chap 9

Joints (articulations)

• places of union between bones, bones & cartilage, or bones & teeth

• bones articulate at a joint

• arthrology: study of joints

• form by 6th week of development

• categorized structurally on the basis of whether a space (called a joint cavity) occurs between the articulating bones & the type of CT that binds the articulating surfaces of the bones

• classified by structure & function

  • structural (what fills between bones)

    • fibrous

    • cartilaginous

    • synovial

  • functional (extent of movement)

    • synarthroses

    • amphiarthroses

    • diarthroses

• range of motion

  • no movement → extensive movement

  • structure of each determines its mobility & stability

  • inverse relationship (tradeoff) between mobility & stability

    • immobile = stable

    • mobile = unstable

    • ex. skull sutures are immobile but very stable

• most stable → least stable / immobile → most mobile

  • suture → interosseous membrane → intervertebral joints → knee joint → glenohumeral joint (shoulder)

arthr- / arthro-

• relating to joints

Fibrous joint

• structural class

• bones held together by dense regular CT (collagen)

• primary function: hold 2 bones together

• immobile or slightly mobile (synarthroses or amphiarthroses)

  • no joint cavity

• ex. gomphosis, suture, syndesmosis

  • suture & syndesmosis has interosseous membrane

Cartilaginous joint

• structural class

• bones joined by cartilage

  • either hyaline cartilage or fibrocartilage

• primary function: resist compression / tension stress, act as resilient shock absorbers

• immobile or slightly mobile (synarthroses or amphiarthroses)

  • no joint cavity

• ex. synchondrosis (hyaline), symphysis (intervertebral joints, pubic symphysis)

Synovial joint

• structural class

• bones joined by ligaments w fluid filled joint cavity separating bone surfaces

  • lined by synovial membrane

• primary function: movement

• freely mobile (diarthroses)

  • has joint cavity (articular cavity)

    • filled w synovial fluid

• common features

  • articular capsule & joint cavity

  • synovial fluid / membrane

  • articular cartilage (end of each bone)

  • ligaments, nerves, blood vessels

• also has bursae, tendon sheaths, & fat pads

• classes by movement

  • uniaxial

    • bone moves in just 1 plane or axis

    • forward & back or up & down

  • biaxial

    • bone moves in 2 planes or axes

  • multiaxial / triaxial

    • bone moves in multiple planes or axes

• classes by shape (least mobile → most mobile)

  • plane joints (uniaxial)

  • hinge joints (uniaxial)

  • pivot joints (uniaxial)

  • condylar joints (biaxial)

  • saddle joints (biaxial)

  • ball & socket joints (multiaxial / triaxial)

• movements that occur at __ __ are

  • gliding

  • angular

  • rotational

  • special

• ex. glenohumeral joint (shoulder), knee joint, elbow joint, temporomandibular joint

• may be compared to levers

Articular cartilage

• hyaline cartilage on bone surface at joint

• lacks perichondrium

• avascular

• functions

  • reduces friction during movement

  • acts as a cushion to absorb joint compression

  • prevents damage to articulating ends of bones

• articulating surface are enclosed within a CT capsule

Joint capsule / Articular capsule

• encloses a synovial joint

• encapsulating joint cavity is double layered __

  • outer fibrous layer

    • dense CT

    • strengthens joints to prevent bones being pulled apart

  • inner synovial layer / membrane

    • composed primarily of areolar CT

    • covers internal joint surfaces not covered by cartilage

    • helps produce synovial fluid

Joint cavity / Articular cavity

• space between articulating bones

  • separates articulating surfaces of the bones

• lined by synovial membrane secreting synovial fluid

• viscous, oily substance

• functions

  • lubricate articular cartilage on articulating surfaces

  • nourishes the chondrocytes of articular cartilage

  • acts as a shock absorber (distributes stresses)

  • permits movement of the articulating bones

Ligaments

• dense regular CT

• connect one bone to another

• stabilize, strengthen, & reinforce synovial joints

• extrinsic ligaments

  • outside of & physically separate from articular capsule

• intrinsic ligaments

  • thickening of the articular capsule itself (fibrous layer)

