Rat Dissection Guide

Introduction

• Rats are used in dissection for their availability and similarity to mammalian anatomy.
• Anatomy learned from rats applies to other mammals, including humans.

External Features

• Vibrissae: Whiskers for sensory function, judging opening sizes.
• Nares: External openings into the nasal cavity.
• Female Urogenital Structures:
  • Urethral orifice: Opening to the urethra.
  • Vaginal orifice: Opening to the vagina.
• Male Urogenital Structures:
  • Penis: Hidden beneath the foreskin.
  • Scrotum: Pouch containing testes.

Skinning the Rat

• Make a midventral incision using a probe, scissors, and fingers.
• Encounter muscles: Cutaneous maximus (trunk) and platysma (neck).

Muscular System

Head and Throat Muscles

• Digastric: V-shaped, opens mouth.
• Mylohyoid: Raises mouth floor.
• Sternohyoid: Pulls hyoid to sternum.
• Sternomastoid: Rotates head.
• Masseter: Cheek muscle, aids chewing.

Chest and Front Leg Muscles

• Pectoralis Major/Minor: Pulls arm to chest.
• Biceps Brachii: Flexes lower arm.
• Epitrochlearis: Extends lower arm.
• Flexors: Flex wrist and hand.

Shoulder and Lateral Muscles

• Clavotrapezius, Acromiotrapezius, Spinotrapezius: Stabilize scapula.
• Latissimus dorsi: Pulls arm down.
• Serratus ventralis, Cleidobrachialis, Acromiodeltoid, Spinodeltoid: Move scapula and arms.
• Triceps brachii: Extends lower arm.
• Brachialis: Flexes lower arm.
• Extensors: Extend wrist and hand.

Deep Shoulder Muscles

• Rhomboideus, Supraspinatus, Infraspinatus, Teres Major: Move and stabilize scapula and upper arm.

Hip and Hind Leg Muscles

• Gluteus Superficialis, Biceps Femoris, Semitendinosus: Move thigh and leg.
• Gastrocnemius, Soleus, Tibialis Anterior: Move foot.

Hip and Medial Muscles

• Gracilis, Rectus femoris, Vastus medialis: Move thigh and leg.
• Adductors, Pectineus: Pull thigh inward.

Abdominal Muscles

• External Oblique, Rectus Abdominis: Compress and hold organs.

Throat and Oral Cavity

• Salivary Glands: Parotid, Mandibular, and Sublingual for saliva secretion.
• Lymph Nodes: Part of the immune system.
• Lacrimal Gland: Lubricates eye.

Abdominal Cavity and Digestive System

• Dissect with midventral cut to explore.
• Peritoneum: Parietal and Visceral layers.
• Liver, Stomach, Esophagus, Intestines: Key digestion roles.
• Spleen, Pancreas: Immunity and digestion.

Respiratory System

• Trachea, Bronchus, Lungs: Main breathing structures.
• Diaphragm: Muscle for drawing air into lungs.

Circulatory System

• Heart: Located between lungs, pumps blood.
• Major Arteries: Aorta, Brachiocephalic, Carotid, Subclavian, Iliac, Femoral.
• Major Veins: Subclavian, Vena Cavae, Iliac, Hepatic Portal.

Female Urinary and Reproductive Structures

• Kidney, Ureter, Ovary, Uterus: Involved in excretion and reproduction.

Male Urinary and Reproductive Structures

• Testis, Epididymis, Vas Deferens: Sperm storage and transport.
• Seminal Vesicles, Prostate Gland: Secrete nourishing fluids for sperm.

Mammal Skeleton

• Learn skeletal anatomy applicable to other mammals like cats and monkeys.