Learn: Anatomy lecture mideterm 2

functional classifications of joints

synarthrosis, amphiarthrosis, diarthrosis

synarthroses

immovable; common in the axial skeleton

amphiarthroses

slightly movable; common in axial skeleton

diarthroses

freely movable; common in appendicular skeleton (all synovial joints)

structural classifications of joints

fibrous, cartilaginous, synovial

structure of fibrous joints

connected by fibrous connective tissue, no joint cavity, immovable or slightly movable

types of fibrous joints

sutures, synchondroses, gomphoses

sutures

bones are tightly bound by a minimal amount of dense fibrous connective tissue, only between skull bones, allows bone growth so the brain can expand during childhood

syntoses

closed sutures

syndesmoses

bones connected exclusively by ligaments, amount of fibers depends on length of fibers

examples of syndesmoses

tibiofibular joint (immovable synarthrosis), interosseous membrane (between radius and ulna, freely movable diarthrosis)

gomphoses

peg in socket joint, only example is teeth in socket connected by periodontal ligament

structure of cartilaginous joints

bones are united by cartilage, lack a joint cavity

types of cartilaginous joints

synchondroses, symphyses

synchondroses

hyaline cartilage unites bones; epiphyseal plates and first sternocostal joint (between 1st rib and manubrium)

symphyses

fibrocartilage unites bones, resists tension and compression; hyaline cartilage present as articular cartilage; slightly movable joints that provide strength with flexibility

examples of symphyses

intervertebral discs, pubic symphysis

synovial joints

most movable; all are diarthroses (freely movable); each contains a fluid filled joint cavity (unique to synovial joints)

structure of all synovial joints - articular cartilage

ends of epiphyses are covered with hyaline cartilage; absorbs compression

structure of all synovial joints - joint (articular) cavity

unique to synovial joints; cavity is a potential space that holds a small amount of synovial fluid

structure of all synovial joints - articular capsule

enclosed in a 2 layered capsule; fibrous layer (dense irregular connective tissue which strengthens joint), synovial membrane (loose connective tissue)

synovial membrane

lines joint capsule and covers internal joint surfaces; functions to make synovial fluid

structure of all synovial joints - reinforcing ligaments

often are thickened parts of the fibrous layer; sometimes are extrascapular ligaments located outside the capsule (fibular and tibial collateral ligaments of the knee; sometimes are intrascapular ligaments (located internal to the capsule)

structure of all synovial joints - synovial fluid

a viscous fluid similar to raw egg white; filtrate of blood (leaks from capillaries in synovial membrane); contains glycoprotein molecules secreted by fibroblasts

structure of all synovial joints - richly supplied with sensory nerves

detect pain; most monitor how much the capsule is being structured

structure of all synovial joints - rich blood supply

most supply the synovial membrane; extensive capillary beds produce basis of synovial fluid; branches of several major nerves and blood vessels

weeping lubrication

pressure on joints squeezes synovial fluid into and out of the articular cartilage (avascular); lubricates the joint; prevents overheating and subsequent destroyal of joint tissue

articular discs

in some synovial joints (meniscus); occurs in temporomandibular, sternoclavicular, and knee joint; occurs in joints whose articulating bones have somewhat different shape; distributes load more evenly and minimizes wear and damage; may also allow two different movements at the same joint (jaw)

bursae

a flattened fibrous sac lined by a synovial membrane; closed bags of lubricant; reduce friction between body sheaths

tendon sheaths

an elongated bursa that wraps around a tendon; reduce friction between body sheaths

synovial joint movements

gliding: one bone slides across the surface of another

angular movements: movements that change the angle between bones

rotation: movement around a bone’s long axis

gliding

flat surfaces of 2 bones slip across each other; occurs between carpals, tarsals, and articular processes of vertebrae

angular movements

increase or decrease angle between bones; usually in the sagittal plane

flexion - decreasing angle

extension - increasing angle

abduction - moving a body part away from the midline in the frontal plane

adduction - moving a body part towards the midline in the frontal plane

circumduction - moving as a cone (circle) in space

rotation

involves turning movement of a bone across its longitudinal axis; only movement allowed between Atlantoaxial joint; occurs at hip and shoulder joint

medial rotation - rotating towards the median plane

lateral rotation - rotating away from median plane

special movements

elevation - lifting body part superiorly

depression - moving elevated part inferiorly

protraction - non angular movement anteriorly

retraction - non angular movement superiorly

special movements

supination - forearm rotates laterally, palm faces anteriorly

pronation - forearm rotates medially, palm faces posteriorly; brings radius across the ulna

opposition - thumb moves across the palm to touch the tips of other fingers

special movements

inversion - special movement at the foot; turns sole medially

eversion - special movement at the foot; turns sole laterally

dorsiflexion - up movement of the foot; lifting the foot so its superior surface approaches the shin

plantar flexion - depressing the foot, elevating the heel

types of synovial joints

can be described functionally; nonaxial, uniaxial, biaxial, multiaxial

nonaxial

adjoining bones dont move around a specific axis

nonaxial joints - plane joint

articular surfaces are flat planes; short gliding movements are allowed; doesnt involve rotation around any axis

ex: intertarsal and intercarpal joints

uniaxial

movement occurs around a single axis; flexion/extension or rotation

uniaxial joints - hinge joint

cylindrical end of 1 bone fits into a trough on another bone; angular movement is allowed on 1 plane