  • include ligaments outside (extracapsular ligaments) & within the articular capsule (intracapsular ligaments)

Sensory receptors & blood vessels

• numerous in synovial joints

• proprioceptors: report on movement, compressive forces, positioning, stretch,

• nociceptors: detect painful stimul

Tendons

• composed of dense regular CT

• not part of the synovial joint itself

• attach muscle to bone

• help stabilize joints

• sometimes limit the range of movement

Bursae

• fibrous, saclike structures containing synovial fluid

• lined internally by synovial membrane

• either associated w joint cavity or completely separate from it

• found in synovial joints where bones, ligaments, muscles, skin, or tendons rub together

  • large # in shoulder

• alleviate friction

Tendon sheaths

• elongated bursae

• wrap around tendons where friction is excessive

• common in wrist & ankle

Fat pads

• act as protective packing material in joint periphery

• can fill spaces when joint shape changes

Synarthroses / Synarthrosis

• functional class

• immobile joints

  • no joint cavity

  • stationary

• can be fibrous (2) or cartilaginous (1) joints

Amphiarthroses / Amphiarthrosis

• functional class

• slightly mobile joints

  • no joint cavity

• can be fibrous (1) or cartilaginous (1) joints

Diarthroses / Diarthrosis

• functional class

• freely mobile joints

  • has joint cavity

• all synovial joints

Gomphosis

• type of fibrous joint

• “peg in a socket”

• articulations of teeth w sockets of mandible & maxillae

• tooth held in place by fibrous periodontal ligaments (periodontal membranes)

  • the only __ in the body

  • located within alveolar sockets

• function as synarthroses / synarthrotic joints (immobile)

periodontal ligaments

• peri = around / dontal = tooth

• the only gomphoses in the body

• specialized, dense fibrous connective tissue that suspends each tooth root inside its socket in the alveolar bone

  • rather than being fused directly to the bone like a dental implant, teeth are cushioned and held in place by thousands of tiny, shock-absorbing collagen fibers

Sutures

• type of fibrous joint

• found between some skull bones

• very short collagen fibers

• interlocking, irregular edges

  • increase stability & decrease risk of fracture

• function as synarthrosis / synarthrotic joints (immobile)

• allow growth in childhood

  • permit the skull to grow by new bone being deposited

• become ossified synostoses in older adults

synostoses

• the fusion or union of two or more separate bones into a single bone

Syndesmosis / Syndesmoses

• type of fibrous joint

• bones bound by interosseous membrane (interosseous ligament) a broad ligamentous sheet

  • dense regular CT

• function as amphiarthroses / amphiarthrotic joints (limited mobility)

  • provide pivot for 2 long bones

• ex. found between radius & ulna / tibia & fibula

Synchondrosis / Synchondroses

• type of cartilaginous joint

• bones joined by hyaline cartilage

• immobile (synarthroses)

• ex. epiphyseal plate, costochondral joints (attach ribs to sternum), first sternocostal joint

Symphyses / Symphysis

• type of cartilaginous joint

• disc / pads of fibrocartilage between articulating bones

• resist compression & act as shock absorbers

• allow slight mobility (amphiarthroses)

• ex. pubic symphysis / intervertebral discs / joints

Clinical: Costochondritis

• inflammation of the costochondral joints

• localized chest pain

• cause usually unknown (trauma or infection)

• may be mistaken for pain from a myocardial infarction (heart attack)

• treated w nonsteroidal anti - inflammatory drugs

Plane joint

• articular surfaces flat (or slightly curved)

• simplest, least mobile synovial articulation

• uniaxial: limited side-to-side gliding movement in a single plane

• angle between bones do not change, only limited movement possible in any direction

• ex.

  • intercarpal joints

  • intertarsal joints

  • acromioclavicular (AC) joint

  • temporomandibular (TMJ)

  • intervertebral (between superior & inferior articular processes of adjacent vertebrae)

  • vertebrocostal

  • lumbosacral (between articular processes)

  • sternocostal

Hinge joint

• convex surface within concave depression

• uniaxial: like the hinge of a door

• movement in one place, flexion/extension

• ex.

