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.
2.
3.
4.
5.
6.
Location in the body
Origin and insertion
Fascicle organization
Relative position
Structural characteristics
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