Biology 231
Biology 231
Human Anatomy and Physiology
Chapter 11 Lecture Outline
Skeletal Muscle Function
exerts force to cause movements or stabilization of bone or soft tissue
structures
attached to bone or soft tissues by connective tissue – usually tendons
Structure of Tendons
dense regular connective tissue
extension of endomysium, perimysium, and epimysium
attached to periosteum of bone
periosteum anchored to bone by Sharpey’s fibers
tendon shapes
cable-like (calcaneal tendon)
aponeuroses – flat sheets of tendon
most muscles cross joints and move one bone in relation to another
origin – muscle attachment to more stationary bone
insertion – muscle attachment to more moveable bone
action – movement produced by muscle
Muscle Arrangement
muscle belly – fleshy central portion of muscle
composed of bundles of fascicles
muscle shape – depends on arrangement of fascicles
parallel muscle – fascicles parallel to long axis of muscle
strap-like or spindle-shaped
convergent muscle – fascicles from broad origin converge towards a
central tendon or insertion
pennate muscle – feather-like fascicle arrangement
unipennate – fascicles on one side of tendon
bipennate – fascicles on both sides of central tendon
multipennate – multiple tendons with pennate arrangement
circular muscle – fascicles encircle an opening (orifice)
form a sphincter that can open or close the orifice
shape affects the power and range of motion of a muscle
longer, parallel bundles – greater range of motion
broader, thicker bundles – greater power
Coordination of Muscle Groups
arranged in opposing pairs at joints
prime mover (agonist) – contracts to cause an action
antagonist – relaxes to allow prime mover’s action
(a given muscle may act as prime mover for one movement and
antagonist for the opposite movement)
synergists – promote action of prime mover, usually by stabilizing
intermediate joints
fixators – stabilize origin of a prime mover
muscle compartments – groups of muscles with related functions and their associated nerves and vessels bundled together by fascia
fascia – tough, fibrous connective tissue surrounding muscle groups or
other organs
Naming Skeletal Muscles
origin and insertion
orientation of fascicles relative to body planes
rectus (straight)
transverse
oblique
positional names – lateralis, medialis, anterior, posterior
anatomical location – temporalis, brachialis
size of muscle – major, minor, longus, maximus
shape of muscle – deltoid, trapezius
principle action of muscle – flexor, extensor, adductor
number of origins
biceps – 2 origins
triceps – 3 origins
quadriceps – 4 origins
Axial Muscles – 60% of muscles
stabilize and move axial skeleton
Head and Neck Muscles
move head, jaw, throat, tongue, eyes
facial expressions
chewing and swallowing
speech production
Vertebral Muscles
flex, extend and rotate spine
Thoracic and Abdominal Muscles
breathing muscles
flex spine
support and protect abdominal organs
Pelvic Floor Muscles
enclose pelvic outlet
sphincters for digestive, urinary, and reproductive tracts
APPENDICULAR MUSCLES – 40% of muscles
stabilize and move appendicular skeleton
Disorders Related to Muscle and Tendons
tendonitis – inflammation of tendon due to trauma or excessive use
carpal tunnel syndrome – inflammation in carpal tunnel; involves tendons,
tendon sheath, and median nerve passing through carpal tunnel
carpal tunnel – anterior wrist between carpal bones and flexor
retinaculum
plantar fasciitis – inflammation of plantar aponeurosis supporting arch
of the foot; usually most painful in heel
hernia – opening in tendon sheets allows soft tissue structures to pass through
inguinal hernia – in groin area; more common in males
hiatal hernia – abdominal organs tear through diaphragm
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