Untitled Flashcard Set

First lecture after exam 1 (10/1)

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Joint (articulation)-

Any point where two bones meet, whether or not the bones are moveable at that interface. 

-where 2 bones come together 

-some allow movement, some are just structure 

Joint classification: 

Four major types

-bony joint (synostosis)

-fiberous joints (synarthrosis)

-cartilaginous joints (amphiarthrosis)

-synovial joints (diarthrosis) 

**can replace “sis” ending with dial, EXCEPT for bony joints 

“Synostosis” (bony joints)

  -an immovable joint formed when the gap between two bones ossifies, and becomes one single bone. 

-Can occur in fibrous and cartiligenious tissue.

Ex: frontal and mandibular in infants

-Frontal and mandibular bones in infants

-Formation of sternum, coxal bone, sacrum, coccyx

-Epiphyseal line in post-adolescents

-Cranial sutures in elderly

-Attachment of first rib and sternum in elderly

Joints (fibrous joints)

“synarthrosis”

-where adjacent joints are bound by collagen fibers that emerge from one bone, cross the space between them and penetrate into the other.

  Three types of fibrous joints

- sutures

-syndesmoses

-gomphoses

Sutures

-immovable or slightly or slightly moveable fibrous joints that closely bind the bones of the skull together.

Serrate: interlocking wavy lines (coronal, sagittal, and lambdoid sutures)

Lap (Squamous): overlapping beveled edges (temporal and parietal bones)

Plane (butt): straight, nonoverlapping edges (palatine processes of the maxillae)

Syndesmosis:

-Bones are bound by longer collagenous fibers, making the bones more moveable (interosseous membrane) 

-Most moveable syndesmosis

-interossus membranes unite radius to ulna allowing supination and pronation.

-Less moveable syndesmosis

-tibia to fibula 

Gomophoses

-attatchment of a tooth to its socket

-held in place by fibrous periodontal ligament 

*collagen fibers attach to the tooth to the maxillae or mandible.

*allows the tooth to move a little under the stress of chewing 

*joint in which a cone-shaped peg fits into the pocket

Joints (Cartilaginous Joints)

-“amphiarthrosis”

-2 bones linked by cartilage

-2 types of cartilaginous tissue 

Synchondroses

        *non-moveable joint

        * connecting tissue is hyaline cartilage 

Symphyses

    *slightly moveable joint 

    *The ends of the articulating bones are covered with hyaline cartilage, but a disc of fibrocartilage connects

 the bones.

Joints (Cartilaginous Joints)

*temporarily joint in the epiphyseal plate in children 

-binds epiphysis and diaphysis

*First rib attachment to sternum

-other costal cartileges are joined to sternum by synovial joints 

Joints (Cartilaginous Joints)

Symphesis

-2 bones brought joined by fibrocartilege 

-pubic symphysis in which right and left pubic bones joined by interpubic disc

-bodies of vertebrae and intervertebral discs

*only slight amount of movement between adjacent 

Vertebrae

*collective effect of all 23 discs gives spine  considerable flexibility

Joints (Synovial Joints)

“diarthrosis”

Joint in which two bones are separated by a space called the synovial cavity:

-Most familiar type of joint

 -Most are freely movable

-Most structurally complex type of joint

-Most likely to develop painful dysfunction

Architecture of a simple Synovial Joint

A sleeve-like capsule that encloses the synovial cavity.

Outer fibrous capsule:

Dense irregular CT, heavy in collagen:

*Flexible

*High tensile strength

Inner synovial membrane:

*areolar connective tissue with elastic fibers.

*Produces synovial fluid.

Flexion, Extension and Hyperextension

flexion – movement that decreases the a joint angle

*common in hinge joints

More movement: slightly looser ligament (NOT double jointed) 

extension – movement that straightens a joint and generally returns a body part to the zero 

position

hyperextension – further extension of a joint beyond the zero position flexion and extension

 occur at nearly all diarthroses, hyperextension is limited to a few

 Flexion extension: (touching your toes, 

(10/3)

Abduction and Adduction

-Abduction: movement of a body part in the frontal plane away from the midline of the body

-hyperabduction: raiser arm over back of front or head

Adduction: 

-Elevation and Depression

-Protraction and retract

-Circumduction 

Rotation

-movement when a bone spins on its longitudinal axis

Supination and Pronation 

-primarily forearm movements

-turns the palm to face the anterior surface 

Special movements of mandible 

-lateral excursion: right or left movement from the zero position

-medial excursion: movement back to the median, zero position)

