Lecture 14: Bones & Joints Flashcards
What is the basic contractile unit of muscles? What are they innervated by?
Sarcomeres. PNS lower motor neurons.
What happens at the neuromuscular junction?
LMN interface with skeletal muscle at the motor end plate.
Where is ACh released in the neuromuscular junction? What does this cause?
The synaptic cleft. Causes membrane depolarization, leads to calcium release and allows contraction in the presence of ATP.
Name the 5 steps of cross bridge cycling.
- Binding of myosin to actin.
- Power stroke
- Rigor (myosin in low-energy form)
- Unbinding of myosin and actin
- Cocking of the myosin head (myosin in high-energy form)
What 4 things are necessary for force production?
Muscle length, action potential frequency, motor units, fiber types.
What are the three types of joints?
Fibrous, cartilaginous, synovial
Fibrous joint are connected by _____ tissue and have ______ movement. What is an example of a fibrous joint?
Fibrous, limited. Sagittal suture is an example.
Cartilaginous joints are connected by ________ or ___________. What are the two varieties?
Hyaline, fibrocartilage. Synchondroses = ex. growth plates. Symphyses = slightly flexible fusion ex. in pelvis.
Synovial joints have _____ cartilage at __________ surfaces. The joint capsule is lined by a ___________ membrane and has six ______.
Hyaline, articulating, synovial, classes.
What are the four factors that affect stability and range of motion?
- Shape/arrangement of articulating surfaces
- Tone & arrangement of surrounding muscles
- Ligaments crossing the joint
- Hormones
Which cartilage is present in each class of joint?
No cartilage in fibrous. Hyaline & fibrocartilage in cartilaginous. Hyaline present in synovial.
What 5 tissue components interact to form & stabilize a joint?
Bones, ligaments/capsule, tendons/muscle, intra-articular structures, bursae.
Bone is a __________ tissue consisting of abundant ____ surrounding widely spaced cells.
Connective, ECM (extracellular matrix)
What are some purposes of bones?
Bodily framework, protection, attachment points, storage of minerals, production of blood cells
What are the names/locations of the 2 ossification sites? What is between these two?
Primary = diaphysis, located in middle of bone.
Secondary = epiphysis, distal/proximal to epiphyseal plate.
Metaphysis is between these two.
What is the epiphyseal plate? Periosteum?
Growth plate made of cartilage. Covering of bone.
What is the medullary cavity?
Hollow, fat filled portion of diaphysis in long bones.
What do osteoprogenitor cells develop into? What does this cell do?
Osteoblast. Bone deposition, buildup of bone ECM.
What two cell types maintain bone density?
Osteoblast build up bone tissue, osteoclasts break down bone tissue.
Bone forms from _______ __________ (perichondrium) that are replaced by ______, a process called ___________.
Cartilage models, bone, ossification
What happens after ossification?
Osteoprogenitors become osteoblasts, periosteum is formed.
After ossification, ______ ossification centers form in the _________, distal to the ___________ _________.
Secondary, epiphyses, epiphyseal plates.
After secondary ossification, what two anatomy form?
Medullary cavity & trabeculae form via osteoclasts.
What is the last step of bone formation?
Cartilage forms @ epiphyseal plates.
Compact bone is deep to the ________ and arranged in circular _______. Function?
Periosteum, osteons. Protection & support.
Spongy bone is either __________ or ______ bone and is deep to the _______ bone. What is filled with and where?
Trabecular, cancellous, compact. Filled with red marrow in metaphysis and epiphysis.
What two layers exist in the periosteum?
Outer fibrous, inner osteogenic layer.
What increases/decreases bone density?
Increase = loading through sport.
Decrease = age/atrophy
What do osteoclasts do? What does an imbalance cause?
Constantly work to reabsorb bone and release calcium. Osteoporosis.
Bones serve as a reservoir of __________. What two hormones play a role in calcium homeostasis?
Calcium. Calcitonin = heightened osteoblast activity. Parathyroid hormone = heightened osteoclast activity.
_______ fractures occur when bone is fractured in 3+ places. _________ fractures occur when the bone is crushed.
Comminuted, compression.
____________ fractures occur when epiphysis and diaphysis separate along plate. ___________ fractures occur when the bone is pressed inwards.
Epiphyseal, depression.
________ fractures produce ragged breaks from twisting. ______ ________ fractures produce incomplete breaks (one side broken, one side bent).
Spiral, green stick.
What are the three phases of fracture healing?
Reactive, reparative, bone remodeling.
What are boney landmarks used for?
Where joints form, depressions exist, openings form, muscles attach.
Ligaments connect what? They are ________ and made of ________, and an injury of ligaments is called a _______.
Connect bone to bone. Dense, collagen, sprain.
What are the difference in function between extracapsular and intracapsular ligaments?
Extracapsular = stabilize joint capsule.
Intracapsular = within joint but excluded from synovial cavity.
What ate the goals of ligaments?
Stabilize joints, form an interosseous membrane (inside bone).
Hyaline cartilage is most abundant but ______. Smooth surface ________ and support @ _________ such as?
Weakest, flexibility, joints. Ex. synovial, nose, bronchi, etc.
Elastic cartilage is ________ tissue with _____ fibers. Provides _________ + __________ to maintain shape & structure. Examples?
Specialized, elastic, strength, elasticity. Ex. epiglottis, outer ear.
Fibrocartilage is a _______ absorber, very durable, lots of _________. Example?
Shock, collagen. Ex. intervertebral disc
What is the difference between osteoarthritis and rheumatoid arthritis?
Osteo = wear and tear, usually unilateral, ex. hip and knee.
Rheuma = typically bilateral, autoimmune disease, inflammation of joint linings + cartilage.
What do articular discs and menisci do?
Absorb shock and distribute weight, fit between bony surfaces.
What do labrum do?
Fibrocartilaginous lip within ball & socket joint to deepen socket + stabilize.
