Lecture 3: Muscles, Joints, & Biomechanics Flashcards
Each skeletal muscle is composed of fascicles, which are bundles of muscle ________ aka muscle cells
Fibers
Muscle fibers contain __________ which are made up of ____________
Myofibrils; myofilaments
__________ attaches the muscle to bone, skin, or another muscle and usually have thick, cordlike structure
Tendon
Tendons sometimes form a thin, flattened sheet called an ____________
Aponeurosis
What is the difference between tendons and ligaments?
Tendons bind muscle to bone
Ligaments bind bone to bone
Most skeletal muscles extend between bones and cross at least one movable joint. Upon contraction, one of the bones moves while the other bone usually remains fixed. The less movable attachment of a muscle is called its _________; the more movable attachment is its _____________
Origin; insertion
The insertion of a muscle is typically pulled __________ the origin. The origin typically lies _________ to the insertion
Toward; proximal
Name the 4 organizational patterns in fascicles of muscle fibers
Circular
Convergent
Parallel
Pennate
What fascicle organizational pattern is a sphincter, where contraction of the muscle closes off the opening?
Circular
What fascicle organizational pattern has fascicles running in the same direction as its long axis and has a central belly or gaster?
Parallel
What fascicle organizational pattern has widespread muscle fibers that have a common attachment site often triangular in shape?
Convergent
What fascicle organizational pattern has one or more tendons extending through the body with fascicles arranged at an oblique angle?
Pennate
Which fascicle pattern would allow you to bear the most weight: unipennate, bipennate, or multipennate?
Multipennate, because it has the most fascicles per unit area
Skeletal muscles can be grouped by action - what is an agonist?
Aka prime mover; contracts to produce a particular movement
What type of skeletal muscle opposes the action of the agonist?
Antagonist
Skeletal muscles can be grouped by action - what is a synergist?
Assists the prime mover (agonist) in performing its action, usually by stabilizing the point of origin
sometimes called a fixator
Describe the relationship between the mobility and stability of joints
Indirectly proportional
The more mobile the joint, the less stable it is
What type of joint occurs where bones are held together by dense regular connective tissue?
Fibrous joint
What type of joint occurs where bones are joined by cartilage?
Cartilaginous joint
What type of joint is most complex and has a fluid filled cavity?
Synovial joint
In terms of joint classification: ___________ is an immovable joint
Synarthrosis
In terms of joint classification: __________ is a slightly movable joint
Amphiarthrosis
In terms of joint classification: _________ is a freely movable joint
Diarthrosis
Most fibrous joints are classified as ____________ or __________
Synarthrosis (immovable)
Amphiarthrosis (slightly movable)
True or false: most fibrous joints have a joint cavity
False, most do not have a joint cavity
What are the 3 types of fibrous joints and how are they classified in terms of mobility?
Gomphosis (synarthrosis)
Sutures (synarthrosis)
Syndesmosis (amphiarthrosis)
The membranes of connective tissue in the arms and legs that allow supination/pronation are what type of joint?
Syndesmosis (amphiarthrosis)
Do cartilaginous joints have a joint cavity?
No
What are the 2 types of cartilaginous joints?
Synchondrosis (amphiarthrosis or synarthrosis)
Symphyses (amphiarthrosis)
What type of joints are freely movable articulations, classified as diarthrosis, and are separated by a joint cavity?
Synovial joints
What are the basic features of synovial joints?
Articular capsule Joint cavity Synovial fluid Articular cartilage Ligaments Nerves Blood vessels
What accessory structure to synovial joints is composed of a fibrous, saclike structure that contains synovial fluid and is lined by a synovial membrane?
Bursae
What accessory structures to synovial joints are often distributed along the periphery of a synovial joint and act as packing material to provide protection for the joint?
Fatpads
What accessory structure to synovial joints has the primary purpose of stabilizing the joint itself?
Tendons
Name the 6 types of synovial joints from least movable to most movable
Planar joints Hinge joints Pivot joints Condyloid joints Saddle joints Ball-and-socket joints
What type of joint is the dens of the axis in the neck?
Pivot
What type of joint is the elbow?
Hinge
Where might you find a condyloid joint?
The knuckles
Where might you find a saddle joint?
Base of the thumb
How would you increase the efficiency of a lever system?
Increase the length of the effort arm in relation to the load arm, that way you need less muscular effort to move the load
In terms of lever systems in the body, a long bone acts as a ___________, a joint serves as the __________, and the effort is generated by ________ attached to the bone
Lever
Fulcrum
Muscle
What type of lever system has resistance between the fulcrum and the applied force?
Second class
What type of lever system has the force applied between the resistance and the fulcrum?
Third-class
** this is the most common lever system in the body **
What type of lever system has a fulcrum in the middle, between the force and resistance?
First-class
What is an anatomical example of a first class lever system?
Nuchal musculature
The face is the load, the fulcrum is at the base of the head, and the effort is the nuchal musculature
What is an anatomical example of a second-class lever system?
Standing on the ball of the foot
The fulcrum is the ball of the foot, the load is the weight of the body, the effort is the calf musculature
What is an anatomical example of a third-class lever system?
Lifting a dumbbell with the biceps
Load is the weight in your hand, fulcrum is the elbow, effort is the biceps musculature
What anatomical difference is seen in the forearm of bears, resulting in very strong but relatively slower flexion?
The biceps tendon inserts further down (distally) on the forearm
In humans, the biceps tendon inserts closer to the joint. We can move our forearms much faster but we cannot lift as much as a bear
What anatomical difference in chimps and apes results in their waddle-like gait when walking bipedally?
Their small gluteal musculature is not in the same place as ours, so in order to stabilize themselves they have to center their weight on either leg with each respective step
60% of the gait sequence is spent in what phase?
Stance (majority of which is double support, divided evenly between right and left foot forward)
40% of the gait sequence is spent in what phase?
Swing
Swing phase occurs during single support stance phase
According to Dr. Wright, what are the most important muscles for habitually bipedal gait?
Small gluteal muscles located laterally on the ilia
What is the term for the pathological gait in humans that appears similar to the great apes? This occurs when the small gluteal muscles do not function normally and the person rocks from side to side while walking
Trendelenburg’s sign
What are the 4 primary differences between the male and female pelvis?
The female pelvis has:
More obtuse angle of the subpubic arch
Straighter sacra (males is more curved)
Wider greater sciatic notch
More steep femoral angle
The femoral angle is an example of what type of lever system?
First-class
The mandible is an example of what type of lever system?
Third-class
How has the mandible become more efficient in modern humans?
The face has become shorter, allowing the muscles of mastication to work closer to the teeth
What is Greave’s triangle of support?
The jaw is actually 2 third class levers attached anteriorly
To avoid separation of the TMJ, the resultant of all muscle force vectors must stay within the triangle of support (which is made between where the animal is biting and its 2 TMJs)