Special movements of the foot

-dorsal flexion (heel strike)

-planter flexion (toe off)

-inversion (soles turned medially)

-eversion (soles turned laterally)

-supination of foot (plantar flexion, inversion, adduction)

-pronation of foot (dorsiflexion, eversion, and abduction)

Planar joints

-back and forth, side to side movements

-intercarpas and intertarsal joints

Hinge joints

-only flexion and extension 

-elbow joint (humeroulnar joint)

-joints between phalanges 

Types of Synovial Joints

-Pivot joints: joints that allow palms to turn anteriorly and posteriorly 

Exs:

Condyloid Joint 

-Oval depression that another joint sits into

-flexion extension in two different planes

Ex: writs and metarcarpal phalangeal joints 

Saddle Joints

-Bone sits in something more of a saddle, a little more rotation

Exs:sternoclavicular joint 

Ball-and-socket joint

-most movebake joint

-complex

-bears a lot of weight (hips)

Exs: shoulder and hip

Hip Joint 

-Acetabular labrum

-Acetabulum

-head of femur

-greater trochanter

-round ligament 

-shaft of femur

Dislocation of the hips is rare.

Some infants suffer congenital dislocation

-Actabulum is not deep enough to hold the head of the femur in place 

-harness is worn for 2-4 months & can assist with proper positioning

Synovial joint accessories

-collateral ligaments of the knee joint

-menisci

*allow bones of different shapes to fit together more tightly 

*pads of cartilage lie between the articular surfaces of the bones 

Tibia collateral ligament (MCL)- runs on the inside of the knee

FIbular collateral ligament (lateral collateral ligament)- runs on the outside of the knee

                              * both prevent tibia from sliding in or out 

In between these bones 2 ligaments criss-cross. One comes from the front of tibia to the back of femur (ACL) - prevents tibia from sliding backward ex: stepping back sliding

The other comes from the back forward (TCL)- prevents from hyper extending

KNOW THESE FOR EXAM (she gave us these)

To keep the meniscus in place, transverse ligament anchors it down. 

If you get a tear, it won’t be able to freely flap around, it will aggravate the tissue, cause the tissue to be inflamed and may release more synovial fluid. 

Knee injuries and Arthroscopic Surgery

-highly vulnerable to rational and horizontal stress

-most common injuries are from the meniscus and anterior cruciate ligament (ACL) 

-heal slowly due to scanty blood flow

Anthroscopy 

-when the interior of the joint is viewed through a pencil-thin arthroscope inserted through a small incision. 

-less damage 

-quicker recovery 

-about 9 months to fully repair

Bursae & Tendon Sheaths

Bursae

-sac-like structures containing fluid like synovial fluid

-located between tendons, ligaments, and bones

-cushion between the movement of these body types

Tendon Shealth's

-wrap around tendons

-reduce friction at joints

(10/8)

Joint & Range of motion 

*Arrangement and tension of the muscles 

-muscle tension reinforces the restraint placed on a joint by its ligaments which restricts movement.

*Contact of soft parts

-the point where body surface contacts another may limit mobility

*Hormones 

-flexability can be effect by hormones

-Relaxing increases the flexibility of the public symphysis and loosens the ligaments between the sacrum and hip bone towards the end of pregnancy.

*Disuse

-Movement may be restricted if a joint has not been used for an extended period. 

 -When you don't pull on a ligament, tissue, muscle, it will eventually tense up. 

-When it tightens up it's going to hurt and you will need to stretch it out! 

-must keep moving!

Joints and levers

Levers enhance the speed or power of the limb that is moving.

-any elongated rigid object that rotates around a fixed point called fulcrum

-rotation occurs when an effort applied overcomes resistance (load) at some other point 

Types of levers

*First-class lever

-has fulcrum in the middle between effort and resistance (EFR)

-atlanto-occipita; joint lies between the muscles on the back of the neck and the weight of the face

-loss of muscle tone occurs when you nod off in class (cuts the signal from the nerves off and causes head to bob forward, when efforts is not large enough then, head goes forward)

*Second-class lever

-resistance between fulcrum and effort (FRE)

-resistance from the jaw joint and the pull of the digastric muscle on the chin as it opens the mouth quickly. 

