Practical 2 Review
Joints and Movement
- Articulation refers to the connection between two bones that forms a joint. It allows for varying degrees of movement and provides stability to the skeletal system.
- Joints are classified based on their structure (types of connective tissues) and function (degree of mobility).
- Structure: Determines the stability and range of motion.
- Example: A fibrous joint like a suture has limited movement but provides strength.
- Function: Defines how much movement is possible.
- Example: Synovial joints (e.g., knee) allow a wide range of motion compared to cartilaginous joints (e.g., symphysis).
- Suture: Immovable, found in the skull.
- Syndesmosis: Slightly movable, connected by ligaments (e.g., between the radius and ulna).
- Gomphosis: Immovable, peg-in-socket joints (e.g., teeth in sockets).
- Synchondrosis: Immovable, connected by hyaline cartilage (e.g., rib to sternum).
- Symphysis: Slightly movable, connected by fibrocartilage (e.g., pubic symphysis).
3. Synovial Joints: Freely movable joints characterized by a joint cavity (e.g., shoulder, knee).
- Examples:
- Suture (fibrous)
- Gomphosis (fibrous)
- Synchondrosis (cartilaginous)
- Examples:
- Syndesmosis (fibrous)
- Symphysis (cartilaginous)
- Hinge: Flexion and extension (e.g., elbow).
- Pivot: Rotation (e.g., atlantoaxial joint).
- Condyloid (Ellipsoidal): Biaxial movement (e.g., wrist).
- Gliding: Sliding movement (e.g., intercarpal joints).
- Saddle: Biaxial movement (e.g., thumb).
- Ball and Socket: Multiaxial movement (e.g., shoulder, hip).
- Articular Cartilage: Smooth tissue covering the ends of bones.
- Synovial Membrane: Lines the joint capsule and secretes synovial fluid.
- Articular Capsule: Two layers (outer fibrous and inner synovial membrane).
- Joint Cavity: Space filled with synovial fluid.
- Bursa: Fluid-filled sac that reduces friction.
- Anterior and Posterior Cruciate Ligaments (ACL/PCL): Stabilize the knee.
- Lateral and Medial Meniscus: Cartilage that cushions and stabilizes.
- Tibial (Medial) Collateral Ligament: Provides medial stability.
- Fibular (Lateral) Collateral Ligament: Provides lateral stability.
- Patellar Ligament: Connects patella to tibia.
- Tendon of the Quadriceps Femoris Muscle: Extends the knee.
- Accurately describe actions such as:
- Flexion: Decreasing the angle between bones (e.g., bending the elbow).
- Extension: Increasing the angle between bones (e.g., straightening the elbow).
- Abduction: Moving a limb away from the midline (e.g., lifting the arm).
- Adduction: Moving a limb towards the midline (e.g., lowering the arm).
- Rotation: Turning around an axis (e.g., turning the head).
- Circumduction: Circular movement combining flexion, extension, abduction, and adduction (e.g., arm circles).
- Elevation/Depression: Moving structures superiorly/inferiorly (e.g., shoulder shrug).
- Pronation/Supination: Rotating the forearm to turn the palm down/up.
- Inversion/Eversion: Turning the sole of the foot inward/outward.
Objective 6: Differentiation of Movements at a Synovial Joint
- Flexion: Decreases joint angle.
- Extension: Increases joint angle.
- Hyperextension: Extension beyond the normal range.
- Abduction: Moves away from the body's midline.
- Adduction: Moves towards the body's midline.
- Rotation: Movement around a central axis.
- Circumduction: Circular movement at a joint.
- Elevation: Lifting a body part.
- Depression: Lowering a body part.
- Pronation: Rotating the forearm so the palm faces down.
- Supination: Rotating the forearm so the palm faces up.
- Inversion: Turning the foot inward.
- Eversion: Turning the foot outward.
Muscle Tissue
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Muscle tissue is specialized for contraction, enabling movement, posture maintenance, and heat production in the body. The main properties include:
- Excitability: Ability to respond to stimuli, typically from motor neurons.
- Contractility: Ability to shorten forcefully when stimulated.
- Extensibility: Ability to stretch without being damaged.
- Elasticity: Ability to return to original length after stretching or contracting.
Functions:
- Movement: Muscles produce movement of the body (skeletal), pump blood (cardiac), and move contents through hollow organs (smooth).
- Posture and Stability: Muscles help maintain body posture and stabilize joints.
- Heat Production: Muscle contractions generate heat, which helps regulate body temperature.
- Support of Soft Tissues: Muscles in the abdominal wall support visceral organs.
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Type-Location-Function-Nuclei-Striations-Specialized Structures |
Skeletal | Attached to bones | Voluntary movement of skeleton | Multiple, peripheral | Yes | Neuromuscular junction, motor end plate |
Cardiac | Heart | Pump blood involuntarily | One or two, central | Yes | Intercalated discs, H zone |
Smooth | Walls of hollow organs | Involuntary movement (e.g., digestion) | Single, central | No | Dense bodies |
- Skeletal Muscle: Long, cylindrical fibers with striations. The function is voluntary movement. They are multinucleated and have clear connective tissue coverings (endomysium, perimysium, epimysium).
- Cardiac Muscle: Branched fibers, also striated, with a central nucleus and intercalated discs that enable coordinated contraction of the heart.
- Smooth Muscle: Non-striated with spindle-shaped fibers. Found in the walls of hollow organs such as intestines and blood vessels, involved in involuntary movements.
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- Skeletal Muscle: Long, striated fibers, multiple nuclei at the periphery.
- Cardiac Muscle: Striated, branched fibers with centrally located nuclei and intercalated discs.
- Smooth Muscle: Spindle-shaped cells with no striations and a single, centrally located nucleus.
Look for striations in skeletal and cardiac muscles, intercalated discs in cardiac muscle, and dense bodies in smooth muscle tissue slides.
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- Muscle Organ: Surrounded by the epimysium, it contains bundles of fascicles.
- Fascicle: Surrounded by the perimysium, a fascicle is a bundle of muscle fibers (cells).
- Muscle Fiber (Cell): Each fiber is surrounded by the endomysium and contains many myofibrils.
- Myofibril: Rod-like units inside the muscle fiber that contain sarcomeres.
- Sarcomere: The functional unit of contraction in muscle tissue, containing thick (myosin) and thin (actin) filaments.