ex: elbow joint, ankle joint, and joints between phalanges

uniaxial joints - pivot joint

sleeve and axle or facet and process articular surfaces; rotating bone turns only around its long axis

ex: proximal radioulnar joint, Atlantoaxial joint

biaxial

movement occurs around 2 axes; thus the joint enables motion along both the frontal and sagittal planes; flexion/extension and abduction/adduction (rotation is generally restricted or absent)

biaxial joints - condylar (or ellipsoid) joints

oval articular surfaces; side to side (abduction/adduction), back and forth (flexion/extension)

ex: metacarpopharangeal (knuckle) joints, wrist joint

biaxial joints - saddle joints

each articular surface has concave and convex surfaces; side to side (abduction/adduction), back and forth (flexion/extension)

ex: 1st carpometacarpal (allows opposition of the thumb)

multiaxial

movement can occur around all 3 axes and along all 3 body olanes; flexion/extension, abduction/adduction, and full rotation

multiaxial joints - ball and socket joint

spherical head of 1 bone fits into round socket of another

ex: shoulder joints, hip joints

temporomandibular joint features

modified hinge joint; condylar process of mandible articulates with mandibular fossa of temporal bone; multiaxial but not ball and socket

temporomandibular joint movements

2 surfaces of the articular disc allow hinge-like movement and gliding of superior surface anteriorly

• sagittal axis (lateral excursion): side to side

• vertical axis (hinge): elevation/depression

• horizontal axis (gliding): protrusion/retraction

temporomandibular joint information

most easily dislocated joint because of the shallow socket

• almost always dislocates anteriorly

• condylar process glides anteriorly, ending up in the infratemporal fossa of the skull

sternoclavicular joint

saddle joint; performs multiple complex movements; 4 ligaments surround joint

sternoclavicular joint ligaments

• anterior and posterior sternoclavicular ligaments

• interclavicular ligament

• costoclavicular ligament

glenohumeral joint features

ball and socket joint; head of humerus and shallow glenoid cavity of scapula (glenoid cavity is slightly deepened by a rim of fibrocartilage called the glenoid labrum

• glenoid labrum extends from margin of cavity to anatomical neck of humerus

glenohumeral joint ligaments

• only strong thickening of capsule is superior coracohumeral ligament (helps support weight of upper limb)

• anterior part of capsule thickens slightly into 3 weak glenohumeral ligaments

glenohumeral joint and rotator cuff tendons

muscle tendons contribute to joint stability

rotator cuff is made of 4 muscles and associated tendons

• subscapularis

• supraspinatus

• infraspinatus

• teres minor

rotator cuff injuries are common shoulder injuries

humeroulnar joint features

hinge joint (allows only flexion/extension); articulation of humerus with trochlear notch of ulna forms hinge

humeroulnar joint ligaments

• articular capsule attaches to humerus and ulna and to anular ligament of radius (ring around radius’ head)

• radial collateral and ulnar collateral ligaments prevent lateral and medial movements

• tendons of biceps and triceps brachii provide stability

radiocarpal joint features

condylar joint; composed of radiocarpal and intercarpal joints

• radiocarpal joint: joint between radius and proximal carpals (scaphoid + lunate); allows for flexion/extension, abduction/adduction, circumduction

• intercarpal joint: joint between proximal and distal rows of carpals; allows for gliding movements

radiocarpal joint ligaments

stablized by numerous ligaments

• palmar radiocarpal ligament anteriorly

• dorsal radiocarpal ligament posteriorly

• radial collateral ligament laterally

• ulnar collateral ligament medially

hip joint features

ball and socket; movement occurs in all axes (limited by ligaments and acetabulum); head of femur articulates with acetabulum

hip joint ligaments

• stability comes chiefly from acetabulum and capsular ligament

• acetabulum labrum fibrocartilage prevents slippage from socket

• muscle tendons contribute somewhat to stability

knee joint features

largest and most complex; acts primarily as a hinge joint; wheel shaped condyles of femur roll along almost flat condyles of tibia; has some capacity for rotation when leg is flexed

knee joint structure

• structurally considered compound and bicondyloid

• 2 fibrocartilage menisci occur within joint cavity

• femoropatellar joint: shares joint cavity; allows patella to glide across distal femur

knee joint capsule

covers tibial and femoral condyles (posterior and lateral aspects of knee but not anterior

reinforced by several capsular and extracapsular ligaments

knee joint extracapsular and capsular ligaments

become taut when knee is extended

• fibular and tibial collateral ligaments

• oblique popliteal ligament

• arcuate popliteal ligament

knee joint anterior ligaments

• patellar ligament

• medial and lateral patellar retinacula

knee joint intracapsular ligaments

cruciate ligaments: cross each other like an “X” ; runs from proximal tibia to distal femur; prevent undesirable movements at the knee

• anterior cruciate ligament: prevents anterior sliding of the tibia

• posterior cruciate ligament: prevents anterior sliding of the femur or posterior displacement of the tibia

ankle joint features

• hinge joint between united inferior ends of tibia and fibula + talus of the foot

• allows dorsiflexion and plantar flexion only

ankle joint ligaments

medially and laterally stabilized by ligaments

• medial (deltoid) ligament

• lateral ligament

inferior ends of tibia and fibula are joined by ligaments

• anterior and posterior tibiofibular ligaments

arthritis

describes more than 100 kinds of joint damaging dieases

osteoarthritis

most common type of wear and tear arthritis

rhuematoid arthritis

chronic inflammatory arthritis

gouty arthritis (gout)

uric acid buildup causes pain in joints