Chapter 10 - The Muscular System Notes Flashcards
Lever
(Bone) - Rigid structure
Fulcrum
(Joint) - Fixed point
Muscles (produce what)
- Apply the forces that produce MOVEMENT
Basic Muscle Concept
When a muscle contracts (shortens), a force is generated that acts on bones (or surrounding tissues) to create motion
Components of typical skeletal muscle
- Origin 2, Insertion 3. Muscle Belly 4. Tendons
Origin
- “Fixed” end; may be called the head of the muscle
Insertion
- “Moveable end
Muscle Belly
- The largest portion of the muscle. It lies between the origin and insertion
Tendons
- Attach muscles to bones
Aponeurosis
- (Sheet-like) - Is a thin, flat tendon located where the muscles attach to large flat regions on the body
Synergists
- Muscles working together to cause a movement
Agonist
- Prime Mover - If one muscle in a group does most of the work involved
Antagonists
- Muscles that cause a movement opposite that of the synergists - flexors/extensosr - adductors/abductors
Stabilizers
- Stabilize the joints
Number of Muscles Identified
- Over 700 - Averaging just over 3 per every bone
Naming Schema for Muscles
- Origin and Insertion 2. Size 3. Shape 4. Direction of muscle fibers 5. Location 6. Number of Heads 7. Action/Function
Naming: Origin & Insertion
- named landmarks found on the bones - origin is fixed end - insertion moveable end
Naming: Size
- Maximus 2. Minimus 3. Brevis 4. Major 5. Minor 6. Longus/Longissimus 7. Teres
Naming: Shape
- Triangular 2. Trapezoid 3. Saw-Toothed 4. Rhomboid 5. Round
Naming: Direction of Muscle Fibers
- Rectus: runs parrell to the midline of the body 2. Perpendicular: runs at a right angle to the midline of the body 3. Angle
Naming: Location
-May indicate a nearby bone or body region
Naming: Number of Heads
- multiple heads or attachments
Naming: Action/Function
- Terms such as FLEXOR, EXTENSOR, ABDUCTOR, and ADDUCTOR are all added to muscle names to indicate the kind of movement generated by the muscle.
Muscle Shapes
- Pennate: feather-shaped 2. Parallel: fasciculi run in line w/tendon 3, Convergent: triangle shaped 4. Circular: circle shaped
Fascicles
- Muscle fibers are grouped into bundles called Fascicles
Levers
- Three classes of levers with respect to skeletal muscle function: 1. Class I - see saw R-F-AF 2. Class II - loaded wheel barrel F - R - AF 3. Class III (most common in the body) ladder against building - F - AF - R
Frontalis
-Forehead -Raises eye brows, wrinkles forehead
Orbicularis oculi
- Around the eyelids - Closes the eyes
Buccinator
- Lines the cheeks - Compresses cheek
Orbicularis oris
- Around the lips - Purses the lips
Zygomaticus
- Upper cheek - Elevates corner of mouth
Depressor Anguli Oris
- Side of the chin - Depresses corner of the mouth
Temporalis
- Side of head above ear - Elevates mandible
Masseter
- Rear of the cheek - strongest muscle in the jaw - Elevated mandible
SCM
- Side of the neck - Rotates the neck opposite side, laterally flex same side
Platysma
- Side of neck superficial - Tenses neck, depresses mandible
Scalenes
- Deep, side of neck - Elevated ribs, flexes neck
Torticollis
- “pinched nerve” in neck - Acute spasm of the SCM - Usually caused by a cervical acceleration - deceleration injury
Erector Spinae - Iliocostalis
- Deep posterior trunk muscles - Extension of the spine
Erector Spinae - Longissimus
- Along the back, from head to sacrum - Extension of the spine
Erector Spinae - Spinalis
- ?? - Extension of the Spine