biomechanics test 3

shoulder complex

sternoclavicular joint

acromioclavicular joint

scapulothoracic joint

glenohumeral joint

pectoral girdle

sternoclavicular joint

acromioclavicular joint

scapulothoracic joint 

concave laterally, convex medially

concave laterally, convex medially

flat

acromial end of clavicle is

rounded

sternal end of collar bone is what

scapula 

large, flat triangular on posterior thorax

provides platform to move humerus by articulating w glenocavity

thorax and scapula 

lead to stabelizing and movement

scapula humerus and glenohumeral

more superficial part of shoulder

scapula articulates with 

coracoid process 

on scapula that allows for attachment of muscles and ligaments 

acromion process

articulates with distal clavicle

forms roof over glenoid fossa 

no

is the humerus part of the pectoral girdle

sternoclavicular

joint

multiaxial saddle that articulates with medical clavicle at the sternal end and manubrium

modified ball and socet

clavicle

what is the strut that holds the pectoral girdle onto axial skeleton

acromioclavicular and coracoclavicular 

joints formed by the lateral end of the clavicle and medial end of the anterior portion of the acromion

stabilized by acromioclavicular and coracoclavicular ligament 

coracoclavicular ligament

what stabilized joint

trapezoid and conoid 

scapulothoracic joint

articulation between scapula and the posterolateral aspect of the thorax and ribs

physiological joint

true

t/f scapula hangs from clavicle

30

how many degrees is the scapula rotated froward from the frontal plane 

sternoclavicular frontal plane 

what joint and plane is a shrug associated with

elevation 45

depression 5

sternoclavicular transverse plane

what joint and place is reaching forward and pulling back associated with 

protraction and retraction 15-30

sternoclavicular sagittal plane

what joint and plane is arm rotation with a bent arm associated with 

posterior rotation 15-5-

anterior rotation 10

acromioclavicular joint

what join performs same movement as sternoclavicular joint but a lot less ROM

Acromoioclavicula

allows independent motion between scapula and clavicle

permit subtle movement of the scapula 

scapulothoracic joint

moves on thoracic because of rotation of sternoclavicular joints

works in concert with other joints of upper extremity 

scapulothoracic translation

depression/elevation

abduction/protraction

adduction/retraction 

scapulothoracic rotation 

anterior vs posterior tilting

superior vs inferior rotation

internal vs external rotation 

scapula elevators

levator scapulae, upper trapezius, rhomboids

scapular depressors

lower trapezius, pec minor

scapula protractor 

serratus anterior, pectoralis minor 

scapula retractor

middle and lower trapezius, rhomboids

scapula superior rotator 

serratus anterior, trapezius 

scapula inferior rotators

rhomboids, levator scapulae, pec minor

glenohumeral joint

humeral head artiulate with shallow flenoid fossa

ball and socket joint to help with mobility

NOT MUCH STABILITY

glenoid labrum

around glenoid to make socket deeper

increases shoulder stability by resisting shear

fibrocartilage ring

glenohumeral joint capsule

attached at labrum

loose in mid ROM but tightes at extreme ROM

completely sealed- to create suction and stability 

glenohermal ligaments 

thick regions of the capsule,

superior tightens when adduction

middle tight when abduction

inferior tight in abduction

supraspinatus, infraspinatus, teres minor, subscapulatris 

muscles of rotator cuff

SITS

provide most of dynamic stability in mid ROM

rotator cuff stability

SITS provides compression to resist shear and stabilize

creases a posterior and inferior shear to resist the dominant superior and anterior shears created by superficial muscles

protective resistance shear 

true

t/f hard to separate glenohumeral rotation from scapulothoracic rotation

osteokinematics

relation rotation of 2 bones relative to one another

arthrokinematics definition

relative motion of 2 bones surfaces as rotation occurs at a joint

how 2 joint surfaces move, relevant to each other 

arthrokinematics

spinning at longitudinal axis, no translation of 2 bone surfaces

roll, always results in translation in direction of rol

glide like a tire slideing 

role and glide

roll in one direction, slide in other to stay articulate

roll and glide in opposite direction

when convex bone rotates on a fixed concave surface

roll and glide in same direction

when a concave bone rotates on a fixed convex surface

scapulohumeral rhythm

att full 180 decrease or abduction or flexion, only 1/3 of total rotation comes from scapulothoracic