On a diagram or model, these structures should be identifiable, with connective tissue coverings and tendons (attachment points) clearly labeled.
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Key parts to label on a diagram or model:
- Muscle fiber (cell): The basic cellular unit of muscle.
- Endomysium: Connective tissue surrounding each muscle fiber.
- Fascicle: A bundle of muscle fibers within a muscle.
- Perimysium: Connective tissue surrounding each fascicle.
- Muscle organ: The entire muscle, covered by epimysium.
- Tendon: Connects muscle to bone, transmitting force.
Muscle Fiber Structures:
- Nuclei: Skeletal muscles have multiple peripheral nuclei; cardiac has 1-2 central nuclei.
- Sarcolemma: The plasma membrane of the muscle cell.
- Sarcoplasmic Reticulum (SR): Specialized smooth endoplasmic reticulum that stores calcium ions.
- Mitochondria: Provide energy for muscle contraction.
- Myofilaments:
- Thin filaments: Composed of actin.
- Thick filaments: Composed of myosin.
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- Skeletal and Cardiac Muscle:
- Transverse (T) Tubules: Invaginations of the sarcolemma that allow electrical impulses to reach deep into the muscle fiber.
- Sarcomere: The repeating structural unit, bounded by Z discs.
- Z Disc: The boundary of each sarcomere.
- I Band: Contains only thin filaments (actin).
- A Band: The region containing thick filaments (myosin) with some overlap of thin filaments.
- M Line: The center of the sarcomere.
- H Zone: The center part of the A band, containing only thick filaments (in both skeletal and cardiac muscle).
Skeletal Muscle Specific:
- Neuromuscular Junction (NMJ): Where the motor neuron contacts the muscle fiber.
- Motor End Plate: The specialized region of the sarcolemma at the NMJ.
- Motor Neuron: Transmits signals from the central nervous system to the muscle fiber.
Cardiac Muscle Specific:
- Intercalated Discs: Specialized junctions between cardiac muscle cells that facilitate synchronized contraction.
Smooth Muscle Specific:
- Dense Bodies: The equivalent of Z discs in smooth muscle, where thin filaments attach.
Muscles
Fascicle arrangement affects the range of motion and the power of a muscle. Different fascicle arrangements include:
- Parallel (e.g., sartorius): Muscles have fascicles running parallel to the long axis, providing extensive range of motion but less power.
- Pennate (e.g., rectus femoris): Fascicles attach obliquely to a central tendon. This structure allows for greater power but limits range of motion.
- Convergent (e.g., pectoralis major): Fascicles converge from a broad area to a single tendon, offering versatility in muscle movement.
- Circular (e.g., orbicularis oris): Fascicles are arranged in concentric rings, useful for closing openings like the mouth or eyes.
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- Agonist (Prime Mover): The primary muscle responsible for generating a specific movement (e.g., biceps brachii for elbow flexion).
- Antagonist: The muscle that opposes the movement of the agonist (e.g., triceps brachii for elbow extension).
- Synergist: Assists the agonist by providing additional force or reducing unwanted movement (e.g., brachialis assisting the biceps brachii).
- Fixator: Stabilizes the origin of the agonist, enabling it to function more effectively (e.g., muscles of the shoulder girdle stabilizing the scapula).
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The axial muscles include those located on the head, neck, and trunk, while appendicular muscles are associated with the limbs. Use models and diagrams to study the location of these muscles.
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- Occipitofrontalis (epicranius):
- Frontal belly: Raises eyebrows, wrinkles forehead.
- Occipital belly: Pulls scalp backward.
- Orbicularis oculi: Closes the eye (blinking, squinting).
- Orbicularis oris: Closes and protrudes the lips (kissing muscle).
- Levator labii superioris: Elevates upper lip (smiling).
- Zygomaticus (major and minor): Elevates the corners of the mouth (smiling).
- Depressor anguli oris: Lowers corners of the mouth (frowning).
- Depressor labii inferioris: Lowers lower lip.
- Temporalis: Elevates and retracts the mandible (chewing).
- Masseter: Elevates the mandible (chewing).
- Sternocleidomastoid: Flexes neck, rotates head.
- Trapezius: Elevates, retracts, and rotates the scapula.
- External intercostals: Elevate ribs during inhalation.
- Internal intercostals: Depress ribs during forced exhalation.
- Pectoralis major: Adducts and medially rotates the arm.
- Pectoralis minor: Stabilizes the scapula by drawing it anteriorly.
- Serratus anterior: Protracts and rotates the scapula.
- Latissimus dorsi: Extends, adducts, and medially rotates the arm.
- Diaphragm: Prime mover for inhalation, contracts to flatten and enlarge the thoracic cavity.
- Rectus abdominis: Flexes the vertebral column.
- Linea alba: Fibrous structure running down the midline of the abdomen.
- External obliques: Flex and rotate the vertebral column.
- Internal obliques: Flex and rotate the vertebral column.
- Rhomboideus major: Retracts and elevates the scapula.
- Infraspinatus: Laterally rotates the arm.
- Supraspinatus: Abducts the arm.
- Subscapularis: Medially rotates the arm.
- Teres major: Medially rotates and adducts the arm.
- Teres minor: Laterally rotates the arm.
- Deltoid: Abducts the arm.
- Biceps brachii: Flexes the elbow, supinates the forearm.
- Brachialis: Flexes the elbow.
- Triceps brachii: Extends the elbow.
- Brachioradialis: Flexes the forearm.
- Extensor carpi radialis longus: Extends and abducts the wrist.
- Extensor digitorum: Extends the fingers.
- Extensor carpi ulnaris: Extends and adducts the wrist.
- Flexor carpi ulnaris: Flexes and adducts the wrist.
- Palmaris longus: Flexes the wrist.
- Flexor carpi radialis: Flexes and abducts the wrist.
- Pronator teres: Pronates the forearm.
- Gluteus maximus: Extends and laterally rotates the thigh.
- Tensor fasciae latae: Abducts and medially rotates the thigh.
- Iliotibial tract: Provides stability to the knee.
- Gracilis: Adducts the thigh.
- Sartorius: Flexes, abducts, and laterally rotates the thigh.
- Rectus femoris: Extends the knee and flexes the thigh.
- Vastus medialis: Extends the knee.