  • elbow joint

    • humeroulnar joint

  • knee joint

  • IP (Interphalangeal joints)

  • temporomandibular (TMJ) (elevation & depression)

Pivot joint

• bone w rounded surface fits into ligament ring

• uniaxial: rotation of longitudinal axis

• ex.

  • atlantoaxial joint (between first two cervical vertebrae)

  • radioulnar joint

Condylar / Condyloid joint

• oval, convex surface articulating w oval, concave surface

• biaxial (back & forth and side to side / flex & extend and abduct & adduct

• ex.

  • MP (metacarpophalangeal or metatarsophalangeal) joints (also known as knuckles)

  • radiocarpal joint (wrists)

  • atlanto occipital joint

Saddle joint

• both articulating bones have convex & concave surface resembling saddle shape

• biaxial

  • allow movement across two perpendicular plane

• ex.

  • articulation between a carpal bone (trapezium) & first metacarpal (carpometacarpal joint) also known as trapeziometacarpal

    • permits thumb opposition (the ability of the thumb to move toward the other fingers) so that we can grasp objects

  • sternoclavicular joint

Ball and socket joint

• spherical head of one bone fitting into cuplike socket

• multiaxial, permitting movement in 3 planes

• the most freely mobile type of joint

• ex.

  • glenohumeral (shoulder) joint

  • hip (coxal) joint

Costochondral joint

• joint between each bony rib & its respective costal cartilage

• is a synchondrosis

First sternocostal joint

• attachment of the 1st rib to the sternum (manubrium) by costal cartilage

• is a synchondrosis

Types of motion that occur at synovial joints

• gliding

• angular

• rotational

• special movements

  • motions that occur only at specific joints

Gliding motion

• 2 opposing articular surfaces slide past each other in almost any direction, the amount of movement is slight (limited)

  • back & forth or side to side

• typically occurs along plane joints

  • ex. between carpals or tarsals

• imagine sliding door

Angular motion

• involve decreasing or increasing the angle of a joint

• ex.

  • flexion

  • extension (+hyperextension)

  • lateral flexion

  • abduction

  • adduction

  • circumduction

Flexion

• the angle between articulating bones decreases in an anterior posterior (AP) plane

  • brings bones closer together

• ex. bending finger

• opposing movement: extension

Extension

• the angle between articulating bones increases in an anterior posterior (AP) plane

• ex. straightening your fingers after making a fist

• opposing movement: flexion

Hyperextension

• extension beyond normal range of motion

• possible w extensively mobile joints or an injury

Lateral flexion

• the vertebral column / trunk moves (bends) in a lateral direction along a coronal plane

  • occurs between vertebrae in the cervical & lumbar region

  • angular movement

• opposing movement: none

Abduction

• lateral movement of a body part away from the midline

  • angular movement

• ex. arm or thigh moved laterally from body midline

• opposing movement: adduction

Adduction

• medial movement of a body part toward the midline

  • angular movement

• ex. arm or thigh brought back toward midline

• opposing movement: abduction

Circumduction

• a sequence of movements in which the proximal end of an appendage remains relatively stationary while the distal end makes a circular motion

  • movement makes an imaginary cone shape

  • complex movement that occurs as a result of a continuous sequence of flexion, abduction, extension & adduction

  • angular movement

• ex. drawing a circle on the blackboard

• opposing movement: none

Rotational motion

• a bone pivots around its own longitudinal axis

• ex

  • pronation

  • supination

  • lateral rotation: turns anterior surface of bone laterally

  • medial rotation: turns anterior surface of bone medially

Pronation

• rotation of the forearm where the palm is turned posteriorly or inferiorly

  • medial rotation of forearm so palm of hand posterior

• opposing movement: supination

• radius & ulna pivoting along interosseous membrane

• palm of hand facing posteriorly

• head of radius still on lateral side of elbow

• distal end of radius has crossed over

• movement does not happen in elbow, happens in forearm

• “pour that out”

Supination

• rotation of the forearm in which the palm is turned anteriorly or superiorly

  • lateral rotation of forearm so palm of hand anterior

• opposing movement: pronation

• in anatomic position, palm of hand facing anteriorly

• radius & ulna parallel

• radius on lateral side of forearm

• ulna on medial side

• movement does not happen in elbow, happens in forearm

• “side by side” “how you carry soup”

Special movements

• types of movement that do not fit into previous categories

• ex.

