Exam 1 (Biomechanics) Flashcards by Brianna Spinnato

In what direction does the roll of a joint always occur?

Always occurs in the same direction as the osteokinematic motion (ex: humeral head rolls superior during shoulder flexion)

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Where is the scapular plane?

30-45° anterior to frontal plane

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Open vs Closed Pack Position

· Open-Packed: passive stabilizers (ligaments) on slack/loosest so mobility is increased (used to treat hypomobility)
· Closed: ligaments on tension so least amount of mobility

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Capsular Pattern

· Pattern of motion loss where whole capsule is hypomobile/limited/tight
· Entire joint is effected so ALL joint motions are limited (gross motor loss)
· Ex: Adhesive Capsulitis (NOT subacromial impingement bc capsule not the issue)

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How is supination improved at PRUJ and DRUJ if hypomobile?

PRUJ: glide anterior
DRUJ: glide posteriorly

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Concave on Convex vs Convex on Concave

· Concave on Convex: roll and glide are in same direction
· Convex on Concave: roll and glide are in opposite directions

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What motions would an anterior glide of the proximal radius, what motions are improved?

· Elbow flexion at Humeroradial joint because concave radius moves on convex capitulum of humerus
· Supination at PRUJ because convex radius moves on concave trochlear notch of ulna

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Radius

· Fovea of head: concave
· Head: convex
· Distal radius: concave

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What nerve innervates the Thenar Eminence vs Hypothenar Eminence?

· Thenar: Median N (“One For All”
· Hypothenar: Ulnar N (“All For One”)

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What elbow flexors are innervated by the Musculocutaneous Nerve?

Biceps Brachii and Brachialis

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What elbow flexor is innervated by the Radial N?

Brachioradialis

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What head of biceps brachii produces more torque?

Short head because it inserts more distal thus larger IMA

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What muscle is the primary elbow flexor vs extensor?

· Flexor: brachialis
· Extensor: medial head of tricep (bc only crosses one joint)

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What muscle is the primary supinator for force production related tasks?

Supinator (bc only crosses one joint)

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What muscle is a direct antagonist to the brachialis?

Medial head of triceps

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In a WB position, what muscles could assist with supination of the forearm assuming the radius is in a fixed position?

Humerus will ER via Teres Minor

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Why is the glenoid fossa retroverted?

Helps to create stability by creating more contact between the head of humerus and glenoid fossa

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Angel of Inclination vs Angle of Torsion

· Angle of Inclination: angle between humeral head and shaft (~135° in frontal plane)
· Angle of Torsion: angle between humeral head and neck in relation to condyles (twist, ~30° posterior to transverse plane)

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What is the most common position for shoulder dislocation?

90/90 ABD and ER (high five position)

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What keeps the shoulder joint at 0°?

Coracohumeral ligament, Superior GH ligament, and vacuum created by joint capsule

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What is the subacromial space and what does it contain?

· Subacromial space is the space between the coracromial arch and humeral head
· Contains long head bicep tendon, supraspinatus, and subacromial bursa

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What happens to the subacromial space as the shoulder ABDucts?

Space decreases in size, structures inside can be impinged

What muscles resist upward translation of humeral head during elevation?

· Infraspinatus, Teres Minor, and Subscapularis

What structures limit anterior glide of the humerus?

· At 0°: Superior GH ligament
· Between 45-90°: Middle GH ligament
· At 90/90 (ABD/ER): Anterior Band of Inferior GH Ligament Complex
· Anterior GH Joint Capsule

What structures limit posterior glide of the humerus?

· At 90°ABD and IR: Posterior Band of IGHLC · Posterior GH Capsule

What structures limit inferior glide of the humerus?

· At 0°: Superior GH ligament and Coracohumeral Ligament · At 90° ABD: Axillary Pouch of IGHLC · Glenoid rim · Intra-articular vacuum pressure

Why does ABD have to be coupled with ER?