- Vastus lateralis: Extends the knee.
- Biceps femoris: Extends the thigh, flexes the knee.
- Semitendinosus: Extends the thigh, flexes the knee.
- Semimembranosus: Extends the thigh, flexes the knee.
- Tibialis anterior: Dorsiflexes and inverts the foot.
- Extensor digitorum longus: Extends the toes, dorsiflexes the foot.
- Peroneus (Fibularis) longus: Everts and plantarflexes the foot.
- Soleus: Plantarflexes the foot.
- Gastrocnemius: Plantarflexes the foot, flexes the knee.
- Calcaneal tendon (Achilles tendon): Connects the gastrocnemius and soleus to the heel bone, aiding in plantarflexion.
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Central Nervous System
- Organs & Organ Structures:
- Brain (Cerebrum, Cerebellum, Brainstem)
- Spinal Cord
- Cranial Nerves & Spinal Nerves
- Cells & Cell Structures:
- Neurons: Dendrites, Soma (cell body), Axon, Axon Hillock, Synapse
- Neuroglia: Astrocytes, Microglia, Oligodendrocytes, Schwann Cells
- Synapse: Observe the synaptic cleft, synaptic vesicles containing neurotransmitters, and post-synaptic receptors.
- Functions of the Nervous System:
- Sensory Input: Detect internal and external stimuli.
- Integration: Process and interpret sensory data.
- Motor Output: Response to stimuli by activating effector organs (muscles/glands).
- Parts of the Neuron:
- Dendrites: Receive signals from other neurons.
- Cell Body (Soma): Contains nucleus and organelles.
- Axon: Transmits signals to other neurons or effectors.
- Synapse: Site of communication between neurons or between a neuron and an effector cell.
- Structural Classification of the Nervous System:
- Central Nervous System (CNS): Brain and spinal cord.
- Peripheral Nervous System (PNS): Cranial and spinal nerves.
- Functional Classification:
- Somatic Nervous System: Controls voluntary muscle movements.
- Autonomic Nervous System: Controls involuntary responses, subdivided into:
- Sympathetic Division (fight or flight)
- Parasympathetic Division (rest and digest)
- Neurons Classification:
- Sensory Neurons (Afferent): Carry information from sensory receptors to the CNS.
- Motor Neurons (Efferent): Carry signals from the CNS to muscles/glands.
- Interneurons: Process information within the CNS.
- Neuron vs. Neuroglia:
- Neurons: Conduct electrical impulses.
- Neuroglia (Glial Cells): Support, protect, and nourish neurons.
- Grey Matter vs. White Matter:
- Grey Matter: Contains neuron cell bodies and dendrites.
- White Matter: Consists of myelinated axons.
- Nucleus vs. Ganglion:
- Nucleus: Cluster of neuron cell bodies in the CNS.
- Ganglion: Cluster of neuron cell bodies in the PNS.
- Tract vs. Nerve:
- Tract: Bundle of axons in the CNS.
- Nerve: Bundle of axons in the PNS.
- Types of Neuroglia:
- CNS: Astrocytes, Oligodendrocytes, Microglia, Ependymal cells.
- PNS: Schwann cells, Satellite cells.
- Dendrites: Branched projections receiving stimuli.
- Soma: Contains the nucleus and other organelles.
- Axon: Long projection transmitting electrical signals.
- Axon Hillock: Initiates action potentials.
- Myelin Sheath: Insulating layer around the axon.
- Synaptic Terminals: Release neurotransmitters to the synapse.
- Composition: Myelin is a fatty substance produced by oligodendrocytes in the CNS and Schwann cells in the PNS.
- Function: Insulates axons, increases the speed of electrical impulse transmission (saltatory conduction).
- Nerve Structure:
- Epineurium: Outer connective tissue covering.
- Perineurium: Surrounds bundles (fascicles) of axons.
- Endoneurium: Surrounds individual axons.
- Nerves contain: Sensory and motor axons, blood vessels, and connective tissue.
- Reflex Arc Components:
- Receptor: Detects stimulus.
- Sensory Neuron: Transmits information to the CNS.
- Integration Center: Processes information (often in the spinal cord).
- Motor Neuron: Carries the command to the effector.
- Effector: Muscle or gland that responds.
- Monosynaptic Reflex:
- Involves a single synapse between the sensory neuron and motor neuron.
- Example: Patellar (knee-jerk) reflex.
- Polysynaptic Reflex:
- Involves one or more interneurons between sensory and motor neurons.
- Example: Withdrawal reflex (e.g., pulling your hand away from a hot surface).
Nervous System
- Cranial Protection:
- Skull: Protects the brain from physical damage.
- Meninges: Three layers of connective tissue that protect the brain and spinal cord.
- Dura Mater: Outermost, tough layer providing structural support.
- Arachnoid Mater: Middle layer with web-like fibers, contains the subarachnoid space where cerebrospinal fluid (CSF) circulates.
- Pia Mater: Innermost layer that closely adheres to the brain and spinal cord surface.
- Spinal Cord Protection:
- Vertebrae: Bony structure encasing the spinal cord.
- Epidural Space: Space between vertebrae and dura mater, contains fat and blood vessels for cushioning.
- CSF flows through the following:
1. Lateral ventricles →
2. Interventricular foramen →
3. Third ventricle →
4. Cerebral aqueduct →
5. Fourth ventricle →
6. Central canal of the spinal cord and subarachnoid space around the brain and spinal cord →
7. Absorbed into the bloodstream via arachnoid villi in the superior sagittal sinus.
- Meninges: Dura mater, arachnoid mater, pia mater.
- Brain Regions:
- Cerebrum: Hemispheres, lobes (frontal, parietal, occipital, temporal).
- Cerebellum: Coordinates movement and balance.
- Brainstem: Midbrain, pons, medulla oblongata—controls vital functions.
- Spinal Cord: Cervical, thoracic, lumbar, sacral regions.
- Spinal Nerve Plexuses:
- Cervical Plexus (C1-C4): Controls the diaphragm via the phrenic nerve.
- Brachial Plexus (C5-T1): Innervates the arms.
- Lumbar Plexus (L1-L4): Innervates the lower abdomen and legs.
- Sacral Plexus (L4-S4): Includes the sciatic nerve, which innervates the legs.
