Download Chp. 10 Muscles-Lab

Chapter 10
Muscular System
Gross Anatomy
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General Principles
• Tendons: attach muscles to bones
– Aponeurosis: a very broad tendon
• Muscle terminology
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Origin or head: muscle end attached to more stationary of two bones
Insertion: muscle end attached to bone with greatest movement
Belly: largest portion of the muscle between origin and insertion
Agonist: muscle that, when it contracts, causes an action
Antagonist: a muscle working in opposition to agonist
Synergists: muscles that work together to cause a movement
• Prime mover: plays major role in accomplishing movement
• Fixators: stabilize joint/s crossed by the prime mover; prevent movement of
the origin of the prime mover.
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Muscle attachment
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Muscle Types
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Examples of Muscle Shapes
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Nomenclature
• Muscles are named according to:
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Location: pectoralis gluteus, brachial
Size: maximus, minimus, longus, brevis
Shape: deltoid, quadratus, teres
Orientation: rectus
Origin and insertion: sternocleidomastoid,
brachioradialis
– Number of heads: biceps, triceps
– Function: abductor, adductor, masseter
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Muscle Movements
• Muscles and their tendons and bones act together
as lever systems to move either parts of the body
or the whole body. Muscle contractions are a pull
or force by relative positions of
– Lever: rigid shaft or bone
– Fulcrum: pivot point or joint
– Weight or resistance (force of gravity either in the
form of the weight of the body parts or the weight of an
object being lifted, pulled, or pushed)
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Muscle Anatomy: Anterior View
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Muscle Anatomy: Posterior View
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Head and Neck Muscles
• Flexion: muscles deep within
the neck along the anterior
margins of the vertebral
bodies
• Extension: posterior neck
muscles attached to occipital
bone
• Rotation and abduction:
lateral and posterior groups
• Examples:
sternocleidomastoid,
trapezius, splenius muscles
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Muscles of Facial Expression
• Cutaneous; origin and
insertion in the
superficial fascia.
• Confined primarily to
head and neck.
• Move the skin; some act
as sphincters.
• Examples: orbicularis
oris, orbicularis oculi,
platysma.
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Tongue Movements
• Important in speech:
changes shape
• Swallowing
– Moves food around in
mouth
– Holds food in place during
grinding
– Pushes food up to palate
and back toward pharynx
• (Intrinsic: entirely within
• Extrinsic: change in shape
and movement)
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Muscles of Larynx
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Extrinsic Muscles of the Eye
• Rectus muscles: insert on
sclera anterior to center of
sphere. Move eyeball and
thus pupil laterally,
superiorly, inferiorly, and
medially
• Oblique muscles: insert
onto the posterolateral
margin of the eyeball and
both laterally deviate the
eyeball. The superior
oblique passes through a
pulley-like trochlea
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Muscles that Move the Vertebral
Column
• Muscles that extend,
laterally flex, and rotate the
vertebral column. Used to
produce erect posture
• Divided into deep and
superficial groups
– (Deep group: from vertebra
to vertebra
– Superficial group extend
from vertebrae to ribs)
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Thoracic Muscles
• Involved in breathing
• Four groups associated with
rib cage
– Scalenes: elevate first two ribs
during inspiration
– External intercostals: elevate
the ribs
– Internal intercostals: depress
ribs during expiration
– Transversus thoracis: depresses
ribs during expiration
– Diaphragm: major movement
of inspiration. Flattens during
contraction and increases the
volume of the thoracic cavity
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Abdominal Wall
• Flex and rotate vertebral
column, decrease volume
of abdominal and
thoracic cavities
• Aid in forced expiration,
vomiting, defecation,
urination, childbirth
• Crossing pattern of
muscles adds strength to
abdominal wall to
support organs
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Abdominal Wall
• Rectus Abdominis
– Flexes vertebral column
• External abdominal oblique: flexes and rotates abdomen
• Internal abdominal oblique: flexes and rotates abdomen
• Transversus abdominis: compresses abdominal wall
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Scapular
Movements
• Muscles that attach the
upper limb to the body
and move or stabilize the
scapula and clavicle.
• Originate on the axial
skeleton.
• Trapezius, levator
scapulae, rhomboideus,
serratus anterior,
pectoralis minor
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Arm Movements
• Muscles that attach arm
to thorax: pectoralis
major, latissimus dorsi
• Deltoid and pectoralis
major both act as flexors
and extensors of the
shoulder
• Deltoid abducts and
medially and laterally
rotates arm
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Rotator Cuff
• Primary muscles holding
humerus in the glenoid
cavity
• Form a cuff or cap over
the proximal humerus
• Involved in flexion,
extension, abduction,
adduction, rotation and
circumduction
• Infraspinatus,
subscapularis,
supraspinatus, teres minor
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Forearm
Movement
• Movements at the elbow
• Extension: triceps brachii
and anconeus
• Flexion: biceps brachii,
brachioradialis, and
brachialis
• Supination and pronation:
– Supination: supinator and
biceps brachii
– Pronation: pronator quadratus
and pronator teres
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Wrist, Hand, and
Finger
Movements
• Muscles on anterior surface
of forearm: flexion as well as
abduction and adduction of
the wrist.
• Muscles on posterior surface
of forearm: extension and
abduction.
• Retinacula- bands of deep
fascia which hold tendons of
muscles of forearm, blood
vessels, and nerves close to
wrist.
– Flexor retinaculum (transverse
carpal ligament): on the flexor
surface
– Extensor retinaculum (dorsal
carpal ligament): on the
extensor surface
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Intrinsic Muscles of the Hand
• Originate and insert in hand.
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Thigh Movement
• Originate on coxa; insert
onto femur
• Anterior, posterolateral,
deep
– Anterior: flex hip. Iliacus
and psoas major often
referred to as iliopsoas
since they share a tendon
of insertion
– Posterolateral: gluteals
and tensor fasciae latae
Extension of thigh
– Deep: thigh rotators
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Leg Movements
• Quadriceps femoris: anterior surface of thigh
– Extension of the leg at the knee.
– Rectus femoris also flexes the hip.
– Insert by common tendon (patellar tendon) on and
around the patella
– Patellar tendon extends from patella to tibial tuberosity
• Sartorius: flexes hip and knee, laterally rotates
thigh
• Medial thigh muscles: adduction
• Posterior thigh muscles: hamstrings. Flexion and
rotation of the knee
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Muscles that Move the Leg
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Ankle, Foot,
and Toe
Movements
• Extrinsic foot muscles
• Three leg compartments
– Anterior compartment:
extensors involved in
dorsiflexion and
eversion/inversion of foot;
extension of toes. Dorsiflex
foot, extend toes.
– Lateral compartment: plantar
flexion and eversion.
– Posterior compartment• Superficial muscles
(plantar flexion) have
common tendon of
insertion called the
calcaneal (Achilles)
tendon. Gastrocnemius,
plantaris
• Deep muscles: plantar flex
and invert foot
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Extrinsic Muscles of the Foot
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Extrinsic Muscles of the Foot
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Intrinsic Muscles of the Foot
• Analogous to intrinsics
of hand, but serve in
support and locomotion
• Flexion, extension,
abduction and adduction
of toes
• Deep fascia forms plantar
aponeurosis.
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