Muscle types, muscles and terminology

Question 1

Three types of muscle

Answer 1

Smooth muscle, skeletal muscle, cardiac muscle

Question 2

Smooth muscle

Answer 2

Found in visceral structures - blood vessels, gastrointestinal tract, uterus, bladder. Cells overlap onto each other. Movement is involuntary, controlled by the autonomous nervous system or hormones.

Question 3

Skeletal muscle

Answer 3

Associated with the skeleton and individual muscles for movement. Consists of individual muscle cells (fibres) grouped together into bundles.

Question 4

Cardiac muscle

Answer 4

Found in the heart and made up of branched muscle cells grouped by discs. Structure is similar to skeletal muscle.

Question 5

Purpose of skeletal muscle

Answer 5

Movement, maintaining posture, prevents excess movement of bones and joints. Found at opening of internal tract to allow voluntary control over movement (swallowing, urination, defecation). Supports internal organs where there is no skeletal support. Barrier to external pressure and trauma. Maintains homeoastasis by generating heat through involuntary movement (shivering).

Question 6

Origin of a muscle

Answer 6

Starting point of a muscle, contracts the least, contains the tendon of the origin.

Question 7

Muscle belly

Answer 7

Thick, fleshy, central part of the muscle. Tapers at each end, muscle can have more than one belly that inserts at one point. The muscle then has number of heads.

Question 8

Muscle insertion

Answer 8

Insertion point of a muscle is the muscle attachment point to the bone that moves. Opposite of the origin and contains the tendon of insertion.

Question 9

Tendons connect

Answer 9

muscle to bone

Question 10

Ligaments connect

Answer 10

bone to bone

Question 11

Tendons and ligaments are made up of

Answer 11

Fibrous connective tissue bundles rich in collagen fibres. They are a strong extension of a muscle but rigid compared to elastic muscle fibres.

Question 12

How do tendons attach to the bone

Answer 12

Collagen in the three layers of the muscle (mysia) bind with collagen of a tendon which connects to the periosteum of a bone.

Question 13

Aponeuroses

Answer 13

Flattened sheets of connective tissue.

Question 14

Skeletal muscle fibres

Answer 14

Long, striated, multinucleated. Each muscle fibre contains myofibrils. Myofibrils divide into sarcomere units which contain actin and myosin proteins. Myofibrils contain thousands of sarcomeres within one muscle fibre.

Question 15

How skeletal muscle moves

Answer 15

Voluntarily by contraction, as the the bundles of prottein filaments within the muscle fibres shorten.

Question 16

How muscle contraction occurs

Answer 16

When a nerve impulse triggers the release of calcium. It alters the environment within sarcomere to allow the attraction between myosin and actin.

Question 17

Isotonic contraction

Answer 17

Muscle contracts when it’s working. If contraction results in movement it is isotonic contraction.

Question 18

Isometric contraction

Answer 18

When there is resistance with muscle tension, but without movement. Occur to maintain posture, bone, joint stability, moving an unmovable object.

Question 19

Muscle atrophy

Answer 19

If a muscle is not used, it becomes weak, looses muscle fibres and the muscle itself.

Question 20

Muscle hypertrophy

Answer 20

A muscle that is constantly and vigorously used will become larger in mass and generate more muscle fibres.

Question 21

Hypotonia

Answer 21

Absence of low-level muscle contractions that maintain muscle tone. Results in flaccid, soft appearance and absent reflexes. Can be caused by nerve damage.

Question 22

Hypertonia

Answer 22

Excessive muscle tone presenting with muscle rigidity, spasmodic tension and relaxation. May result from damage to motor neurons/ stroke or other disease.

Question 23

Flexion/flexor muscles

Answer 23

Angle of a joint is reduced/ muscle found on the side to which the joint bends.

Question 24

Extension/extensor muscles

Answer 24

Angle of a joint is increased/ muscles lie to the opposite side of the joint to the flexor muscles.

Question 25

Abduction/abductor muscles

Answer 25

Limb is moved away from the midline of the body (dog cocking his leg). Abductor muscles lie on the lateral part of the limb.

Question 26

Adduction/adductor muscles

Answer 26

Limb moved towards the midline of the body (dog putting his leg down after urinating). Adductor muscles lie between the limb and the midline.

Question 27

Pronation

Answer 27

When dorsal surface of the paw is turned upper/outermost. Involves the long axis of the radius rotating around the ulna at the elbow, while the carpus is twisted.

Question 28

Supination

Answer 28

Palmar surface of the paw being turned uppermost. (Cat licks its paws to clean them).

Question 29

Protraction

Answer 29

Limb is moved forwards

Question 30

Retraction

Answer 30

Limb is moved backwards

Question 31

Circumduction

Answer 31

Entire limb is rotated through a complete circle involving the hip or shoulder joint.

Question 32

Agonist muscle

Answer 32

Muscle that causes the primary movement of the joint. (Biceps)

Question 33

Antagonist muscle

Answer 33

Muscle that causes opposing action to the agonist muscle. (Triceps)

Question 34

Synergists

Answer 34

Muscles that contract at the same time as the prime mover and help to rotate the joint.

Question 35

Fixators

Answer 35

Are muscles that act to stabilise a joint.

Question 36

Muscles of mastication

Answer 36

Group of muscles associated with the movement of the jaw.

Question 37

Trapezius muscle

Answer 37

Inserts on the spine of the scapula. Abducts the forelimb.

Question 38

Epaxial muscles

Answer 38

Lie dorsal to the transverse processes of the vertebrae and extend the vertebral column.

Question 39

Biceps brachii

Answer 39

The biceps muscle group contains two muscles which flex the elbow and extend the shoulder.

Question 40

Triceps brachii

Answer 40

Triceps muscle consists of three muscles which run from the caudal border of the scapula. Flex the shoulder and extend the elbow.

Question 41

Intercostal muscles

Answer 41

Line the rib cage, categorised into external and internal. Assist with breathing in and out.

Question 42

Rectus abdominus

Answer 42

Lie either side of the linea alba, forms the floor of the abdomen. (6pack)

Question 43

Gluteals

Answer 43

Gluteals relate to the buttock area and act to extend the hip and abduct the limb.

Question 44

Quadriceps

Answer 44

Group of four muscle bellies that work to extend the stifle.