- Meninges: Protect the CNS, anchor it to the skull and vertebral column, and allow for CSF circulation.
- Brain: Controls cognitive functions, motor activities, and homeostasis.
- Spinal Cord: Transmits signals between the brain and body, coordinates reflexes.
- Pyramidal Cells: Found in the cerebral cortex, large triangular shape, responsible for motor control.
- Purkinje Cells: Located in the cerebellum, have extensive dendrites, involved in coordinating fine motor movements.
- Limbic System: Includes the amygdala, hippocampus, thalamus; involved in emotion, memory, and motivation.
- Reticular Formation: A network in the brainstem that regulates wakefulness, arousal, and sleep.
- Structure: A selective barrier formed by endothelial cells of capillaries in the brain, connected by tight junctions.
- Function: Protects the brain from harmful substances in the blood while allowing nutrients like glucose to pass through.
- Cranial Nerves:
1. Olfactory (I) - Smell.
2. Optic (II) - Vision.
3. Oculomotor (III) - Eye movement.
4. Trochlear (IV) - Eye movement.
5. Trigeminal (V) - Sensation from the face; chewing.
6. Abducens (VI) - Eye movement.
7. Facial (VII) - Facial expression, taste.
8. Vestibulocochlear (VIII) - Hearing, balance.
9. Glossopharyngeal (IX) - Taste, swallowing.
10. Vagus (X) - Heart, lungs, digestion.
11. Accessory (XI) - Head movement.
12. Hypoglossal (XII) - Tongue movement.
- Spinal Nerve Plexuses: Cervical, brachial, lumbar, sacral (see point 3).
- Frontal Lobe: Motor function, problem-solving, memory.
- Parietal Lobe: Sensory processing.
- Occipital Lobe: Vision.
- Temporal Lobe: Hearing, memory.
- Cerebellum: Balance, coordination.
- Broca’s Area: Speech production.
- Wernicke’s Area: Language comprehension.
- Autonomic Nervous System (ANS): Involuntary control, regulates heart rate, digestion, respiratory rate. Subdivided into:
- Sympathetic: "Fight or flight" responses.
- Parasympathetic: "Rest and digest" functions.
- Somatic Nervous System: Voluntary control of skeletal muscles.
- Located alongside the spinal column, part of the sympathetic division of the ANS, involved in distributing sympathetic innervation to various organs.
- By Location:
- Exteroceptors: Detect external stimuli (e.g., skin).
- Interoceptors: Detect internal body stimuli (e.g., organs).
- Proprioceptors: Detect position and movement (e.g., muscles, joints).
- By Stimulus Detected:
- Mechanoreceptors: Respond to touch, pressure, vibration.
- Thermoreceptors: Detect temperature changes.
- Nociceptors: Sense pain.
- Photoreceptors: Respond to light (eyes).
- Chemoreceptors: Detect chemicals (taste, smell).
- By Structure:
- Free nerve endings: Detect pain and temperature.
- Encapsulated receptors: Detect pressure and vibration.
Special Senses
- Fungiform Papillae: Mushroom-shaped, scattered across the tongue, and contain taste buds.
- Filiform Papillae: Thin, conical, and located all over the tongue, they provide texture but do not contain taste buds.
- Circumvallate Papillae: Large, dome-shaped, arranged in a V-shape at the back of the tongue, and contain taste buds.
- Fibrous Layer: Outer layer consisting of the sclera (white of the eye) and cornea (transparent, focuses light).
- Vascular Layer (Uvea): Middle layer consisting of the choroid (pigmented, supplies blood), ciliary body (controls lens shape), and iris (controls the diameter of the pupil).
- Neural Layer: Inner layer consisting of the retina, which contains photoreceptors (rods and cones) for vision.
- Ganglion Cell Layer: Neurons whose axons form the optic nerve.
- Bipolar Cell Layer: Cells that transmit signals from photoreceptors to ganglion cells.
- Photoreceptor Layer: Contains rods (low-light vision) and cones (color vision).
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- Touch: Skin contains mechanoreceptors such as Pacinian corpuscles (deep pressure) and Meissner’s corpuscles (light touch).
- Taste: Located on the tongue, the taste buds within the papillae contain gustatory cells that detect taste.
- Smell: Olfactory epithelium located in the nasal cavity contains olfactory receptors that send signals to the olfactory bulb.
- Hearing: The cochlea in the inner ear contains the Organ of Corti, which has hair cells that detect sound vibrations.
- Sight: The retina in the eye contains rods and cones for detecting light and color.
- Equilibrium: The semicircular canals and vestibule (saccule and utricle) in the inner ear detect balance and spatial orientation.
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- Lacrimal gland: Produces tears.
- Lacrimal canals (canaliculi): Drain tears from the eyes to the lacrimal sac.
- Lacrimal sac: Collects tears from the canaliculi.
- Nasolacrimal duct: Drains tears into the nasal cavity.
- Palpebrae (eyelids): Protect and lubricate the eyes.
- Lacrimal caruncle: Small, pink structure at the inner corner of the eye.
- Conjunctiva: Transparent mucous membrane covering the sclera.
- Sclera: White outer layer.
- Cornea: Transparent front part, helps focus light.
- Choroid: Vascular, pigmented layer.
- Ciliary body: Controls lens shape.
- Iris: Colored part of the eye, controls pupil size.
- Pupil: Opening that allows light into the eye.
- Lens: Focuses light onto the retina.
- Anterior Segment: Filled with aqueous humor, nourishes the cornea and lens.
- Posterior Segment: Filled with vitreous humor, helps maintain eye shape.
- Retina: Contains rods and cones for vision.
- Optic nerve: Carries visual information to the brain.
- Fovea centralis: Area of sharpest vision.
- Blind spot (Optic disc): Where the optic nerve exits the eye, no photoreceptors.
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- Pinna (Auricle): Collects sound.
- Ear canal (External acoustic meatus): Transmits sound to the tympanic membrane.
- Tympanic membrane (Eardrum): Vibrates in response to sound.
- Ossicles (Malleus, Incus, Stapes): Amplify sound vibrations and transmit them to the oval window.
- Cochlea: Contains the Organ of Corti, which detects sound.
- Vestibule (Saccule and Utricle): Detects gravity and linear acceleration.
- Semicircular Canals: Detect rotational movement and balance.
