles that extend vertically or obliquely in several layers and in a complex manner.
Tongue Muscles Muscles that allow for the intricate motions involved in speaking, chewing, and swallowing.
Sternocleidomastoid This strong muscle extends superiorly from the sternum across the lateral neck to the mastoid process and its function is to flex the head and rotate the head toward the opposite side from the muscle
Torticollis Wry-neck; a condition that may be caused by muscle injury or spasm in which the head is abnormally fixed in a position where it is tilted to one side.
Muscles of the Upper Extremities Includes the muscles that determine the position of the shoulder, the anterior and posterior muscles that move the arm, and the muscles that move the forearm and hand.
Trapezius A triangular muscle that covers the posterior neck and extends across the posterior shoulder to insert on the clavicle and the scapula; its function is to raise the shoulder and pull it back, and also to extend the head.
Latissimus Dorsi The wide muscle of the back and lateral trunk that originates from the vertebral spine in the middle and lower back and covers the inferior half of the thoracic region its function is to extend and adduct the arm behind the back
Pectoralis Major Is located on either side of the superior chest and arises from the sternum, the upper ribs, and the clavicle and forms the anterior wall of the axilla; its inserts onto the superior humerus;
Serratus Anterior Is located below the axilla on the lateral chest and originates on the upper eight or nine ribs on the lateral and anterior thorax and inserts in the scapula on the side toward the vertebrae
Deltoid Covers the shoulder joint and is responsible for the roundness of the upper arm just inferior to the shoulder and arises from the shoulder girdle and its fibers converge to insert on the lateral surface of the humerus
Rotator Cuff The group of muscles and their tendons that act to stabilize the shoulder; these muscles arise from the shoulder and connect to the head of the humerus forming a cuff at the shoulder joint.
Supraspinatus Muscle It is a relatively small muscle of the upper limb that takes its name from its origin from the supraspinous fossa superior to the spine of the scapula. It is one of the four rotator cuff muscles and also abducts the arm at the shoulder
Infraspinatus Muscle A thick triangular muscle of the rotator cuff that is found below the spine of the scapula and occupies a chief part of the infraspinous fossa
Teres Minor Muscle A narrow elongated muscle of the rotator cuff
Subscapularis Muscle A large triangular muscle which fills the subscapular fossa and inserts into the humerus and the front of the capsule of the shoulder joint.
Epicranial Aponeurosis (Tendon) A tough layer of dense fibrous tissue which covers the upper part of the cranium.
Frontalis A thin muscle of quadrilateral form and is intimately adherent to the superficial fascia, located in the front of the head with no bony attachments.
Nasalis A sphincter-like muscle of the nose whose function is to compress the nasal cartilage.
Quadratus Labii Superioris Also known as the levator labii superioris is a broad sheet muscle the origin of which extends from the side of the nose to the zygomatic bone and blends in with the Orbicularis Oris and elevates the upper lip.
Zygomaticus Is a muscle of facial expression which draws the angle of the mouth superiorly and posteriorly; it extends from each cheekbone to the corners of the mouth. It raises the corners of the mouth when a person smiles.
Quadratus Labii Inferioris Also known as the Depressor Labii Inferioris it is a facial muscle that helps to control the bottom lip by depressing it.
Mentalis Is situated at the tip of the chin, it raises and pushes up the lower lip, causing wrinkling of the chin, as in doubt or displeasure. Sometimes referred to as the “pouting muscle,” and it also protrudes the lower lip.
Triangularis Also known as the Depressor Anguli Oris, it arises from the oblique line of the mandible, whence its fibers converge, to be inserted into the angle of the mouth, and its function is to depress the angles of the mouth therefore causing frowning
Digastricus – Is a small muscle located under the jaw, it has its origin in the mandible and the mastoid process of the temporal bone, its function is to open the jaw when the masseter and the temporalis are relaxed
Flexor Carpi Radialis Is a muscle of the human forearm that originates on the medial epicondyle of the humerus; it runs just laterally of flexor ditigortum superficialis and inserts on the anterior aspect of the base of the second metacarpal,
Flexor Carpi Ulnaris Abbreviation is FCU and it is a muscle of the human forearm that acts to flex and adduct the wrist and is located on the ulna side of the forearm.
