IPHY 3410 Human Anatomy Exam 2 CU Boulder Spring 2026

Joints

an articulation

A place of union between two or

more bones

Fibrous joint

Joint cavity- no

Construction- Dense regular CT

connect bones

Cartilaginous

Joint cavity- no

Construction- Cartilage connect

bones

Synovial

Joint Cavity- yes

Construction- Ligaments and articular

capsule connect

bones; ends of bone

covered by articular

cartilage

Synarthrosis

immobile joint

Amphiarthrosis

slightly moveable

Diarthrosis

freely movable

Suture

•Fibrous Joint

Synarthrotic

•Short dense regular CT fibers

•Allow for skull growth but

gradually fuse as we age

Syndesmosis

Fibrous Joints

•Amphiarthrotic (most)

•Dense regular CT fibers

longer than in sutures

•Typically found between long

bones

Gomphosis

Fibrous joint

•Synarthrotic

•Periodontal ligament attaches

tooth to bone of socket

Symphysis

•Cartilaginous joint

Amphiarthrotic

•Bones separated by fibrocartilage pad

Synchondrosis

Cartilaginous joint

Synarthrotic

•Bones united by hyaline cartilage

Synovial Joint

Diarthrotic- freely moveable

Ligament= bone to bone (dense regular CT)

Fibrous capsule

dense irregular CT

which is an extension of the

periosteum

Synovial membrane

loose CT that

produces synovial fluid and is

vascular (lots of blood vessels)

- Synovial fluid=lubricant w/in capsule

• Blood filtrate

• Glycoproteins added from secretory

cells of CT

• Nourishes chondrocytes pressure

changes on cartilage causes fluid to

move in and out of cartilage

Joint cavity

contains

synovial fluid

Articular disc

Fibrocartilage disc

found within some

synovial joints

Rheumatoid arthritis

• Chronic inflammatory disorder

• Autoimmune immune

system attacks bodies own

tissues

• Causes inflammation of synovial

membranes pain & swelling

of joints

Osteoarthritis

Most common and mostly due to normal aging process

•Articular cartilage breaks down via normal enzyme activity or

excessive use

•Resulting bone to bone contact further damages articular surface

Gouty arthritis

Uric acid is normal waste product

produced by liver during purine

metabilization

•High levels of uric acid in blood will

precipitate out as crystals into synovial

joints TOPHUS

•Body will initiate inflammatory response

to digest crystals

Translational

joint can move in multiple directions but only w/in one plane

No AXIS of rotation

Uniaxial

joint moves around only one

axis

Biaxial

joint moves around 2 axis

Multiaxial

joint moves around 3 or

more axis

Hinge Joint

Uniaxial

Pivot Joint

Uniaxial

Plane Joint

NO AXIS

•Translational movements side to side

Conyloid Joint

•Biaxial

•Flexion/Extension

•Abduction/Adduction

Saddle Joint

•Biaxial

•Flexion/extension

•Abduction/adduction

Ball and Socket Joint

•Multiaxial

•Flexion/extension

•Abduction/adduction

•Circumduction

•Rotation

BURSA

closed fibrous sac lined by synovial membrane &

filled w/ synovial fluid

Bursa rolls and reduces friction

TENDON SHEATH

an elongated bursa-like structure

that wraps around tendons in high friction areas

Tibiofemoral

1.)between tibia and femur

2) Must withstand body weight

3) Bicondylar hinge joint

4 )Articulations between both lateral and medial condyles

5 )Bixaxial hinge joint

6 )Flexion and extension

7 )Medial and lateral rotation

8) Weight bearing joint that must reconcile 2 different and dissimilar needs

9) Stability

10) Mobility

11)In addition articulating surfaces are not well matched and the meet each other at an angle

Femeropatellar

Plane joint-> glinding action

Works with quadriceps femoris muscle in leg extension

Knee

Ligaments

Tendons

Menisci

Fibrocartilaginous discs

Articular capsule 2 layers

Fibrous outer layer

Inner synovial membrane

Oblique popliteal ligament

Expands throuhg prosterior portion capsule

Arcuate popliteal

Attaches head of fibula to posterior region of capsule

Tibial (medial ) collateral

Attaches tibia to femur

Also attaches to medial meniscus

Prevents medial movement of leg

Stops leg extension

Fibular (lateral) collateral

Attaches fibula to femur

Prevents lateral movement of leg

Stops leg extension

Anterior cruciate ligament

Attaches at supero anterior of tibia and posterior surface of femur (prevents tibia from going forward and femur going back)

Posterior cruciate ligament

Attaches posterior region of tibia and more anterior region of femur (prevents femur from going forward and tibia from going back)

Menisci

Horshoe shaped fibrocartilaginous discs that sit on top of tibia (tibial plateau)