- Vestibulocochlear Nerve: Transmits hearing and balance information to the brain.
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- Skin: Protects internal organs, regulates temperature, and contains receptors for touch.
- Tongue: Facilitates taste and aids in digestion and speech.
- Nasal Cavity: Warms, moistens air, and detects odors via the olfactory epithelium.
- Eye: Detects light, processes visual information, and allows for sight.
- Ear: Detects sound and maintains balance and equilibrium.
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- Epidermis, Dermis, Hypodermis: Layers that protect the body, regulate temperature, and contain sensory receptors.
- Pacinian Corpuscles: Detect deep pressure.
- Meissner’s Corpuscles: Detect light touch.
- Stratified Squamous Epithelium: Provides protection.
- Papillae: House taste buds.
- Taste Buds: Contain taste receptors.
- Ganglion Cells: Neurons that form the optic nerve.
- Bipolar Cells: Transmit signals from photoreceptors to ganglion cells.
- Rods and Cones: Detect light and color.
- Choroid: Pigmented, vascular layer.
- Sclera: Outer fibrous layer.
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- Scala Vestibuli: Transmits sound vibrations to the cochlear duct.
- Scala Tympani: Transmits vibrations from the cochlea to the round window.
- Cochlear Duct (Scala Media): Contains the Organ of Corti.
- Organ of Corti: Detects sound vibrations via hair cells.
- Vestibular, Basilar, and Tectorial Membranes: Play a role in the transmission of sound within the cochlea.
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- Papillae: Fungiform, filiform, and circumvallate.
- Taste Buds: Located within papillae, detect taste.
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- Olfactory Bulb: Processes smell information.
- Olfactory Epithelium: Contains smell receptors.
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- Pinna (Auricle): Collects sound.
- Ear Canal (External Acoustic Meatus): Transmits sound to the tympanic membrane.
- Tympanic Membrane: Vibrates in response to sound.
- Ossicles (Malleus, Incus, Stapes): Amplify sound vibrations.
- Oval and Round Windows: Transmit sound vibrations into the inner ear.
- Auditory Tube (Eustachian Tube): Equalizes pressure in the middle ear.
- Vestibulocochlear Nerve: Transmits sound and balance information to the brain.
- Semicircular Canals: Detect rotational movement.
- Vestibule: Detects gravity and linear acceleration.
- Cochlea: Contains the organ of Corti for sound detection.
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Joints and Movement
- Articulation refers to the connection between two bones that forms a joint. It allows for varying degrees of movement and provides stability to the skeletal system.
- Joints are classified based on their structure (types of connective tissues) and function (degree of mobility).
- Structure: Determines the stability and range of motion.
- Example: A fibrous joint like a suture has limited movement but provides strength.
- Function: Defines how much movement is possible.
- Example: Synovial joints (e.g., knee) allow a wide range of motion compared to cartilaginous joints (e.g., symphysis).
- Suture: Immovable, found in the skull.
- Syndesmosis: Slightly movable, connected by ligaments (e.g., between the radius and ulna).
- Gomphosis: Immovable, peg-in-socket joints (e.g., teeth in sockets).
- Synchondrosis: Immovable, connected by hyaline cartilage (e.g., rib to sternum).
- Symphysis: Slightly movable, connected by fibrocartilage (e.g., pubic symphysis).
3. Synovial Joints: Freely movable joints characterized by a joint cavity (e.g., shoulder, knee).
- Examples:
- Suture (fibrous)
- Gomphosis (fibrous)
- Synchondrosis (cartilaginous)
- Examples:
- Syndesmosis (fibrous)
- Symphysis (cartilaginous)
- Hinge: Flexion and extension (e.g., elbow).
- Pivot: Rotation (e.g., atlantoaxial joint).
- Condyloid (Ellipsoidal): Biaxial movement (e.g., wrist).
- Gliding: Sliding movement (e.g., intercarpal joints).
- Saddle: Biaxial movement (e.g., thumb).
- Ball and Socket: Multiaxial movement (e.g., shoulder, hip).
- Articular Cartilage: Smooth tissue covering the ends of bones.
- Synovial Membrane: Lines the joint capsule and secretes synovial fluid.
- Articular Capsule: Two layers (outer fibrous and inner synovial membrane).
- Joint Cavity: Space filled with synovial fluid.
- Bursa: Fluid-filled sac that reduces friction.
- Anterior and Posterior Cruciate Ligaments (ACL/PCL): Stabilize the knee.
- Lateral and Medial Meniscus: Cartilage that cushions and stabilizes.
- Tibial (Medial) Collateral Ligament: Provides medial stability.
- Fibular (Lateral) Collateral Ligament: Provides lateral stability.
- Patellar Ligament: Connects patella to tibia.
- Tendon of the Quadriceps Femoris Muscle: Extends the knee.
- Accurately describe actions such as:
- Flexion: Decreasing the angle between bones (e.g., bending the elbow).
- Extension: Increasing the angle between bones (e.g., straightening the elbow).
- Abduction: Moving a limb away from the midline (e.g., lifting the arm).
- Adduction: Moving a limb towards the midline (e.g., lowering the arm).
- Rotation: Turning around an axis (e.g., turning the head).
- Circumduction: Circular movement combining flexion, extension, abduction, and adduction (e.g., arm circles).
- Elevation/Depression: Moving structures superiorly/inferiorly (e.g., shoulder shrug).
- Pronation/Supination: Rotating the forearm to turn the palm down/up.
- Inversion/Eversion: Turning the sole of the foot inward/outward.
Objective 6: Differentiation of Movements at a Synovial Joint
- Flexion: Decreases joint angle.
- Extension: Increases joint angle.
- Hyperextension: Extension beyond the normal range.
- Abduction: Moves away from the body's midline.
- Adduction: Moves towards the body's midline.
- Rotation: Movement around a central axis.
- Circumduction: Circular movement at a joint.
- Elevation: Lifting a body part.
- Depression: Lowering a body part.
- Pronation: Rotating the forearm so the palm faces down.
- Supination: Rotating the forearm so the palm faces up.
- Inversion: Turning the foot inward.
- Eversion: Turning the foot outward.
Muscle Tissue
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Muscle tissue is specialized for contraction, enabling movement, posture maintenance, and heat production in the body. The main properties include:
- Excitability: Ability to respond to stimuli, typically from motor neurons.
