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AP1 Lab 8 – Movements at Synovial Joints
and Muscles of the Torso, Face, and Neck
Figs. 8.5 & 8.6
Be able to define, identify, and demonstrate examples of each of the following.
Printable flashcards are available on the Web of Life. Some assembly required.
flexion
extension
hyperextension
rotation
circumduction
supination
pronation
abduction
adduction
plantar flexion
dorsiflexion
inversion
eversion
elevation
depression
protraction
retraction
excursion
opposition
gliding
**Learning Activity: Demonstrate as many examples of each motion as you can.
Revised 1/11/2017
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Muscles of the Torso, Neck, and Face
Figs. 10.5 - 10.15
Rarely is a given movement accomplished by a single muscle. Instead, movements are usually the result of
several muscles working together. Each muscle typically helps with several different movements. We’re
learning only the ‘primary’ action of each of the following muscles.
Know these following muscles by name, location, and primary action.
Be able to ID them on both torso models and on yourself.
If I demonstrate a movement you should be able to identify the muscle(s) responsible for that movement.
temporalis (“tem-po-RAL-is) [partially seen on L side of dark torsos]
Most of this muscle is not visible on the torsos. Place your hand on the side of your skull anterior and
superior to the ear. Clench your teeth together repeatedly and feel this muscle contract.
Elevates and retracts the mandible.
masseter (“MASS-se-ter”)
Place your hand on the side of your face just anterior to and inferior to your ear. Clench your teeth and feel
this muscle contract.
Elevates and protracts mandible.
On an ounce-for-ounce basis this is the most powerful muscle in your body. If your legs were this
powerful you could jump over your house.
zygomaticus major & minor (“zygo-MAT-ti-cus”) [seen best on dark torsos]
Two small muscles connecting the corners of your mouth to the zygomatic bone.
They elevate and abduct corners of mouth when smiling.
platysma (“pla-TIZ-ma”) [seen only on dark torso]
A superficial, thin, sheet-like muscle covering the anterior side of the neck.
Depresses lower lip as when making a “lizard face.”
sternocleidomastoid (“STERNO-clydo-mas-toid”) [Best seen on stand-alone half head model and 2nd best
on the dark torsos.]
Rotate your head to the side and you can easily feel and see this muscle… especially the tendon attaching
to the sternum.
If only one contracts… rotation of head. If both contract… flexes head and neck forward.
pectoralis major and pectoralis minor (PEC-to-ral-is)
[Visible only on dark torsos.]
Adducts and flexes upper arm as when doing push-ups or bench press.
Protracts scapulae and shoulders.
serratus anterior (“ser-RAT-us”)
Rotates and protracts scapula during various arm & shoulder motions; especially motions such as thrusting
the arm forward such as boxing and push-ups.
intercostals (external and internal) (inter-COST-als) [Best seen on dark torsos.]
External intercostals elevate the rib cage for inspiration (inhalation).
Internal intercostals draw ribs downward and inward to produce forceful expiration.
When you eat BBQ ribs you’re eating intercostals. Yum! Yum!
**Confirm your identifications of the above with your instructor. **
Revised 1/11/2017
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rectus abdominis [Visible only on the dark torsos.]
Flexes torso when doing sit-ups and crunches.
Compresses abdomen when barfing.
transversus abdominis [seen best on dark torsos.]
Compresses abdomen when belching, barfing, and childbirth.
external and internal obliques (“oh-BLEEKS”)
[seen best on the dark torsos.]
Rotates torso left and right and assists with flexion of torso.
Assists with compression of abdomen.
trapezius (“tra-PEE-z-us”) [best seen on lighter torsos]
Retracts and elevates scapulae when doing chin-ups or when holding your shoulders back.
Also extends neck.
splenius capitis (“SPLEN-nee-us CAP-i-tis) [visible on both torsos but best seen on lighter torsos] Most of
this muscle is hidden from view by the trapezius.
Extends, rotates, and laterally flexes the neck and head.
rotator cuff
A group of four muscles originating on both sides of the scapula and passing through the shoulder joint
area. Don’t bother trying to ID them on our models – just look at the text image. See text Figs. 10-15
(b) and (d). The 4 muscles with an * make up the rotator cuff group. Their distal tendons (insertions) fuse
with the fibrous joint capsule of the shoulder joint. Although they do assist with various movements of the
shoulder and arm their main function is to strengthen the capsule to prevent dislocation of the humerus.
Basically… so you don’t throw your arm out of its shallow socket.
No need to ID the muscles individually. Just know them as a group.
rhomboids (“ROM-boids”)
None visible on models but would be found at an angle between the medial border of the scapula and the
upper thoracic vertebrae. See text image.
Retracts and rotates scapulae (pulls your shoulders back) as when rowing or holding shoulders back.
latissimus dorsi (“la-TIS-si-mus DOR-sy”)
[partially visible on the darker torso models but totally visible on the lighter torso models]
A very large, broad, mostly flat muscle that runs from the lower thoracic and lumbar vertebrae to the
humerus.
Adducts and extends upper arm.
e.g. Pulls your arms down and back when doing chin-ups.
erector spinae (“e-REK-tor SPY-nay”)
None visible on our models but is a significant group of postural muscles running more or less parallel to
the spinal column. See text image.
Extends spinal column when you stand up straight after bending over.
**Confirm your identifications of the above with your instructor. **
Revised 1/11/2017
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Rarely is a given movement accomplished by a single muscle. Instead, movements are usually
the result of several muscles working together.
Synergists are muscles that work together to move a body part.
Antagonists are muscles that produce the opposite actions.
ID some synergistic and antagonistic pairs. Do this AFTER having learned the muscles and
the actions they produce. Use this like a self-quiz.
One action of the rectus abdominis is flexion of the vertebral column in the lumbar region.
Its two synergists for this are _____________________ and _____________________
Its primary antagonist for this is ______________________________
Another action of the rectus abdominis is to compress the abdomen thus increasing intra-abdominal
pressure.
Its three synergists for this are __________________________ and
___________________________ and ______________________________
One action of the trapezius is to retract the scapulae (a.k.a. retract the shoulders).
Its primary synergist for this is ______________________________
One action of the latissimus dorsi is extension of the arm.
Its primary antagonist for this action is ___________________________________________
The external intercostals can assist inspiration by lifting the rib cage upward and outward.
The antagonist for this would be _________________________
The two synergists for elevation of the mandible are _________________ & ______________
Bonus OYO: One action of the latissimus dorsi is adduction of the arm into anatomical position.
Its primary antagonist for this is an arm muscle called the __________________________
.
Revised 1/11/2017
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