Joints&Articulations

What is a joint (articulation)?

Where two bones meet; it is also where body movement occurs

• attach by ligaments

• joint is movable=weak strength

• harder to move=stronger

(tradeoff)

2 classification schemes

– Structural (anatomy)

– Functional (range of motion)

• Joint structure determines function

ex. fossa on olecranon preventing full bend back

What are the 4 structural joint classifications?

• Fibrous

• cartilaginous

• bony

• synovial (IMPORTANT!!)

What are the 3 functional joint classifications?

– Synarthrosis (immovable joint; fibrous/cartilaginous)

– Amphiarthrosis (slightly movable joint)

– Diarthrosis (freely movable joint; synovial)

What is a synarthrosis?

• An immovable, very strong joint

• may be fibrous or cartilaginous

• bones edges may touch/interlock

What are the 4 types of synarthrotic joints?

• Suture

• gomphosis

• synchondrosis

• synostosis

What is a suture?

• immovable joint found only between skull bones

• edges interlock & bound by dense fibrous conn. tissue

What is a gomphosis?

• fibrous joint that binds a tooth to its bony socket via the periodontal ligament (fibrous connection)

What is a synchondrosis?

• rigid cartilaginous bridge between two bones, like between vertebrosternal ribs & sternum

• & epiphyseal cartilage of growing long bones

What is a synostosis?

• joint made when 2 bones fuse (rare)

• like epiphyseal line (of mature long bones)

-ex. metopic suture of frontal bone

What is an amphiarthrosis?

• slightly more movable joint than synarthrosis

• stronger than a diarthrosis

• may be fibrous/cartilaginous

What are the 2 types of amphiarthroses?

• Syndesmosis—bones connected by a ligament

• Symphysis—bones connected by fibrocartilage (between Adjacent vertebrae)

(KNOW THE DIFF)

What is a synovial joint?

• freely movable diarthrosis

• usually at the ends of long bones & surrounded by a joint capsule (articular capsule; has synovial fluid)

Primary functions of synovial fluid

• Lubricates

• distributes nutrients

• absorbs shock

(fills joint cavity)

from synovial membrane; like egg yolk & has proteoglycans/hylaronan

What covers articulating bone surfaces in synovial joints?

Articular cartilage (hyaline)

• prevents direct bone-to-bone contact

• slick/smooth

• periosteum doesn’t cover joint

What structures stabilize synovial joints?

• Cartilages/fat pads

• ligaments

• tendons

• bursae

Synovial joints are mobile but weak

What is a meniscus?

A fibrocartilage pad between opposing bones; within synovial joint

Fat pads

– Adipose tissue covered by synovial membrane

– Protect articular cartilages

Ligaments

– Support & strengthen joints; bone to bone connection

– Sprain: ligament with torn collagen fibers; streatched/damages

ligaments heal slow bc low vascularity

Tendons

Attach to muscles around joint; muscle to bone

What is a bursa?

• small pocket of synovial fluid

• cushions areas where tendons or ligaments rub w other tissues

-front of knee

Factors that stabilize synovial joints/keeps in tacts

• Collagen fibers of joint capsule & ligaments

• Shapes of articulating surfaces & menisci

• Other bones/muscles/fat pads (packing material)

• Tendons attached to articulating bones

(Prevent injury by limiting range of motion)

What are the 3 planes of synovial joint movement?

• Monaxial = 1 plane (elbow)

• biaxial = 2 planes (wrist)

• triaxial = 3 planes (shoulder)

Types of movement at synovial joints

– Gliding movement

– Angular movement

– Circumduction

– Rotational movement

– Special movements

only 3 ways to move pencil

What is gliding movement?

Liner; straight line; Two flat surfaces slide past each other; ex: between carpal bones

Angular movement

movement at an angle still fixed at middle point

– Flexion & extension are movements in the anterior–posterior plane (front to back movement)

– Abduction & adduction are movements in the frontal plane (moving laterally)

What is flexion?

Decreases the angle between articulating bones

What is extension?

Increases the angle between articulating bones

What is hyperextension?

Extension past anatomical position

What is abduction?

Movement away from the longitudinal axis (laterally)

What is adduction?

Movement toward the longitudinal axis

Which body movement involves moving toward the midline?

What is circumduction?

A complete circular movement w/o rotation; at a fixed point moving circularly

Rotational movement

spinning on its axis, like spinning in place; no joint can freely rotate bc of attachments

– Rotation in reference to anatomical position

• ex: left or right rotation of head (nodding no)

– Limb rotation is relative to longitudinal axis of body (lateral/medial; y-axis)

What is medial rotation?

Internal rotation toward the body's long axis (inwards)

(rotating hand from anatomical position facing forward to facing backwards to thigh)

What is lateral rotation?

