Musculoskeletal System

Question 1

Produce movement of the skeleton

Maintain posture and body position

Support and control soft tissues (and circulation)

Regulate orifices

Maintain body temperature

Store nutrient reserves

Most prevalent type, somatic, striated, multi-nucleated, and voluntary

Structure from combined tissue types (muscle, connective tissue, and nerves)

Answer 1

Skeletal muscle

Question 2

Limited to heart (myocardium), visceral, striated, involuntary

Answer 2

Cardiac Muscle

Question 3

Lining of gut, blood vessels, and glands, visceral, non-striated, and involuntary

Answer 3

Smooth Muscle

Question 4

Contract to expel contents of secreting glands

Answer 4

Myoepithelial cells

Question 5

Epimysium

Answer 5

Muscle. Dense layer of collagen fibers

Question 6

Perimysium

Answer 6

Fascicle. Collagen and elastin fibers.

Contain branching blood vessels and nerves.

About 100 microns diameter

Question 7

Endomysium

Answer 7

Surrounding muscle fiber cells. Elastin connective tissue.

Question 8

Formed from collagen fibers of perimysium and epimysium

Attach skeletal muscle to bone

Collagen fibers extend into bone matrix to provide firm attachment

Answer 8

Tendons

Question 9

Relatively long (up to 30cm long)

Multinucleated (myoblasts fuse into muscle fibers)

Rich in mitochondria

Stem cells replace damaged fibers

Answer 9

Skeletal muscle fibers

Question 10

Compose skeletal muscle fiber

Consist of bundles of protein filaments called myofilaments
Thin (actin)
Thick (myosin)

Actively shorten to produce overall muscle contraction

Answer 10

Myofibrils

Question 11

Basic contractile unit of a muscle

Boundaries are the Z-lines

Center is the M-line

I-band composed of myosin filaments - overlaps actin except in H zone

Answer 11

Sarcomere

Question 12

During a contraction

Answer 12

H-zone and I-bands get smaller

Zones of overlap increase

Z-lines move closer together

A-band width remains constant

Question 13

Motor Unit

Answer 13

Motor neuron and all the muscle fibres it supplies

The amount of tension produced depends on the number of these units stimulated to contract

Question 14

Large motor units

Answer 14

Erector spinae posture muscles

Question 15

Small motor units

Answer 15

Fingers, eye muscles; fine motor control

Question 16

Electrical impulse transmitted to neuromuscular junction at synaptic terminal

Release of neurotransmitter (acetylcholine) across synaptic cleft - signals al myofibrils in range to contract

Answer 16

Muscle Contraction

Question 17

Cross bridges

Answer 17

form when myosin binds to actin

Myosin head pivots towards M-line

ADP + P released

Question 18

Muscle tension exceeds load

Muscle shortens

(contraction - example: upwards movement of bicep)

Answer 18

Concentric muscle contraction

Question 19

Load exceeds muscle tension

Muscle lengthens

(elongation - example: downwards movement of bicep)

Answer 19

Eccentric

Question 20

Muscle tension equals load

Muscle length as a whole does not change

Typically oppose the force of gravity

No overall joint movement

Answer 20

Isometric

Question 21

Tension constant as length changes

Answer 21

Isotonic

Question 22

The movement of large numbers of calcium ions through membranes set up an electrical field, which is measured by this.

Answer 22

Electromyography

Question 23

Types of muscle fibers

Answer 23

parallel, convergent, pennate, circular

Question 24

Example of parallel muscle fiber

Answer 24

Biceps brachii. Adds force and contraction to one direction of movement.

Question 25

Example of convergent muscle fiber

Answer 25

Pectoralis major. Muscle fibers go in different directions, and converge on a point of action on the skeleton.

Question 26

Example of pennate muscle fibers

Answer 26

Rectus femoris (bipennate), deltoid (multipennate), extensor digitorum (unipennate)

Question 27

Example of circular muscle fibers

Answer 27

Around eyes or mouth

Question 28

Fascicles parallel to long axis of muscle - efficient motion and force Most common type Contraction: muscle gets shorter and belly (middle of muscle) gets wider

Answer 28

Parallel muscle fibers

Question 29

Fascicles originate over wide area and converge on common attachment site - not as much force Direction of pull can be changed depending on which fascicles contract

Answer 29

Convergent muscle fibers

Question 30

Tendon runs into muscle Fascicles form oblique angles to tendon Contain more muscle fibres than parallel of same size - generates more tension Unipenate - on one side of tendon Bipenate - on both sides of tendon Multipenate - tendon branches within

Answer 30

Pennate muscle fibers

Question 31

Fascicles concentrically arranged around opening of recess Form sphincters Contraction reduces diameter of opening

Answer 31

Circular muscle fibers

Question 32

tendons

Answer 32

bone to muscle

Question 33

ligaments

Answer 33

bone to bone

Question 34

Fulcrum between force and resistance Relatively large range of movement, but requires large force Face hanging off where the neck attaches at the occipital bone is resistant by muscles in the back of the neck.

