KAAP309 Lecture Notes - Lecture 10: Rectus Femoris Muscle, Orbicularis Oris Muscle, The Prime Mover
18 May 2018
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Chapter 10A: Muscular System
https://quizlet.com/_4q3peb
I. Interactions of Skeletal Muscles
A. Skeletal muscles work together or in opposition
B. Muscles only pull (never push)
C. As muscles shorten, the insertion generally moves toward the origin
D. Whatever a muscle (or group of muscles) does, another muscle (or group)
udoes
II. Muscle Classification: Functional Groups
A. Prime movers – provide the major force for producing a specific movement
B. Antagonists – oppose or reverse a particular movement
C. Synergists
1. Add force to a movement
2. Reduce undesirable or unnecessary movement
D. Fixators – sergists that ioilize a oe or usle’s origi
III. Naming Skeletal Muscles
A. By location: associated bone or body region
B. By shape: e.g., deltoid muscle (deltoid = triangle)
C. By relative size – e.g., maximus, minimus, longus
D. By fiber direction: e.g., rectus (fibers run straight), transversus, oblique
E. By number of origins (heads): e.g., biceps, triceps
F. By site of attachment: point of origin or insertion
G. By action: e.g., flexor, extensor
IV. Fascicle Arrangement Varies
A. Parallel – fascicles run parallel to muscle long axis (e.g., sartorius)
B. Fusiform – spindle-shaped muscles (e.g., biceps brachii)
C. Pennate (feather-like) – short fascicles attach obliquely to central tendon
running lengthwise (e.g., rectus femoris)
D. Convergent – fascicles converge from a broad origin to a single tendon insertion
(e.g., pectoralis major)
E. Circular – fascicles are arranged in concentric rings (e.g., orbicularis oris)
V. Lever Systems
A. Leer: rigid ar that rotates aout a …
B. Fulcrum: fixed point or hinge point
C. Effort: force applied to lever
D. Load: resistance to the effort, usually at a different point along the lever
E. A & P equivalents:
1. lever = bone (one or more)
2. fulcrum = joint
3. effort = force applied by muscle
4. load = eteral force which the effort acts against
VI. Muscles: name, origin, insertion, action
A. Name and description of the muscle – be alert to information given in the name
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Document Summary
Load =100 n. distance from joint to load = 20 cm. Distance from joint to muscle insertion = 4 cm. Answer: using the equation above, we see that (muscle force) x 4 cm = 100 n x 20 cm. Therefore: muscle force = 2000 n-cm / 4 cm = 500 n. the muscle force must be bigger than the load. This is not uncommon: muscles of the scalp. Chapter 10b: muscular system: epicranius (occipitofrontalis) pipartite muscle consisting of the, frontalis, occipitalis, galea aponeurotica cranial aponeurosis connecting above muscles, these two muscles have alternate actions of pulling the scalp forward and backward. Muscles of mastication: there are four pairs of muscles involved in mastication, prime movers temporalis and masseter, grinding movements pterygoids and buccinators, all are innervated by cranial nerve v (trigeminal nerve) Trunk movements: short muscles: four short muscles extend from one vertebra to another, these muscles are synergists in extension and rotation of the spine.
