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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