Cat Dissection - Muscle Checklist

🦴 Jaw & Suprahyoid Muscles

Masseter

  • Origin: Zygomatic arch (cheekbone)

  • Insertion: Mandible (lower jaw)

  • Action: Elevates mandible → closes jaw (chewing)

Suprahyoid muscles lie above the hyoid bone and assist swallowing and tongue movement.

Muscle

Origin

Insertion

Action

Geniohyoid

Mandible (inner chin)

Hyoid bone

Pulls hyoid forward; assists swallowing & tongue movement

Hyoglossus

Hyoid bone

Side of tongue

Depresses & retracts tongue

Digastric

Mastoid & jugular processes

Mandible (lower border)

Depresses mandible → opens mouth

Mylohyoid

Medial mandible

Midline raphe & hyoid

Raises floor of mouth; elevates hyoid

Stylohyoid

Styloid process

Hyoid bone

Elevates & retracts hyoid during swallowing

🔻 Infrahyoid Muscles

Infrahyoid muscles lie below the hyoid bone; they depress and stabilize it during swallowing or speaking.

Muscle

Origin

Insertion

Action

Sternohyoid

Manubrium (top sternum)

Hyoid bone

Depresses hyoid after swallowing

Sternothyroid

Manubrium

Thyroid cartilage

Depresses larynx (voice box)

Thyrohyoid

Thyroid cartilage

Hyoid bone

Elevates larynx OR depresses hyoid

Cricothyroid

Cricoid cartilage

Thyroid cartilage

Tenses vocal cords → controls pitch

🧍‍♂ Posterior Neck & Shoulder – Superficial Layer

Sternomastoid (part of sternocleidomastoid in humans)

  • Origin: Manubrium

  • Insertion: Mastoid process

  • Action:

    • Both sides: Flexes neck (chin to chest)

    • One side: Rotates head to opposite side

Cleidomastoid (other part of sternocleidomastoid)

  • Origin: Clavicle

  • Insertion: Mastoid process

  • Action: Same as sternomastoid

Together, sternomastoid & cleidomastoid form the sternocleidomastoid in humans.

🦴 Trapezius Group – Scapula Movers

Muscle

Origin

Insertion

Action

Clavotrapezius

Occipital bone & dorsal midline neck

Clavicle

Pulls clavicle up & forward; extends head

Acromiotrapezius

Cervical & thoracic spinous processes

Scapular spine

Adducts scapula (toward midline)

Spinotrapezius

Thoracic spinous processes

Scapular spine

Pulls scapula downward & backward

💪 Deltoid Group – Shoulder & Humerus Movers

Muscle

Origin

Insertion

Action

Clavodeltoid (clavobrachialis)

Clavicle

Ulna (near elbow)

Flexes forearm

Acromiodeltoid

Acromion process

Humerus

Raises & rotates humerus

Spinodeltoid

Scapular spine

Humerus

Retracts & rotates humerus

🦴 Levator Scapulae Ventralis & Latissimus Dorsi

  • Levator Scapulae Ventralis

    • Origin: Occipital bone & atlas (C1)

    • Insertion: Scapula (metacromion)

    • Action: Pulls scapula cranially (forward)

  • Latissimus Dorsi

    • Origin: Lower thoracic & lumbar spinous processes

    • Insertion: Humerus

    • Action: Pulls forelimb backward; powerful shoulder extensor

🧠 Deep Trunk & Posterior Neck Muscles

Splenius

  • Origin: Midline neck & upper thoracic vertebrae (nuchal ligament)

  • Insertion: Occipital bone & mastoid region

  • Action:

    • Both sides: Extends/raises head

    • One side: Rotates & bends head to same side

🔺 Rhomboideus Group – Scapula Stabilizers

Lie beneath trapezius; connect scapula to vertebral column.

Muscle

Origin

Insertion

Action

Rhomboideus Capitis

Occipital bone

Scapula (vertebral border)

Pulls scapula forward & medially

Rhomboideus Major

Thoracic spinous processes

Vertebral border scapula

Adducts scapula toward spine

Rhomboideus Minor

Cervical spinous processes

Vertebral border scapula

Retracts & elevates scapula

lungs emoji Thoracic & Respiratory Muscles

Serratus Ventralis (Anterior)

  • Origin: Ribs 1–10 & cervical vertebrae

  • Insertion: Scapula (medial surface)

  • Action: Pulls scapula ventrally & backward; supports trunk between forelimbs

Scalenes (Anterior, Posterior, Medial)

  • Origin: Cervical transverse processes

  • Insertion: Ribs 1–2

  • Action:

    • Together: Elevate ribs (inspiration)

    • One side: Flex neck to same side

Muscle

Fiber Direction

Action

External Intercostals

Downward & forward

Elevate ribs (inhale)

Internal Intercostals

Upward & backward

Depress ribs (forced exhale)

🧱 Abdominal Wall Muscles

Muscle

Origin

Insertion

Action

Rectus Abdominis

Pubis

Sternum & costal cartilages

Flexes trunk; compresses abdomen

External Oblique

Ribs & lumbodorsal fascia

Linea alba & pubis

Compresses abdomen; flexes & rotates trunk

Internal Oblique

Ilium & lumbodorsal fascia

Linea alba

Assists trunk rotation & flexion

Transversus Abdominis

Inner ribs, fascia, ilium

Linea alba

Compresses abdominal contents (deepest)

Linea Alba: fibrous midline seam (sternum → pubis); attachment site for abdominal muscles.

