Anatomical Language & Orientation

Body Regions & Cavities

Understanding anatomical terminology is essential for accurately describing locations and relationships of body structures.

• Cephalic: Refers to the head region.

• Thoracic: Chest area, containing the heart and lungs.

• Abdominal: Area between the thorax and pelvis, housing digestive organs.

• Pelvic: Lower trunk, containing reproductive and urinary organs.

• Dorsal Cavity: Posterior body cavity; includes cranial and vertebral cavities.

• Ventral Cavity: Anterior body cavity; includes thoracic and abdominopelvic cavities.

• Abdominal Quadrants/Regions: The abdomen is divided into four quadrants (RUQ, LUQ, RLQ, LLQ) or nine regions for clinical reference.

Directional Terms

Directional terms describe the positions of structures relative to each other.

• Superior/Inferior: Above/below.

• Anterior (Ventral)/Posterior (Dorsal): Front/back.

• Proximal/Distal: Closer to/farther from the trunk or point of origin (used for limbs).

• Medial/Lateral: Toward/away from the midline.

• Superficial/Deep: Toward/away from the body surface.

Body Planes & Sections

Body planes are imaginary lines used to divide the body for anatomical study.

• Sagittal Plane: Divides the body into right and left portions (midsagittal = equal halves).

• Transverse (Cross) Plane: Divides the body into superior and inferior parts.

• Frontal (Coronal) Plane: Divides the body into anterior and posterior sections.

Microscopy & Histology (Tissue Identification)

Epithelial Tissues

Epithelial tissues cover surfaces, line cavities, and form glands. They are classified by cell shape and layers.

• Simple Squamous: Single layer of flat cells; found in alveoli, capillaries.

• Simple Cuboidal: Single layer of cube-shaped cells; found in kidney tubules.

• Simple Columnar: Single layer of tall, column-like cells; lines digestive tract.

• Pseudostratified Ciliated Columnar: Appears layered but all cells touch the basement membrane; found in respiratory tract.

• Stratified Squamous: Multiple layers; protects against abrasion. Keratinized (skin) vs. non-keratinized (esophagus).

• Transitional Epithelium: Stretches; lines urinary bladder.

Connective Tissues

Connective tissues support, bind, and protect organs.

• Areolar: Loose, supports epithelia.

• Adipose: Stores fat, insulates, cushions.

• Reticular: Forms stroma of lymphoid organs.

• Dense Regular: Parallel collagen fibers; tendons, ligaments.

• Dense Irregular: Irregular collagen; dermis of skin.

• Hyaline Cartilage: Most common; nose, trachea, articular surfaces.

• Fibrocartilage: Strong; intervertebral discs, pubic symphysis.

• Elastic Cartilage: Flexible; ear, epiglottis.

• Bone (Osseous Tissue): Rigid support, mineral storage.

• Blood: Fluid matrix; transports cells and substances.

Muscle Tissues

Muscle tissues produce movement.

• Skeletal Muscle: Voluntary, striated, multinucleate.

• Cardiac Muscle: Involuntary, striated, intercalated discs.

• Smooth Muscle: Involuntary, non-striated; walls of hollow organs.

Nervous Tissue

Nervous tissue transmits electrical impulses.

• Neurons: Main cells; consist of soma (cell body), axon, dendrites.

• Neuroglia (Glial Cells): Support, protect, and nourish neurons.

The Integumentary System

Epidermal Layers

The epidermis is the outermost skin layer, composed of stratified squamous epithelium.

• Stratum Basale: Deepest, mitotically active layer.

• Stratum Spinosum: Several layers of keratinocytes.

• Stratum Granulosum: Cells begin keratinization.

• Stratum Lucidum: Present only in thick skin (palms, soles).

• Stratum Corneum: Outermost, dead keratinized cells.

Dermal Layers & Structures

The dermis supports and nourishes the epidermis.

• Papillary Layer: Superficial, areolar connective tissue; forms dermal papillae.

• Reticular Layer: Deep, dense irregular connective tissue; contains hair follicles, glands.

• Dermal Papillae: Projections that increase surface area for exchange.

• Hair Follicles: Produce hair.

• Arrector Pili Muscles: Cause hair to stand (goosebumps).

• Sebaceous Glands: Secrete sebum (oil).

• Sudoriferous (Sweat) Glands: Produce sweat for thermoregulation.

Cutaneous Receptors

• Meissner’s (Tactile) Corpuscles: Detect light touch.

• Pacinian (Lamellar) Corpuscles: Detect deep pressure and vibration.

The Skeletal System

Microscopic Bone Structure

Bones are dynamic organs with complex microscopic architecture.

• Osteons (Haversian Systems): Structural units of compact bone.

• Central (Haversian) Canal: Contains blood vessels and nerves.

• Lacunae: Small spaces housing osteocytes.

