honors anatomy & physiology chapter 10 the muscular system
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HONORS ANATOMY & PHYSIOLOGYCHAPTER 10
The Muscular System
Anatomy of the Muscular System
• OriginMuscle 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 SystemMuscles 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
movementBuccinator
horizontal cheek/compresses cheek
Tongue Muscles
“glossus”: tongueGenioglossusHyoglossusStyloglossus
Muscles of the Anterior Neck & Throat
1. Digastric forms “V” shape under chin opens mouth & depresses mandible
2. Sternocleidomastoid attaches to sternum, clavicle, & mastoid process flexes & laterally rotates head
Muscles of Respiration
1. External Intercostals 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 inspirationflattens on contractionforms floor of thoracic cavity
pierced by 3 structures:1. Aorta2. Inferior Vena Cava (IVC)3. 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 armDeltoid
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 joint1. Rectus femoris2. Vastus lateralis3. Vastis medius4. Vastus intermedius
Muscles of the Posterior Compartment of Thigh
Hamstrings: 3 muscles that together extend thigh and flex knee1. Biceps femoris2. Semitendinosus3. 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