General Principles of Biomechanics Flashcards
Articulation of humeroradial joint
Distal end of humerus (capitulum) with concave oval facet of proximal radius
Is the capsule of the elbow joint thick or thin
Thin
the annulus fibrosis is composed of….
Collagen (Type 1) and fibrocartilage
Shape of proximal end of humerus
Half a sphere
Define boggy end feel
Edema, joint swelling
Where does the first 30-60 degrees of elevation occur
Glenohumeral
What is the acetabular fossa
center of acetabulum
what ligament connects medial and lateral meniscus
Transverse ligament
What is T2 MRI used for
Soft tissue structures (shows tissues with high water content)
What does the quadrate ligament do
Reinforce inferior joint capsule
Maintains position of radial head in opposition to ulna
Limits amount of spin in supination and pronation
what is the angle for coxa valga
Over 125
When finger flexors are weak, what muscles substitute
Passive finger flexion by contraction of wrist extensors
what is the Resistance in a lever system
the force that opposes movement
What is T1 MRI used for
Bony anatomy
Is the medial or lateral femoral condyle more inferior
Medial descends more inferiorly
What is the direction of the proximal humerus
Retroverted 20-30 degrees
Shape of ulnar collateral ligament
Triangle
What happens when a concave surface moves on a convex surface
Same direction (anterior roll, anterior glide)
orientation of the head of the femur
superior
anterior
medial
A what type of joint is TMJ
synovial
Define soft end feel
Soft tissue approximation
What menisci is large and C shaped
Medial
Three motions describing movement of one joint surface on another
Roll, glide, spin
Inner surface of the labrum is lined with…
Articular cartilage
what is the acetabular fossa filled with
fat pad for shock absorption
THE ELBOW
.
Angle of femoral neck and what direction
anterior 10-15 degrees
What do the anterior and posterior radioulnar ligaments do
Strengthen radioulnar capsule
For accessory joint motion, what is better: interrater or intrarater reliability
Intrarater
The orientation of the glenoid fossaplaces true _______ at ______ anterior to frontal plane
true abduction at 30 degrees anterior to frontal plane
What is the main contributor to bony stability in the elbow
Trochlea (humerus) and trochlear fossa (ulna)
Why is the hip joint very stable
Bony anatomy as well as strength of ligaments and capsule
Arthrology of glenohumeral joint
Convex humeral head articulates with concave glenoid fossa
What does the ulnar collateral ligament do
Reinforces humeroradial joint medially
In the wrist, what is the convex concave relationship of the radius and carpals
Radius is biconcave to carpals
What covers articular surfaces of TMJ
dense fibrous cartilage (not hyaline)
the CMC joint is a ______ articulation
Saddle
What position does the annular ligament protect the radial head in
Semi-flexion (most unstable)
What’s the center of the head of the femur that is a depression
fovea capitis femoris
where is the effort in a second Class Lever
effort is farthest away from axis (axis-resistance-effort)
Define arthrokinematics
Movement between joint surfaces
What does PCL check
posterior displacement of the tibia in femur
Radial nerve distribution
Remainder of dorsum of hand not by median or ulnar
Functions of glenoid labrum
Lubrication
Protection
What direction does ACL run
Oblique superiorly and laterally
On x-rays, what color do more dense structures appear
White
Two types of images on a MRI
T1
T2
What does radial collateral ligament do
Reinforce humeroradial joint laterally
How many bands in the glenohumeral ligament
Three bands
Is the medial or later tibial condyle more stable
Medial is more stable = less mobile
Lateral is less stable = more mobile
Purpose of the labrum of the hip
Deepens acetabulum
Where does radial collateral ligament run
Lateral epicondyle —> annular ligament
Where does the transverse humeral ligament sit
Over the top of the bicipital groove
Where does the iliofemoral ligament run
both bands start at AIIS
medial runs to distal intertrochanteric line
lateral proximal disintertrochanteric line
Articulation of distal radioulnar joint
Convex ulna with concave radius
what’s the shape of the head of femur
two-thirds of a sphere
Define firm end feel (pathological)
Decreased elasticity, fibrosis of soft tissue
What is the extensors hood
fibrous mechanism on the dorsum of each finger that is a fibrous expansion of the extensor digitorum tendon