• Osteocytes: Mature bone cells.

• Canaliculi: Tiny canals connecting lacunae for nutrient exchange.

• Lamellae: Concentric rings of bone matrix.

Axial Skeleton

• Skull:

  • Cranial Bones: Frontal, parietal, temporal, occipital, sphenoid, ethmoid.

  • Facial Bones: Maxilla, mandible, zygomatic, nasal, lacrimal, palatine.

• Vertebral Column:

  • Cervical Vertebrae: 7; atlas (C1), axis (C2) are specialized.

  • Thoracic Vertebrae: 12; articulate with ribs.

  • Lumbar Vertebrae: 5; largest, support weight.

  • Sacrum: 5 fused vertebrae.

  • Coccyx: 3–5 fused vertebrae (tailbone).

  • Key Features: Spinous processes, transverse foramina (cervical), vertebral canal.

• Thoracic Cage:

  • Sternum: Manubrium, body, xiphoid process.

  • Ribs: 12 pairs—true (1–7), false (8–12), floating (11–12).

Appendicular Skeleton

• Pectoral Girdle & Upper Limb: Scapula, clavicle, humerus, radius, ulna, carpals, metacarpals, phalanges.

• Pelvic Girdle & Lower Limb: Os coxae (ilium, ischium, pubis), femur, patella, tibia, fibula, tarsals (calcaneus, talus), metatarsals, phalanges.

Joints & Articular Structures

• Major Synovial Joints: Knee, shoulder, hip—allow free movement.

• Ligaments: Connect bone to bone, stabilize joints.

• Bursae: Fluid-filled sacs reducing friction.

• Menisci: Cartilage pads in knee joint for shock absorption.

The Muscular System

Major Skeletal Muscles

Skeletal muscles are responsible for voluntary movements and are named for their location, shape, or action.

• Head & Neck: Orbicularis oculi (closes eye), orbicularis oris (closes lips), masseter (elevates mandible), temporalis (elevates mandible), sternocleidomastoid (rotates/flexes neck).

• Torso & Abdomen: Pectoralis major/minor (adducts arm), latissimus dorsi (extends/adducts arm), rectus abdominis (flexes trunk), external/internal obliques (rotate trunk), transversus abdominis (compresses abdomen), diaphragm (breathing), intercostals (move ribs).

• Upper Limb: Deltoid (abducts arm), biceps brachii (flexes elbow), brachialis (flexes elbow), triceps brachii (extends elbow), brachioradialis (flexes forearm), flexor/extensor groups (move wrist/fingers).

• Lower Limb: Gluteus maximus/medius (extends/abducts thigh), quadriceps group (extends knee), hamstrings group (flexes knee), gracilis (adducts thigh), sartorius (flexes/rotates thigh), gastrocnemius (plantarflexes foot), soleus (plantarflexes foot), tibialis anterior (dorsiflexes foot).

Example: The quadriceps femoris group consists of four muscles (rectus femoris, vastus lateralis, vastus medialis, vastus intermedius) that extend the knee.

The Nervous System & Special Senses

Brain Structures

• Cerebrum: Largest part; divided into frontal, parietal, temporal, occipital lobes.

• Cerebellum: Coordinates movement and balance.

• Brainstem: Midbrain, pons, medulla oblongata; controls vital functions.

• Corpus Callosum: Connects cerebral hemispheres.

• Thalamus: Sensory relay station.

• Hypothalamus: Regulates homeostasis, endocrine functions.

• Ventricles: Cavities containing cerebrospinal fluid (CSF).

Cranial Nerves

There are 12 pairs of cranial nerves (I–XII), each with specific sensory or motor functions.

Spinal Cord Cross-Section

• Gray Matter (Horns): Contains neuron cell bodies.

• White Matter (Columns/Funiculi): Contains myelinated axons.

• Central Canal: Contains CSF.

• Dorsal/Ventral Roots: Carry sensory/motor fibers.

• Dorsal Root Ganglion: Contains sensory neuron cell bodies.

Eye Anatomy

• Sclera: White, protective outer layer.

• Cornea: Transparent, refracts light.

• Choroid: Vascular layer.

• Retina: Contains photoreceptors.

• Optic Disc: Blind spot where optic nerve exits.

• Macula/Fovea: Area of sharpest vision.

• Lens: Focuses light.

• Iris: Controls pupil size.

• Pupil: Opening for light entry.

• Ciliary Body: Controls lens shape, produces aqueous humor.

• Aqueous/Vitreous Humor: Fluids maintaining eye shape.

Ear Anatomy

• External Ear: Pinna (auricle), auditory canal.

• Tympanic Membrane: Eardrum; vibrates with sound.

• Middle Ear: Malleus, incus, stapes (ossicles).

• Inner Ear: Cochlea (hearing), vestibule and semicircular canals (balance).