- Contractility: Ability to shorten forcefully when stimulated.
- Extensibility: Ability to stretch without being damaged.
- Elasticity: Ability to return to original length after stretching or contracting.
Functions:
- Movement: Muscles produce movement of the body (skeletal), pump blood (cardiac), and move contents through hollow organs (smooth).
- Posture and Stability: Muscles help maintain body posture and stabilize joints.
- Heat Production: Muscle contractions generate heat, which helps regulate body temperature.
- Support of Soft Tissues: Muscles in the abdominal wall support visceral organs.
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Type-Location-Function-Nuclei-Striations-Specialized Structures |
Skeletal | Attached to bones | Voluntary movement of skeleton | Multiple, peripheral | Yes | Neuromuscular junction, motor end plate |
Cardiac | Heart | Pump blood involuntarily | One or two, central | Yes | Intercalated discs, H zone |
Smooth | Walls of hollow organs | Involuntary movement (e.g., digestion) | Single, central | No | Dense bodies |
- Skeletal Muscle: Long, cylindrical fibers with striations. The function is voluntary movement. They are multinucleated and have clear connective tissue coverings (endomysium, perimysium, epimysium).
- Cardiac Muscle: Branched fibers, also striated, with a central nucleus and intercalated discs that enable coordinated contraction of the heart.
- Smooth Muscle: Non-striated with spindle-shaped fibers. Found in the walls of hollow organs such as intestines and blood vessels, involved in involuntary movements.
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- Skeletal Muscle: Long, striated fibers, multiple nuclei at the periphery.
- Cardiac Muscle: Striated, branched fibers with centrally located nuclei and intercalated discs.
- Smooth Muscle: Spindle-shaped cells with no striations and a single, centrally located nucleus.
Look for striations in skeletal and cardiac muscles, intercalated discs in cardiac muscle, and dense bodies in smooth muscle tissue slides.
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- Muscle Organ: Surrounded by the epimysium, it contains bundles of fascicles.
- Fascicle: Surrounded by the perimysium, a fascicle is a bundle of muscle fibers (cells).
- Muscle Fiber (Cell): Each fiber is surrounded by the endomysium and contains many myofibrils.
- Myofibril: Rod-like units inside the muscle fiber that contain sarcomeres.
- Sarcomere: The functional unit of contraction in muscle tissue, containing thick (myosin) and thin (actin) filaments.
On a diagram or model, these structures should be identifiable, with connective tissue coverings and tendons (attachment points) clearly labeled.
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Key parts to label on a diagram or model:
- Muscle fiber (cell): The basic cellular unit of muscle.
- Endomysium: Connective tissue surrounding each muscle fiber.
- Fascicle: A bundle of muscle fibers within a muscle.
- Perimysium: Connective tissue surrounding each fascicle.
- Muscle organ: The entire muscle, covered by epimysium.
- Tendon: Connects muscle to bone, transmitting force.
Muscle Fiber Structures:
- Nuclei: Skeletal muscles have multiple peripheral nuclei; cardiac has 1-2 central nuclei.
- Sarcolemma: The plasma membrane of the muscle cell.
- Sarcoplasmic Reticulum (SR): Specialized smooth endoplasmic reticulum that stores calcium ions.
- Mitochondria: Provide energy for muscle contraction.
- Myofilaments:
- Thin filaments: Composed of actin.
- Thick filaments: Composed of myosin.
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- Skeletal and Cardiac Muscle:
- Transverse (T) Tubules: Invaginations of the sarcolemma that allow electrical impulses to reach deep into the muscle fiber.
- Sarcomere: The repeating structural unit, bounded by Z discs.
- Z Disc: The boundary of each sarcomere.
- I Band: Contains only thin filaments (actin).
- A Band: The region containing thick filaments (myosin) with some overlap of thin filaments.
- M Line: The center of the sarcomere.
- H Zone: The center part of the A band, containing only thick filaments (in both skeletal and cardiac muscle).
Skeletal Muscle Specific:
- Neuromuscular Junction (NMJ): Where the motor neuron contacts the muscle fiber.
- Motor End Plate: The specialized region of the sarcolemma at the NMJ.
- Motor Neuron: Transmits signals from the central nervous system to the muscle fiber.
Cardiac Muscle Specific:
- Intercalated Discs: Specialized junctions between cardiac muscle cells that facilitate synchronized contraction.
Smooth Muscle Specific:
- Dense Bodies: The equivalent of Z discs in smooth muscle, where thin filaments attach.
Muscles
Fascicle arrangement affects the range of motion and the power of a muscle. Different fascicle arrangements include:
- Parallel (e.g., sartorius): Muscles have fascicles running parallel to the long axis, providing extensive range of motion but less power.
- Pennate (e.g., rectus femoris): Fascicles attach obliquely to a central tendon. This structure allows for greater power but limits range of motion.
- Convergent (e.g., pectoralis major): Fascicles converge from a broad area to a single tendon, offering versatility in muscle movement.
- Circular (e.g., orbicularis oris): Fascicles are arranged in concentric rings, useful for closing openings like the mouth or eyes.
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- Agonist (Prime Mover): The primary muscle responsible for generating a specific movement (e.g., biceps brachii for elbow flexion).
- Antagonist: The muscle that opposes the movement of the agonist (e.g., triceps brachii for elbow extension).
- Synergist: Assists the agonist by providing additional force or reducing unwanted movement (e.g., brachialis assisting the biceps brachii).
- Fixator: Stabilizes the origin of the agonist, enabling it to function more effectively (e.g., muscles of the shoulder girdle stabilizing the scapula).
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The axial muscles include those located on the head, neck, and trunk, while appendicular muscles are associated with the limbs. Use models and diagrams to study the location of these muscles.
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- Occipitofrontalis (epicranius):
- Frontal belly: Raises eyebrows, wrinkles forehead.
- Occipital belly: Pulls scalp backward.
- Orbicularis oculi: Closes the eye (blinking, squinting).
- Orbicularis oris: Closes and protrudes the lips (kissing muscle).
- Levator labii superioris: Elevates upper lip (smiling).
- Zygomaticus (major and minor): Elevates the corners of the mouth (smiling).
- Depressor anguli oris: Lowers corners of the mouth (frowning).
- Depressor labii inferioris: Lowers lower lip.
