Unit 1: Mechanisms and Characteristics of Musculoskeletal and Nerve Trauma
Part I
What is one of the main roles of an Athletic Trainer?
 Recognizing a specific injury to a _______________________ or nerve structure
o Musculo- muscle
o Skeletal- bone
And
 The mechanical forces that produce that trauma.
VOCABULARY
Trauma
 A physical injury or wound produced by an external or internal force
Tissue Properties
 Described using mechanical terminology (terms used in physics, engineering, etc.)
Load
 An external force acting on the body causing internal reactions within the tissues
Stiffness
 Ability of a tissue to resist a load
Stress
 Internal resistance to an external load
Strain
 Internal change in tissue (i.e. length) resulting in deformation (change of the tissue)
Elasticity
 Property that allows tissue to return to normal after deformation
Yield Point
 When tissue is deformed to the extent that is not longer reacts elasticity
Plastic
 When a load is removed, deformation of the tissue to an extent remains
Creep
 Deformation of a tissue over a period of time
Mechanical Failure
 Exceeding the ability of the tissue to withstand the load and the tissue breaks down
5 Types of Tissue Loading
 Tension
o Force that pulls and stretches tissue
 Compression
o Force that results in tissue crush – two forces applied towards one another
 Shearing
o Force that moves across the parallel organization of tissue
 Bending
o Convex side is elongated and subject to tension while the concave side is
subjected to compression resulting in shortening
 Torsion
o Loads caused by twisting in opposite directions from opposite ends
Traumatic vs. Overuse Injuries or Acute vs. Chronic
Acute vs. chronic injuries
 Acute Injury
o Something initiated the injury process (_________________________)
 Chronic Injury
o When it doesn’t properly heal (________________________________________)
Defined by mechanism
 Traumatic (i.e. a direct blow) vs. Overuse (i.e. repetitive dynamic use over time)
Musculotendinous Unit (3 parts) Gross Anatomy
 Muscle
o ______________________________________________ that produce movement
 Tendon
o Thicker part of muscle that ___________________________________________
 Fascia
o Fibrous _________________________________________ (over the epimysium)
Skeletal Muscle Diagram
Muscle Injuries
Muscle Strains
 Stretch, tear or rip to muscle or its tendon
 Cause: _______________________________________________ is the result of:
o Coordination of agonist and antagonist
o Electrolyte imbalance
o Strength imbalance
 Grade I –
o Some fibers have been _____________________ or actually torn Tenderness and
pain on active ROM but full range
 Grade II –
o Moderate Number of fibers have been torn
o Active contraction is painful
o ____________________________________ is palpable
o Some swelling and discoloration result
 Grade IIIo _______________________________ of muscle
o Significant impairment
o Initially a great deal of pain that diminishes
 Rehabilitation
o Healing time may be lengthy
o Treatment and recovery may take 6-8 weeks depending on severity
o Return to play too soon could result in re-injury
Paraphrase the 3 Grades
Grade I:
Grade II:
Grade III:
Muscle Cramps
 Painful _____________________________ skeletal muscle contraction
 Cause: Can coincide with heat cramps due to excessive water loss or electrolytes
Muscle Guarding
 Involuntary muscle contraction in ______________________________ following injury
 Elaboration: The muscles that surround the injured area contract or splint the area
Muscle Spasm
 A _____________________________ caused by trauma
 Elaboration: May lead to muscle or tendon injuries

Types
o Clonic - _______________________________ involuntary muscular
contractions and relaxations in quick succession
o Tonic - ______________________________________ that lasts a period of time
Muscle Soreness
 Pain caused by _____________________________ in exercise
 Elaboration: Generally occurs following participation in activity that individual is
unaccustomed
 Two types:
o Acute-onset muscle soreness
 Accompanies fatigue
 Pain experienced ________________________________ after exercise
o Delayed-onset muscle soreness (DOMS)
 Pain that occurs _______________ hours following activity that
gradually subsides
 Pain free 3-4 days later
Tendon Injuries
Tendons
 Connects muscle to bone
 Elaboration
o Some elasticity (more than bone, less than muscle)
o Breaking point occurs at 6-8% of increased length
o Tears generally _____________________________ and not tendon
Tendinitis
 _____________________________________ of the tendon
 Mechanism
o Gradual onset, due to microtrauma of the tendon
o Tendon becomes irritated
 Signs/ Symptoms:
o Swelling, pain, warmth, and crepitus (crackling feeling or sound)
 Management:
o Key to treatment is _____________ (substitute an activity)
Tendonosis
 Break down of the tendon __________________________
 Signs and Symptoms:
o Less inflammation
o ________________ movement or touching
o Stiffness and restricted motion
 Management:
o Stretching and strengthening
Tenosynovitis
 Inflammation of the tendon _________________________________________
 Types
o Acute case: rapid onset, crepitus, and diffuse swelling
o Chronic cases: result in thickening of tendon with pain and crepitus
Myofascial Trigger Points
 Discrete, __________________________________________ within tight band of
muscle or fascia (knots)
 Types
o Latent trigger point
 Become aware when pressure is applied
 May restrict movement or cause muscle weakness
o Active trigger point
 Causes pain at rest
 Applying pressure = pain = jump sign (w/ referred pn)
 Found mostly postural muscles
Contusion
 ____________________________________________ tissue that results in bleeding into
surrounding area, AKA- a bruise
 Mechanism:
o Result of sudden blow to body
o Can be both deep and superficial
 Signs and Symptoms:
o Ecchymosis (_________________________________________ of the skin)
o Pain with palpation and movement
Myositis Ossificans
 Chronically inflamed and contused tissue may result in generation of ________________
__________________________
 Bone spurs in the muscle
Atrophy
 Muscle _____________________________________________
 Due to immobilization, inactivity, or loss of nerve functioning
Contracture
 Abnormal __________________________________ of muscle
 Usually due to scar tissue