🐱 Cat-Only Chest Muscles

Muscle

Origin

Insertion

Action

Note

Pectoantebrachialis

Manubrium

Forearm fascia

Adducts forelimb

Cats only

Xiphihumeralis

Xiphoid process

Humerus

Adducts forelimb

Cats only

Pectoralis Major

  • Origin: Sternum & upper ribs

  • Insertion: Proximal humerus

  • Action: Adducts & medially rotates forelimb

Pectoralis Minor

  • Origin: Mid-to-lower sternum

  • Insertion: Humerus

  • Action: Draws forelimb toward midline & backward

💪 Forelimb – Brachium (Upper Arm)

Triceps Brachii (3 heads)

  • Origin: Long head – scapula; Lateral & medial – humerus

  • Insertion: Olecranon of ulna

  • Action: Extends forearm at elbow

Biceps Brachii

  • Origin: Scapula (near glenoid)

  • Insertion: Radius

  • Action: Flexes forearm; supinates paw

Muscle

Origin

Insertion

Action

Note

Epitrochlearis

Latissimus dorsi

Olecranon

Extends forearm

Cats only

Brachialis

Lateral humerus

Ulna (coronoid)

Flexes forearm

—

Anconeus

Lateral epicondyle

Olecranon

Extends elbow

Assists triceps

🦴 Forelimb – Antebrachium (Forearm)

Dorsal Extensors (back of forearm)

  • Extensor Carpi Radialis Longus & Brevis: extend wrist

  • Extensor Digitorum Communis: extends digits

  • Extensor Carpi Ulnaris: extends wrist & adducts paw

  • Brachioradialis (Supinator Longus): supinates paw

Ventral Flexors (palm side)

  • Flexor Carpi Radialis: flexes wrist

  • Flexor Carpi Ulnaris: flexes wrist

  • Flexor Digitorum Profundus: flexes digits

  • Pronator Teres: pronates paw (palm down)

  • Palmaris Longus: flexes wrist & digits

🦵 Hindlimb – Posterolateral Thigh

Tensor Fascia Latae

  • Origin: Ilium (anterior superior spine)

  • Insertion: Fascia lata

  • Action: Tenses fascia; flexes hip; abducts thigh

Gluteus Medius & Maximus

  • Medius: abducts & medially rotates thigh

  • Maximus: extends & abducts thigh

Caudofemoralis – Cats only

  • Origin: Caudal vertebrae

  • Insertion: Patella/tibia via fascia

  • Action: Abducts thigh; extends shank

Hamstring Group (posterior thigh)

Muscle

Origin

Insertion

Action

Biceps Femoris

Ischial tuberosity

Patella, tibia, fascia

Extends hip, flexes knee, abducts thigh

Semitendinosus

Ischial tuberosity

Proximal tibia

Extends hip, flexes knee

Semimembranosus

Ischial tuberosity

Medial tibial condyle

Extends hip, flexes knee

🦵 Hindlimb – Anteromedial Thigh

Sartorius

  • Origin: Ilium (anterior superior spine)

  • Insertion: Patella & tibia

  • Action: Flexes hip; extends or flexes knee (region-dependent)

Gracilis

  • Origin: Pubis & ischium

  • Insertion: Medial tibia

  • Action: Adducts thigh; flexes knee

Quadriceps Group – Knee Extensors

Muscle

Origin

Insertion

Action

Rectus Femoris

Ilium (anterior inferior spine)

Tibial tuberosity (via patellar ligament)

Extends knee, flexes hip

Vastus Lateralis

Greater trochanter & linea aspera

Tibial tuberosity

Extends knee

Vastus Medialis

Medial femur

Tibial tuberosity

Extends knee

Vastus Intermedius

Anterior femoral shaft

Tibial tuberosity

Extends knee

Adductor Group – Thigh Adductors

  • Adductor Femoris: adducts & medially rotates thigh

  • Adductor Longus: adducts thigh

  • Pectineus: adducts & flexes thigh

Iliopsoas

  • Origin: Ilium & lumbar vertebrae

  • Insertion: Lesser trochanter

  • Action: Flexes hip

Femoral Triangle: bordered by sartorius, adductors, inguinal ligament; contains femoral artery, vein, nerve.

🦵 Hindlimb – Posterolateral Leg

Triceps Surae (Calf) – Plantarflexors

Muscle

Origin

Insertion

Action

Gastrocnemius

Distal femoral condyles

Calcaneus via Achilles

Plantarflexes foot; flexes knee

Soleus

Fibula & tibia

Calcaneus via Achilles

Plantarflexes foot

Plantaris

Femoral supracondylar ridge

Calcaneus via Achilles

Assists plantarflexion

Achilles Tendon = common tendon of gastrocnemius, soleus, plantaris → inserts on calcaneus

Peroneus (Fibularis) Group

  • Longus, Brevis, Tertius

  • Action: Everts and flexes foot (sole outward)

Extensor Digitorum Longus

  • Action: Extends digits; dorsiflexes foot (pulls toes up)

🦵 Hindlimb – Anteromedial Leg

Muscle

Origin

Insertion

Action

Flexor Digitorum Longus

Posterior tibia

Distal phalanges

Flexes toes; assists plantarflexion

Tibialis Anterior

Lateral tibia

Medial metatarsals

Dorsiflexes & inverts foot

Flexor Hallucis Longus

Posterior fibula

Distal hallux phalanx

Flexes big toe; assists plantarflexion