Download The Muscular System

The Muscular System
• Muscles are attached to bones by tendons which are thick
cords of collagen.
• One end of a muscle will be relatively fixed and is called
the Origin, eg the Pectorals attach at one end to the
sternum which does not move.
• The other end attaches to a bone that moves and this
connection is called the Insertion, eg the pectorals attach
at one end to the humerus which is pulled towards the
sternum when the pectorals contract.
The Muscular System
Agonist (or Prime Mover) – is the muscle mainly responsible
for causing an action, eg Biceps is the main muscle causing
elbow flexion.
Antagonist – is the muscle that is mainly responsible for
opposing an action.
Synergists – are muscles that assist agonists in causing a
movement, eg Brachioradialis helps the Biceps cause elbow
flexion.
Stabilisers – are muscles that keep the body parts in the
correct position (stabilised) so an action can occur, eg in a
bench press stabilisers keep the arms steady and in the
correct position for pushing the weight up.
The Muscular System
Reciprocal Inhibition
• In each action the Agonist contracts and the Antagonist
relaxes.
• The Antagonist controls how quickly the Agonist
contracts by how slowly it relaxes.
The Muscular System
Biceps Brachii
• Origin – 2 different spots
on the scapula
• Insertion – Radius
• Main Action - Elbow
flexion
The Muscular System
Triceps Brachii
Origin – scapula & 2
different spots on the
humerus
Insertion – Ulna
Main Action – Elbow
extension
Synergist Action –
shoulder extension
The Muscular System
Erector Spinae
Origin – Ilium(pelvis bone)
& various vertebrae
Insertion – Ribs, vertebrae
and cranium
Main Action – Spine
extension including neck
The Muscular System
Rhomboids
Origin – Spinous process of
Cervical no. 7 & first 5
thoracic vertebrae
Insertion – medial border
of scapula
Main Action – adducts
scapula, slight elevation of
scapula and rotation of
scapula
The Muscular System
Trapezius
Origin – base of cranium,
ligaments of neck &
cervical 7 and all thoracic
vertebrae
Insertion – outer third of
clavicle, scapula
Main Action – adducts
scapula, slight elevation of
scapula and rotation of
scapula
The Muscular System
Levator Scapulae
Origin – transverse process
of first 4 cervical
vertebrae
Insertion – upper medial
border of scapula
Main Action – elevates the
scapula, rotates the
scapula
The Muscular System
Latissimus Dorsi
Origin – crest of Ilium,
sacrum, lumbar and lower
5 thoracic vertebrae
Insertion – humerus
Main Action – adduction
of shoulder, extension of
shoulder, inward rotation
of shoulder
The Muscular System
Pectoralis Major
Origin – clavicle &
sternum
Insertion – humerus
Main Action –
adduction of shoulder,
inward rotation of
shoulder
The Muscular System
Deltoid
Origin – clavicle & scapula
Insertion – humerus
Main Action – abduction,
flexion, extension of
shoulder
The Muscular System
Rectus Abdominis
Origin – crest of Pubis
Insertion – cartilage of 5th,
6th & 7th Ribs
Main Action – flexion of
spine
The Muscular System
External Oblique
Abdominals
Origin – border of lower 8
ribs
Insertion – crest of Ilium &
Pubis, inguinal ligament
Main Action – flexion of
spine, right side twists
spine left, left side twists
spine right
The Muscular System
Internal Oblique
Abdominals
Origin – inguinal ligament,
crest of Ilium
Insertion – cartilage of 8th,
9th & 10th ribs
Main Action – flexion of
spine, right side twists
spine right, left side twists
spine left
The Muscular System
Transverse Abdominals
Origin – inguinal ligament,
