musculoskeletal system definitions Flashcards
(99 cards)
1
Q
skeletal muscle
A
- The muscles that move bones and enable us to walk, run and carry out a wide range of voluntary physical activities
- Voluntary: under conscious control
- Attached to the bones of the skeleton.
- Striated
- Contractions of the skeletal muscles bring about movement at the joints.
- They also give the body its form and contours, and allow it to maintain posture.
2
Q
smooth muscle
A
- Involuntary: not under conscious control, involuntary muscles.
- Non-striated
- When the smooth muscles that wrap around the alimentary canal contract, the diameter of the canal narrows, pushing the contents along. (Peristalsis).
- Stomach, small intestine
3
Q
cardiac muscle
A
When cardiac muscle contracts, it reduces the space in the chambers of the heart and pushes the blood from the heart into the blood vessels.
4
Q
contractibility
A
The ability to shorten
5
Q
Extensibility
A
The ability to be stretched.
6
Q
elasticity
A
The ability to return to the original length after being stretched.
7
Q
perimysium
A
A sheath of connective tissue called the perimysium surrounds each bundle so that it can function as an individual unit.
8
Q
epimysium
A
Sheaths of connective tissue that hold the bundles together. Towards the end of the muscle they taper and blend to form the tendon.
9
Q
sarcolemma
A
A thin, transparent plasma membrane around the cell containing cytoplasm, called the sarcoplasm.
10
Q
myofibrils
A
Bundles of thread-like protein filaments
11
Q
sarcoplasmic reticulum
A
A tubular network that surrounds the myofibrils.
A storage site for calcium ions, which are released during muscle contractions.
12
Q
myofilaments
A
Each myofibril is composed of many smaller myofilaments, made of protein, which are the actual units involved in the contraction of the muscle.
13
Q
thick myofilaments
A
Composed mainly of the protein myosin
14
Q
thin myofilaments
A
Composed mainly of the protein actin
15
Q
sarcomere
A
The distance between successive Z-lines
16
Q
sliding filament theory: contraction
A
When a muscle fibre is supplied with sufficient energy, in the form of adenosine triphosphate (ATP), and is activated by a nerve impulse, these thick and thin protein filaments slide past each other. As the thin actin filaments slide over the thick myosin filaments, the Z lines are drawn closer together and the sarcomere is shortened. This results in a shortening of the muscle fibres and, hence, a shortening of the whole muscle.
17
Q
excitability
A
Ability to be stimulated by a nerve impulse
18
Q
Z lines
A
Protein discs in the middle of the thin filaments.
19
Q
A band
A
The length of a thick filament (myosin). At the ends of the A band, the thin and thick filaments overlap.
20
Q
H zone
A
The middle of the A band, containing the thick filaments only (so it is lighter).
21
Q
I band
A
The distance between successive thick filaments, containing only thin filaments.
22
Q
sliding filament theory: relaxation
A
When the muscle relaxes, the actin and myosin filaments can be pulled past one another in the opposite direction and the muscle fibre returns to its original, uncontracted state.
23
Q
tendons
A
Fibrous, inelastic connective tissue that connects muscle to bone. They bridge the joints, so when a muscle contraction occurs, the bones move.
24
Q
antagonistic muscles
A
If muscles contract pulling a bone in one direction, another set of muscles must contract to pull the bone in the opposite direction. Thus, the muscles that move parts of the skeleton are always grouped in pairs.
Example: biceps and triceps, hamstring and quadriceps.
When the biceps muscle contracts to bend the arm, the triceps must relax, and vice versa to straighten the arm.
25
biceps
One end is fixed to the scapula (shoulder blade), and the other end is attached to the radius.
26
triceps
Fixed to the scapula and to the humerus at one end, and to the ulna at the other.
27
origin
The end of the muscle fixed to the stationary bone.
28
insertion
The attachment to the movable bone of the other end of the muscle.
29
belly
The fleshy portion of the muscle between the tendons of the origin and the insertion.
30
agonist/prime mover
A muscle that causes a desired action.
