Human Anatomy - Lecture 5 & 6 - Muscles and Lever Mechanics

What are the main functions of muscles?

1. Heat generation

2. Force generation

3. Stabilization of joints

4. Maintenance of posture

What are the four properties of muscle tissue?

Contractability (ability to shorten forcefully)

Excitability (responsive to stimulus)

Extensibility (ability to be stretched even beyond resting length)

Elasticity (ability to return to resting length after stretching)

Where is cardiac muscle found?

Only in the walls of the heart

Where is smooth muscle found?

Single unit smooth muscle found in walls of hollow visceral organs, multi-unit found in large arteries

Where is skeletal muscle found?

Attached to bone via ligaments and other muscle via tendons. Some skeletal muscle is attached directly to the skin (some facial muscles)

Which types of muscles have striations?

Skeletal muscle and cardiac muscle only, smooth muscle doesn't not have striations.

Which of the three types of muscles are under voluntary (somatic) control?

Skeletal muscle only, smooth muscle and cardiac muscle are under autonomic control

Can cardiac muscle operate anaerobically

No, only skeletal muscle and smooth muscle can operate anaerobically

cardiac muscle is ........ or ........ nucleate

Uni or bi

Skeleta muscle is ....... nucleated and striated

multi

Smooth muscle is uninucleate only, true or false?

True

The origin point moves when the muscle contracts, true or false?

False, the origin point does NOT move when the muscle contracts, the insertion point moves.

How many bones do humans have?

206

Humans have over ......... skeletal muscles

600

The .......... point moves when the muscle contracts

Insertion

What is an example of a circular shape muscle?

Orbicularis oris

What is an example of a parallel, strap like muscle?

Sternocleidomastoid

What is an example of a parallel fusiform muscle?

Biceps Brachii

What are four other types of muscle shape other than parallel, circular and parallel fusiform?

Unipennate, Bipennate, Multipennate and Convergent

What are 8 anatomical terms for motion?

• Adduct: To move a structure towards the midline of the body.

• Abduct: To move a structure away from the midline.

• Extend: To stretch limb segments away from one another.

• Flex: To contract limb segments closer to one another.

• Pronate: To turn face down (or palm down).

• Supinate: To turn face up (or palm up).

• Dorsiflex: To rotate the foot up.

• Plantarflex: To rotate the foot down.

What does adduct mean?

To move a structure towards the midline of the body

What does abduct mean?

To move a structure AWAY from the midline of the body, opposite of adduction

What does extend mean as an anatomical term for motion?

To stretch limb segments away from one another

What does flex mean?

To contract limb segments closer to one another?

Flexing a muscle is the opposite of?

Extending a muscle

What is the opposite of adduct?

Abduct (to move away from the midline)

Pronate is?

To turn face up (palm down)

Supinate is?

To turn face up (palm up)

What is the opposite of pronate?

Supinate (palm up)

Dorsiflex and plantarflexion are?

Dorsiflex is to rotate the foot up, and plantarflex is to rotate the foot down

What are the four pairs of muscles involved in mastication?

Masseter

Temporalis

Medial pterygoid

Lateral pterygoid

What nerve innervated the four paired muscles of mastication?

CN V, the trigeminal

What are the 3 extrinsic muscles involved in tongue movement?

Genioglossus, Hypoglossus and Styloglossus

What are the three types of joint?

Synarthroses (immovable)

Amphiarthroses (slightly movable)

Diarthroses (highly movable)

Synarthroses are what type of joint?

These are immovable joints in which the edges of bones are in close proximity and sometimes interlock

What are the four types of synarthrose (immovable joint)

1. Sutures (between skull bones)

2. Gomphoses (Binding teeth to maxilla/mandible)

3. Synchondroses (rigid cartilagenous bridge between two articulating bones)

4. Synostoses (a totally rigid joint formed between two fused bones)

What are the two types of amphiarthrose (slightly movable joint)

1. Syndesmoses (connected by ligament)

2. Symphysis (seperated by cartilage)

What is an example of a synostose (synarthrose)

Metopic suture

What is another name for diarthrose?

Synovial joint (freely moving)

Where are synovial joints (diarthroses) normally found?

At the end of long bones (e.g. Femur)

Synovial joints contain ....... fluid

Synovial

How are diarthroses (synovial joints) stabilized?

They are generally stabilized by ligaments, shape (restricting movement in some directions), muscles, tendons or by other bones

How does flexion effect the angle of a joint?

Angle of joint decreases

How does extension effect the angle of a joint?

Increases angle

Circumduction of a limb is?

Movement of a limb that describes a cone

What is an example of opposition as a type of articular motion?

Touching thumb to fingers

Lifting shoulders up and down is an example of?

Elavation and depression

Moving jaw forwards and backwards is an example of what type of movement?

Protraction and retraction

What are some different examples of synovial joints?

Plane joint (intercarpal joint)

hinge joint (elbow joint)

Pivot joint (proximal radioulnar joint)

Condyloid joint (metacarpophalangeal joint)

Saddle joint (carpometacarpal joint of thumb)

Ball and socket joint (shoulder joint)

What determines level efficiency?

The position of insertion relative to the joint determines the level efficiency

Which joint in the body has the widest range of movement?

The shoulder

What is the ball and socket joint of the shoulder formed by?

The articulation of the humerus with the glenoid cavity or scapula

Movement of the arm at the shoulder include what two processes?

1. Muscles acting on the humerus at the shoulder joint

2. Muscles that rotate the scapula

Which two muscles are involved in rotation of the scapula?

Trapenzies and serratus anterior

Which muscles are involved in abduction and flexion of the humerus at the shoulder joint?

The deltoid, supraspinatus and pectoralis major

In level mechanics, what is the fulcrum?

The joint

What is the arrangement of effort, load and fulcrum in a class 1 lever?

Fulcrum between load and effort

What is the arrangement of effort, load and fulcrum in a class 2 lever?

Load between effort and fulcrum

What is the arrangement of effort, load and fulcrum in a class 3 lever?

Effort between fulcrum and load

A seesaw is an example of what type of lever?

Type 1

A wheel barrow is an example of what type of lever?

Class 2

A castle drawbridge is an example of what type of lever?

Class 3

What is elevation of the jaw an example of?

Class 3 lever

How is lever efficiency calculated?

Efficiency = MA effort/MA load

Levers either amplify ......... or ............

force or distance

What is an example of a force amplifying lever?

A crowbar

What is an example of a distance amplifying lever?

A baseball bat

What distinguishes whether a lever is force or distance amplifying?

If distance to load is > distance to force then it is a force amplifier, if distance to load > distance to force then it is a distance amplifier

What type of amplifier is most common in nature?

Distance amplifier