Welcome to Dr. Kate Brilakis' Learning Portal

                 Muscle Lab: Week 1

Terms to Understand and Apply: Origin, Insertion, Prime Mover (PM), Synergist, Antagonist
 For each muscle, know where it is located on the body and the primary motion it produces at the joint.
 Skeletal muscles attach to bone (or tissue) at two (or more) places:
           if the attachment is immobile = origin...if the attachment moves during an action = insertion. 
             For those muscles below marked with an *asterisk, learn the origin/insertion.
The name of the muscle often tells you something about the location, size, or action of the muscle.
 Ex: pectoralis major = large chest muscle

Memory Tips for Muscle Action:
(many muscle follow these patterns although there are exceptions)

Muscles on the anterior surface of the body are usually involved in FLEXION
Muscles on the posterior surface of the body are usually involved in EXTENSION
Muscles on the medial surface of the body are usually involved in ADDUCTION
Muscles on the lateral surface of the body are usually involved in ABDUCTION

Muscle Groups to Know:

Name the 4 muscles that form the “quadriceps group” of the thigh.

​Name the 3 muscles that form the “hamstring group” of the thigh.

​Name the 4 muscles that form the “rotator cuff” of the shoulder:



Major Muscles of the Face Action

Frontalis: raises eyebrows, wrinkles forehead
Orbicularis oculi: closes eye
Orbicularis oris: closes lips
Zygomaticus major: elevates corners of mouth
Buccinator: compresses cheeks
Risorius: draws lips laterally
Depressor labii inferioris: draws lower lip inferiorly
Masseter*: P.M. elevates mandible (closes jaw)
Temporalis: elevates mandible


Antero-lateral Muscles of the Neck 

Platysma: tightens skin of neck
Sternocleidomastoid*: neck flexion, rotates head
Scalenes (anterior, middle, posterior): neck flexion
 elevates ribs when inhaling
Digastric: opens mouth (depresses mandible)
Mylohyoid: raises hyoid/tongue during swallowing



                  Anterior Trunk Muscles
 (shoulder, neck, vertebral column, or rib cage)

Pectoralis major*: P.M of shoulder flexion, adduction of arm
Pectoralis minor: assists with elevation of ribcage (inhale)
Deltoid*: P.M. of shoulder (arm) abduction
Serratus anterior: pulls scapulae forward against ribcage
External intercostals:
       elevate ribs for inhalation phase of breathing
Internal intercostals:
​      depress ribs for exhalation phase of breathing
Diaphragm: P.M. inhalation (breathing)
Rectus abdominis*: flexes trunk, rotates vertebral column,
External oblique* : rotation of trunk, lateral flexion of trunk
Internal oblique: rotation of trunk, lateral flexion of trunk
Transverse abdominis: compresses abdomen



​Posterior Trunk Muscles
      (shoulder, neck, or vertebral column)

Trapezius* :elevates, rotates, retracts scapula, extends head
Levator scapulae: elevates scapula
Supraspinatus: starts abduction of arm, stabilizes shoulder
Infraspinatus: lateral rotation of arm, stabilizes shoulder
Subscapularis: medial rotation of arm
Latissimus dorsi* :P.M. of arm extension, medially rotates & adducts arm
Teres major*: synergist w/latissimus dorsi – extend, adduct, medial rotation
Teres minor: lateral rotation of shoulder
Rhomboid major: stabilize scapula, retract scapula
Splenius capitis: extends head
Erector spinae group: extends vertebral column (upright), lateral flexion
Quadratus lumborum: extends vertebral column (upright), lateral flexion





​                  Muscle Lab: Week 2

Superficial Arm Muscles
                   (act on elbow and/or wrist)

Triceps brachii*: P.M. extension of elbow (forearm)
Biceps brachii* :flexion of elbow, P.M. in supination
Brachialis: flexion of elbow (forearm)
Brachioradialis: synergist to biceps brachii for elbow flexion
Pronator teres: pronation of forearm
Flexor carpi radialis: flexion & abduction of wrist
Palmaris longus: flexion of wrist
Flexor digitorum: flexes fingers 2-5
Flexor carpi ulnaris: P.M. of flexion & adduction at wrist
Extensor carpi ulnaris: extension & adduction of wrist
Extensor digitorum: extension of fingers & abduction of fingers
Extensor carpi radialis brevis: extension & abduction of wrist
Extensor carpi radialis longus: extension & abduction of wrist




Anterior Hip/Thigh Muscles

                        (act on hip and/or knee)

Sartorius*: flexes, abducts & laterally rotates thigh, flexes knee
Gracilis: flexes & adducts thigh (hip)….as in walking
Adductor longus: adducts, flexes, medially rotates thigh
Adductor magnus: adducts, flexes, medially rotates thigh
Pectineus: adducts, flexes, medially rotates thigh
Iliopsoas = iliacus + psoas major: flexion of trunk at hip,
​                                                              flexion of thigh
Tensor fasciae latae: flexes & abducts thigh
Iliotibial tract: tendon band that stabilizes knee joint, not a muscle
Quadriceps group:
   Rectus femoris* extends knee and flexes hip (thigh)
   Vastus lateralis: extends knee
   Vastus medialis: extends knee
   Vastus intermedius: extends knee (deep to rectus femoris)

Posterior Hip/Thigh Muscle
                    (act on hip and/or knee)

Gluteus maximus*: P.M. of hip (thigh) extension
Gluteus medius: abducts, medially rotates thigh
Hamstring group:
   Biceps femoris* extends hip and flexes knee
   Semitendinosus: extends hip and flexes knee, medial leg rotation
   Semimembranosus: extends hip and flexes knee, medial leg rotation


                      ​Lower Leg Muscles
                     (act on ankle & foot)

Tibialis anterior*: P.M. foot dorsiflexion (walking) inverts foot
Soleus plantar: flexion of foot…..walking
Gastrocnemius*: plantar flexion of foot….walking
Fibularis longus: (= peroneus) plantar flexion and eversion of foot
Extensor digitorum: toe extension, dorsiflexion
Flexor digitorum: toe flexor, plantar flexion



​Sample Lab Test Questions on Muscle Actions:

In addition to the visual ID of muscles, you should be prepared to answer this style of
about muscles.......

1. The triceps brachii is antagonistic to the ___________________for elbow movement.
2. Name two muscles that plantar flex the ankle: _______________ and ____________
3. Name the muscle that can elevate, retract, and rotate the scapula: __________________
4. Name the prime mover of hip extension:__________________________
5. The external obliques cause _________________ and ________________of the trunk:
6. Name the muscle that assists the biceps brachii with flexion of the elbow:__________
7. Name the origin & insertion of the rectus femoris O = ____________ I = _____________
8. Name the origin & insertion of the latissumus dorsi: O =___________ I =______________
9. Which muscle causes flexion of the neck?
      a. pectoralis major b. latissimus dorsi c. sternocleidomastoid d. trapezius
10. The vastus lateralis assists with:
      a. knee flexion b. knee extension c. knee rotation d. hip flexion
11. Which muscle is antagonistic to the rectus abdominus?
     a. transverse abdominus b. pectoralis major c. quadratus lumborum
12. Which muscle does NOT adduct the thigh?
     a. adductor longus b. pectineus c. gracilis d. sartorius

  The Muscular System