What does medial meniscus attach to
MCL
fibrous capsule
In the proximal radioulnar joint, what is the shape of the radial head
Convex
Articulation of humeroulnar joint
Trochlea and trochlear notch
what covers the head of the femur
Articulation cartilage (except fovea capitis)
How does the convex-concave rule apply to the spine
convex rule at Atlanto-occipital joint
concave rule below second vertebrae
What shape is the hip labrum
Triangle
What ribs does the scapula sit over
2-7 ribs
What does the glenoid labrum attach to
Capsule superiorly and inferiorly
Long head of biceps tendon superiorly
Function of collateral ligaments in hand
Tighten with flexion and voles fibers tighten with extension
Define rubbery end feel
Muscle spasm
what cervical joint is the yes joint
Atlanto-occipital
When pectoral is major is weak, what muscles substitute
Long head of biceps
Coracobrachialis
Anterior deltoid
Is the glenoid fossa shallow
Yes very shallow
What other ligament does the LCL run in the same direction as
PCL
What is the function of the transverse humeral ligament
Act as a retinaculum for long biceps tendon
what is a Second Class Lever
when two forces are applied on one side of an axis
In what direction is the shoulder capsule least supported and most lax
Inferirorly
Acetabulum orientation
Lateral
Inferior
Anterior
what is the volar plate
Thickening of the capsule
The elbow capsule is continuous medially with ——- and laterally with ———
Medial UCL
lateral LCL
Direction MCL runs
oblique anteriorly and inferiorly
Where does the labrum attach
Bony rim of acetabulum
The inter surface of the annular ligament is lined with…
Fibrocartilage
Example of third Class Lever in body
Most muscles (elbow flexion)
Is the UCL or RCL stronger and why
UCL…RCL attaches to soft tissue structure (annular ligament)
what do the two atypical vertebrae allow for
increase AROM without compressing spinal cord, uncinate processes, and transverse foramen
Both of the articulations in the sternoclavicular joint are covered with
Fibrocartilage
Is the lateral meniscus smaller or larger than the medial meniscus
smaller
Define hyper mobility end feel
End feel at a later time than the other side
The coracohumeral ligament is taut with
External rotation
What position is the annular ligament most taut
Extremes of pronation and supination
What are CTs used for
Complex fractures Facet dysfunction Disc disease Stenosis of spinal canal IV foramen
What happens when convex surface moves on a concave surface
opposite direction (anterior roll, posterior slide)
Articulation of radiocarpal joint with CC
convex scaphoid and lunate
concave radius
Purpose of extensor hood
Assist with extension of the PIP and DIP joints
Define firm end feel
Capsular/ligamentous stretching
what joint is the no joint
atlanto-axial
Where are uncinate joints and what do they do
Found at C3-C7 and limit lateral cervical movement
What is encircled with the annular ligament
Radial head
What are x-rays best used for
Dysfunction/disease of bones (not soft tissue)
Define osteokinematics
Movement between two bones
When hip extensors are weak, what muscles sub
Lower back extensors
Adductor magnus
Quadratics lumborum
is the acetabular fossa articulating
no
When hip flexors are weak, what muscles sub
Lower abdominals
Lower obliques
Hip adductors
Lattisimus dorsi
What does the clavicle link
Manubrium to acromion
What kind of joint is the tibiofemoral joint
Synovial hinge with two degrees of freedom
In shoulder elevation, what happens at 75 degrees in the GH
External rotation
for the screw ho,e mechanism, what happens at the elbow
Elbow flexion: ulna ER (supinate)
Elbow extension: ulna IR (pronates)
Where does ACL attach
anterior intercondylar fossa of tibia and to femur at medial aspect of lateral condyle
CC for proximal tibuofemoral joint
tibia is convex
fibular is concave
Function of radial collateral and ulnar collateral ligaments
RCL limit ulnar deviation
UCL limit radial deviation
At 60 degrees of elevation in the shoulder, where does movement occur
60 degrees
What is nucleus purposis made of
water and proteoglycans it’s minimal collagen
what is a third Class Lever
when two forces are applied on one side of an axis
what other ligament does MCL run with in the same direction
ACL
when do the menisci follow the tibia
flexion/extension
What does PCL attach to
posterior intercondylar fossa of tibia and on lateral surface of femoral medial condyle
