1. Honors Anatomy & Physiology Chapter 10
The Muscular System
Honors Anatomy & Physiology
Chapter 10

2. Anatomy of the Muscular System
Origin
Muscle attachment that remains fixed
Insertion
Muscle attachment that moves
Action
What joint movement a muscle produces
i.e. flexion, extension, abduction, etc.

3. A muscle that helps the agonist is a synergist
For muscles to create a movement, they can only pull, not push
Muscles in the body rarely work alone, & are usually arranged in groups surrounding a joint
A muscle that contracts to create the desired action is known as an agonist or prime mover
A muscle that helps the agonist is a synergist
A muscle that opposes the action of the agonist, therefore undoing the desired action is an antagonist

5. An Overview of the Major Skeletal Muscles
Figure 7-11(a)

6. An Overview of the Major Skeletal Muscles
Figure 7-11(b)

7. Anatomy of the Muscular System
Muscles of the Head and Neck
Figure 7-12(a)

8. Muscles of the Head & Neck
Muscles of facial expression lie in scalp and face just deep to skin or other muscles
overall are thin with variation in shape & strength
lateral scalp muscles are vestigial in humans

9. Muscles of the Scalp Epicranius (Occipitalfrontalis) Frontal Belly:
covers forehead & dome of head
raises eyebrows
wrinkles forehead horizontally
Occipital Belly:
covers posterior occiput
pulls scalp posteriorly
Aponeurosis:
flat, sheet –like tendon
attaches frontal and occipital bellies

11. Muscles of the Face 1 Corrugator supercilii Orbicularis oculi
@ border of frontalis
wrinkles forehead vertically
Orbicularis oculi
flat, sphincter muscle surrounding orbit
closes eye, blinking, squinting
Zygomaticus: major & minor
diagonally across cheekbone  mouth
smiling

13. Muscles of Facial Expression 2
Risorius
slender muscle inferior & lateral to zygomaticus
tenses lips, draws corner of mouth laterally
Buccinator
horizontal cheek muscle
compresses cheek (whistling or sucking)
holds food between cheek when chewing
Platysma
thin, sheet-like superficial neck muscle
tenses skin of neck, helps depress mandible, produces downward sag of mouth

15. Muscles of Mastication
Masseter
covers mandibular ramus
prime mover of jaw closure
Temporalis
fan-shaped, covers temporal, frontal, & parietal bones
closes jaw
Pterygoids: Medial & Lateral
along internal surface of mandible
protrudes mandible, promotes side-to-side grinding movement
Buccinator
horizontal cheek/compresses cheek

17. Tongue Muscles
“glossus”: tongue
Genioglossus
Hyoglossus
Styloglossus

18. Muscles of the Anterior Neck & Throat
Digastric
forms “V” shape under chin
opens mouth & depresses mandible
Sternocleidomastoid
attaches to sternum, clavicle, & mastoid process
flexes & laterally rotates head

20. Muscles of Respiration
External Intercostals
11 pair lie between ribs running down & forward
pull ribs toward each other to elevate rib cage
Internal Intercostals
11 pair between ribs, lie deep to right angles to #1 (run down & posterior
draw ribs together & depress rib cage

21. Muscles of Respiration - 2
3. Diaphragm
broad, flat , dome-shaped(when relaxed) muscle
prime mover of inspiration
flattens on contraction
forms floor of thoracic cavity
pierced by 3 structures:
Aorta
Inferior Vena Cava (IVC)
Esophagus

23. Muscles of the Anterior Abdominal Wall
Rectus abdominis
medial, superficial pair found between pubis & rib cage
segmented by 3 tendinous insertions
flex vertebral column & compress abdominal wall
External oblique
fibers run down & medially
aponeurosis turns under inferiorly forming inguinal ligament

24. Muscles of the Anterior Abdominal Wall - 2
Internal Oblique
fibers run upward & medially
flex vertebral column & compress abdominal wall
Transversus abdominis
deepest of muscles in abdominal wall
fibers run horizontally
compresses abdominal contents

26. Superficial Muscles of the Thorax: Anterior
Pectoralis minor
directly beneath pectoralis major
with ribs fixed, draws scapula forward & downward
Serratus anterior
fan-shaped, deep to scapula
forms medial wall of axilla
rotates scapula so its inferior angle moves laterally & upward
boxers muscle
Subclavius

28. Superficial Muscles of the Posterior Thorax
*Trapezious
most superficial muscle of posterior thorax
flat, triangular
stabilizes, raises, & rotates scapula
Levator scapulae
deep to trapezius,straplike
elevates & adduct scapula
Rhomboids
2 diamond-shaped muscles deep to trapezius
stabilize scapula

30. Muscles Crossing Shoulder Joint
Pectoralis major
large, fan-shaped covering superior portion of chest
prime mover of arm flexion, rotates arm medially, adducts arm
Deltoid
forms rounding to shoulder
prime mover of arm abduction when all its fibers contract together

32. Muscles Crossing Shoulder Joint - 2
Latissimus dorsi
broad, flat, triangular muscle of lumbar region
prime mover of arm extension
powerful arm adductor
rotates arm at shoulder
Swimming muscle

34. Muscles Crossing the Elbow: Posterior
Triceps brachii
large , fleshy muscle
3-headed origin
powerful arm extensor

36. Muscles Crossing Elbow: Anterior
Biceps brachii
2-headed fusiform muscle
flexes elbow & supinates forearm
Brachialis
deep to biceps
major forearm flexor

38. Muscles Crossing the Hip Joint
Iliopsoas
made up of 2 related muscles:
Iliacus
more lateral of the 2
prime mover for flexing thigh or flexing trunk on thigh (taking a bow)
Psoas
longer & thicker of the 2
as motion for iliacus , also flexes vertebral column laterally

40. Muscles Crossing the Hip - 2
Sartorius
strap-like superficial muscle running obliquely across anterior surface of thigh
longest muscle in body
crosses both hip & knee joint
flexes, abducts, & laterally rotates thigh
helps produce cross-legged position

42. Muscles of the Medial Compartment of Thigh
Adductors:
Adductor magnus
Adductor longus
Adductor brevis
all 3 adduct, flex, & medially rotate thigh

44. Muscles of the Anterior Compartment of Thigh
Quadriceps femoris
4 muscles that extend knee, flex thigh at hip, & rotates thigh laterally, stabilizes hip joint
Rectus femoris
Vastus lateralis
Vastis medius
Vastus intermedius

46. Muscles of the Posterior Compartment of Thigh
Hamstrings:
3 muscles that together extend thigh and flex knee
Biceps femoris
Semitendinosus
Semimembranous

48. Muscles of Anterior Compartment Lower Leg
Tibialis anterior:
parallel to sharp anterior margin of tibia
prime mover of dorsiflexion

50. Muscles of Anterior Compartment Lower Leg
Extensor digitorum longus
lateral to tibialis anterior
prime mover of toe extension

52. Muscles of the Posterior Compartment of Leg
Gastrocnemius:
form proximal curve on back of leg
plantar flexes foot
Soleus:
broad, flat muscle, deep to gastrocnemius

54. Muscles of the Posterior Compartment of Leg
Tibialis posterior:
thick, flat muscle , deep to soleus
prime mover of foot inversion