-allows you to lift more 

*Third-class lever

-effort between the resistance and the fulcrum (REF)

-most joints of the body 

-the effort applied by the biceps muscle is applied to the forearm between the elbow joint and the weight of the hand and the forearm

Levers confer two advantages:

-exert more force against a resisting object than the force applied to the lever

Ex: human moving a heavy object with the help of a crowbar

-to move the resisting object farther and faster than the effort arm is used

Ex: movement of the rowing a boat & as one increases, the other decreases

(Ex) Temporomandibular joint 

-articulation of the condyle of the mandible with the mandibular fossa of the temporal bone 

-This joint synovial cavity is divided into superior and inferior chambers by an articular disc.

TMJ syndrome 

(Temporomandibular Joint)

-you can wear down the articular disks and you will have bone pushing on bone and wear down the bone and it will be hard to open your mouth and slide. 

Signs:

-moderate intermittent facial pain

-clicking sounds in jaw

-Limitation of jaw movement

-headaches, vertigo (dizziness), tinnitus (ringing in the ears)

-pain radiating from jaw down the neck, shoulders, and back

Cause 

-a combination of psychological tension and malocclusion 

(misalignment of teeth)

Treatment

-psychological management, physical therapy, analgesic and anti-inflammatory drugs, corrective dental appliances to align teeth.

Aging

-may result in decreased production of synovian fluid

-articular cartilage become thinner

-ligaments shorten and lose some of their flexibility

-osteoarthritis is partially age-related

-stretching and aerobic exercises are helpful in minimizing these effects

-help to maintain the effective functioning of ligaments, tendons, muscles, synovian fluid, and articular cartilage 

“Rheumatism”

-any painful disorder of supporting system 

Osteoarthritis

-wear and tear

-decay of articular cartilage - new bone formation at joint magins - spurs

Factors

-aging

-obesity (crushing weight on joints will crush cartilage)

-irritation of joints (prior injury)

-muscle weakness (hold joints together and keep joints together, support joint and movement of joints, weakness means more movement which will wear on joints)

    NO genetic components!!!

Rheumatoid Arthritis

-autoimmune disorder

-inflammation of synovial membranes

*membrane thickens, synovial fluid accumulates - swelling

*synovial membrane produces “pannus” - adheres to and erodes articular cartilage 

*with cartilage loss, fibrous tissue joins bones, calcifies to fuse joint 

As we wear out cartilage (not really seen in big joints) those two bones can fuse together (small bones). Most commonly effects smaller joints bc lack of fluid n the bones are so close together to start with 

Effects

-Children (response to viral infection and body responds with immune infection)

-Older people 

 No true cure

Joints (arthroplasty)

Arthroplasty

-joints may be replaced surgically with artificial joints 

-most commonly replaced: hips, knees, and shoulders

(10/15)

Three types of muscular tissue

skeletal 

-long fiber structure

-multinuclei (nuclei found on outer edges  (helps me ,move, allow wink, smile, chew & Externally movement)

-cardiac 

-shorter, branched

-one nuclei found generally in the middle 

-comes together merges when the ends of the cells come together

-(heart, so it can beat and circulate blood throughout body)

-smooth 

-skinny little taper cells

-one nucleus 

-looks like maggots

-(internal movement, intestines, bladder urine, blood vessels)

Skeletal muscle tissue

-moves muscle or maintain stability in the body

-straited

-voluntary (can control all muscles)

    Functions:

-producing body movements (walking and running)

-stabalizing body positions (posture) 

-moving substances within the body (heart muscle pumping blood) (moving substances in the digestive tract)

-generating heat (contracting muscle produces heat–generates ATP, leading to shivering increases heat production)

Properties of muscular tissue

-excitability (ability to respond to stimuli)

-contractability (ability to contract forcefully when stimulated)

-extensibility (ability to stretch without being damaged)

-elasticity (ability to return to an original length)

Skeletal muscle components

-cells (“fibers” generative force)

-connective tissue (anchor, structure)

-blood (nutrients, waste)

-nerves (control, feedback)

Components

Epimysium 

-outter most layer

-surrounds numerous bundles of fascicles 

Perimysium

-seperates 10-100 muscle fibers into bundles called fascicles  

Endomysium

-seperate individual muscle fibers from one another 

Skeletal muscle cells

-arise from mesenchyme as myoblasts

-replicate, then fuse to form mature muscle fiber

-10-100 micron diameter

-up to 30 cm long

-hundreds of nuclei

-do not divide

-Same number of cells at birth,most last a lifetime 

-growth by hypertrophy

-some myoblasts persist as "satellite cells” -can fuse to make new fibers (IMPORTANT!!)