External rotation away from the body

(palm facing back closer to body to palm facing away further from body)

What is pronation?

Forearm rotation causing the palm to face posteriorly

-radius rolls across ulna

What is supination?

Forearm rotation causing the palm to face anteriorly

(forearm is supinated in anatomical position)

What is inversion?

Twisting the sole of the foot medially

What is eversion?

Twisting the sole of the foot laterally

What is dorsiflexion?

Ankle flexion; lifting the toes

What is plantar flexion

Ankle extension; pointing the toes

Which foot movement enables the ballerina to stand on her toes?

What is opposition?

pinching thumb towrds the fingers

thumb moves across the palm to face & touch tips of the fingers

What is reposition?

The movement opposite to opposition; back to normal resting/anatomical position

What is protraction?

Anterior movement in the horizontal plane; moving forward

What is retraction?

The movement opposite to protraction; pulling backward

What is depression?

Moving a structure inferiorly, or down

What is elevation?

Moving a structure superiorly, or up

What is lateral flexion?

Bending the vertebral column to the side; bending body/neck sideways away from midline

What are the 6 types of synovial joints?

• Plane

• hinge

• condylar

• saddle

• pivot

• ball-and-socket.

What is a plane joint?

A gliding joint with flattened/slightly curved surfaces & limited motion (nonaxial)

-limited motion but very strong SOLID

What is a hinge joint?

A joint allowing angular motion in a single plane; monaxial

What is a condylar joint?

(ellipsoid) oval articular surface that fits in a depression; motion in two planes (biaxial)

What is a saddle joint?

Articular surfaces fit tgt like a rider in a saddle; biaxial (THUMB)

What is a pivot joint?

A monaxial joint allowing rotation only

What is a ball-and-socket joint?

A round head fits into a cup-shaped depression; triaxial

What type of joints are between vertebral bodies?

adjacent vertebral bodies form Symphyses (Symphysis/amphiarthrosis)

Intervertebral joints

– First 2 cervical vertebrae joined by a synovial joint (pivot joint; rotation)(atlas&axis)

– Synovial joints lie between adjacent articular processes

Intervertebral disc

– Separates vertebral bodies

What is the anulus fibrosus?

tough outer fibrocartilage layer of an intervertebral disc

-attaches disc to vertebrae

What is the nucleus pulposus?

elastic, gelatinous core of an intervertebral disc that absorbs shocks

Vertebral end plates of cartilage

• Cover superior and inferior surfaces of intervertebral disc

• hyalin+fibrocartilage

What is a bulging disc?

-damage to intervertebral disc

A bulge in the anulus fibrosus that invades the vertebral canal.

What is a herniated disc?

-damage to intervertebral disc

The nucleus pulposus breaks through the anulus fibrosus & compresses spinal nerves

What do intervertebral ligaments do?

Bind vertebrae together & stabilize the vertebral column

not talk abt yet

As vertebral column moves

– Nucleus pulposus compresses

– Disc shape conforms to motion

not talk abt yet

Intervertebral ligaments

– Ligamenta flava

• Connect laminae of adjacent vertebrae

– Posterior longitudinal ligament

• Connects posterior surfaces of vertebral bodies

– Anterior longitudinal ligament

• Connects anterior surfaces of vertebral bodies

not talk abt yet

Intervertebral ligaments continued

– Interspinous ligaments

• Connect spinous processes of adjacent vertebrae INSIDE

– Supraspinous ligament

• Connects tips of spinous processes (C7 to sacrum)

• Continuous with ligamentum nuchae (C7 to skull)

not talk abt yet

What movements can the vertebral column perform?

• Flexion

• extension

• lateral flexion

• rotation.

What type of joint is the elbow?

A hinge joint involving the humerus , radius, & ulna

Joints of elbow

– Humero-ulnar joint

– Humeroradial joint

Humero-ulnar joint

• Largest, strongest joint at elbow

• Between trochlea of humerus & trochlear notch of ulna

• Limited movement

Humeroradial joint

• Smaller joint

• Articulation between capitulum of humerus & head of radius

Structures of the elbow

– Biceps brachii muscle

• Attaches to radial tuberosity; Flexes the elbow & Supinates the forearm

• Controls elbow motion

– Elbow ligaments

• Radial collateral

• Anular

• Ulnar collateral

Knee joint

– Complex hinge joint

– Transfers weight from femur to tibia

What are the 3 articulations of the knee?

• 2 femur-tibia articulations (At medial & lateral condyles)

• 1 patella-femur articulation (provides support to front of the knee joint)

What do the knee menisci do?

joint capsule & joint cavity of knee; Medial & lateral menisci

• Fibrocartilage pads

• At femur–tibia articulations

• Cushion & stabilize joint

Knee major supporting ligaments

1. Patellar ligament (front)

2. & 3. 2 popliteal ligaments (back)

4. & 5. Anterior & posterior cruciate ligaments (inside joint capsule)

6. & 7. Tibial collateral ligament (medial) & fibular collateral ligament (lateral)

Shoulder joint

(glenohumeral joint)

– Ball-and-socket diarthrosis

– Head of humerus + glenoid cavity of scapula

– Greatest range of motion; most frequently dislocated.