  • depression

  • elevation

  • dorsiflexion

  • plantar flexion

  • eversion

  • inversion

  • protraction

  • retraction

  • opposition & reposition

Depression

• movement of a body part inferiorly

• ex. movement of mandible while opening mouth

• opposing movement: elevation

Elevation

• movement of a body part superiorly

• ex. movement of mandible when closing mouth

• opposing movement: depression

Dorsiflexion

• ankle joint movement where the dorsum (superior surface) of the foot is brought toward the anterior surface of the leg

  • talocrural (ankle) joint bent so the dorsum of foot moves toward the leg

• ex. digging in your heels

• opposing movement: plantar flexion

• “dig in your heels”

Plantar flexion

• ankle joint movement where the sole of the foot is brought toward the posterior surface of the leg

  • talocrural (ankle) joint bent so dorsum pointed inferiorly

• ex. ballet dancer on tiptoes in full plantar flexion

• opposing movement: dorsiflexion

• “push your toes into the plant”

Eversion / foot pronation

• twisting motion of the foot that turns the sole laterally or outward

  • occurs only at intertarsal joints (between tarsals) of foot

• opposing movement: inversion

Inversion / foot supination

• twisting motion of the foot that turns the sole medially or inward

  • occurs only at intertarsal joints (between tarsals) of foot

• opposing movement: eversion

Protraction

• anterior movement of a body part from anatomic position

• ex. jutting jaw anteriorly at temporomandibular joint

• opposing movement: retraction

Retraction

• posterior movement of a body part from anatomic position

• ex. pulling in jaw posteriorly at temporomandibular joint

• opposing movement: protraction

Opposition

• special movement of the thumb across the palm toward the tips of fingers to permit grasping & holding of an object

  • at carpometacarpal joint

• opposing movement: reposition

  • back in anatomical position

biomechanics

• practice of applying mechanical principles to biology

Levers

• elongated, rigid object

• rotates around fixed point, fulcrum

• ability to alter the speed & distance of movement produced by a force, direction of an applied force, & force strength

• effort applied to one point

• resistance located at some other point

  • movement occurs if effort exceeds resistance

• effort arm

  • part of lever from fulcrum to point of effort

• resistance arm

  • part of lever from fulcrum to point of resistance

• synovial joint movement can be compared to the mechanics of a lever system

• FRE123 = the part near the middle of each type lever

  • Fulcrum in 1st class levers

  • Resistance in 2nd class lever

  • Effort in 3rd class lever

• Class 1 = scissors, atlanto occipital joint

• Class 2 = wheelbarrow, plantarflexion of ankle

• Class 3 = tweezers, most common in our body

• longer lever arms generate force

• shorter level arms generate speed

(1st) First Class Levers

• fulcrum is between effort & resistance

• ex. pair of scissors / playground teeter totter

  • effort applied to handle of scissors

  • fulcrum along the middle of scissors

• ex. atlanto-occipital joint of neck

(2nd) Second Class Levers

• resistance is between fulcrum & effort

  • rare in body

• small force able to balance larger weight

  • bc the effort is always farther from the fulcrum than the resistance

• ex. wheelbarrow

  • fulcrum far from effort

• ex. standing ontiptoe (plantarflexion of ankle)

  • ball of the foot is fulcrum, gravity trying to pull us down is resistance, muscle puling is effort

(3rd) Class Levers

• effort applied between resistance & fulcrum

  • ex. tweezers / forceps

• most common in body

  • ex. forceps

  • ex. elbow joint

    • joint is fulcrum, bicep tendon applies effort, weight in hand provides resistance (or by the weight of the forearm itself)

  • ex. mandible when you bite food

    • temporomandibular joint is fulcrum, temporalis muscle exerts effort, food eaten is resistance