Answer 34

First class lever

Question 35

Resistance is between the force and fulcrum Force is farther from the fulcrum than the resistance Therefore a small force can move a larger weight Resistance moves slowly and covers a short distance Chewing a jawbreaker: Muscles in the jaw pulling up at the side of the face. Fulcrum is at temporal mandibular joint, load is at the back of the molar, and forces are on the mandible of the jaw.

Answer 35

Second class lever

Question 36

Force applied between resistance and fulcrum Speed and distance traveled increases at the expense of effective force Muscles must generate greater tension to support resistance/weight at end of lever Most common lever type in the body Jaw for a load at the incisors

Answer 36

Third class lever

Question 37

Agonist

Answer 37

Prime mover muscle

Question 38

Synergist

Answer 38

Assists agonist muscle

Question 39

Antagonist

Answer 39

Opposes the movement of an agonist muscle

Question 40

Fixator

Answer 40

Steadies joint

Question 41

Moves and stabilizes the trunk Facilitates breathing Divided into anterior (hypaxial) and posterior (epaxial) musculature

Answer 41

Trunk Musculature

Question 42

Moves ribs Supports abdominal viscera Maintains inter-abdominal pressure (key for breathing and digestion)

Answer 42

Anterior (hypaxial) musculature

Question 43

Maintains body position Supports head and neck Erector spinae group composed of longissimus, spinalis, and illiocostalis Shoulder musculature Stabilize scapula during arm movement, rotate glenohumeral joint

Answer 43

Posterior (epaxial) musculature

Question 44

Muscular covering of the abdominal cavity Compress abdomen, rotate/flex trunk, stabilize trunk on the pelvis Originate on ribs/vertebral column

Answer 44

Abdominal Wall

Question 45

Parts of abdominal wall

Answer 45

External oblique, internal oblique, transversus abdominis (rectus sheath formed by the aponeuroses of the above muscles), rectus abdominis (6-pack, originates on pubis, inserts on ribs and xiphoid process)

Question 46

Breathing musculature Raise/lower the ribs to change thoracic volume (occupy space between ribs) External and internal types

Answer 46

Intercostal Musculature

Question 47

Controls position of the scapula Ascending, transverse, descending

Answer 47

Trapezius

Question 48

Rhomboids

Answer 48

Major, minor

Question 49

Serratus anterior

Answer 49

Protracts the scapula

Question 50

Vertebral, scapular, costal, iliac components

Answer 50

Latissimus dorsi

Question 51

Designed for flexibility and mobility Sometimes sacrifice stability Muscles at glenohumeral, cubital, and radiocarpal joints act to stabilize and rotate arm and hand Muscles of limb divided into functional compartments by fascia (anterior and posterior)

Answer 51

Upper Limb Musculature

Question 52

Rotate and stabilize the humerus Tendons contribute to the shape of the glenoid cavity - originate on scapula (anterior and posterior parts) and insert on the humerous (greater and lesser tubercule), and inctease stability about the joint

Answer 52

Rotator Cuff

Question 53

Muscle groups of the rotator cuff (SITS)

Answer 53

Supraspinatus Infraspinatus Teres minor Subscapularis

Question 54

Goes from the shoulder to the elbow Permit movement about the glenohumeral and cubital joints Anterior parts: Biceps brachii Brachialis (from humerus across elbow joint) Coracobrachialis (from scapula to humerus) Posterior parts: Triceps brachii

Answer 54

Arm

Question 55

Elbow to wrist Control fingers -origin on humerus, ulna, and radius -Insertion on carpals and phalanges Anterior parts (origin from medial epicondyle) -Flexor carpi (radialis, ulnaris) -Flexor digitorum (superficialis or profundus) Posterior (origin from lateral epicondyle) -Extensor carpi (ulnaris, radialis brevis, radialis longus) -Extensor digitorum -Extensor indicus

Answer 55

Forearm

Question 56

Extensors of wrist and hand originate from the

Answer 56

Lateral epicondyle of the humerus near the elbow