31
antagonist
A muscle that has an effect that is opposite to that of the agonists (i.e. it yields to the movement of the agonist)
32
synergists
Muscles that help the prime mover/agonist. May produce the same movement as the prime mover, or they may steady a joint during a particular movement so that unwanted movement is prevented and the agonist can function more efficiently.
*Example: without synergistic muscles, the wrist would flex every time the fist was clenched, because the muscles that curl the fingers also pass across the wrist. Synergistic muscles immobilise the wrist, stopping it from flexing.*
33
fixer
A synergist that works by immobilising a joint, acting as a stabiliser of one part of the body during movement of another part.
34
muscle tone
Maintaining partial contraction of skeletal muscles. This tightens a muscle, but not enough fibres are contracting at a time to produce movement.
Muscle tone is caused by many different fibres taking turns to contract, rather than the constant contraction of the same fibres.
Muscle tone holds many of our body parts in position.
*Example: the head is held up by the partial contraction of the neck muscles.*
35
posture
The characteristic way in which someone holds their body when standing or sitting.
*Posture depends on muscle tone.*
36
*!!!!!!! functions of the skeleton
- provides a scaffold to support the weight of the rest of the body.
- facilitates movement by being points of attachment for muscles.
- protects vital internal organs.
- produces red blood cells.
- act as storage organs for mineral salts and fat. (yellow)
37
# define
axial skeleton
- bones that lie around the *central axis* of the body.
- provides support for erect posture
- protection of the central nervous system and the organs within the thorax
38
components of the axial skeleton
- (bones forming) skull
- vertebral column
- ribs
- sternum (breastbone)
39
# define
appendicular skeleton
40
components of the appendicular skeleton
- bones of the upper and lower limbs
- pectoral girdle (shoulder)
- pelvic (hip) girdle
- girdles allow for the articulation of the limbs with the axial skeleton.
41
articulation
Where bones meet so that they are able to move relative to one another.
- Allows varying degrees of movement, depending on the bones involved. so the skeleton determines the extent of movement of body parts.
42
diaphysis
The shaft making up the main portion of the bone. A hollow cylinder of compact bone surrounding a medullary cavity.
43
medullary cavity
Used as a fat storage site and is often called the yellow bone marrow cavity.
When the bone is cut lengthwise, the diaphysis is seen to be a hollow cylinder of compact bone surrounding a medullary cavity.
44
epiphyses
| epiphysis singular
The enlarged ends of the bone, covered with a thin layer of cartilage (articular cartilage).
- Outside: compact bone
- Central region: spongy or cancellous bone
45
periosteum
The dense, white, fibrous outer covering of the bone.
*There is no periosteum at the joints.*
*At joints: bone is covered with an articular cartilage.*
46
connective tissue
Consist of cells separated from each other by large amounts of non-cellular material called matrix.
47
compact bone
Consists of many similar units called osteons/Haversian systems.
- Run parallel to the long axis of the bone
- Gives the bone its maximum strength
48
osteon
| structure
- central canal (Haversian canal) at centre
- concentric layers of bony matrix called lamellae surrounding the central canal
- a bone cell, or osteocyte occupying each lacuna
- tiny canals, known as canaliculi, running between the lacunae
- projections from the bone cells entering the canaliculi and making contact with adjacent bone cells, allowing materials to be passed from cell to cell
- at least one blood capillary, and possibly nerves and lymph capillaries, in the central canal of each osteon
49
lacunae
Small spaces in the matrix between lamellae
50
lamellae
Concentric layers of bony matrix
51
osteocyte
52
canaliculi
Tiny canals running between the lacunae
53
spongy/cancellous bone
Consists of an irregular arrangement of thin, bony plates called trabeculae.
- Bone cells occupy spaces in the trabeculae
- Nerves and blood vessels pass through irregular spaces in the matrix
54
cartilage
Contains fibres made of a protein called collagen.
- Collagen fibres are embedded in a firm matrix of a protein-carbohydrate complex called chondrin
- Strong but flexible: why cartilage is found on the surface of bones at the joints, in the trachea and bronchi, and forms the nose, larynx, and outer ear.
55
function of matrix in cartilage
- Has embedded collagen fibres.
- Firm matrix enables cartilage to work as a structural support.
- Within the matrix are spaces that contain cartilage cells called chondroblasts.