Axial skeleton joints

• suture

• temporomandibular

• atlanto-occipital

• atlantoaxial

• intervertebral

• vertebrocostal

• lumbosacral

• sternocostal

Suture joint

• adjacent skull bones

• fibrous joint

• synarthrosis

  • no movement

Temporomandibular joint (TMJ)

• head of mandible & mandibular fossa of temporal bone

  • head of mandible & articular tubercle of temporal bone

• synovial (hinge & plane) joints

• diarthrosis

  • depression (opening mouth), elevation (biting down), lateral displacement (waggling jaw side to side), protraction (sticking jaw out), retraction (returning jaw back), gliding, & slight rotation of mandible

• only mobile joint between bones in the skull

• has loose articular capsule

  • surround joint

  • promotes extensive range of motion

• has articular disc

  • thick pad of avascular dense regular CT

  • divides synovial cavity into 2 chambers

    • so tmj is 2 synovial joints, one between temporal bone & articular disc and one between articular disc and mandible

• ligaments

  • sphenomandibular ligament (extracapsular)

    • extends anteriorly & inferiorly from sphenoid to mandible

  • temporomandibular ligament (lateral)

    • 2 short bands that extends inferiorly & posteriorly from articular tubercle of temporal bone to mandible

• movements

  • exhibits hinge, gliding, & some pivot joint movements

    • functions like a hinge during mandible depression & elevation (chewing)

    • glides during protraction of the mandible for biting, side to side grinding

articular disc

• a thin, oval plate of fibrocartilage found within certain synovial joints

  • diff from intervertebral discs bc they have nucleus pulposus & annulus fibrosus and arent inside synovial joints

• found within the TMJ, wrist, and the sternoclavicular joint

• divides the joint (horizontally), directing flow of synovial fluid

• absorbs shock

Clinical: TMJ Disorders

• most commonly occurs due to alternation in the ligaments securing the joint

• articular disc forced out of normal position

• clicking or popping heard as person opens or closes mouth

• possible paint in joint, paranasal sinuses, tympanic membrane, oral cavity, eyes, & teeth

Atlanto occipital joint

• superior articular facets of atlas & occipital condyles of occipital bone

• synovial (condylar) joint

• diarthrosis

  • flexion & extension of the head

  • slight lateral flexion of the head

Atlantoaxial joint

• anterior arch of atlas & dens of axis

• synovial (pivot) joint

• diarthrosis

  • rotation of the head

Intervertebral joint

• vertebral bodies of adjacent vertebrae

  • cartilaginous joint (symphysis) between vertebral bodies

  • amphiarthrosis

• superior & inferior articular processes of adjacent vertebrae

  • synovial (plane) joint between articular processes

  • diarthrosis

• movements: flexion, extension, lateral flexion of vertebral column

Vertebrocostal joint

• facets of heads of ribs & bodies of adjacent thoracic vertebrae & intervetebral discs between adjacent vertebrae

• articular part of tubercles of ribs & facets of transverse processes of thoracic vertebra

• synovial (plane) joint

• diaarthrosis

  • some slight gliding of the ribs

Lumbosacral joint

• body of the 5th lumbar vertebra & the base of the sacrum

  • cartilaginous joint (symphysis) between lumbar body & base of sacrum

  • amphiarthrosis

• inferior articular facets of 5th lumbar vertebra & superior articular facets of 1st sacral vertebra

  • synovial (plane) joint between articular processes

  • diarthrosis

• movements: flexion, extension, lateral flexion of vertebral column

Sternocostal joint

• sternum (breastbone) and the costal cartilages of the first 7 ribs

• cartilaginous joint (synchondrosis) between sternum & first ribs

  • synarthrosis

    • no movement

• synovial (plane) joint between sternum & ribs 2-7

  • diarthrosis

    • some gliding movement

Pectoral girdle & upper limb joints

• joints associated w movement at shoulder

  • sternoclavicular

  • acromioclavicular

  • glenohumeral

• elbow (humeroulnar & humeroradial)

• radioulnar (proximal & distal)

• radiocarpal

• intercarpal

• carpometacarpal

• metacarpophalangeal (MP, knuckles)

• interphalangeal (IP)