this is called what

frontal

scapular adduction and abduction, upward and downward 

what plane

sagital 

sagittal flexion and extension

down- posteriorly tilt

up- anterior tilt 

what plane

transverse

scapular horizontal abduction- retraction, and adduction- protraction 

internally rotate

laterally rotate 

what plane

anterior delt, pic majors, coracobrachialis

shoulder elevators

flexors 

deltoid, suprsapinatus

shoulder elevators

lat dorsi, teres major, post delt, pec major

shoulder extensors

lat dorsi, teres majors, post delt

horizontal ABD of the shoulder

lat dorsi, teres major, pec major, coracobrachialis 

shoulder ADDuction

ant delt,m lat dorsi, subscapularis, pec major, teres major

shoulder internal rotator

post delt, infraspinatus, teres minor

shoulder external rotator

rotator cuff

supraspinatus

subscapularis 

infraspinatus

teres minor

supraspinatus

most superior rotator cuff

compresses humeral head into glenoid fossa

ABD

subscapularis

largest cross section and anterior portion of rotator cuff

inferior and posterior translation force on humerus head

strong internal rotator 

infraspinatus

posterior portion of rotator cuff

inferior and posterior translation force on humerus head

externally rotate humerus

teres minor

part of rotator cuff that functions similar to infraspinatus

CG

how we represent the single force acting at the center of gravity 

force couple

2 forces exactly equal and opposite, separated by perpendicular distance 

net effect is 0, net rotation effect

free body diagram

representation of a body isolated from its environment, with a representation of all external forces acting upon a body 

muscle torque in opp direction of external torque 

muscle torque in opp direction of external torque 

FOOSH

falls on out stretched had

point of the shoulder transmit large forces through the clavicle 

fractured clavicle 

FOOSH in children

sprained/dislocated acromioclavicular

FOOSH in adult 

subacromial impingement syndrome

compression of ratrof cuff tendons in subacromial space

caused by superior trsnalation of humurs caused by lack of GH stability

causes pain and chronic damage to rotator cuff tendons

GH dislocation

dangerous positions with arm out and ruther back causes larger anterior shear force

pull medial and anterior which shortens

common in basketball

elbow 

composed of humeroulnar joint, humeroradial joint, and proximal radioulnar joint 

humeroradial joint

elbow flexion and extension

convex distal capitulum of th ehuerus articulate with concave radial head

hinge flexion

proximal radioulnar joint

forearm supination and pronation

epicondyle

in elbow for ligament and tendon attachment

trochlea

in elbow articulates with ulna

looks like a spool of thread 

capitulum

in elbow articulated with radius

fossas

in elbow, contact area for corresponding ulnar processes 

olecranon 

in elbow

limits extension

point of elbow when bent

coronoid process

in elbow, limits flexion

radial head

articulates with ulna and capitulum of humerus 

humeroulnar joint

rounded convex trochela of the humerus fit into the concave trochlear groove of proximal ulna

modified hinge joint

carrying angle

in full extension, forearm deviates in a valgus direction due to shape of articulating surfaces

deviation disappears as forearm flexes

deviation disappears as forearm flexes

valgus

distal away from midline

varus

towards midline

proximal radioulnar joint

radius crosses over ulna, head of radius fits into radial fossa on ulna, pivot joint 

elbow joint capsule

encloses all three joints

strengthened by extensive set of collateral ligaments 

radial collateral ligament

stabilizes lateral side of the elbow

resists external varus torque

• toward midlien

ulnar collateral ligament

stabilize medial side of elbow

resists external valgus torques

• away from midline

annular ligament 

holds radial head in place

still allows rotation

quadrate ligament

reinforces inferior joint capsule

limits forearm supination 

interosseous membrane

connects and transmits forces between radius and ulna

provides longitudinal stability in the forearm

stiffens 2 bones to act as a unit 

elbow sagital

elbow what plane does flexion and extension

and hyper extension

elbow transverse

supination and pronation in elbow is in what plane

elbow flexors

biceps brachii, brachialis, and brachioradialis

biceps brachii

elbow flexor

good mechanical advantage

best supination

long notice arm 

impacted by pronation and supination 

brachialis

elbow flexor, largest cross sectional area

workourse

smallest mechanical advantage- moment arm

unaffected by pronation/supination

connects to ulna 

brachioradialis

elbow flexor

smallest cross section area

good mechanical advantage

strong flexor in neutral 

mid ROM

where are elbow flexors the strongest

this is where they have the best moment arm 

mid- supination, pronation

strongest to weakest elbow flexors

bicepts brachia for supitaiton, bicept and brachialis in pronation, less efficitive