Muscle System
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Muscular system
Includes all skeletal muscle tissue that
can be controlled voluntarily
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Classification of
Skeletal Muscles
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Types of Muscles
Muscles can be classified by action
Agonist (prime mover)
Primary responsible for the movement
Antagonist
Opposes the agonists
Synergist
Aids the action of agonists
Fixator
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Origins and Insertions
Muscles can be identified by origin,
insertion and action
Origin = stationary end
Insertion = movable end
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Names of skeletal muscles
Names give clues to muscle characteristics
Location of muscle’s origin and insertion
Sternohyoid
Direction of fibers
Tranverse, oblique, rectus
Number of origins
Biceps, triceps
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Names of skeletal muscles
Size of the muscle
Maximus, minimus
Shape
Deltoid, trapezius
Action
Adductor, flexor
Location of the muscle
Frontalis, orbicularis
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Organization of skeletal muscle fibers
Parallel muscle
Convergent muscle
Pennate muscle
Unipennate
Bipennate
Multipennate
Circular muscle (sphincter)
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Organization of skeletal muscle fibers
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Muscles of the Head and Neck
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Head
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Muscles of the head and neck
Epicranius muscles
Occipital
• O: occipital bone
• I: galea aponeurotic
• A: pulls the scalp posteriorly
Frontal
• O: galea aponeurotic
• I: skin of the eyebrow
• A: raise the eyebrow
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Muscles of the head and neck
Orbicularis oculi
O: frontal and maxillary bones
I: eyelid
A: closes eyes
Corrugator supercilli
O: frontal bone
I: skin of eyebrow
A: draws eyebrow inferiorly and
medially
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Muscles of the head and neck
Levator labii superioris
O: zigomatic and maxilla bones
I: upper lip
A: raises upper lips
Depressor labii inferioris
O: mandible
I: lower lip
A: pulls lower lip inferiorly
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Muscles of the head and neck
Depressor anguli oris
O: mandible
I: angle of mouth
A: pulls corner of mouth down and
laterally
Mentalis
O: mandible
I: skin of chin
A: protudes lower lip
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Muscles of the head and neck
Zigomatics
O: zigomatic bone
I: corner the mouth
A: smiling muscle
Risorius
O: masseter
I: angle of the mouth
A: pulls corner of lips laterally
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Muscles of the head and neck
Orbicularis oris
O: maxilla and mandible
I: lips
A: compresses lips
Buccinator
O: maxilla and mandible
I: orbicularis oris
A: compresses the cheek (whistling)
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Muscles of Mastication
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Muscles of mastication
Masseter muscles
O: zigomatic and maxilla bones
I: mandible
A: closes the jaw
Temporalis muscles
O: temporal fossa
I: mandible
A: closes the jaw
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Muscles of mastication
Pterygoids
O: sphenoid, palatine and maxillary
bones
I: mandible
A: elevates mandible, grinding the teeth
Buccinator
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Muscles of the head and neck
Platysma
O: fascia of chest and deltoid
I: mandible, skin, corner of the mouth
A: depresses mandible, pulls lip back
and down
Sternocleidomastoid
O: manubrium and clavicle
I: temporal and occipital bones
A: flexion forward of the neck
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Neck
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Neck
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Muscles of the head and neck
Scalenes – anterior, middle, posterior
O: cervical vertebrae
I: first 2 ribs
A: elevates first 2 ribs
Digastric
O: mandible and mastoid process
I: hyoid
A: elevates hyoid bone
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Muscles of the head and neck
Mylohyoid
O: mandible
I: hyoid bone
A: elevates hyoid bone
Sternohyoid
O: manubrium and clavicle
I: hyoid bone
A: depresses hyoid bone
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Extrinsic eye muscles
Inferior and superior rectus muscles
Lateral and medial rectus muscles
Inferior oblique muscles
Elevates the eye and turns it laterally
Superior oblique muscles
Depresses the eye and turns it laterally
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Chapter 25
Muscles of the Trunk
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Muscles of the trunk and shoulder
Serratus anterior muscles
O:ribs
I: scapula (anterior surface)