Sternoclavicular joint

• manubrium of sternum & sternal end of clavicle

• synovial (saddle)

• diarthrosis

  • depression, elevation, circumduction of clavicle

    • small-scale, precise circumduction during large arm movements

• fibrocartilaginous articular disc

  • partitions joint into 2 parts forming 2 synovial cavities

• stability provided by fibers & ligaments

  • makes this specific joint very stable & difficult to dislocate

  • sternoclavicular ligament & costoclavicular ligament

Acromioclavicular (AC) joint

• acromion of scapula & acromial end of clavicle (lateral)

• synovial (plane)

• diarthrosis

  • gliding of scapula on clavicle

• fibrocartilaginous articular disc within joint cavity

• joint capsule strengthened superiorly by acromioclavicular ligament

  • connects clavicle to the acromion

• clavicle bound to coracoid process by coracoclavicular ligament

  • if torn, acromion & clavicle no longer align (shoulder separation)

Glenohumeral (shoulder) joint

• glenoid cavity of scapula & head of humerus

• synovial (ball and socket)

• diarthrosis

  • abduction, adduction, circumduction, flexion, extension, lateral rotation & medial rotation of arm

• permits greatest range of motion of any joint in the body

  • most unstable & most frequently dislocated

  • shallow cup + minimal support from ligaments

• fibrocartilaginous glenoid labrum encircles & covers the surface of the glenoid cavity

• abundant bursae

  • decrease friction where tendons & muscles extend across capsule

• supporting ligaments & tendons

  • coracoacromial ligament

    • extends across the space between the coracoid process & the acromion

  • coracohumeral ligament

    • thickening of the superior part of the articular capsule, extends from coracoid process to the humeral head

  • glenohumeral ligament

    • 3 thickening of the anterior portion of the articular capsule, are often indistinct or absent & provide only minimal support

  • tendon of long head of biceps brachii

    • within articular capsule

    • helps stabilize the humeral head in the joint

• most joint stability due to rotator cuff muscles

  • subscapularis, supraspinatus, infraspinatus, teres minor

  • work as a group to hold head of humerus in glenoid cavity

  • tendons encircle joint & fuse w articular capsule

• loose articular capsule attaches to the surgical neck of the humerus

glenoid labrum

• a ring of soft fibrocartilage attached to the rim of the shoulder blade's socket (the glenoid)

Clinical: Shoulder Joint Dislocations

• common due to joint instability

• shoulder separation refers to acromioclavicular joint dislocation

  • pain when arm abducted more than 90 degrees

  • acromion appearing prominent

• glenohumeral joint dislocations usually occur when fully abducted humerus struck hard

  • should appears flattened and “squared off”

  • humeral head anterior & inferior to glenohumeral joint capsule

Elbow joint

• hinge joint composed of 2 articulations

  • flexion & extension

• both enclosed within a single articular capsule

• involves humerus, radius, & ulna

  • Humeroulnar joint

    • trochlea of humerus & trochlear notch of ulna

    • hinge joint

  • Humeroradial joint

    • capitulum of humerus & head of radius

• diarthrosis

  • flexion & extension of forearm

• is very stable (not as mobile) bc

  • articular capsule is thick (encloses both joints)

  • bony surfaces of humerus & ulna interlock closely

  • multiple, strong ligaments reinforce articular capsule

    • radial / lateral collateral ligament (RCL)

      • extends from lateral epicondyle (humerus) to head of radius

      • stabilizes joint at lateral surface

    • ulnar / medial collateral ligament (UCL)

      • extends from medial epicondyle (humerus) to coronoid & olecranon processes (ulna)

      • stabilizes medial side of the joint

    • annular ligament

      • surrounds neck of radius

      • binds head of the radius to the ulna

Clinical: Subluxation of the head of the radius

• subluxation: refers to incomplete dislocation

• head pulled out of annular ligament

• occurs almost exclusively in children (usually < 5 yrs)

  • bc of the loose positioning of the still developing head of the radius, within a thin annular ligament

