MAJOR SKELETAL
MUSCLES
Naming Muscles
Muscles are often named for:
1. size (pectoralis major vs. pectoralis minor)
2. shape (rhomboideus, deltoid)
3. location (tibialis anterior, frontalis)
4. action (flexor digitorum)
5. points of attachment
(sternocleidomastoid)
6. direction of fibers (external oblique)
• There are over 700 muscles in the human body
• Cats have a mere 517
• We will learn approx. 50 muscles that cats & humans have in common
Action of Muscles
• Flex – to bend a joint
• Extend – to straighten a joint
• Adduct – to move toward the midline of the
body
• Abduct – to move away from the midline of the
body
• Elevate – to raise a body part ( as in shrugging
the shoulders)
• Depress – to lower a body part ( drooping the
shoulders)
Action of Muscles
• Dorsiflexion – moving the ankle to bring the
foot closer to the shin (walking on heels)
• Plantar flexion – moving the ankle to bring the
foot farther from the shin (walking on toes)
• Eversion – turning the foot so plantar surface
faces laterally
• Inversion - turning the foot so plantar surface
faces medially
Muscles of Facial Expression,
Chewing & Movement of the Head
Epicranius
(Frontalis &
Occipitalis)
Orbicularis oculi
Orbicularis oris
Buccinator
Zygomaticus
Masseter
Temporalis
Platysma
Sternocleidomastoid
(Sternomastoid in cat)
Muscles of Facial Expression
• Epicranius (Frontalis & Occipitalis) – raises eyebrows
• Orbicularis oculi – closes eyes
• Orbicularis oris – closes & protrudes
lips (kissing muscle)
• Buccinator – compresses cheeks
inward (blowing a “bugle”)
• Zygomaticus – raises corners
of mouth (smiling muscle)
• Platysma – pulls angle of mouth
downward (pouting)
Muscles of Mastication
(Chewing) &
Movement of the Head
• Masseter – raises mandible (chewing
muscle)
• Temporalis – raises mandible (chewing)
• Sternocleidomastoid – pulls head to side
Facial Muscle Practice
•
•
•
•
•
•
•
•
1- Obicularis Oculi
2- Obicularis oris
3- Buccinator
4- Zygomaticus
5- Masseter
6- Temporalis
7- Platysma
8- Sternocleidomastoid
Muscles that Move
the Pectoral Girdle
• Trapezius – elevates & lowers
scapula & shoulders
•
(cat has 3 separate trapezius muscles)
• Rhomboid major &
minor - both raise scapula
• Pectoralis Minor –
pulls scapula forward
& raises ribs
Muscles That Move
the Upper Arm
Flexors:
1. Pectoralis major
Abductors:
1. Deltoid
Extensors:
Latissimus dorsi
Muscles That Move the Forearm
• Flexors (flex forearm):
1. Biceps brachii
2. Brachialis
3. Brachioradialis
• Extensors (extend forearm):
1. Triceps brachii
Muscles That Move the Hand
Flexors: (all flex the wrist)
Flexor carpi radialis
Flexor carpi ulnaris
Palmaris longus
Flexor digitorum
superficialis flexes fingers
Forearm & Hand Muscles
Extensors: (both extend wrist)
Extensor carpi ulnaris
Extensor carpi radialis longus
(not present in cat)
Extensor carpi radialis brevis
Extensor digitorum –
extends fingers
Muscles of the Abdomen
• External oblique
• Internal oblique
• Transversus
abdominis
• Rectus
abdominis
• Functions:
• All tense abdominal
wall
Muscles of the Leg
•
Hamstrings – Flex knee &
extend thigh; include:
1. Biceps femoris
2. Semitendinosus
3. Semimembranosus
• Gluteus maximus – extend
thigh at hip
• Gluteus medius – abducts
thigh
• Gracilis – adducts thigh & flexes
leg at knee
Muscles of the Leg
• Quadriceps – all extend leg
at knee; include:
1. Rectus femoris
2. Vastus lateralis
3. Vastus medialis
• Adductor longus – adducts
& flexes thigh
• Sartorius – flexes knee &
hip
Muscles of the
Lower Leg
Tibialis anterior – dorsiflexion
& inversion of foot
Ext. digitorum longus –
dorsiflexion & eversion of foot
Flexor digitorum longus –
plantar flexion & inversion
Gastrocnemius &
Soleus – plantar flexion
of foot
Practice Packet Review
Website for Cat Pics
• homes.bio.psu.edu/people/faculty/strauss/
anatomy/musc/muscular.htm