Transcript The Muscular System

The Muscular System
HONORS ANATOMY &
PHYSIOLOGY
CHAPTER 10
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.
• 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
An Overview of
the Major
Skeletal Muscles
Figure 7-11(a)
An Overview of
the Major Skeletal
Muscles
Figure 7-11(b)
Anatomy of the Muscular System
 Muscles of the Head and Neck
Figure 7-12(a)
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
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

Muscles of the Face 1
 Corrugator supercilii
 @ 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
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
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
Tongue Muscles
 “glossus”: tongue
 Genioglossus
 Hyoglossus
 Styloglossus
Muscles of the Anterior Neck & Throat
Digastric
1.


forms “V” shape under chin
opens mouth & depresses mandible
2. Sternocleidomastoid

attaches to sternum, clavicle, & mastoid process

flexes & laterally rotates head
Muscles of Respiration
External Intercostals
1.


11 pair lie between ribs running down & forward
pull ribs toward each other to elevate rib cage
2. Internal Intercostals

11 pair between ribs, lie deep to & @ right angles to #1 (run
down & posterior

draw ribs together & depress rib cage
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

1.
2.
3.
pierced by 3 structures:
Aorta
Inferior Vena Cava (IVC)
Esophagus
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
 flex vertebral column & compress abdominal wall
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
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
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
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
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
Muscles Crossing the Elbow: Posterior
 Triceps brachii
 large , fleshy muscle
 3-headed origin
 powerful arm extensor
Muscles Crossing Elbow: Anterior
 Biceps brachii
 2-headed fusiform muscle
 flexes elbow & supinates forearm
 Brachialis
 deep to biceps
 major forearm flexor
Muscles Crossing the Hip Joint
 Iliopsoas
 made up of 2 related muscles:
1.
Iliacus
 more lateral of the 2
 prime mover for flexing thigh or flexing trunk on thigh
(taking a bow)
1.
Psoas
 longer & thicker of the 2
 as motion for iliacus , also flexes vertebral column laterally
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
Muscles of the Medial Compartment of Thigh
 Adductors:
 Adductor magnus
 Adductor longus
 Adductor brevis
 all 3 adduct, flex, & medially rotate thigh
Muscles of the Anterior Compartment of Thigh
 Quadriceps femoris
 4 muscles that extend knee, flex thigh at hip, & rotates thigh
laterally, stabilizes hip joint
1.
Rectus femoris
2.
Vastus lateralis
3.
Vastis medius
4.
Vastus intermedius
Muscles of the Posterior Compartment of Thigh
 Hamstrings:
 3 muscles that together extend thigh and flex knee
1.
Biceps femoris
2.
Semitendinosus
3.
Semimembranous
Muscles of Anterior Compartment Lower Leg
 Tibialis anterior:
 parallel to sharp anterior margin of tibia
 prime mover of dorsiflexion
Muscles of Anterior Compartment Lower Leg
 Extensor digitorum longus
 lateral to tibialis anterior
 prime mover of toe extension
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
 plantar flexes foot
Muscles of the Posterior Compartment of Leg
 Tibialis posterior:
 thick, flat muscle , deep to soleus
 prime mover of foot inversion