- Temporalis: Elevates and retracts the mandible (chewing).
- Masseter: Elevates the mandible (chewing).
- Sternocleidomastoid: Flexes neck, rotates head.
- Trapezius: Elevates, retracts, and rotates the scapula.
- External intercostals: Elevate ribs during inhalation.
- Internal intercostals: Depress ribs during forced exhalation.
- Pectoralis major: Adducts and medially rotates the arm.
- Pectoralis minor: Stabilizes the scapula by drawing it anteriorly.
- Serratus anterior: Protracts and rotates the scapula.
- Latissimus dorsi: Extends, adducts, and medially rotates the arm.
- Diaphragm: Prime mover for inhalation, contracts to flatten and enlarge the thoracic cavity.
- Rectus abdominis: Flexes the vertebral column.
- Linea alba: Fibrous structure running down the midline of the abdomen.
- External obliques: Flex and rotate the vertebral column.
- Internal obliques: Flex and rotate the vertebral column.
- Rhomboideus major: Retracts and elevates the scapula.
- Infraspinatus: Laterally rotates the arm.
- Supraspinatus: Abducts the arm.
- Subscapularis: Medially rotates the arm.
- Teres major: Medially rotates and adducts the arm.
- Teres minor: Laterally rotates the arm.
- Deltoid: Abducts the arm.
- Biceps brachii: Flexes the elbow, supinates the forearm.
- Brachialis: Flexes the elbow.
- Triceps brachii: Extends the elbow.
- Brachioradialis: Flexes the forearm.
- Extensor carpi radialis longus: Extends and abducts the wrist.
- Extensor digitorum: Extends the fingers.
- Extensor carpi ulnaris: Extends and adducts the wrist.
- Flexor carpi ulnaris: Flexes and adducts the wrist.
- Palmaris longus: Flexes the wrist.
- Flexor carpi radialis: Flexes and abducts the wrist.
- Pronator teres: Pronates the forearm.
- Gluteus maximus: Extends and laterally rotates the thigh.
- Tensor fasciae latae: Abducts and medially rotates the thigh.
- Iliotibial tract: Provides stability to the knee.
- Gracilis: Adducts the thigh.
- Sartorius: Flexes, abducts, and laterally rotates the thigh.
- Rectus femoris: Extends the knee and flexes the thigh.
- Vastus medialis: Extends the knee.
- Vastus lateralis: Extends the knee.
- Biceps femoris: Extends the thigh, flexes the knee.
- Semitendinosus: Extends the thigh, flexes the knee.
- Semimembranosus: Extends the thigh, flexes the knee.
- Tibialis anterior: Dorsiflexes and inverts the foot.
- Extensor digitorum longus: Extends the toes, dorsiflexes the foot.
- Peroneus (Fibularis) longus: Everts and plantarflexes the foot.
- Soleus: Plantarflexes the foot.
- Gastrocnemius: Plantarflexes the foot, flexes the knee.
- Calcaneal tendon (Achilles tendon): Connects the gastrocnemius and soleus to the heel bone, aiding in plantarflexion.
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Central Nervous System
- Organs & Organ Structures:
- Brain (Cerebrum, Cerebellum, Brainstem)
- Spinal Cord
- Cranial Nerves & Spinal Nerves
- Cells & Cell Structures:
- Neurons: Dendrites, Soma (cell body), Axon, Axon Hillock, Synapse
- Neuroglia: Astrocytes, Microglia, Oligodendrocytes, Schwann Cells
- Synapse: Observe the synaptic cleft, synaptic vesicles containing neurotransmitters, and post-synaptic receptors.
- Functions of the Nervous System:
- Sensory Input: Detect internal and external stimuli.
- Integration: Process and interpret sensory data.
- Motor Output: Response to stimuli by activating effector organs (muscles/glands).
- Parts of the Neuron:
- Dendrites: Receive signals from other neurons.
- Cell Body (Soma): Contains nucleus and organelles.
- Axon: Transmits signals to other neurons or effectors.
- Synapse: Site of communication between neurons or between a neuron and an effector cell.
- Structural Classification of the Nervous System:
- Central Nervous System (CNS): Brain and spinal cord.
- Peripheral Nervous System (PNS): Cranial and spinal nerves.
- Functional Classification:
- Somatic Nervous System: Controls voluntary muscle movements.
- Autonomic Nervous System: Controls involuntary responses, subdivided into:
- Sympathetic Division (fight or flight)
- Parasympathetic Division (rest and digest)
- Neurons Classification:
- Sensory Neurons (Afferent): Carry information from sensory receptors to the CNS.
- Motor Neurons (Efferent): Carry signals from the CNS to muscles/glands.
- Interneurons: Process information within the CNS.
- Neuron vs. Neuroglia:
- Neurons: Conduct electrical impulses.
- Neuroglia (Glial Cells): Support, protect, and nourish neurons.
- Grey Matter vs. White Matter:
- Grey Matter: Contains neuron cell bodies and dendrites.
- White Matter: Consists of myelinated axons.
- Nucleus vs. Ganglion:
- Nucleus: Cluster of neuron cell bodies in the CNS.
- Ganglion: Cluster of neuron cell bodies in the PNS.
- Tract vs. Nerve:
- Tract: Bundle of axons in the CNS.
- Nerve: Bundle of axons in the PNS.
- Types of Neuroglia:
- CNS: Astrocytes, Oligodendrocytes, Microglia, Ependymal cells.
- PNS: Schwann cells, Satellite cells.
- Dendrites: Branched projections receiving stimuli.
- Soma: Contains the nucleus and other organelles.
- Axon: Long projection transmitting electrical signals.
- Axon Hillock: Initiates action potentials.
- Myelin Sheath: Insulating layer around the axon.
- Synaptic Terminals: Release neurotransmitters to the synapse.
- Composition: Myelin is a fatty substance produced by oligodendrocytes in the CNS and Schwann cells in the PNS.
- Function: Insulates axons, increases the speed of electrical impulse transmission (saltatory conduction).
- Nerve Structure:
- Epineurium: Outer connective tissue covering.
- Perineurium: Surrounds bundles (fascicles) of axons.
- Endoneurium: Surrounds individual axons.
- Nerves contain: Sensory and motor axons, blood vessels, and connective tissue.
- Reflex Arc Components:
- Receptor: Detects stimulus.
