Muscle Form and Function

Question 1

What is the median plane?

Answer 1

Splits the body in half, right down the middle

Question 2

What is the coronal plane?

Answer 2

Splits posterior and anterior

Question 3

What is the saggital plane?

Answer 3

Divides body into left and right, parallel to the median

Question 4

What is the transverse plane?

Answer 4

Horizontal

Superior and Inferior

Question 5

What is the Oblique plane?

Answer 5

Diagonal plane

Combination of 2 other planes

Question 6

What does superior mean?

Answer 6

Cranial, nearer to head

E.g. heart is superior to the stomach

Question 7

What does superficial mean?

Answer 7

Nearer to the surface

E.g. The muscle of the arm is superficial to its bone (humerus)

Question 8

What does intermediate mean?

Answer 8

Between a superficial and a deep structure, the biceps muscle is intermediate between the skin and the humerus

Question 9

What does deep mean?

Answer 9

Farther from surface, the humerus is deep to the arm muscle

Question 10

What does medial mean?

Answer 10

Nearer to median plane

E.g. the 5th digit (little finger) is on the medial side of the hand

Question 11

What does lateral mean?

Answer 11

Farther from median plane

e.g. the 1st digit (thumb) is on the lateral side of the hand

Question 12

What does flexion mean?

Answer 12

Bring muscles to the centre, curl up in a ball- reduces the angle between segments

Question 13

What does extension mean?

Answer 13

This increases the angle between segments, straighten everything away from the body

Question 14

What is abduction?

Answer 14

Movement of structure AWAY from midline (away from centre of body)

Question 15

What is adduction?

Answer 15

Movement of structures towards the midline (or median plane) bringing the things towards centre of body

Question 16

What is circumduction?

Answer 16

Conical movement of a limb, full range of movement of limbs

Question 17

What is Opposition?

Answer 17

Brining the thumb to all the other fingers

Question 18

What is Reposition?

Answer 18

Opening fingers

Question 19

What mammal has opposition and reposition?

Answer 19

Only humans, e.g. typing, texting

Question 20

What is muscle contractility?

Answer 20

An inherent property of all cells

Question 21

What are examples of muscle contractility?

Answer 21

Myoepithelial cells in exocrine glands
Pericytes of blood vessels
Fibrillar (string like, holds everything together) proteins present in the cytoplasm linked by bonds

Question 22

What are the 3 types of muscle?

Answer 22

1. Skeletal
2. Visceral (smooth) muscle
3. Cardiac muscle

Question 23

What is skeletal muscle?

Answer 23

Movement of the skeleton and organs

Referred to as voluntary muscle

Question 24

What do the arrangements of contractile proteins give rise to in skeletal muscle?

Answer 24

Cross-striations

• Multi-nucleate= many nuclei
• Cross striations

Question 25

What is visceral (smooth) muscle?

Answer 25

Blood vessels, GI tract, urinary bladder, uterus (no control) Under autonomic (rest and digest and fight or flight)and hormonal control

Question 26

What is the structure of smooth muscle?

Answer 26

No cross-striations - One nucleus - Randomly space

Question 27

What is cardiac muscle?

Answer 27

Long, cylindrical cells, One or two nuclei centrally located - Shorter fibres - Connected end to end by complex junctions (intercalated disks/discs) Cardiac muscle cells have intrinsic contractibility One or two nuclei, fibres are shorter for quick contraction

Question 28

What is sacrolemma?

Answer 28

Plasma membrane

Question 29

What is sacroplasm?

Answer 29

cytoplasm

Question 30

What is Sacroplasmic reticulum?

Answer 30

Endoplasmic reticulum

Question 31

What are sacrosomes?

Answer 31

Mitochondria (for energy, passed on from mother)

Question 32

What are the features of skeletal muscles?

Answer 32

• Variety of shapes and sizes (morphology) • Elongated, multinucleate contractile cells (muscle fibres) • Vary in diameter from 10-100µm (i.e. x10−6) • Can extend throughout the whole length of a muscle i.e. 35cm

Question 33

What does connective muscle do?

Answer 33

Holds everything together- prevents muscle popping out during contraction

Question 34

What are the 3 layers of connective tissue?

Answer 34

Endomysium Perimysium Epimysium

Question 35

What are skeletal muscles fine movements?

Answer 35

E.g. eye muscles Small fasciculi, greater proportion of perimysial supporting tissue

Question 36

What are skeletal muscles larger movements?

Answer 36

Large fasciculi and a smaller proportion of perimysial supporting tissue

Question 37

What do collage and elastic fibres act as in skeletal muscle?

Answer 37

Support for the muscle

Question 38

How do muscles contract?

Answer 38

Skeletal muscle works by contracting | They pull, never push

Question 39

What happens when a muscle contracts?

Answer 39

One attachment is FIXED and the other is pulled Towards it

Question 40

What is isometric contraction?

Answer 40

Length of the muscle doesn't change No movement Contraction necessary to prevent movement

Question 41

What is isotonic (concentric) contraction?

Answer 41

Muscles shortens and brings attachment sites closer together

Question 42

What is isotonic (eccentric) contraction?

Answer 42

Muscle elongates under tension Force generated must be less than the load Used for control and precision Always opposing a concentric contraction

Question 43

What type of muscle contraction do almost all muscle injuries occur?

Answer 43

During eccentric contractions | I.e. the load cannot be controlled by the muscle

Question 44

Why do muscles rarely work alone?

Answer 44

For every contraction that creates movement (concentric) at least one other muscle on the other side of the joint is working to control the movement (eccentric)

Question 45

What does musculo-tendinous junction do?

Answer 45

Typically abrupt transition Different tissue types interdigitate Weak point

Question 46

What do enthesis do?

Answer 46

The tendon-bone, or ligament-bone transition May be abrupt, but usually involves fibrocartilage - dampens the effect of the force

Question 47

Why does enthesis bone thicken?

Answer 47

Nighbouring bone is thinner because it is exposed to less force The thick "tough" bone may be pulled away from the think "weak" bone; this is called an AVULSION FRACTURE

Question 48

What are the most stable joints?

Answer 48

Hip and knee joints

Question 49

What joints are the least stable?

Answer 49

Ankles

Question 50

What position does the body tend to be?

Answer 50

Tendency for the body to fall forward