Lecture 14: Bones & Joints

Question 1

What is the basic contractile unit of muscles? What are they innervated by?

Answer 1

Sarcomeres. PNS lower motor neurons.

Question 2

What happens at the neuromuscular junction?

Answer 2

LMN interface with skeletal muscle at the motor end plate.

Question 3

Where is ACh released in the neuromuscular junction? What does this cause?

Answer 3

The synaptic cleft. Causes membrane depolarization, leads to calcium release and allows contraction in the presence of ATP.

Question 4

Name the 5 steps of cross bridge cycling.

Answer 4

1. Binding of myosin to actin.
2. Power stroke
3. Rigor (myosin in low-energy form)
4. Unbinding of myosin and actin
5. Cocking of the myosin head (myosin in high-energy form)

Question 5

What 4 things are necessary for force production?

Answer 5

Muscle length, action potential frequency, motor units, fiber types.

Question 6

What are the three types of joints?

Answer 6

Fibrous, cartilaginous, synovial

Question 6

Fibrous joint are connected by _____ tissue and have ______ movement. What is an example of a fibrous joint?

Answer 6

Fibrous, limited. Sagittal suture is an example.

Question 7

Cartilaginous joints are connected by ________ or ___________. What are the two varieties?

Answer 7

Hyaline, fibrocartilage. Synchondroses = ex. growth plates. Symphyses = slightly flexible fusion ex. in pelvis.

Question 8

Synovial joints have _____ cartilage at __________ surfaces. The joint capsule is lined by a ___________ membrane and has six ______.

Answer 8

Hyaline, articulating, synovial, classes.

Question 9

What are the four factors that affect stability and range of motion?

Answer 9

1. Shape/arrangement of articulating surfaces
2. Tone & arrangement of surrounding muscles
3. Ligaments crossing the joint
4. Hormones

Question 10

Which cartilage is present in each class of joint?

Answer 10

No cartilage in fibrous. Hyaline & fibrocartilage in cartilaginous. Hyaline present in synovial.

Question 11

What 5 tissue components interact to form & stabilize a joint?

Answer 11

Bones, ligaments/capsule, tendons/muscle, intra-articular structures, bursae.

Question 12

Bone is a __________ tissue consisting of abundant ____ surrounding widely spaced cells.

Answer 12

Connective, ECM (extracellular matrix)

Question 13

What are some purposes of bones?

Answer 13

Bodily framework, protection, attachment points, storage of minerals, production of blood cells

Question 14

What are the names/locations of the 2 ossification sites? What is between these two?

Answer 14

Primary = diaphysis, located in middle of bone.
Secondary = epiphysis, distal/proximal to epiphyseal plate.
Metaphysis is between these two.

Question 15

What is the epiphyseal plate? Periosteum?

Answer 15

Growth plate made of cartilage. Covering of bone.

Question 16

What is the medullary cavity?

Answer 16

Hollow, fat filled portion of diaphysis in long bones.

Question 17

What do osteoprogenitor cells develop into? What does this cell do?

Answer 17

Osteoblast. Bone deposition, buildup of bone ECM.

Question 18

What two cell types maintain bone density?

Answer 18

Osteoblast build up bone tissue, osteoclasts break down bone tissue.

Question 19

Bone forms from _______ __________ (perichondrium) that are replaced by ______, a process called ___________.

Answer 19

Cartilage models, bone, ossification

Question 20

What happens after ossification?

Answer 20

Osteoprogenitors become osteoblasts, periosteum is formed.

Question 21

After ossification, ______ ossification centers form in the _________, distal to the ___________ _________.

Answer 21

Secondary, epiphyses, epiphyseal plates.

Question 22

After secondary ossification, what two anatomy form?

Answer 22

Medullary cavity & trabeculae form via osteoclasts.

Question 23

What is the last step of bone formation?

Answer 23

Cartilage forms @ epiphyseal plates.

Question 24

Compact bone is deep to the ________ and arranged in circular _______. Function?

Answer 24

Periosteum, osteons. Protection & support.

Question 25

Spongy bone is either __________ or ______ bone and is deep to the _______ bone. What is filled with and where?

Answer 25

Trabecular, cancellous, compact. Filled with red marrow in metaphysis and epiphysis.

Question 26

What two layers exist in the periosteum?

Answer 26

Outer fibrous, inner osteogenic layer.

Question 27

What increases/decreases bone density?

Answer 27

Increase = loading through sport.
Decrease = age/atrophy

Question 28

What do osteoclasts do? What does an imbalance cause?

Answer 28

Constantly work to reabsorb bone and release calcium. Osteoporosis.

Question 29

Bones serve as a reservoir of __________. What two hormones play a role in calcium homeostasis?

Answer 29

Calcium. Calcitonin = heightened osteoblast activity. Parathyroid hormone = heightened osteoclast activity.

Question 30

_______ fractures occur when bone is fractured in 3+ places. _________ fractures occur when the bone is crushed.

Answer 30

Comminuted, compression.

Question 31

____________ fractures occur when epiphysis and diaphysis separate along plate. ___________ fractures occur when the bone is pressed inwards.

Answer 31

Epiphyseal, depression.

Question 32

________ fractures produce ragged breaks from twisting. ______ ________ fractures produce incomplete breaks (one side broken, one side bent).

Answer 32

Spiral, green stick.

Question 33

What are the three phases of fracture healing?

Answer 33

Reactive, reparative, bone remodeling.

Question 34

What are boney landmarks used for?

Answer 34

Where joints form, depressions exist, openings form, muscles attach.

Question 35

Ligaments connect what? They are ________ and made of ________, and an injury of ligaments is called a _______.

Answer 35

Connect bone to bone. Dense, collagen, sprain.

Question 36

What are the difference in function between extracapsular and intracapsular ligaments?

Answer 36

Extracapsular = stabilize joint capsule.
Intracapsular = within joint but excluded from synovial cavity.

Question 37

What ate the goals of ligaments?

Answer 37

Stabilize joints, form an interosseous membrane (inside bone).

Question 38

Hyaline cartilage is most abundant but ______. Smooth surface ________ and support @ _________ such as?

Answer 38

Weakest, flexibility, joints. Ex. synovial, nose, bronchi, etc.

Question 39

Elastic cartilage is ________ tissue with _____ fibers. Provides _________ + __________ to maintain shape & structure. Examples?

Answer 39

Specialized, elastic, strength, elasticity. Ex. epiglottis, outer ear.

Question 40

Fibrocartilage is a _______ absorber, very durable, lots of _________. Example?

Answer 40

Shock, collagen. Ex. intervertebral disc

Question 41

What is the difference between osteoarthritis and rheumatoid arthritis?

Answer 41

Osteo = wear and tear, usually unilateral, ex. hip and knee.
Rheuma = typically bilateral, autoimmune disease, inflammation of joint linings + cartilage.

Question 42

What do articular discs and menisci do?

Answer 42

Absorb shock and distribute weight, fit between bony surfaces.

Question 43

What do labrum do?

Answer 43

Fibrocartilaginous lip within ball & socket joint to deepen socket + stabilize.