Menisci funcitons

Enlarge contact area between tibia and femur

Guide and support condyles

Increase surface across which weight is transferred

2 Types of meniscus

Lateral Meniscus

Medial Meniscus (The tibial collateral ligament has an attachment to the medial meniscus

Frequently torn together)

Sprain

Ligament stretched or torn

Strain

Tendon/muscle stretched or torn

Functions of muscle tissues

Muscle tissues contract in response to a stimulus from the nervous system in order to:

1 )move material through the body

2)Move parts of the body produce movement

3) Generate heat

Excitability

Motor signal to contract reaches the muscle and initiates a contraction

Contractility

Muscle contracts and shortens

Extensibility

Motor signal and contraction of muscle stops and muscle is pulled back to resting length

Elasticity

Muscle is pulled beyond resting length by antagonistic muscles and is able to regain resting length after this stretch

Skeletal muscle

1. Moves the skeleton

2. 40% of body weight

3. Under voluntary control

4. Striated

Cardiac muscle

1. Only found in heart wall

2. Under involuntary control

3. Striated

Smooth muscle

1. Found within the walls of most internal organs

2. Under involuntary control

Myofilaments

Thin (actin ) filament

Thick (myosin) filament

Sarcolemma

plasma membrane

What does skeletal muscle typically attach?

Bone to bone

What else can skeletal muscle attach to besides bone?

Bone to skin or connective tissue

How long can a single muscle fiber be?

Can be the length of the entire muscle

What is the length range of skeletal muscle?

From less than 1 inch to over a foot

What is the structure of skeletal muscle cells?

Long, cylindrical, multinucleated cells (fibers)

Endomysium

loose areolar CT surrounding a single muscle fiber

Perimysium

dense CT irregular surrounding a muscle fasicle

Fascicle

a collection of muscle fibers

Epimysium

dense irregular CT surrounding a muscle

What runs through connective tissue sheaths in skeletal muscle

Arteries - provide oxygen and nutrients

Veins- remove cellular waste

Nerves- innervate muscle cells

Muscle fiber

single muscle cell

Sarcolemma

plasma membrane of a muscle cell

Sarcoplasm

cytoplasm of a muscle cell

What are myofibrils?

Rodlike bundles of actin and myosin that run parallel within the muscle cell.

What is a sarcomere?

The functional unit within a myofibril that repeats the entire length of each myofibril.

What gives muscle a striated appearance?

The organization within each sarcomere.

What is a T-tubule?

An extension of the sarcolemma that extends into the cell and wraps around myofibrils.

What is the function of T-tubules?

To carry electrical stimulus into the cell.

Sarcoplasmic reticulum

modified endoplasmic reticulum that stores and pumps calcium ions

Myofilaments

Actin and myosin

Z disc(line)

Protein disc joining adjacent sarcomeres associates within t tubule

A band

Primarily myosin (thick filaments) but some overlapping actin

I band

Primarily actin ( thin filaments)

Titin

Large spring like protein that attaches Z disc to myosin

Sliding filament theory

During a contraction actin and myosin filaments slide across one another(Sliding filament theory)

Neuron

single nerve cell

What is a motor unit?

1 motor neuron and all the muscle fibers it innervates

What happens when a single motor neuron is activated?

All fibers innervated by that motor neuron contract at the same time

How can the force exerted by a muscle be increased?

Activating more motor units within the muscle increases the force exerted

Large muscles

2000 fibers/motor unit

Smaller muscles

10 fibers/motor unit

Fine motor control

Neuromuscular junction

where neuron

stimulates muscle cell

PARALLEL MUSCLES

•Muscle fascicles run parallel to axis of

muscle

•Tendon on either end

•Look long & ropelike

•Fewer fibers than other types

•Longer fibers so able to shorten more

PENNATE MUSCLES

•Tendon runs whole length of muscle

•Fascicles attach to tendon at an angle

•Shorter fibers than parallel muscles

•Allows for more fibers so stronger

than parallel

•Resemble a feather

Unipennate

fascicles attach to

one side of tendon

Bipennate

fascicles attach to both

sides of tendon

Multipennate

branching tendon

with fascicles attaching at many

points

CONVERGENT MUSCLES

•Origin of muscle is long & broad

•Muscle fascicles collected into tendon at

insertion

•FAN SHAPED

•Relationship to other muscle types:

•More fibers than parallel

•Longer fibers than pennate

STRENGTH of comparably sized muscles

Parallel (weakest)

Convergent

Pennate (strongest)

SHORTENING ability of comparably sized muscles

Pennate (least)

Convergent

Parallel (greatest)

CIRCULAR MUSCLES

•Fascicles arranged as a ring

•Sphincter muscles when contracted the

muscle constricts an orifice (opening) keeping it

closed

Origin

Attachment site that is not moved

during a muscle action

Insertion

Attachment site that is moved

when muscle shortens