-limited potential- heavily damaged muscle does not repair

Fascia

-sheet of irregular connective tissue

Tendons

Cord like structure that attaches a muscle to a bone

Nerve supply

Neurons that stimulate skeletal muscle to contract 

Blood supply

Fascicle orientation of muscles

-strength of a muscle and the direction of its pull are determined partly by the orientation of its fascicles 

Identify different orientations and examples of them that the books provides

Muscle origins and insertions

Origin

-bony attachment at stationary end of muscle 

Belly

-thicker, middle region of muscle between origin and insertion\

Insertion

-bony attachment to mobile end of muscle

Muscle actions across elbow

Prime mover- brachialis

Synergist- biceps brachii

Antagonist- triceps brachii

Fixator- muscle that hold scapular firmly in place

-rhomboids

(10/13)

Prime mover- brachialis (does most of the work)

Synergist- biceps brachii (helps out)

Antagonist- triceps brachii

Fixator- muscle that hold scapula firmly in place

-rhomboids

Intrinsic and extrinsic muscles 

Intrinsic muscles act on a designated region, but has its origin elsewhere

Fingers- extrinsic muscles in the forearm 

Muscle cell (image)

-muscle cells/muscle fibers 

-sarco means something to do with muscle cell

-cell membrane made up of phospholipic bilayer 

Cell membrane, plasma mema, carcolemma (all of the same thing) 

-transverse tubules- extensions of the sacrallemma 

Mitochondria- keeps the same name -makes ATP and need glucose and oxygen to make ATP

Smooth endoplasmic reticulum- sarcoplasmic reticulum (blueish) 

Fluid filled environment inside the membrane- cytoplasm - sacroplasm 

Lots of calcium stored un sarcoplasm reticulum 

Myofibrils- contractile units of the cell, determines the strength. The more you have, the size gets bigger, grows hypertrophically, and gets stronger. Fewer you have, the smaller the size gets and it gets weaker. (rope made of multiple threads together)

Internal structure of a muscle fiber: 

Glycogen- stored form of glucose (combines together in 1 molecule)

Oxygen- get oxygen from blood -need to store oxygen just incase not getting blood quick enough

Mitochondia

Muscle cells 

Repeating structures (purple orange) 

Must identify Muscle Striations and Their Molecular Basis and Contraction and Relaxation of Skeletal Muscle (slides)!!

Motor proteins 

-use ATP

Myofibirl features 

1. Contractile proteins 

-generate force during contraction

2. Regulatory proteins

-switch the contraction process on and off

3. Structural proteins

-Align the thick and thin filaments properly, Provide elasticity and extensibility, Link the myofibrils to the sarcolemma

Structural proteins 

Titin

-stabalize the position of myosin

-accounts for much of the elasticity and extensibility of myofibrils 

-extends from Z disc to M line 

Dysrophin

-links thein filaments to sacrolemma 

-hook myofilaments to the membrane 

Tropamyocin (big brown one)

Tropman (short blue one) 

-when by itself, the tropomyosin will be covering up the bending spots

-hooked on to tropamycin

When calcium is present in the cell it will bing the trapman 

When you take calcium away, cytoplasmic reticulum- no  muscle retraction

(10/15)

 important lecture lots will be on the exam!!!!!!

(little review from last lecture)

Myofibrils run the whole length of the cell

When they get a signal from the nerve it will cause the sarcomere to shorten when the cell is told its time for you to contract

In between z discs are the sarcomeres

Myocin- thick filament 

 When calcium binds to troponin it'll change the shape of it and pull on the tropomyosin and change it up causing a muscle contraction 

Anytime calcium is floating around in cells it will be able to bind to troponin and cause a muscle contraction (must know!!)

In order for it to let go it needs to bind to an ATP then it’ll let go. Then it needs an app to let go. 

On the surface there are calcium pumps pumping calcium into —-- system. 

When you die you'll no longer be making ATP. 

Rogor mortis

-hardening of muscles and stiffening of body beginning 3 to 4 hours after death

-deteriorating sarcoplasmic reticulum releases Ca

-deteriorating sarcolemma allows Ca to enter cytosol

-Ca activates myosin-actin cross bridging

-muscles contracts, but cannot relax

Muscle relation requires ATP, and ATP production is no longer produced after death

-peaks around 12 hours after death, diminishes over 48-60 hours after death

Triggering muscle contraction 

All the way around the membrane you will have something called a sodium potassium pump that uses ATP to work.