A: fixates, protracts the scapula
Pectoralis minor muscles
O: ribs
I: scapula
A: ribs fixed: moves scapula forward
and inferiorly and with scapula fixed it
moves up the rib cage
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Muscles of the trunk and shoulder
Deltoid muscles
O: clavicle and scapula
I: humerus
A: abduction of the shoulder
Pectoralis Major
O: clavicle, sternum, ribs
I: humerus
A: agonist for shoulder flexion
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Muscles of the thorax (front)
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Muscles of Respiration
External intercostal
O: rib above
I: rib below
A: elevates rib cage
Internal intercostal
O: rib below
I: rib above
A: depresses rib cage
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Muscles of Respiration
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Muscles of Respiration
Diaphragm
O: ribs and its cartilage, sternum,
vertebrae
I: central tendon of the diaphragm
A: prime action in inspiration
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Diaphragm
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Muscles of the Trunk (back)
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Muscles of the trunk (back) and
shoulder
Supraspinatus muscles
O: scapula
I: humerus
A: synergist for arm abduction
Infraspinatus muscles
O: scapula
I: humerus
A: helps to hold the head of the
humerus in the glenoid cavity, lateral
rotation of humerus
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Muscles of the trunk (back) and
shoulder
Teres major
O: scapula
I: humerus
A: adducts humerus, medial rotation of
humerus
Teres minor muscles
O: scapula
I: humerus
A: helps to hold the head of the
humerus in glenoid cavity, lateral
rotation of the humerus
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Muscles of the trunk (back) and
shoulder
Trapezius muscles
O: occipital bone, vertebrae
I: scapula, clavicle
A: extend head, elevate scapula
Rhomboids
O: vertebrae
I: scapula
A: adduct and stabilize scapula
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Muscles of the trunk (back) and
shoulder
Levator scapulae
O: vertebrae
I: scapula
A: elevates scapula
Latissimus dorsi muscles
O: vertebrae, ribs, ilium
I: humerus
A: agonist for shoulder extension
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Muscles of Abdominal Wall
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Muscles of Abdominal Wall
Rectus abdominis
O: pubis
I: xiphoid process, ribs
A: flexes vertebral column,increase
abdominal pressure
 External oblique,
O: ribs
I: linea alba, pubis, ilium
A: see above, helps trunk rotation and
lateral flexion
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Muscles of Abdominal Wall
Internal oblique
O: lumbar fascia, ilium, inguinal
ligament
I: linea alba, pubis, ribs
A: same as external oblique
Transversus abdominis
O: ribs, inguinal ligament, ilium, lumbar
fascia
I: linea alba, pubis
A: compresses abdominal content
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Posterior muscles of the back
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Chapter 25
Muscles of the Arm
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Muscles of the arm
Biceps brachii muscle
O: scapula, shoulder joint
I: radius
A: agonist for flexion of the elbow
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Muscles of the arm
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Muscles of the arm
Brachialis
O: humerus
I: ulna
A: flex the elbow
Brachioradialis
O: humerus
I: radius
A: synergist for flexion of the elbow
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Muscles of the arm
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Muscles of the arm
Triceps brachii muscle
O: scapula, humerus
I: ulna
A: agonist for extension of the elbow
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Muscles of the arm
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Muscles of the arm
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Rotator Cuff Muscles
Supraspinatus, infraspinatus, teres minor,
and subscapularis
Function mainly to reinforce the capsule of the
shoulder
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Rotator Cuff Muscles
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Muscles of the forearm
Flexion of the wrist (O: humerus)
Flexor carpi ulnaris
I: metacarpus and carpus
Flexor carpi radialis
I: metacarpus
Palmaris longus
I: palm of the hand
A: also extends the palm of the hand
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Muscles of the arm and
forearm
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Muscles that affect the wrist
Extension of the wrist (O: humerus)
Extensor carpi radialis
I: metacarpus
Extensor carpi ulnaris
I: metacarpus
Pronation of the forearm (I: radius)
Pronator teres muscle
O: humerus
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Muscles of the forearm
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Muscles of the forearm
