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