• childs annular ligament thin & radial head not fully formed

• pediatrician may maneuver radial head back into annular ligament

Radioulnar joint

• proximal joint

  • proximal end / head of radius & radial notch of ulna

• distal joint

  • distal end of ulna & ulnar notch of radius

• synovial (pivot)

• diarthrosis

  • pronation & supination of forearm

Radiocarpal joint

• distal end of radius (scaphoid, lunate, & triquetrum)

• synovial (condylar)

• diarthrosis

  • abduction, adduction, circumduction, flexion & extension of wrist

Intercarpal joint

• adjacent carpal bones

• synovial (plane)

• diarthrosis

  • gliding of the carpals

Carpometacarpal joint

• thumb: trapezium & first metacarpal

  • synovial (saddle)

• other digits: carpal & metacarpals II-V

  • synovial (plane)

• diarthrosis

  • flexion, extension, abduction, adduction, circumduction, & opposition at thumb, gliding at other digits

Metacarpophalangeal (MP, knuckles) joint

• head of metacarpals & bases of proximal phalanges

• synovial (condylar)

• diarthrosis

  • flexion, extension, abduction, adduction, circumduction of phalanges

Interphalangeal (IP) joint

• heads of proximal & middle phalanges w bases of middle & distal phalanges, respectively

• synovial (hinge)

• diarthrosis

  • flexion & extension of phalanges

Pelvic girdle & lower limb joints

• sacroiliac

• hip (coxal)

• pubic symphysis

• knee (tibiofemoral & patellofemoral)

• tibiofibular (superior & inferior)

• talocrural (ankle)

• intertarsal

• tarsometatarsal

• metatarsophalangeal (MP)

• interphalangeal (IP)

Sacroiliac joint

• auricular surfaces of sacrum & ilium

• synovial (plane)

• diarthrosis

  • slight gliding of the hip bones, more movement during pregnancy & childbirth

Hip joint (coxal)

• head of femur & acetabulum of os coxae (hip)

• synovial (ball and socket)

• diarthrosis

  • flexion, extension, abduction, adduction, circumduction, medial, & lateral rotation of thigh

• acetabular labrum

  • fibrocartilaginous ring that deepens socket

  • more stable, less mobile than glenohumeral joint

• secured by articular capsule, ligaments & muscles

• articular capsule

  • extends from acetabulum to trochanters

  • encloses femoral head & neck

• retinacular fibers

  • ligamentous fibers of articular capsule

  • reflect around femur neck

  • retinacular arteries here

    • supply most blood to femur head & neck

• intracapsular ligaments

  • iliofemoral ligament

    • Y shaped, provide support for anterior articular capsule

  • ischiofemoral ligament

    • spiral shaped, posteriorly located

  • pubofemoral ligament

    • triangular thickening of capsules inferior region

  • become taut when hip extended

    • so hip joint is most stable in its extended position

• ligament of head of femur (ligamentum teres)

  • small ligament from acetabulum to fovea of head of femur

  • does not provide stability

  • typically contains small artery supplying head of femur

taut

• stretched or pulled tight, rigid, tense, or concise

Clinical: Fracture of the femoral neck

• fracture of femur often incorrectly referred to as fractured hip

• intertrochanteric fractures (between the trochanters)

  • extracapsular fractures

  • usually in younger & middle aged individuals

• subcapital fractures

  • occur within hip articular capsule (intracapsular)

  • usually in older individuals w osteoporosis

  • may result in tearing of retinacular arteries

    • may have avascular necrosis in the region

Pubic symphysis joint

• symphyseal surface of both pubic bones

• cartilaginous (symphysis)

• amphiarthrosis

  • very slight gliding of the pubic bones, more movement during childbirth

Knee joint

• largest & most complex diarthrosis

  • flexion, extension, lateral rotation of leg in flexed position, slight medial rotation

  • / capable of slight rotation & lateral gliding when flexed

• primarily hinge joint

• tibiofemoral joint

  • medial condyle (femur), medial meniscus, & medial condyle (tibia)

  • synovial (hinge)

• patellofemoral joint

  • patella & patellar surface of femur

  • synovial (hinge & plane)

• articular capsule

  • encloses only medial, lateral, & posterior knee regions (NOT anterior)

