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: 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 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