10. Axial Muscles

Question 1

How is muscle nomenclature descriptive?

Answer 1

Based on: bones they attach to, shapes, actions, size, direction of muscle fibers, and multiple origins/number of heads

Question 2

Groups of muscles of the head

Answer 2

Muscles of facial expressions and muscles of mastication

Question 3

Characteristics of muscles of facial expression

Answer 3

Over 40 muscles overall

Multiple layers originating on bone and inserting into skin or other muscles

Question 4

OIA of Orbicularis oculi

Answer 4

Origin: margin of orbit
Insertion: skin surrounding eyelids
Action: closes eyes

Question 5

OIA of orbicularis oris

Answer 5

Origin: maxilla and mandible
Insertion: skin surrounding mouth
Action: purses lips

Question 6

OIA of buccinator

Answer 6

Origin: maxilla and mandible
Insertion: orbicularis oris
Action: compresses cheeks, holds food between them

Question 7

OIA of platysma

Answer 7

Origin: skin of shoulder and chest
Insertion: skin of mandible and cheek
Action: tenses skin of neck

Question 8

Characteristics and types of muscles of mastication

Answer 8

Move mandible to masticate food

4 muscles (temporalis, masseter, medial & lateral pterygoid muscles)

Buccinator muscle helps manipulate food in the oral cavity but is NOT a muscle of mastication

Question 9

OIA of masseter

Answer 9

Origin: zygomatic arch
Insertion: lateral surface of mandibular ramus and angle
Action: elevates and protracts mandible

Question 10

OIA of temporalis

Answer 10

Origin: temporal lines (lateral side of neurocranium)
Insertion: coronoid process of mandible
Action: elevates and retracts mandible

Question 11

What is the saggital crest?

Answer 11

Origin of temporalis muscle the forms a bony crest
Larger attachment sit for stronger muscles
Not found in humans

Question 12

Types of muscles of the neck and deep back

Answer 12

Sternocleidomastoid, infrahyoid muscles, suprahyoid muscles, and erector spinae consisting of spinalis, longissimus, and iliocostalis

Question 13

Types of muscles of facial expression

Answer 13

Orbicularis oculi, orbicularis oris, buccinator, and platysma

Question 14

OIA of sternocleidomastoid

Answer 14

Origin: manubrium and clavicle
Insertion: mastoid process of temporal bone
Action:
unilaterally: ipsilaterally side bends the neck and contralaterally rotates the head
bilaterally: flexes neck

Question 15

Bilateral vs unilateral contraction

Answer 15

Bilateral- muscles on both sides contract

Unilateral- muscle on one side contracts

Question 16

Ipsilateral vs contralateral movement

Answer 16

Ipsilateral- move toward same side
Contralateral- move toward opposite side

Question 17

Clinical diagnosis of a shortening, spasm, or fibrosis of the sternocleidomastoid that can be congenital or acquired

Answer 17

Torticollis

Question 18

What is reflected by the action of the sternocleidomastoid

Answer 18

Position of the head

Question 19

OIA of infrahyoid muscles

Answer 19

Origin: sternum, scapula
Insertion: hyoid bone
Action: depresses or stabilizes the hyoid

Question 20

OIA of suprahyoid muscles

Answer 20

Origin: mastoid & styloid processes, hyoid
Insertion: mandible
Action: depresses the mandible or elevates the hyoid

Question 21

How do the infrahyoid and suprahyoid muscles work together

Answer 21

Infrahyoid muscles stabilize the hyoid bone while suprahyoid muscles can only depress the mandible

Question 22

Movements of the spine

Answer 22

Flexion, extension, side bending, rotation

Question 23

Muscles of the erector spinal

Answer 23

Spinalis, longissimus, and iliocostalis

Question 24

OIA of erector spinae

Answer 24

Origin: spinous processes, sacrum, and ilium
Insertion: vertebrae and ribs
Action: Extends the spine (maintain posture)

Question 25

Muscles of the abdominal wall and their overall action

Answer 25

Rectus abdominis, external oblique, and internal oblique
Action: flexes and rotates the trunk and compressed abdomen

Question 26

OIA of rectus abdominis

Answer 26

Origin: pubic bone
Insertion: xiphoid process and inferior ribs
Action: flex trunk; compress abdomen
Covered by rectus sheath

Question 27

OIA and characteristics of external oblique

Answer 27

Origin: inferior ribs
Insertion: linea alba
Action: flex and rotate trunk, compress abdomen

Fibers directed “down and in” or “hands in pockets”
Most superficial muscle layer

Question 28

OIA and characteristics of internal oblique

Answer 28

Origin: iliac crest
Insertion: linea alba
Action: flex and rotate trunk, compress abdomen

Fibers directed “up and in”
Second muscle layer

Question 29

Muscles of breathing

Answer 29

Respiratory diaphragm and intercostal muscles

Question 30

How does breathing occur

Answer 30

Breathing occurs when the thorax increases or decreases its volume
Lungs sit in a vacuum where expanding the chest inhales and compressing the chest exhales
Lungs are manipulated by muscles acting in the ribs
Different muscles work for breathing at rest vs forced breathing

Question 31

OIA of respiratory diaphragm

Answer 31

Origin: internal surface of ribs, xiphoid process, lumbar vertebrae
Insertion: central tendon
Action: diaphragm flattens for inhalation

Active for breathing at rest and forced breathing

Question 32

OIA of intercostal muscles

Answer 32

Origin: ribs
Insertion: adjacent rib
Action: assists with respiration

Active during forced inhalation and exhalation