Lab 14

Muscles Overview

Muscle Labs

• Most of the labs for the next two weeks will consist of looking at models and diagrams to learn the muscles.

• The models will be the same models used on the practical quizzes

• I will post these lectures on the website

Muscle Practical

• Tuesday 11/20• 50 points• Covers all the muscles on the Muscle List

(available on the website and in the syllabus:– head and face; neck; chest; abdominal; and back and

shoulder , upper arm; lower arm; hip and thigh; upper leg; and lower leg

– You need to know origins and insertions for the ones listed in bold only

– Know general functions• Uses about half models (little men, torsos, hand,

foot, arms, legs) and half B&W book pictures

Muscle exam

• The muscle exam will include some muscle labeling from the first half of the muscles

Divisions of the Muscular System

1. Axial muscles:– position head and spinal column– move rib cage– 60% of skeletal muscles

2. Appendicular muscles:– support pectoral and pelvic girdles– support limbs– 40% of skeletal muscles

Origins and Insertions

• Muscles have 1 fixed point of attachment (origin) and 1 moving point of attachment (insertion)

• Most muscles originate or insert on the skeleton

• Origin is usually proximal to insertion

Origin and Insetaions

• Fixed end in (b) below is the origin, while moving end is the insertion

Figure 10–13

Actions

• Movements produced by muscle contraction

• Body movements – e.g., flexion, extension, adduction, etc.

• Described in terms of bone, joint, or region

Muscle Interactions

• Muscles work in groups to maximize efficiency

• Smaller muscles reach maximum tension first, followed by larger, primary muscles

Muscle Terminology Based on Function

• Agonist (prime mover):– produces a particular movement

• Antagonist:– opposes movement of a particular agonist

Muscle Terminology Based on Function

• Synergist:– a smaller muscle that assists a larger agonist– helps start motion or stabilize origin of agonist

(fixator)

Muscle Opposition

• Agonists and antagonists work in pairs:– when 1 contracts, the other stretches– i.e., flexors–extensors, abductors–adductors,

etc.

How does the name of a muscle help identify its location, appearance, or

function?

Names of Skeletal Muscles

• Correct names of muscles include the term muscle

• Exceptions: – platysma– diaphragm

Descriptive Names for Skeletal Muscles

1. Location in the body

2. Origin and insertion

3. Fascicle organization

4. Relative position

5. Structural characteristics

6. Action

Location in the Body

• Identifies body regions:– e.g., temporalis muscle

Origin and Insertion

• First part of name indicates origin

• Second part of name indicates insertion:– e.g., genioglossus muscle

Fascicle Organization

• Describes fascicle orientation within muscle:– rectus (straight) = parallel to body or limb– transversus = perpendicular to the midline– oblique

Relative Position

• Externus (superficialis):– visible at body surface

• Internus (profundus):– deep muscles

• Extrinsic:– muscles outside an organ

• Intrinsic:– muscles inside an organ

Structural Characteristics

• Number of tendons (or heads):– bi = 2, tri = 3

• Shape: – trapezius, deltoid, rhomboid

• Size…

Names for Muscle Size (1 of 2)

• Longus = long

• Longissimus = longest

• Teres = long and round

• Brevis = short

• Magnus = large

Names For Muscle Size (2 of 2)

• Major = larger

• Maximus = largest

• Minor = small

• Minimus = smallest

Action

• Movements: – e.g., flexor, extensor, retractor

• Occupations or habits: – e.g., risor = laughter

Naming Skeletal Muscles

Table 11–1 (1 of 2)

Naming Skeletal Muscles – contiuned

Table 11–1 (2 of 2)

Lab 14

• Examine muscle structure

• Look at and draw NMJ slide

• Drawing and Reviews Sheet due next week

• Due next Thursday