Must be coupled in order to clear the coraromial arch or else the greater tuberosity will impinge on the arch (occurs between 60-120°)

WHy does the clavicle rotate posteriorly during elvation

To put the coracoclavicular ligament on slack so can elevate more

What is the normal resting position of the scapula?

IR, Anterior tilt, and upwardly rotated

What is scapular winging and what are potential causes?

· Scapular Winging: Excessive IR of scapula · Potential Causes: weak SA, Long Thoracic Nerve damage, damage to C5/6/7

Impact of tight Pec Minor on shoulder elevation?

Difficulty elevating bc Pec Minor tightness would cause excessive Anterior Tilt and IR

What is the most commonly torn RTC muscle?

Supraspinatus

Muscles involved with upward vs downward rotation force couple of the shoulder

· Upward Rotation 1) Seratus Anterior (ER scapula) 2) Upper and Lower Traps · Downward Rotation 1) Teres Minor 2) Infraspinatus 3) Lats 4) Rhomboids

What muscles may contribute to scapular dyskinesia (abnormal movements during flexion and abduction) ?

· SA weakness (causing decreased upward rotation) · Tight Pec Minor (causing excessive IR) and weak SA (causing decreased ER) · Lower Trap and Subscap weakness (causing decreased posterior tilt) and tight Pec Minor (causing increased Anterior tilt)

Doubl-V System

Some ligaments on stretch while others are on slack

DISI vs VISI of wrist

· DISI: lunate dislocates and distal articular surface faces dorsally · VISI: lunate dislocates and distal articular surface faces ventrally * Both will impact arthrokinemtatics

Impact of injuries to scapholunate ligament

Lunate can become unstable and will impact arthrokinematics of both carpal rows

What muscles work synergistically to produce ulnar deviation to hit a nail with a hammer?

FCU and ECU

What muscles work synergistically to radial deviate when pulling hammer up from nail?

FCR and ECRL

What position of the wrist helps optimize grip?

Extension and ulnar deviaton of wrist (bc optimizes length-tension relationship for extrinsic finger flexors to go and grip)

Lateral Epicondylagia Muscle Impacted Most Often

ECRB (bc low load and long duration muscle)

What is the effect of the Ligamentum Flavum thickening on the spinal canal?

· Cervical Spine Central Stenosis causing UMN lesion (presents as hyperreflexia, positive babinski, regional pattern presentation, atrophy of hands, balance issues, etc.)

What helps contribute to lordosis?

Anterior thickness of IVD in cervical and lumbar regions (IVD absorb and distribute forces)

What functional activities put the most pressure on the IVD?

1) Slight forward flexion (brushing teeth) 2) Stoop lift

Types of disc herniations

1) Protrusion 2) Prolapse 3) Extrusion 4) Sequestration

What direction are disc herniations most common?

Postereolateral because of thinner annulus fibrosus posteriorly and PLL is not super strong

What is an impact of bad posture of spinal curvature?

· Bad posture can increase thoracic kyphosis thus creating a larger EMA which means muscles will have to counteract by creating a bigger internal torque

What positions pose a potential to occlude the vertebral artery?

END range motions of cervical ext, lat flexion, or rotaiton

Damage to the Transverse Ligament may do what to the Atlantodental Interval (space between arch of atlas and dens of axis)?

It may increase the ADI space (structural instability)

Impact of Degenerative Disc Disease (DDD)

· Discs lose height (vertebral bodies and facet joints get closer together) · Decrease size of intervertebral foramen (causing nerve root compression)

What position would relieve symptoms of right C5 nerve root irritation from foramenal stenosis?

· Left rotation · Left SB · Flexion

3 Types of Thoracic Outlet Syndrome

1) Costoclavicular Syndrome 2) Anterior Scalene Syndrome 3) Pec Minor Syndrome

Why are disc herniations less common in the T-spine?

· Bc Tspine has more posterior joints that take up more space thus leaving less room for disc to bulge postereolateral (Costovertebral and Costotransverse) · Bc Tspine has more stability