crest of Ilium, lower 6 ribs
Insertion – crest of pubis
Main Action – pulls
abdominal wall in
The Muscular System
Hamstrings – Biceps
Femoris
Origin – Ishium, femur
Insertion – Tibia & Fibula
Main Action – hip
extension, knee flexion,
outward rotation of thigh
The Muscular System
Hamstrings –
Semitendinosus
Origin – Ishium
Insertion – Tibia
Main Action – hip
extension, knee flexion,
inward rotation of thigh
The Muscular System
Hamstrings –
Semimembranosus
Origin – Ishium
Insertion – Tibia
Main Action – hip
extension, knee flexion,
inward rotation of thigh
The Muscular System
Quadriceps – Rectus
Femoris
Origin – Ilium
Insertion – Patella and
patella ligament to Tibia
Main Action – hip flexion,
knee extension
The Muscular System
Quadriceps – Vastus
Lateralis
Origin – Femur
Insertion – Patella and
patella ligament to Tibia
Main Action – knee
extension
The Muscular System
Quadriceps – Vastus
Medialis
Origin – Femur
Insertion – Patella and
patella ligament to Tibia
Main Action – knee
extension
The Muscular System
Quadriceps – Vastus
Intermedius
Origin – Femur
Insertion – Patella and
patella ligament to Tibia
Main Action – knee
extension
The Muscular System
Iliopsoas
Origin – Inner Ilium,
sacrum, last thoracic and
all lumber vertebrae
Insertion – Femur
Main Action – Hip
flexion, outward rotation
of thigh.
The Muscular System
Adductor Longus
Origin – Pubis
Insertion – Femur
Main Action – Hip
adduction
Synergist Action – flexion
of hip
The Muscular System
Gluteus Maximus
Origin – crest of Ilium,
sacrum
Insertion – Femur
Main Action – Hip
extension, outwards
rotation of thigh
Synergist Action – lower
fibre assist in adduction of
hip
The Muscular System
Gluteus Medius
Origin – just below crest
Ilium
Insertion – Femur
Main Action – Hip
abduction, outwards
rotation of thigh
The Muscular System
Gastrocnemius
Origin – bottom of femur
Insertion –
Calcaneous(heel bone)
Main Action – Plantar
Flexion of ankle, flexion
of knee.
The Muscular System
Soleus
Origin – top two 3rds of
Tibia & Fibula
Insertion –
Calcaneous(heel bone),
joins the tendon of the
Gastrocnemius.
Main Action – Plantar
Flexion of ankle
The Muscular System
Tibialis Anterior
Origin – top two 3rds of
front of Tibia
Insertion – tarsal and 1st
metatarsal.
Main Action – Dorsi
flexion, adduction,
inversion.
The Muscular System
Serratus Anterior
Origin – top 9 ribs at side
of chest.
Insertion – underneath the
medial border of the
scapula.
Main Action – Abduction
of scapula(shoulder
girdle), slight rotation
Muscle types
• Skeletal
– Striated,
– Most of the muscle
mass in the body
– Voluntary
• Cardiac
– Striated,
– Heart
– Involuntary
Muscle types continued
• Smooth
– Nonstriated,
– viscera and all blood
vessels
– Involuntary
Comparison
Skeletal Muscle
Skeletal Muscle
Sarcomeres
• Functional contractile unit of striated muscle
• Striations
– Represent the transverse alignment of myofibrils
in sarcomeres
– Made up of regular overlapping pattern
• of actin (thin filaments)
• myosin (thick filaments)
– Delineated by Z lines
– Center line is I band
– 2-3 mm in length
Sliding filament mechanism
• Sarcomeres shortened
• Thin filaments(actin)
slide over thick
filament(myosin)
• Requires ATP
– other proteins and calcium
Motor nerve supply
• Neuromuscular
junction
– motor neuron
and its axonal
branches sitting
on the skeletal
muscle fibers it
innervates
• Motor end plate
– The end plate of
the neuron
Motor nerve supply
• Motor Unit
– The motor neuron and the muscle fibers it
innervates
– When a motor unit fires ALL the muscle
fibres connected to the motor unit
contract.