When the pump runs its pumps 3 sodium out of the cell and 2 potassium into the cell. Sodium out 2 potassium in

200,000 pumps of potassium a second

300,000 pumps of sodium a second

Huge amounts of sodium outside the cell

Huge amounts of potassium on the inside of the cell

The outside of the cell is going to become more positively charged

The inside of the cell is going to become very negatively charged 

It is polarized because you have opposite charges on two sides of the membrane 

This pump is constantly pumping sodium out, while constantly pumping potassium (k) in. 

If they were allowed to move where they wanted to go, they would diffuse across the membrane.

A channel is different then a pump.  A pump is picking them up and moving them specific, a channel is simply just an open door. Sodium is going to desperately try to move inside of the cell. It will start moving very fast. Sodium is positive and the charge will go up. But if you  close the sodium channel and open up the K channel, and K gets to move anywhere it wants to go, it'll want to go from where it's in highest concentration to where there is less or none. It'll wanna go outside of the cell, if you take it out the charge will go up then it'll go down. This is called an action potential. Need to understand that because of the fact that we have sodium pumps outside of the muscle cell and potassium inside of muscle, if you open up channels for Na to freely move, it'll always try to move inside of the cell. If you allow K to freely move, it'll always wanna move outside of the cell. ACTION POTENTIAL!!! WILL CHANGE CHARGE OF THE CELL!!!

If you have a muscle cell, inside there are myofibrils attached to the membrane. On the outside of the cell you have a nerve. When you get to the very end of the nerve you will find synaptic balls. 

The nerve only communicates with the outside of the cell with the neuromuscular junction (nerve and muscle come together where it gets its name).

The part of the sarcolemma motor end plate is the part of the sarcolemma that the nerve is coming up to and forming 

In the nerve, in the synaptic ball, there are vessels formed in the ball, store a chemical inside them called acetylcholine (ACH). 

When you send the signal down the nerve and when it gets to the synaptic ball, the ball will release the chemicals to the outside of the synaptic ball. 

Sodium channels, closed normally, found closed. Lydongaged channels because receptors o oe slide that bind to certain leiains. When they bind to acetylcholine. 

The acetylcholine will bind to sodium receptors and when they bind they will open up. When they open up, sodium is coming in. creating an ACTION POTENTIAL. That sodium, will tell the channels to open up and when they do, calcium will be released outside the cell. 

 When the signal is down there and the cedocolene is released. When sodium comes in it allows the channels to open up and calcium be released. 

As long as acedocolin is in here, the heart can not relax. Need to stop sodium from coming in. They only open when having an action potential. How do you get rid of acedocolene? The cinatic cleft will release acetylcholinesterase. This is like a pacman and will go right through there and chew up acetylcholine. This will allow the muscle to relax. 

End of the nerve -synaptic ball

What's stored in synaptic ball- acetylcholine

What happens when acetylcholine get released from ball- 

When they open what direction does sodium go to- towards the cell

This will cause - action potential

What does action potential do- opens  

Sodium has entered the cell- 

Calcium comes out, what does it bind to- tropamyne

What unit shortens when u get a muscle contraction- sarcomeres

What gets released as acetochoyne- aacetylcholinesterase

What does acetylcholinesterase do- chews up acetylcholine

This will close- sodium channels

How to study this: be able to write every step

If i block the release of acetocholyne - stop muscle contractions 

If you have bacteria in the can it'll replicate and produce antoxins.

(10/17)

The synaptic ball stores Acetocholyne.

Calcium binds to troponin causing myocin to shift.

Once it shifts these repeating structure (sarcomeres) will start to shorten

While acetylcholine is released acetylcholinesterase is also released. 

Curare

-a plant poison used by South American Indians on arrows and blowgun darts

-causes muscle paralysis by blocking ACh receptors inhibiting Na+ ion channels 

-derivatives of curare are used during surgery to relax skeletal muscles 

Anticholinesterase

-slow actions of acetylcholinesterase and removal of ACh 

-can strengthen weak muscle contractions

Muscle Metabolism 

Production of ATP in muscle fibers 

   -a huge amount of ATP is needed to:

      Power the contraction cycle

      Pump Ca+ into the SR

The ATP inside muscle fibers will power contraction for only a few seconds

ATP must be produced by the muscle fiber after reserves are used up

Muscle fibers have 3 ways to get ATP

1. From creatine phosphate (substrate level

phosphorylation/phosphagen system)

2. By anaerobic cellular respiration (fermentation/ glycogen-lactate system) 

      3.) By aerobic cellular respiration

Immediate energy

-short, intense exercise 

-muscles meet most ATP demand by borrowing phosphate groups from other molecules and transferring them to ADP

-2 enzymes control these phosphate transfers

Myokinase & Creatine Kinase

Myokinase: Binds to 2 ADP, burning through ATP, so a lot more ADP. Taking less energy ADPs and creating another ATP.