What does LCL prevent
ER and stability against varus forces
what muscle attaches to medial meniscus
semimembranosus
What positions are the MCL taut and slackened with
taut extension
slackened flexion
CC relationship between ulna and triquetrum
Ulna is convex, triquetrum concave
when do menisci follow the femoral condyles
internal/external rotation
what does ACL check
forward gliding of tibia on femur
limits IR of tibia during flexion as it twists around PCL
Rules of 3:
Spinous process of T1-T3 even with transverse process of same level
T4-T6 SPs one half level below TP
T7-T9 SPs one full level below TP
T10 full level below
T11 one-half level below
T12 level
Primary function of coracohumeral ligament
Reinforce biceps tendon
Reinforce superior capsule
Prevent caudal dislocation of humerus
Where does the coracohumeral ligament attach
Base of coracoid process to greater and lesser tubercle of humerus
Where does the MCL knee run
Medial aspect of medial femoral condyle to upper end of tibia
Both bands of the iliofemoral ligament are taut with
Extension and ER
where does LCL knee run
Lateral femoral condyle to head of fibula
Shape of radial collateral ligament
Fan
What is the articulate surface of the humerus covered in
Hyaline cartilage
What is the coxa vara angle
Less than 115
What ligament is the Y ligament
Iliofemoral Ligament
Define hard end feel
When bone and cartilage meet
What type of joint is the hip joint
Synovial joint
what is excessive anteversion
Over 25-30 degrees
what is a First Class Lever
when two forces are applied on either side of an axis
what does MCL prevent
prevents ER and forces against valgus forces
when hip abductors are weak, what muscles substitute
Lateral trunk muscles/tensor fascia latae
What are the functions of the menisci
Deepens fossa of tibia Increases congruency of tibia and femur Provides stability to tibiofemoral joint Provides shock absorption and lubrication to knee Reduces friction during movement Improves weight distribution
Direction of the LCL run
Inferior and posterior
Define empty end feel
Loose, then very hard, associated with muscle guarding or patient avoiding painful range
Direction of the glenoid fossa of the scapula
Anterior
Laterally
Superiorly
What is the purpose of the glenohumeral ligament
Reinforce anterior glenohumeral capsule
In the distal femur, what is the shape of the femoral condyles
Spiral
What’s the normal angle of inclination for the head of the femur
115-125
Median nerve distribution
Remainder of palmar surface not inner gated by ulnar
Dorsal portions of 2, 3, and lateral half of 4
The ulnar collateral ligament provides strong resistance to _____ forces
Valgus
Why does ER occur at 75 degrees of elevation in the shoulder
Prevents compression of greater tubercle against the acromion
Where does the annular ligament attach
Medial ulna
What is the glenoid labrum
Fibrocartilaginous ring that deepens glenoid fossa
Excessive retroversion angle
Less than 10 degrees
Arthrology of sternoclavicular joint
Convex SI
concave AP clavicle
articulates with opposite sternum
The three normal end feels
Soft
Firm
Hard
Where does the capsule of the shoulder attach
Medially to glenoid margin
Laterally to humeral anatomical neck
What rule describes the relationship between arthrokinematics and osteokinematics
Convex-concave rule
Where does the coracoacromial ligament run
Coracoid to acromion
example in human body of First Class Lever
contraction of triceps at elbow joint
What does the annular ligament don
Protects radial head
Ulnar nerve distribution
Hypothenar region (palmar and dorsal)
Pinky 5th
Medial half of 4th
when shoulder abductors are weakened, what muscles substitute for shoulder motion
Scapular stabilizers
What direction does PCL run
Obliquely medially and anteriorly-superiorly
what is the Effort in a lever system
the force that attempts to cause movement
What is computed tomography (CT)
Plain x-ray slices that are enhanced by a computer to improve resolution
Does the LCL attach to the capsule
no
What is the hip labrum made of
Fibrocartilage
Shape of coracoacromial ligament
Triangle
How many atypical cervical vertebrae are there
2
where is the effort in a third Class Lever
next to the axis (axis-effort-resistance)
example of second Class Lever in body
toe raise
What does the radiate do
Stabilize hand for any impact
what is the screw home mechanism in the knee
5 degrees of tibial ER which occurs during terminal extension
