Gross Anatomy of the Muscular System – Lab Report
Assistant
Exercise 1: Muscles of the Head and Neck
Data Table 1. Action(s) performed by Muscles of the Head and Neck
Muscle Action(s) Performed
Example: Deltoid Example: Abducts the arm
Frontalis Wrinkles skin on forehead, elevates eyebrows
Levator Scapulae Elevates scapula
Masseter Elevates mandible
Obicularis oris Closes lips, protrudes lips
Orbicularis oculi Closes eyes
Sternocleidomastoid Pulls head to one slide, flexes neck or elevates sternum
Rotates scapula; various fibers raise scapula, pull scapula medially, or
Trapezius
pull scapula and shoulder downward
Zygomaticus Raises corner of mouth
Questions:
A) List a muscle that is a prime mover/agonist for pivoting the head.
a. The muscle that is the prime mover for pivoting the head is the
sternocleidomastoid.
B) List one prime mover/agonist for extension of the head. List one antagonist for extension of
the head.
a. The prime mover for extension is the semispinalis capitis. The antagonist for the
extension is the sternocleidomastoid.
C) List one muscle that raises your eyebrow.
a. One muscle that raises the eyebrow is the frontalis.
D) List one muscle from Data Table 1 that is named for its function and explain why.
a. One muscle named for its function is the Levator scapulae. As its name suggest, it
elevates the scapula.
, Exercise 2: Muscles of the Torso
Data Table 2. Action(s) Performed by Muscles of the Torso
Muscle Action(s) Performed
Deltoid Abducts, extends, and flexes arm
External oblique Tenses abdominal wall and compresses abdominal contents
Infraspinatis Lateral rotates of the humerus
Extends, adducts, and rotates the arm medially, or pulls the shoulder
Latissimus dorsi
downward and back
Pectoralis major Flexes, adducts, and rotates arm medially
Pectoralis minor Pulls scapula forward and downward or raises ribs
Rectus abdominis
Tenses abdominal wall and compresses abdominal contents
(under fascia)
Rhomboid major Retracts, elevates, and rotates scapula
Rhomboid minor Retracts and elevates scapula
Serratus anterior Pulls scapula anteriorly and downward
Subscapularis Rotates arm medially
Supraspinatus Abducts arm
Teres major Extends, adducts, and rotates arm medially
Teres minor Rotates arm laterally
Trapezius Adducts and stabilizes the scapula; elevates scapula
Questions:
A) List one muscle that is a prime mover/agonist for adducting the arms.
a. One muscle that is the prime mover for adducting the arms is the deltoid.
B) List one shoulder muscle that abducts the arm.
a. A shoulder muscle that abducts the arm is the supraspinatus.
C) List a prime mover for shoulder flexion (upper arm moving toward the ear).
a. Prime mover for shoulder flexion is the pectoralis major.
Assistant
Exercise 1: Muscles of the Head and Neck
Data Table 1. Action(s) performed by Muscles of the Head and Neck
Muscle Action(s) Performed
Example: Deltoid Example: Abducts the arm
Frontalis Wrinkles skin on forehead, elevates eyebrows
Levator Scapulae Elevates scapula
Masseter Elevates mandible
Obicularis oris Closes lips, protrudes lips
Orbicularis oculi Closes eyes
Sternocleidomastoid Pulls head to one slide, flexes neck or elevates sternum
Rotates scapula; various fibers raise scapula, pull scapula medially, or
Trapezius
pull scapula and shoulder downward
Zygomaticus Raises corner of mouth
Questions:
A) List a muscle that is a prime mover/agonist for pivoting the head.
a. The muscle that is the prime mover for pivoting the head is the
sternocleidomastoid.
B) List one prime mover/agonist for extension of the head. List one antagonist for extension of
the head.
a. The prime mover for extension is the semispinalis capitis. The antagonist for the
extension is the sternocleidomastoid.
C) List one muscle that raises your eyebrow.
a. One muscle that raises the eyebrow is the frontalis.
D) List one muscle from Data Table 1 that is named for its function and explain why.
a. One muscle named for its function is the Levator scapulae. As its name suggest, it
elevates the scapula.
, Exercise 2: Muscles of the Torso
Data Table 2. Action(s) Performed by Muscles of the Torso
Muscle Action(s) Performed
Deltoid Abducts, extends, and flexes arm
External oblique Tenses abdominal wall and compresses abdominal contents
Infraspinatis Lateral rotates of the humerus
Extends, adducts, and rotates the arm medially, or pulls the shoulder
Latissimus dorsi
downward and back
Pectoralis major Flexes, adducts, and rotates arm medially
Pectoralis minor Pulls scapula forward and downward or raises ribs
Rectus abdominis
Tenses abdominal wall and compresses abdominal contents
(under fascia)
Rhomboid major Retracts, elevates, and rotates scapula
Rhomboid minor Retracts and elevates scapula
Serratus anterior Pulls scapula anteriorly and downward
Subscapularis Rotates arm medially
Supraspinatus Abducts arm
Teres major Extends, adducts, and rotates arm medially
Teres minor Rotates arm laterally
Trapezius Adducts and stabilizes the scapula; elevates scapula
Questions:
A) List one muscle that is a prime mover/agonist for adducting the arms.
a. One muscle that is the prime mover for adducting the arms is the deltoid.
B) List one shoulder muscle that abducts the arm.
a. A shoulder muscle that abducts the arm is the supraspinatus.
C) List a prime mover for shoulder flexion (upper arm moving toward the ear).
a. Prime mover for shoulder flexion is the pectoralis major.