56
function of collageneous fibres in cartilage
Gives cartilage a certain amount of flexibility
57
chondroblasts
These cells produce matrix and gradually become surrounded by it until they are trapped in lacunae (small spaces). <- Once this has occurred, they are mature, and called chondrocytes.
58
hyaline cartilage
- Contains many closely packed collagen fibres throughout matrix.
- Fibres are too fine to be seen with a microscope.
- strong but flexible
- rings of trachea and bronchi
- articular cartilage at the ends of bones, where bones meet to form a movable joint
59
elastic cartilage
- Has clearly visible elastic fibres.
- Contains collagen fibres similar to those in hyaline cartilage, but less closely packed.
- Provides flexible elastic support.
- External ear
60
fibrocartilage
- Has a coarse appearance due to parallel bundles of thick collagen fibres.
- Fibres are not as compacted as hyaline cartilage, and therefore it is able to be compressed slightly.
- Ideal for regions that support the body weight, or where there is a need to withstand heavy pressure.
- Intervertebral discs of spinal column (fibrocartilage provides a cushion between vertebrae)
- Meniscus of the knee joint
- In tissue joining two sides of pelvis
61
perichondrium
A fibrous membrane of connective tissue that covers the external surface of cartilage, except where the cartilage forms the articular surface of a joint. Blood supply to cartilage comes from blood vessels located in the inner layer of the perichondrium.
62
joint
The site at which two bones come together
63
functional classification
Range of movement.
- Fibrous
- Cartilaginous
- Synovial
64
structural classification
The type of connective tissue that binds the bones together
- Immobile
- Slightly movable
- Freely movable
65
fibrous/fixed joints
No movement occurs between the bones.
Type of connective tissue: fibrous
- Very difficult to damage
- So strong that the bone is usually broken before the joint gives way
- Sutures of the skull
- Between teeth and jaw
66
cartilaginous joints
Some movement can occur.
Type of connective tissue: cartilage
- Junction of the two pelvic bones (pubic symphysis)
- Joints between adjacent vertebrae
- Joints between ribs and sternum
67
synovial/freely movable joints
Can be freely moved.
Amount of movement limited by:
- Ligaments
- Tendons
- Adjoining bones
- Shoulder
- Elbow
- Wrist
- Fingers
- Hip
- Knee
- Ankle
- Toes
*Most commonly injured joints in sport and other accidents.*
68
types of synovial joints
1. ball-and-socket
2. hinge
3. pivot
4. gliding
5. saddle
6. condyloid (or ellipsoid)
69
ball-and-socket joints
The spherical head of one bone fits into a cup-like cavity of another.
- Head of humerus (upper arm bone) fits into a depression in the scapula (shoulder blade).
- Head of the femur (thigh bone) articulates with the pelvis.
70
hinge joints
The convex surface of one bone fits into the concave surface of another, allowing movement in one plane only.
- Elbow
- Knee
- At ankle
- Between bones of fingers and toes *(you can’t bend your fingers back)*
71
pivot joints
When the rounded, pointed, or conical end of one bone articulates with a ring, formed partly by a bone and partly by a ligament.
- Joint between the first vertebra, on which the head is balanced (the atlas) and the second vertebra (the axis).
- Allows the head to rotate
- Between the radius and ulna of the forearm *(radioulnar joints)*
- Allows rotation of the hand.
72
gliding joints
Allow movement in any direction in a side-to-side or back-and-forth motion. Restricted only by ligaments or bony processes surrounding the joint.
- Between:
- carpal bones
- tarsal bones
- sternum and clavicle
- scapula and clavicle
73
saddle joints
Two bones forming the joint are saddle-shaped (concave in one direction and convex in the other). Allows both side-to-side and back-and-forth movements.
- Only true saddle joint is where the thumb joins the palm.
74
condyloid joints
One surface of a bone slightly convex so that it fits into a slightly concave depression in another bone.
Allow movement in two directions, such as up and down and side to side.
- Between:
- radius and carpal bones
- metacarpal bones and phalanges of the fingers
- *(you can move your finger up and down and side to side)*
- metatarsal bones and phalanges of the toes
75
synovial cavity
The space between articulating surfaces of the bones.