Flexor Digitorum Superficialis Is an extrinsic flexor muscle of the fingers at the proximal interphalangeal joints; and its function is to flex the fingers primarily at the proximal interphalangeal joints.
Extensor Carpi Radialis Longus Is one of the five main muscles that control movements at the wrist; this muscle is quite long starting on the lateral side of the humerus and attaching to the base of the second metacarpal bone
Extensor Carpi Radialis Brevis This muscle is shorter and thicker than the Extensor Carpi Radialis Longus and has its origin in the humerus at the lateral epicondyle and inserts at the base of the 3rd metacarpal
Extensor Carpi Ulnaris Is a muscle located in the human forearm on the ulna side that inserts into the 5th metacarpal bone and its function is to extend and adduct the wrist.
Biceps Brachii A muscle that is located at the anterior arm along the humerus, and is the muscle that is displayed when you want to “flex your muscles,” it inserts on the radius and flexes the forearm
Brachialis A muscle that is located posterior to the biceps brachii; and inserts at the anterior elbow joint; its function is the main flexor of the arm.
Brachioradialis A prominent forearm muscle that originates at the distal humerus and inserts on the distal radius; its function is to flex the forearm at the elbow.
Triceps Brachii Is located on the posterior arm, inserts on the olecranon of the ulna, and its function is to extend the forearm to straighten the upper extremity.
Flexor Digitorum Profundus A muscle in the forearm that flexes the fingers; it is considered to be an extrinsic muscle because its action is at a different location than the main body of the muscle; its origin is in the ulna and its insertion is in the distal phalanges.
Trunk Muscles Include the muscles involved in breathing, the thin muscle layers of the abdomen, and the muscles of the pelvic floor.
Diaphragm The most important muscle involved in the act of breathing; this dome-shaped muscle forms the partition between the thoracic cavity above and the abdominal cavity below
Intercostal Muscles Muscles that are attached to and fill the spaces between the ribs.
Dorsally Toward the back; posterior
Laterally Farther from the midline; toward the side
Ventrally Toward the front or belly surface; anterior
External Oblique The outermost muscle layer that forms the abdominal wall.
Internal Oblique The middle muscle layer that forms the abdominal wall.
Transversus Abdominis The innermost muscle layer that forms the abdominal wall
Rectus Abdominis – A paired muscle running vertically on each side of the anterior wall of the abdomen that are separated by a midline band of connective tissue called the linea alba; it originates in the pubis
Linea Alba A fibrous structure that runs down the midline of the abdomen it is a white line composed mainly of collagen connective tissue
Perineum Is generally defined at the surface region in both males and females between the pubic symphsis and the coccyx; it is a region of the body inferior to the pelvic diaphragm and between the legs
Levator Ani A broad thin muscle, situated on the side of the pelvis; it is attached to the inner surface of the side of the lesser pelvis, and unites with its fellow of the opposite side to form the greater part of the floor of the pelvic cavity
Erector Spinae – These muscles make up a large group located between the sacrum and the skull; its origin is on the spines of the last four thoracic vertebrae; it inserts on both the spines of the cranial thoracic vertebrae and the cervical vertebrae
Muscles of the Lower Extremities These muscles are among the longest and strongest muscles in the body, and are specialized for locomotion and balance; they include the muscles that move the thigh and leg and those that control movement of the foot
Gluteus Maximus Muscle that forms much of the buttock’s fleshy part is relatively large in humans because of its support function when a person is standing erect
Gluteus Medius This muscle is partially covered by the gluteus maximus it abducts the thigh; and it is one of the sites used for intramuscular injections.
