ring around body opening
prime mover (agonist)
produces most of force
contracts & causes action
aid prime mover (located close)
stabilizes nearby joint to prevent unwanted movement
opposes prime mover
preventing excessive movement & injury
stabilize origin of prime mover
prevents movement of bone
It is common to attribute a specific action at a joint to a single muscle bundle, but muscles do not work in _____________
Movements usually result from several skeletal muscles acting as a group. Most skeletal muscles are arranged in _____________ (antagonistic) pairs at joints
In an opposing muscle pair, one is called the prime mover or agonist and is responsible for the action, while the other muscle called the _____________ stretches and yields to effects of the agonist
To prevent unwanted _____________ at other joints or to otherwise aid the movement of the agonist, muscles called _____________ contract and stabilize the intermediate joints.
Other muscles act as _____________ , stabilizing the origin of the agonist so that the agonist is more efficiently
Muscles of facial expression
lie within subcutaneous layer
originate in fascia or skull bones
insert into skin
Because of their insertions, the muscles of facial expression move the ____________rather than a ____________when they contract.
skin rather than a joint
Facial expression muscles innervated by?
facial (VII) nerve (CN VII)
(6) extrinsic eye muscles control movements of each eyeball.
(originate on outside of eyeballs in bony orbit & insert on outer surface of sclera)
moves eye superiorly & medially (elevation & adduction)
rotates eye medially
moves eye inferiorly (depression) & medially (adduction) & rotates medially
lateral & medial rectus
move eye laterally (abduction) & medially (adduction)
elevation & abduction & rotates laterally
depression, abduction & rotates medially
Recti muscles of the eye have obvious actions.
The actions of the (2) oblique eye muscles can't be deduced from their names.
origin & insertion of oblique eye muscles
1) superior oblique
origin: sphenoid, superior & medial to tendinous ring in orbit
insertion: between superior & lateral recti (via tendon that passes through trochlea)
2) inferior oblique
origin: maxilla in floor of orbit
insertion: between inferior & lateral recti
levator palpebrae superioris
origin, insertion, action
does not move eyeball
origin: roof of orbit
insertion: skin of upper eyelids
actions: elevates upper eyelid (opens eyes)
Muscles of the tongue
1) intrinsic - alter shape of tongue
2) extrinsic -move tongue, connect tongue to hyoid, styloid process, palate & inside of chin
(4) extrinsic muscles of the tongue
genioglossus - down & forward
styloglossus - up & backward
Hyoglossus - down & flattens
Palatoglossus - raises posterior portio
Muscles of Mastication (4)
Masseter - close mouth
Temporalis - elevate & retract
Medial Pterygoid - elevate, protrude, side to side
Lateral Pterygoid - protract, depress (open), side to side
Muscles of Mastication
arise from temporomandibular joint (TMJ) insert on mandible
Temporalis and Masseter _________ the mandible
Medial and Lateral Pterygoids help elevate, but produce ________ swinging of jaw
side to side
The ____________, ____________, and medial ____________account for the strength of the bite.
The medial and lateral ____________muscles help to chew by moving the mandible from side to side. Additionally, these muscles protract (protrude) the mandible.
Masseter, Temporalis & medial pterygoid
swallowing & speech
(2) main muscle groups in the anterior neck
1) suprahyoid - superior to hyoid
2) infrahyoid - inferior to hyoid
Both Suprahyoid & Infrahyoid muscles ___ the hyoid bone, allowing it to serve as a firm base on which the __can move.
Muscles of the neck that move the head
e head articulates with the vertebral column at joints formed by the ____________& ____________bone.
atlas & occipital
An important landmark (the ____________muscle) divides the sides of the neck into two major triangles: anterior and posterior
Muscles of the neck that move the head (5)
Muscles of the Abdomen (protect the viscera and move the vertebral column)
The ____________abdominal wall includes the external oblique, internal oblique, and ____________abdominis muscles which form 3 protective layers around the abdomen
The aponeuroses of the external & internal oblique & transversus abdominis form the ____________ which enclose the?
rectus abdominis muscles