76
synovial membrane
Surrounds the synovial cavity
77
articular capsule
surrounds and encloses the joint.
78
layers of articular capsule
- Fibrous capsule: outer layer, made of dense, fibrous connective tissue attached to the periosteum of the articulating bones.
- Its flexibility permits movement at the joint.
- Its strength resists dislocation.
- Synovial membrane: inner layer, consisting of loose connective tissue.
- Inner surface of the connective tissue is well supplied with blood capillaries,.
- Synovial membrane lines the *entire joint cavity,* except articular cartilages, and a structure called the articular disc (if present).
79
synovial fluid
Secreted by the synovial membrane, fills the synovial cavity and forms a thin film over surfaces within the capsule.
80
function and structure of synovial fluid
- Lubricates the joint
- Helps to keep the articulating surfaces from making contact with each other
- Provides nourishment for the cells of the articular cartilage
- Contains phagocytic cells that remove microorganisms and debris resulting from wear and tear at the joint
*Lack of synovial fluid can result in inflammatory arthritis.*
**Structure:** similar consistency and appearance to egg white
- Only a small amount is usually present, but it can increase, especially in a joint that is injured or inflamed: enough fluid may be produced to cause swelling or discomfort.
81
articular cartilage
Covers the articulating surfaces of the bones forming a joint. Provides a smooth surface for movement.
82
articular discs
Divide the synovial cavity in two, so synovial fluid can be directed to the areas of greatest friction.
Occur in *some* synovial joints.
- In the knee, there are menisci *(singular: meniscus)* consisting of fibrocartilage extending inward from the articular capsule.
- *Tearing of the meniscus (often referred to as torn cartilage) is common in athletes.*
83
bursae
Little sacs of synovial fluid are found in some joints.
**Function:** positioned so that they prevent friction between:
- a bone and a ligament or tendon
- a bone and the skin where a bone inside a joint capsule is near the body surface
84
ligaments
Hold the bones together in many joints (connect bone to bone)
85
flexion
Bending. Decreases the angle between the articulating bones.
Bones come closer together.
86
extension
Straightening. Increases the angle between the articulating bones.
Bones move further apart.
87
abduction
Movement away from the midline of the body.
88
adduction
Movement towards the midline of the body.
89
rotation
Movement of a bone around its long axis. E.g. turning the head from left to right due to rotation at the joint between the first two vertebrae.
90
osteoporosis
When loss of bone mass becomes sufficient to impair normal functioning.
- Bone density decreases → risk of fractures increases so that even minor bumps/falls can result in serious fractures.
91
signs of osteoporosis
- Fracture is the first sign of osteoporosis
92
bones most likely to be affected by osteoporosis
- Most likely to be affected:
- vertebrae
- ribs
- pelvis
- wrist
- upper arm
93
osteoporosis prevention
- Adequate calcium intake
- Adequate vitamin D (sunlight or dietary intake)
- Plenty of exercise
- Medication for some patients
94
osteoporosis treatment
- Lifestyle changes to increase:
- calcium intake
- vitamin D production
- Exercise
- Quitting smoking
- Medication for some patients
95
causes/risk factors for osteoporosis
Smoking
96
osteoarthritis
Gradual change in the joints that occurs over time and is frequently associated with aging.
Joint cartilage deteriorates, so the bone surfaces are no longer protected. The exposed bone starts to wear away and bony spurs or growths may develop from the exposed ends of the bone forming the joint. → growths and spurs decrease space within joint cavity, restricting movement of the joint.
97
causes/risk factors for osteoarthritis
- Ageing
- Irritation of the joints
- Wear and abrasion
- < 55, osteoarthritis occurs equally in men and women, > 50: more common in women.
98
osteoarthritis symptoms
- Pain and stiffness in the joints
- More severe pain after exercise and when weight/pressure is put on the joint.
- Rubbing, grating, or crackling sound when joint is moved
- Often appear in middle age
- Almost everyone has some by age 70
- *Usually minor symptoms*
99
osteoarthritis treatment
- Medication to relieve pain
- Physiotherapy to strengthen muscles around affected joints
- Surgery to realign bones
- Joint replacement surgery
