other COPY Flashcards
typical joint elements – synovial joints
- proximal and distal bone
- articular/hyaline cartilage
- capsule
- ligaments
- synomivial membrane synovial fluid
hilton’s law
- john hilton, british surgeon
- joint innervation
- a nerve that innervates a joint also tends to innervate the muscles that move the joint and the skin that covers the distal attachments of the muscle
- example
- elbow: radial, median, musculocutaneous, ulnar nn.
- knee: femoral, sciatic (fibular and tibial), obturator nn.
fibrocatilage in synovial joints
- meniscus, articular disc, laburm
- present in tibiofemoral, glenohumeral, acromioclavicular, sternoclavicular, termporomandibular, femoroacetabular
- purpose: to distibute compressive forces, provide additional joint stability/congruency
types of synovial joints
- plane (gliding)
- acromioclavicular
- hinge (ginglymus)
- humeroulnar, tibiofemoral
- sellar (saddle)
- sternoclavicular
- ellipsoidal (condyloid)
- 2nd MCP
- ball and socket
- glenohumeral
- trochoid (pivot)
- proximal radioulnar (supination/pronation)
planar joint
- lack of convexity/concavity along surfaces
- primary motion is gliding of two surfaces on one another
- examples
- AC joint
- SI joint
- most spinal facet joints
hinge joint
- ginglymus
- stable
- examples
- humeroulnar
- tibiofemoral
sellar (saddle) joint
- examples
- sternoclavicular joint
- 1st carpometacarpal joint (thumb)
- sternoclavicular joint
ellipsoidal jiont
- CC and CV in all planes
- ligaments provide stability
- example
- metacarpal phalangeal joints
pivot (trochoid) joint
- examples
- atlantoaxial
- proximal radioulnar
convex on concave rule
roll and slide/glide opposite
concave of convex rule
roll and slide/glide same diraction
joints of the shoulder girdle
- sternoclavicular: only attachment of shoulder to body
- acromioclavicular: link to skeleton
- glenohumeral
- scapulothoracic: pseudojoint, only muscular attachments
importance of scapular positioning
- glenoid moves like a seal’s nose to remain in right spot to control ball/head of humerus
scapulohumeral rhythm
- consists of integrated movements of GH, ST, AC, and SC joints
- occurs in sequential fashion to allow full functional motion of shoulder complex
- serves three purposes
- allows for greater overall shoulder ROM
- maintains optimal contact between humeral head and glenoid fossa
- assists with maintaining optimal length-tension relationship of glenohumeral muscles
- for stability
evidence summary on arm elevation
- scapular upward rotation may be greater on non-dominant side
- scapulohumeral rhythm between 1:3 and 1:5 depending on plane of humeral motion, side of dominance and age of patient
- unilateral or bilateral movement alters scapular and thoracic movement patterns
role of thoracic spine
- bilateral shoulder motion: 10-30 degrees of thoracic extension (primarily lower) with full shoulder elevation
- unilateral shoulder motion: 10-30 degrees of thoracic rotation and/or side bending
- clinical relevance: assess thoracic motion in patients with shoulder symptoms
restraints to external rotation at shoulder
- 0 degrees abduction
- subscapularis
- SGHL
- 45
- SGHL
- MGHL
- 90
- anterior band IGHLC
restraints to internal rotation
- 0
- posterior band IGHLC
- 45
- anterior and posterior band IGHLC
- 90
- anterior and posterior band IGHLC
restraints to inferior translation
- 0
- SGHL
- coracohumeral ligament
- 90
- IGHLC
GH joint accessory motion
- loose/open packed position
- 55 deg abd, 30 deg horiz add
- closed packed position
- end range abduction and ER
CV-CC rule in shoulder
- ER always rolls posterior and glide anterior
- IR always roll anterior and glide posterior
- flexion always roll superior and glide inferior
NOT ALWAYS in GH joint
humeral head will glide away from the tightest portion of the capsule
primary restraint against GH ER with arm at 45 degrees abduction
- middle glenohumeral ligament
in protraction of shoulder girdle, what glide occurs at the sternoclavicular joint
- anterior
distal attachment of subscapularis muscle
- lesser tubercle of humerus
ligaments that restrict superior migration of the clavicle
- costoclavicular ligament
- conoid ligament
- acromioclavicular ligament
primary stabilizer of GH joint at 90 degrees abduction
- inferior glenohumeral ligament complex
carrying angle of elbow
- angle between axis of humerus and axis of forearm
- female: 12-16
- male: 10-14
pronation and supination
- occurs simultaneously at both proximal and distal radioulnar joints
- also requires rotation of radius (spin) at humeroradial joint in anular ligament
wrist axis of rotation
- flexion/extension: coronal axis between lunate and capitate
- rad/ulnar deviation: sagittal between unate and capitate
- circumduction: polyaxial
- center of rotation is variable dependent upon wrist position and motion
radiocarpal kinematics
- gliding of proximal row on radius and TFCC
- gliding movement opposite from hand (convex on concave)
midcarpal biomechanics
- joint: functional rather than anatomic convex on concave configuration (tongue and groove)
- motion: favors extension over flexion, opposite RC joint
- small amount of RD/UD
ligamentous stability “ring” system
- lichtman describes the carpus as “ring” system”
- bones within each row tethered together by interosseous ligaments
- ring is only complete by addition of midcarpal ligaments
- carpal bones move together as a unit
during wrist flexion, both rows flex and vice versa in extension
- 50% at MC and 50% at RC joints, but amount varies
configuration of SI joints
- extremely variable from person to person in terms of morphology and mobility
- differences are not pathological, but are normal adaptations and anatomical variation
primary function of SIJ
- distribute forces through pelvic ring
stresses on knee ligaments
- valgus F stresses MCL
- varus stresses LCL
- anterior tensions ACL
- posterior tensions PCL
menisci and weight bearing
- designed to distribute forces – hoop stress
- WB restrictions after surgery
meniscal blood supply
- blood flow is greatest in the peripheral 1/3 and is least in central 1/3
- healing capacity is vascularity and age dependent
- also repeated injury
medial meniscus repair considerations
- femoral condyle imparts sheer force to meniscus in weightbearing beyond 115-120 degrees of knee flexion
- hamstring contraction indirectly “tugs” on posterior horn of mensicus
patellofemoral joint – compressive forces
- increase with degree of flexion angle at knee
- increase with quadriceps muscle force production
- surface area of contact increases with flexion
- increased surface area results in reduced focal areas of pressure
rearfoot-midfoot function
- supination
- perpendicular axes –> rigid lever to push off
- good for propelling forward (toe off)
- pronation
- parallel axes –> “loose bag of bones”
- attentuate forces for heel strike
ground up or hip down for supination and pronation
- both