Creatine Kinase: Inside cells we have creatine phosphate stored in our muscle cells bind to an ADP and bind to a creatine phosphate. The enzyme will clean the phosphate off and put it so that creatine and ATP will be released. 

Will last about 15 seconds. 

Muscle metabolism

Aerobic respiration: activity that lasts longer than half a minute depends on aerobic respiration.

Each molecule of glucose yields 36 molecules of ATP

 Muscle tissue has 2 sources of oxygen 

-oxygen from hemoglobin in the blood

-oxygen replaced by myoglobin in the muscle cell

What is muscle fatigue

Fatigue when our doing really high intensity activities

Fatigue in low-intensity (long duration) exercise 

Joints, or articulations, are points where two bones meet, allowing for movement or serving as structural connections. Joints are classified into four major types:

1. Bony Joints (Synostosis)

• Immovable joints formed when two bones ossify into a single bone.

• Examples: infant frontal and mandibular bones, epiphyseal line in adults, fused cranial sutures in elderly.

2. Fibrous Joints (Synarthrosis)

• Adjacent bones are bound by collagen fibers, offering little to no movement.

• Sutures: Immovable or slightly movable joints binding skull bones (Serrate, Lap, Plane types).

• Syndesmoses: Bones bound by longer collagenous fibers, allowing more movement (e.g., interosseous membrane between radius/ulna or tibia/fibula).

• Gomphoses: Attachment of a tooth to its socket via the fibrous periodontal ligament.

3. Cartilaginous Joints (Amphiarthrosis)

• Two bones linked by cartilage.

• Synchondroses: Non-moveable joints where bones are united by hyaline cartilage (e.g., epiphyseal plate, first rib to sternum).

• Symphyses: Slightly moveable joints where bone ends are covered with hyaline cartilage, but a disc of fibrocartilage connects them (e.g., pubic symphysis, intervertebral discs).

4. Synovial Joints (Diarthrosis)

• Characterized by a synovial cavity separating two bones, making them freely movable. They are the most complex and prone to dysfunction.

• Architecture: Consists of an outer fibrous capsule (dense irregular CT) and an inner synovial membrane (areolar CT) that produces synovial fluid.

• Movements: Include flexion, extension, hyperextension, abduction, adduction, elevation, depression, protraction, retraction, circumduction, rotation, supination, pronation, and specialized movements for the mandible and foot.

• Types of Synovial Joints: Include planar, hinge, pivot, condyloid, saddle, and ball-and-socket joints (the most movable, like the hip and shoulder).

• Accessories: Collateral ligaments (MCL, LCL), menisci (cartilage pads for fit), and the transverse ligament (anchors meniscus). Notable ligaments include the Anterior Cruciate Ligament (ACL) and Posterior Cruciate Ligament (PCL) in the knee.

• Knee Injuries and Arthroscopic Surgery: The knee is vulnerable to stress, with meniscal and ACL injuries being common. Arthroscopic surgery offers less damage and quicker recovery for joint repair.

• Bursae & Tendon Sheaths: Sac-like bursae and tendon sheaths reduce friction between tendons, ligaments, and bones.

Joint Range of Motion

• Influenced by the arrangement and tension of muscles, contact of soft body parts, hormones (like Relaxin during pregnancy), and disuse (leading to stiffness).

Joints and Levers

• Levers enhance the speed or power of limb movement, rotating around a fulcrum.

• First-class lever (EFR): Fulcrum is between effort and resistance (e.g., atlanto-occipital joint).

• Second-class lever (FRE): Resistance is between fulcrum and effort (e.g., opening mouth).

• Third-class lever (REF): Effort is between resistance and fulcrum (most body joints, e.g., biceps flexing forearm).

Temporomandibular Joint (TMJ)

• Articulation of the mandibular condyle with the temporal bone, featuring an articular disc.

• TMJ Syndrome: Characterized by facial pain, jaw clicking, limited movement, headaches, vertigo, and tinnitus. Caused by psychological tension and malocclusion, treated with physical therapy, medication, and dental appliances.

Joint Disorders and Aging

• Aging: Leads to decreased synovial fluid, thinner articular cartilage, and shortened ligaments, contributing to osteoarthritis. Regular exercise helps.

• Rheumatism: A general term for painful disorders of the supporting system.

• Osteoarthritis: A