Chapter 10:Muscular System Flashcards
Muscle Tissue
is a primary tissue type specialized for movement
- movement of body, maintain stability (posture)
- soft tissue support
- guard body openings
- thermoregulation
Muscular system
references skeletal muscle:
- muscles of the head, neck and trunk
- muscles acting on upper and lower limbs and their girdles
Muscle Tissue
Skeletal Muscle Shapes
are classified according to the orientation of the fascicles
5 classifications of muscles:
parallel muscles have fascicles parallel to long axis of the muscle
- biceps brachii and rectus abdominis
convergent muscles are broad at origin and taper to a narrow insertion
- pectoralis major
pennate muscles have fascicles insert obliquely on a tendon; develop more tension than parallel muscles
- unipennate, bipennate or multipennate
- extensor digitorum, rectus femoris and deltoid
circular muscles (sphincter) “ring” around a body opening
- orbicularis oculi, pyloric valve and anal sphincters
Fascicle orientation affects
power, range, and speed of muscle movement
Skeletal Muscle Shapes
Leverst
Levers are rigid objects that rotates around a fixed point called a fulcrum
- provides mechanical advantage when effort overcomes resistance
- mechanical advantage increases output of force (power) or move objects faster (speed)
- bones are levers, joints are fulcrums, and muscle is effort
Three kinds of levers:
first-class - fulcrum lies between applied force (AF) and the load (L)
- output and speed usually in balance
second-class - load (L) is between applied force (AF) and fulcrum
- more output but less speed
third-class - applied force (AF) is between load (L) and fulcrum
- less output but more speed
Muscles have 1 fixed point of attachment (origin) and 1 moving point of attachment (insertion)
- origin is usually proximal to insertion
- most muscles originate or insert on the skeleton
Origin and insertion are relative terms;
action of muscle determines both points
Actions are produced by
muscle contraction
muscles work in groups to maximize efficiency
3 types of coordinated muscle actions:
-prime mover (agonist) produces most of force
-synergist aids the prime mover
stabilizes the nearby joint and modifies/assists the direction of movement
-antagonist opposes the prime mover
prevents excessive movement and injury
Muscles work in
pairs and in opposition
Muscles of the face are
small and insert into the dermis
- innervated by facial nerve (CN VII)
- paralysis causes face to sag (Bells palsy)
Muscles of the face:
frontalis
elevates eyebrows
obicularis oculi
closes eyes
buccinator
moves food around the cheeks
obicularis oris
closes/protrudes lips
platysma
tenses neck (and depresses mandible)
Muscle of Facial Expression
Extra-ocular muscles
(extrinsically) responsible for eye movement
* muscles insert on sclera of eye
6 eye muscles:
inferior rectus
eye looks down
medial rectus
eye looks medially
superior rectus
eye looks up
lateral rectus
eye looks laterally
superior and inferior obliques
eye looks laterally up/down
Muscles of mastication
attach to the mandible
- responsible for chewing
Muscles of mastication:
temporalis
elevates mandible
masseter
elevates mandible
strongest jaw muscle
medial pterygoid
produces lateral swinging of jaw
Tongue
shifts food onto teeth and pushes it into pharynx
- muscles connect tongue to hyoid, styloid process, palate and inside of chin
Muscles of tongue:
genioglossus
hyoglossus
Muscles of the neck
are responsible for movement or swallowing
Muscles of the neck:
digastric
opens mouth widely
mylohyoid
elevates floor of mouth
initial stage of swallowing
sternocleidomastoid
upward tilt of head
laryngeal/pharyngeal elevators and constrictors
Erector spinae group
Erector spinae group spans the vertebral column
3 columns of muscle
iliocostalis lumborum
longissimus thoracis
spinalis thoracis