Kinesiology - Module 6

Define balance

The ability to maintain the center of mass over the base of support

Human balance is maintained through a complex system involving these 4 things:

Sensory detection, sensory integration, musculoskeletal, and execution

What 3 systems are involved in balance?

Visual, somatosensory, vestibular

Which system involved in balance is the most sensitive?

Visual

How does the visual system help with balance?

Provides information about body position relative to environment and moving environment

How does the somatosensory system help with balance?

Peripheral receptors

What are peripheral receptors?

Detect motion of the body with respect to the supporting surface and body segments with respect to each other

Why do a lot of people have underused somatosensory systems?

Because gyms have mirrors so we can see that we are doing the movements correctly

How does the vestibular system help with balance?

Maintains upright vertical body alignment

Which system involved in balance is the slowest?

Vestibular

Which system involved in balance is the most accurate?

Vestibular

If there is a conflict in the 3 systems of balance, which is trusted over the others?

Vestibular

Anatomy responsible for vestibular input

Utricle and saccule

What is the function of the electromechanical transducing receptor?

takes mechanical information and translates into an electrical signal that is then used by the brain

What 3 things help with the electromechanical transducing receptor?

Hair cells, fluid, otiliths

Rotation stimulates ____________________ in the angular vestibular system

Semicircular canals

Each semicircular canal has an ________

Ampulla

The ampulla is responsible for __________ and _________

Vertigo and nystagmus

dizzy/spinning sensation

Vertigo

reflex of the eyes when they are nearing the limits of peripheral movement, but eyes start twitching when they get towards the end

Nystagmus

When a person stands next to a large bus that suddenly begins to move, momentary disorientation or imbalance may result. What is this called?

Erroneous sensory

Under most conditions, the ___________ and __________ systems dominate and control orientation and balance

Somatosensory and vision

Point at which all mass acts

Center of Mass (COM)

Area within an objects outermost contact with support surface

Base of Support (BOS)

vertical projection from COM downward to support surface

Line of Gravity (LOG)

maximum angle from vertical that is tolerated without the loss of balance

Limit of stability (LOS)

BOS is proportional with _______

LOS

COM is inversely proportional to ________

LOS

small movements occurring even when you think you are standing still. So small that you may not feel or see them, but they are happening

Sway

how fast you are swaying

Sway velocity

how far from balance you move in any given sway

RMS Sway

strategies to help maintain balance or prevent a fall

Synergistic motor responses

What are the 3 synergistic motor responses?

Ankle strategy, hip/knee strategy, stepping strategy

Synergistic motor response used during quiet stance or in response to small/slow perturbations

Ankle strategy

Synergistic motor response used in slippery/unstable surfaces

Hip/knee strategy

Synergistic motor response used when lower extremity cannot maintain the CoM without the BoS

Stepping strategy

Synergistic motor response that is the basis of gait

Stepping strategy

any way that you project yourself from point A to point B

Gait

Where the line of gravity intersects your support surface

Center of Pressure

How far one foot travels during a gait cycle

Step length

How far body travels during one gait cycle

Stride

There is a spatial distance between the legs as they slide past each other while we walk, this distance is about 3.5 inches

Walking Base

Why do most people have about a 7 degree toe out angle?

It slightly widens our base of support, helping us to become a little more stable

Gait classification during typical walking gait, most people make initial contact with the ground with our heel

Heel strike (HS)

Gate classification depicting that our foot that has previously made initial contact has come flat

Foot flat (FFL)

Gait classification when we are in the middle of a stance phase of whichever leg is in contact with the ground

Midstance

Gait classification when Heel lifts off of our stance leg as we prepare to lift it off the ground and swing it forward

Heel lift (HL)

Gait classification when Foot that was in contact with the ground is leaving the ground, toe is coming up

toe off (TO)

About ____% of a gait cycle is spent doing double-limb support

30%

Number of steps within specific time frame

Cadence

Factor affecting cadence for gait

Height

Speed of ambulation on smooth surface

Velocity

Increase velocity = ___________ stance/swing time

decrease

What is the purpose of a more efficient vertical displacement?

decrease energy expenditure, we don't want to waste energy where we don't need to waste energy

Where is the greatest lateral displacement during gait?

Midstance

If you have flat feet how does this affect your walking gait?

center of pressure pathway will move medially quicker

If you have high arches how does this affect your walking gait?

center of pressure pathway will move medially later, if it moves medially at all

What are the 6 movements of the shoulder?