Joint capsule & joint cavity of shoulder

– Glenoid labrum (cartilage)

• Rim of fibrocartilage

• Extends beyond bony rim & deepens socket of glenoid cavity

– Acromion & coracoid process of scapula

• Project laterally, superior to humerus

• Help stabilize joint

Shoulder ligaments

– Acromioclavicular

– Coracoclavicular

– Coraco-acromial

– Coracohumeral

– Glenohumeral

(Shoulder separation; Partial or complete dislocation of acromioclavicular joint; dislocation)

What are the 4 rotator cuff muscles and what do they do?

• Supraspinatus

• infraspinatus

• teres minor

• subscapularis

(SITS)

surround glenohumeral capsule & create balanced forces couples

reinforce the joint capsule & limit the range of movements.

Shoulder bursae

– Subdeltoid

– Subcoracoid

– Subacromial

– Subscapular

(not talk abt)

What is the hip joint?

A strong ball-and-socket diarthrosis between the femoral head & acetabulum

(wide range of motion)

What does the acetabular labrum do?

Deepens the joint cavity & helps seal in synovial fluid

-rim of fibrocartilage

Ligaments of the hip joint

– Iliofemoral

– Pubofemoral

– Ischiofemoral

– Transverse acetabular

– Ligament of the femoral head

What is rheumatism?

Pain & stiffness in musculoskeletal system

not talk abt yet

What is arthritis?

Joint inflammation; includes rheumatic diseases affecting synovial joints

not talk abt yet

What is osteoarthritis?

Joint degeneration from wear & tear or genetic factors affecting collagen formation

not talk abt yet

What is rheumatoid arthritis?

An inflammatory condition in which the immune system attacks joint tissues.

not talk abt yet

What causes gouty arthritis?

Crystals of uric acid form within synovial fluid.

not talk abt yet

Degenerative changes

– Can be caused by joint immobilization

• Reduces flow of synovial fluid

• Can cause symptoms of arthritis

• Treated by continuous passive motion (CPM)

not talk abt yet

What happens to bones as we age?

Bone mass decreases, bones weaken, & fracture risk increases

not talk abt yet

Remodeling of bone

– Bone formation (osteoblasts)

– bone recycling (osteoclasts)

What factors affect bone formation and recycling?

Age, physical stress, hormones, calcium/phosphorus balance, genetics, & environment

not talk abt yet

Other systems interact w/ the skeletal system

• Muscles: Attach to bones

• Endocrine system: Regulates bones

• Digestive + urinary: Supply Calcium & phosphate (bone growth)

• Skeleton: Stores Calcium, phosphate & minerals

Elbow Joint

Bones

• Humerus

• radius

• ulna

Ligaments

• Ulnar collateral

• radial collateral

• annular

Cartilage

• Articular hyaline (hyalin)

Capsule

• Articular capsule

(IMPORTANT)

Shoulder Joint

Bones

• Humerus

• scapula (acromion & coracoid pross.)

Ligaments

• Acromioclavicular

• Coracoclavicular

• Coraco-acromial

• Coracohumeral

• Glenohumeral

Cartilage

• Articular hyaline

• glenoid labrum

Capsule

• Articular capsule (loose, for movement)

(IMPORTANT)

Hip Joint

Bones

• Femur

• Acetabulum of hip bone (os coxae)

Ligaments

• Iliofemoral

• pubofemoral

• ischiofemoral

• Transverse acetebular

• ligament of head of femur

Cartilage

• Articular hyaline carti.

• acetabular labrum (fibrocar.)

Capsule

• Thick articular capsule

(IMPORTANT)

Knee joint

Bones

• Femur

• tibia

• patella

Ligaments

1. Patellar ligament (front)

2.&3. 2 popliteal ligaments (back)

4.&5. Anterior & posterior cruciate ligaments (inside joint capsule)

6.&7. Tibial collateral ligament (medial) & fibular collateral ligament (lateral)

Cartilage

• Articular hyaline

• medial/lateral menisci (fibrocar.)

Capsule

• articular capsule

• large synovial cavity

(IMPORTANT)

Temporalis (muscle for presentation)

is on the side of the skull near temples

Origin:Temporal line & temporal bone (converge to the mandible narrow down;convergant muscle)

Insertion: Mandible = lower jaw

Action:Elevates mandible =pulls it; important bc it helps us keep mouth closed when we chew food/chew gum

clentch teeth=feel temporalis tighten