Iliopsoas Arises from the ilium and the bodies of the lumbar vertebrae; it crosses the anterior hip joint to insert on the femur;
Adductor Muscles Muscles that are located on the medial part of the thigh; they arise from the pubis and ischium and insert on the femur
Adductor Longus A muscle in the adductor muscle group that adducts the thigh it originates on the pubic body just below the pubic crest and inserts into the middle third of the linea aspera;
Adductor Magnus A large triangular muscle, situated on the medial side of the thigh; it originates in the pubis and the tuberosity of the ischium; it inserts into the femur and it adducts the hip.
Sartorius A long, thin muscle that runs down the length of the thigh; it is the longest muscle in the body; its upper portion forms the lateral border of the femoral triangle
Tailor’s Muscle Another name for the Sartorius because it is used in crossing the legs in the manner of tailors, who in days gone by sat cross-legged on the floor.
Gracilis Is the most superficial muscle on the medial side of the thigh; it is thin and flattened, broad above, narrow and tapering below
Quadriceps Femoris Is a large muscle group that includes the four prevailing muscles on the front of the thigh; it is a great extensor muscle of the knee, forming a large fleshy mass which covers the front and sides of the femur
Rectus Femoris Is one of the four quadriceps muscles; it is situated in the middle of the front of the thigh;
Vastus Medialis Often called the “teardrop” muscle, is a medially located muscle of the quadriceps; it originates in the femur and inserts into the patella and its function is to extend the leg.
Vastus Lateralis It is the largest part of the quadriceps femoris; it originates in the Greater Trochanter and linea aspera of the femur and inserts into the patella via the quadriceps femoris and tibial tuberosity via the patellar ligament
Vastus Intermedius It arises from the front and lateral surfaces of the body of the femur in its upper two-thirds, sitting under Rectus Femoris and from the lower part of the lateral intermuscular septum;
Iliotibial Tract Is a longitudinal fibrous reinforcement of the fascia lata (the deep fascia of the thigh); it is attached to the midpoint of the external lip of the iliac crest and to the lateral condyle of the tibia
Hamstring Muscles Located in the posterior part of the thigh; their tendons can be felt behind the knee as they descend to insert on the tibia and fibula; they flex the leg on the thigh as in kneeling.
Biceps Femoris A muscle of the posterior thigh and as its name implies it has two parts, one of which (long head) forms part of the hamstrings muscle group
Semimembranosus A muscle in the back of the thigh it is the most medial of the three hamstring muscles
Semitendinosus One of the hamstring muscles located on the back of the thigh; its origin is the tuberosity of the ischium
Gastrocnemius The largest muscle in the calf of the leg, extending from the thigh to the Achilles tendon. When it contracts it causes the foot to point downward.
Achilles Tendon Found in the legs, it is a powerful, cordlike band of connective tissue that joins the fused muscles of the calf to the bone of the heel
Soleus A flat muscle deep to the gastrocnemius; it also inserts by means of the Achilles tendon and, like the gastrocnemius flexes the foot at the ankle
Tibialis Anterior A muscle that originates in the upper two-thirds of the lateral surface of the tibia and inserts into the medial cuneiform and inserts into the first metatarsal bones of the foot
Peroneus Longus A superficial muscle in the lateral compartment of the leg that originates in the fibula;
Fibularis Longus Another name for the Peroneus Longus muscle located in the leg
Tendons of the Extensor Muscles (feet) Located in the superior part of the foot and insert on the superior surface of the phalanges (toe bones).
Flexor Digitorium Tendons (feet These tendons cross the sole of the foot and insert on the undersurface of the phalanges.
Dowager’s Hump The name used for kyphosis or hunchback in women
Spasm A sudden and involuntary muscular contraction, which is always painful
Colic A spasm of the visceral muscle
Bellyache Intestinal spasm a good example of colic
Seizure A spasm that occurs in a series
Convulsion Another name for a seizure
Cramps Strong, painful muscle contractions, especially of the leg and foot; most likely to follow unusually strenuous activity
Recumbency Cramps Cramps that occur during sleep or rest
Strains Common muscle injuries caused by overuse or overstretching; there is pain, stiffness, and swelling, most commonly in the lower back or neck.