    • no single unified capsule / joint cavity in the knee

• quadriceps femoris muscle tendon

  • passes over knees anterior surface, surrounds patella

• medial meniscus & lateral meniscus

  • deep to articular capsule within knee joint

  • C shaped fibrocartilage pads on top of tibial condyles

  • cushioning between articular surfaces

  • change shape to conform to articulating surfaces

  • partially stabilize joint medially & laterally

• extracapsular ligaments

  • patellar ligament

    • extends from patella to tibial tuberosity

  • oblique popliteal ligament

    • protects against hyper extension

  • fibular collateral ligament (FCL / LCL)

    • extends from femur to fibula

    • reinforces lateral surface of joint

    • prevents hyperadduction

  • tibial collateral ligament (TCL /

  • MCL)

    • reinforces medial surface of joint

    • extends from femur to tibia

    • prevents hyperabduction

    • also attaches to medial meniscus

  • arcuate popliteal ligament

• intracapsular ligaments

  • cruciate ligaments: cross each other X

    • deep to articular capsule

  • anterior cruciate ligament (ACL)

    • extends from posterior femur to anterior tibia

    • prevents hyperextension & anterior displacement of tibia

      • becomes taut on extension

  • posterior cruciate ligament (PCL)

    • extends from anteroinferior femur to posterior tibia

    • prevents hyperflexion & posterior displacement of tibia

      • becomes taut on flexion

Clinical: Knee injuries & Knee replacement surgery

• knee is highly vulnerable to injury

• tibial collateral ligament injury when leg forcible abducted

• fibular collateral ligament injury when medial side of knee is struck

• ACL injury when leg hyperextended

• PCL injury when leg hyperflexed

• meniscus injury due to trauma and/or overuse

• unhappy triad: injury of tibial collateral ligament, medial meniscus, & ACL

  • occurs due to a lateral blow to the knee that abducts & laterally rotates leg

• ligamentous injuries increase risk of osteoarthritis of knee

• if sever enough, individual may opt for knee replacement surgery

  • arthritic parts of bones removed & replaced w metal or plastic compounds

how do i memorize fcl prevents hyperabduction and tcl prevents hyperabduction

• the ligaments are located on the opposite side of the movement they are trying to stop

• think of them like ropes or anchors. A rope can only stop something from moving away from it by pulling tight

collateral

• a secondary, accessory, or side-by-side structure that runs alongside or supports a main pathway

Tibiofibular joint

• superior joint

  • head of fibula & lateral condyle of tibia

  • synovial (plane)

• inferior joint

  • distal end of fibula & fibular notch of tibia

  • fibrous (syndesmosis)

• amphiarthrosis

  • slight rotation of fibula during dorsiflexion of foot

Talocrural (ankle) joint

• distal end of tibia & medial malleolus of tibia with talus

• lateral malleolus of fibula & talus

• synovial (hinge)

  • highly modified

• diarthrosis

  • dorsiflexion & plantar flexion of the foot

• includes 2 articulations within 1 articular capsule

  • between distal end of tibia & talus

  • between distal end of fibula & lateral aspect of talus

• medial & lateral malleoli of tibia & fibula

  • prevent talus from sliding medially or laterally

• articular capsule

  • covers distal tibia, medial malleolus, lateral malleolus, & talus

• deltoid / medial ligament

  • binds tibia to foot on medial side

  • prevents over eversion

• lateral ligament

  • binds fibula to foot on lateral side

  • prevents over inversion

  • prone to sprain & tears

• anterior & posterior tibiofibular ligaments

Clinical: Ankle Sprains & Pott fractures

• sprain

  • stretching or tearing of ligaments without fracture or dislocation

  • results from twisting foot, usually over inversion

  • fibers of lateral ligament stretched or torn

  • localized swelling & tenderness anteroinferior to lateral malleolus

• pott fracture

  • occurs with over eversion

  • medial malleolus avulsed off of tibia (fracture)

  • talus moves laterally and fractures fibula

Intertarsal

• between the tarsal bones

• synovial (plane)

• diarthrosis

  • eversion & inversion of foot