Elevation/depression, protraction/retraction, upward/downward rotation

What 3 bones compose the shoulder girdle?

Scapula, clavicle, humerus

What are the 4 joints at the shoulder girdle?

Glenohumeral, acromioclavicular, sternoclavicular, scapulothoracic

Is the shoulder girdle an open or closed mechanical system?

Open

The scapula articulates to keep these two things together

Glenoid fossa and humeral head

The scapula rests on these two muscles

Serratus anterior and subscapularis

Only osseous connection between the axial skeleton and the upper extremity

Sternoclavicular joint

What type of joint is the sternoclavicular joint?

Modified ball and socket joint

What type of joint is the acromioclavicular joint?

Synovial joint - gliding

Link between the clavicle and scapula

Acromioclavicular joint

What are the two ligaments at the acromioclavicular joint?

Acromioclavicular (AC) and coracoclavicular (CC)

What are the two functions of the acromioclavicular joint?

To transmit loads on upper extremity to axial skeleton via clavicle and to allow scapular movements to accommodate shape of thoracic wall during arm motion

Which shoulder muscles facilitate scapular retraction?

Lower trapezius and rhomboids

Which shoulder muscles facilitate scapular protraction?

Serratus anterior and pectoralis minor

Which shoulder muscles facilitate scapular elevation?

trapezius (upper and middle fibers), levator scapulae, rhomboids (both)

Which shoulder muscles facilitate scapular depression?

Lower trapezius, subclavius, pectoralis minor

Which shoulder muscles facilitate scapular upward rotation?

Serratus anterior, trapezius (all fibers)

Which shoulder muscles facilitate scapular downward rotation?

Pectoralis minor, levator scapulae, rhomboids

The true shoulder joint

Glenohumeral (GH) joint

Most mobile joint in the body

Glenohumeral joint

The shoulder joint sacrifices ______________ for ______________

Stability for mobility

List the 4 rotator cuff muscles

supraspinatus, infraspinatus, teres minor, subscapularis

Which rotator cuff muscle is anterior?

subscapularis

What are the 8 motions are the glenohumeral joint?

Flexion/extension, abduction/adduction, internal/external rotation, horizontal abduction/adduction

What are the classifications for the glenohumeral joint?

ball and socket ; Triaxial diarthrotic

What are the static stabilizing structures of the glenohumeral joint?

Capsulo-ligamentoux complex (CLC), bony geometry, glenoid labrum

What is the dynamic stabilizing structure of the glenohumeral joint?

Musculo-tendinous influences

What are the 2 mechanisms of the glenohumeral joint for providing stability?

Glenoid fossa and humeral head contact area, articular surface congruency

Effect of the fibrous rim deepening the glenoid fossa, increasing total surface contact area between the glenoid and humeral head

Buttress effect

Primary dynamic stabilizers of the glenohumeral joint

Rotator cuff (supraspinatus, infraspinatus, teres minor, subscapularis)

Secondary dynamic stabilizers of the glenohumeral joint

Teres major, latissimus dorsi, pectoralis major, long head of biceps, deltoid

What muscles facilitate flexion at the glenohumeral joint?

Pectoralis major (clavicular), anterior deltoid, coracobrachialis, biceps brachii

What muscles facilitate extension at the glenohumeral joint?

Posterior deltoid, latissimus dorsi, teres major, triceps brachii (long head only)

What is the primary mover of the glenohumeral extensors and adductors?

Gravity

These two glenohumeral extensors do everything together

Latissimus dorsi and teres major

What muscles facilitate abduction at the glenohumeral joint?

deltoid (anterior, posterior, and medial), supraspinatus

What muscles facilitate adduction at the glenohumeral joint?

latissimus dorsi, teres major, pectoralis major (sternal), coracobrachialis, triceps brachii

What muscles facilitate internal rotation at the glenohumeral joint?

Pectoralis major (all fibers), anterior deltoid, latissimus dorsi, teres major, subscapularis

What muscles facilitate external rotation at the glenohumeral joint?

infraspinatus, teres minor, posterior deltoid (small assistance)

What muscles facilitate horizontal abduction rotation at the glenohumeral joint?

deltoid (posterior and medial), infraspinatus, teres minor

What muscles facilitate horizontal adduction rotation at the glenohumeral joint?

pectoralis major (all fibers), anterior deltoid, coracobrachialis

List the strengths of the shoulder complex from strongest to weakest

Adduction, extension, flexion, abduction, internal rotation, external rotation

Where is the shoulder in the safest position?

Slightly externally rotated