Charley Horse A soreness and stiffness in a muscle caused by strain, usually referring to strain of the thigh’s quadriceps muscle.
Sprains More severe than strains and involve tearing of the ligaments around a joint, usually as a result of abnormal or excessive joint movement.
Atrophy A wasting or decrease in the size of a muscle when it cannot be used, such as when an extremity must be placed in a cast after a fracture.
Shivering The quick contractions of muscle to produce heat when the body is too cold.
Muscular Dystrophy A group of disorders in which there is deterioration of muscles that still have intact nerve function.
Myasthenia Gravis Characterized by chronic muscular fatigue brought on by the slightest exertion. This disease is caused by a defect in transmission at the neuromuscular junction.
Ptosis Drooping of the upper eyelid this is also called lazy eye
Myalgia Muscular pain
Myositis A term that indicates actual inflammation of muscle tissue
Fibrositis Inflammation of connective tissues and refers particularly to those tissues associated with muscles and joints.
Fibromyositis Muscle and connective tissue pain; which may be acute, with severe pain on motion, or may be chronic; sometimes, the application of heat, together with massage and rest, relieves the symptoms.
Bursitis Inflammation of a bursa; a fluid-filled sac that minimizes friction between tissues and bone.
Olecranon Bursitis Inflammation of the bursa over the point of the elbow.
Student’s Elbow Another name for olecranon bursitis; it can be cause by long hours of leaning on the elbow while studying.
Ischial Bursitis common among people who must sit a great deal, such as taxicab drivers and truckers.
Prepatellar Bursitis Inflammation of the bursa anterior to the patella
Housemaid’s Knee Another name for Prepatellar Bursitis; this name came from and earlier time and refers to people who spend great deal of time on their knees
Subdeltoid Bursitis Appears in the shoulder region and is a fairly common form of bursitis. It appears below the deltoid muscle of the shoulder.
Subacromial Bursitis Appears in the shoulder region and is a fairly common form of bursitis. It appears below the acromial muscle of the shoulder.
Bunions Enlargements commonly at the base and medial side of the great toe; usually prolonged pressure has caused the development of a bursa, which as then become inflamed;
Tendinitis An inflammation of muscle tendons and their attachments occurs most often in athletes who overexert themselves;
Tenosynovitis Involves the synovial sheath that encloses tendons, is found most often in women in their 40s after an injury or surgery. It may involve swelling and severe pain with activity.
Shinsplints Experienced as pain and soreness along the tibia from stress injury of structures in the leg. Some causes are tendinitis at the insertion of the tibialis anterior muscle, sometimes with inflammation of the tibia itself
Carpal Tunnel Syndrome Involves the tendons of the flexor muscles of the fingers as well as the nerves supplying the hand and fingers. Numbness and weakness are a couple signs
Lateral Farther from the midline; toward the side
Medial Nearer the midline of the body
Internal Located within something
External Located outside of something
Orbicularis Circular shaped muscle
Deltoid Triangular shaped muscle
Trapezius Trapezoid shaped muscle
Rectus Straight muscle fibers
Oblique Angled muscle fibers
Attachment Points Number of heads of the muscle where it attaches to bone.
Flexor Bending motion that decreases the angle between bones at a joint.
Extensor Motion that increases the angle at a joint
Adductor Movement toward the midline
Abductor Movement away from the midline
Levatator Movement of rising
My/o Muscle
Sarc/o Flesh
Troph/o Nutrition, Nurture
Vas/o Vessel
Iso Same, Equal
Ton/o Tone, Tension
Metr/o Measure
Brachi/o Arm
Erg/o Work
Quadr/i Four
A Absent, Lack of
Dys Disordered, Difficult
Sthen/o Strength
-Algia Pain
Created by: Okiegirl



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