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Muscles of the forearm
Extensors of the digitus
Extensor digitorum
O: humerus
I: phalanges
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Chapter 25
Muscles of the Leg
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Muscles of the pelvis and lower limbs
Gluteus maximus
O: ilium, sacrum, coccyx
I: femur
A: extension of thigh (climbing
stairs)
Gluteus medius and minimus
O:ilium
I: femur
A: abducts thigh, steadies pelvis
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Muscles of the leg
Tensor fascia latae
O: ilium
I: fascia latae
A: flexes, abducts the thigh; tenses the
fascia latae
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Muscles of the leg
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Iliopsoas muscle
Formed from the merging of the
psoas major and the iliacus muscles
O: ilium, vertebrae
I: femur
Flexes trunk on thigh, flexes thigh
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Muscles of the Leg
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Muscles of the leg
Sartorios
O: ilium
I: tibia
A: flexes the thigh and helps in crossing
the leg
Adductors of the leg
O: pubis
I: femur
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Muscles of the pelvis and lower limbs
Gracilis
O: pubis
I: tibia
A: adducts, flexes and medially rotates
the thigh
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Muscles of the leg
Quadriceps (I: tibia; A: extends the knee)
Rectus femoris
O: ilium
Vastus medialis, intermedius, lateralis
O: femur
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Leg
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Leg
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Muscles of the leg
The hamstrings (O: ischium; I: tibia;
A: extend thigh, flexes knee)
Biceps femoris muscles
Semimembranosus muscles
Semitendinosis muscles
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Muscles of the lower leg
Plantar flexion (I: calcaneal tendon)
Gastrocnemius muscle
O: femur
Soleus muscle
O: fibula and tibia
Eversion and plantar flexion
Fibularis muscle
O: fibula
I: metatarsal bones (lateral side)
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Muscles of the lower leg
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Muscles of the lower leg
Popliteus
O: femur
I: tibia
A: unlocks the knee joint
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Muscles of the leg
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Muscles of the lower leg
Tibialis anterior
O: tibia
I: metatarsus and cuneiforme
A: dorsiflexion of the foot
Tibialis posterior
O: tibia
I: tarsal and metatarsal bones
A: foot inversion
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Muscles of the lower leg
Extensor digitorum
O: Tibia and fibula
I: Digitus
A: Extends the digits
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Chapter 25
Cat Dissection
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Skinning the Cat
Leave the skin of the back attached.
Do not skin paws, tail, genital area, or
head.
Remove fat if possible.
When you are done, use the skin to wrap
the cat in.
Use the pencil and tape to label the bag.
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Skinning the Cat
Cut the bag from the top to allow you to
store the cat in it.
Keep as much embalming fluid as possible
in the cat for it’s preservation.
Use several rubber bands; if one breaks,
the bag will remain closed.
Clean and dry tray, tools and lab bench
before leaving.
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Cat Dissection – Neck Muscles
Mylohyoid
Digastric
Sternohyoid
Sternothyroid
Thyrohyoid
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Cat Dissection – Thoracic Muscles
Anterior muscles
Pectoralis
Major and
Minor
Serratus anterior
Intercostals
Internal
External
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Cat Dissection – Thoracic Muscles
Posterior muscles
Trapezius
Latissimus dorsi
Rhomboids
Supraspinatus
Infraspinatus
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Cat Dissection – Abdominal Muscles
External oblique
Internal oblique
Rectus abdominis
Transversus abdominis
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Cat Dissection – Arm Muscles
Brachial muscles
Biceps brachii
Triceps brachii
Long head
Lateral head
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Cat Dissection – Arm Muscles
Antebrachial muscles
Pronator teres
Flexor carpi ulnaris
Palmaris longus
Flexor carpi radialis
Extensor carpi ulnaris
Extensor digitorum
Extensor carpi radialis
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Cat Dissection – Leg Muscles
Upper leg
Sartorius
Gracilis
Rectus femoris
Vastus lateralis
Vastus medialis
Adductors
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Cat Dissection – Leg Muscles
Semimembranosus
Semitendinosus
Biceps femoris
Lower leg
Gastrocnemius
Soleus
Tibialis anterior
Extensor digitorum
Fibularis
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