- Sensory Neuron: Transmits information to the CNS.
- Integration Center: Processes information (often in the spinal cord).
- Motor Neuron: Carries the command to the effector.
- Effector: Muscle or gland that responds.
- Monosynaptic Reflex:
- Involves a single synapse between the sensory neuron and motor neuron.
- Example: Patellar (knee-jerk) reflex.
- Polysynaptic Reflex:
- Involves one or more interneurons between sensory and motor neurons.
- Example: Withdrawal reflex (e.g., pulling your hand away from a hot surface).
Nervous System
- Cranial Protection:
- Skull: Protects the brain from physical damage.
- Meninges: Three layers of connective tissue that protect the brain and spinal cord.
- Dura Mater: Outermost, tough layer providing structural support.
- Arachnoid Mater: Middle layer with web-like fibers, contains the subarachnoid space where cerebrospinal fluid (CSF) circulates.
- Pia Mater: Innermost layer that closely adheres to the brain and spinal cord surface.
- Spinal Cord Protection:
- Vertebrae: Bony structure encasing the spinal cord.
- Epidural Space: Space between vertebrae and dura mater, contains fat and blood vessels for cushioning.
- CSF flows through the following:
1. Lateral ventricles →
2. Interventricular foramen →
3. Third ventricle →
4. Cerebral aqueduct →
5. Fourth ventricle →
6. Central canal of the spinal cord and subarachnoid space around the brain and spinal cord →
7. Absorbed into the bloodstream via arachnoid villi in the superior sagittal sinus.
- Meninges: Dura mater, arachnoid mater, pia mater.
- Brain Regions:
- Cerebrum: Hemispheres, lobes (frontal, parietal, occipital, temporal).
- Cerebellum: Coordinates movement and balance.
- Brainstem: Midbrain, pons, medulla oblongata—controls vital functions.
- Spinal Cord: Cervical, thoracic, lumbar, sacral regions.
- Spinal Nerve Plexuses:
- Cervical Plexus (C1-C4): Controls the diaphragm via the phrenic nerve.
- Brachial Plexus (C5-T1): Innervates the arms.
- Lumbar Plexus (L1-L4): Innervates the lower abdomen and legs.
- Sacral Plexus (L4-S4): Includes the sciatic nerve, which innervates the legs.
- Meninges: Protect the CNS, anchor it to the skull and vertebral column, and allow for CSF circulation.
- Brain: Controls cognitive functions, motor activities, and homeostasis.
- Spinal Cord: Transmits signals between the brain and body, coordinates reflexes.
- Pyramidal Cells: Found in the cerebral cortex, large triangular shape, responsible for motor control.
- Purkinje Cells: Located in the cerebellum, have extensive dendrites, involved in coordinating fine motor movements.
- Limbic System: Includes the amygdala, hippocampus, thalamus; involved in emotion, memory, and motivation.
- Reticular Formation: A network in the brainstem that regulates wakefulness, arousal, and sleep.
- Structure: A selective barrier formed by endothelial cells of capillaries in the brain, connected by tight junctions.
- Function: Protects the brain from harmful substances in the blood while allowing nutrients like glucose to pass through.
- Cranial Nerves:
1. Olfactory (I) - Smell.
2. Optic (II) - Vision.
3. Oculomotor (III) - Eye movement.
4. Trochlear (IV) - Eye movement.
5. Trigeminal (V) - Sensation from the face; chewing.
6. Abducens (VI) - Eye movement.
7. Facial (VII) - Facial expression, taste.
8. Vestibulocochlear (VIII) - Hearing, balance.
9. Glossopharyngeal (IX) - Taste, swallowing.
10. Vagus (X) - Heart, lungs, digestion.
11. Accessory (XI) - Head movement.
12. Hypoglossal (XII) - Tongue movement.
- Spinal Nerve Plexuses: Cervical, brachial, lumbar, sacral (see point 3).
- Frontal Lobe: Motor function, problem-solving, memory.
- Parietal Lobe: Sensory processing.
- Occipital Lobe: Vision.
- Temporal Lobe: Hearing, memory.
- Cerebellum: Balance, coordination.
- Broca’s Area: Speech production.
- Wernicke’s Area: Language comprehension.
- Autonomic Nervous System (ANS): Involuntary control, regulates heart rate, digestion, respiratory rate. Subdivided into:
- Sympathetic: "Fight or flight" responses.
- Parasympathetic: "Rest and digest" functions.
- Somatic Nervous System: Voluntary control of skeletal muscles.
- Located alongside the spinal column, part of the sympathetic division of the ANS, involved in distributing sympathetic innervation to various organs.
- By Location:
- Exteroceptors: Detect external stimuli (e.g., skin).
- Interoceptors: Detect internal body stimuli (e.g., organs).
- Proprioceptors: Detect position and movement (e.g., muscles, joints).
- By Stimulus Detected:
- Mechanoreceptors: Respond to touch, pressure, vibration.
- Thermoreceptors: Detect temperature changes.
- Nociceptors: Sense pain.
- Photoreceptors: Respond to light (eyes).
- Chemoreceptors: Detect chemicals (taste, smell).
- By Structure:
- Free nerve endings: Detect pain and temperature.
- Encapsulated receptors: Detect pressure and vibration.
Special Senses
- Fungiform Papillae: Mushroom-shaped, scattered across the tongue, and contain taste buds.
- Filiform Papillae: Thin, conical, and located all over the tongue, they provide texture but do not contain taste buds.
- Circumvallate Papillae: Large, dome-shaped, arranged in a V-shape at the back of the tongue, and contain taste buds.
- Fibrous Layer: Outer layer consisting of the sclera (white of the eye) and cornea (transparent, focuses light).
- Vascular Layer (Uvea): Middle layer consisting of the choroid (pigmented, supplies blood), ciliary body (controls lens shape), and iris (controls the diameter of the pupil).
- Neural Layer: Inner layer consisting of the retina, which contains photoreceptors (rods and cones) for vision.
- Ganglion Cell Layer: Neurons whose axons form the optic nerve.
- Bipolar Cell Layer: Cells that transmit signals from photoreceptors to ganglion cells.
- Photoreceptor Layer: Contains rods (low-light vision) and cones (color vision).
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- Touch: Skin contains mechanoreceptors such as Pacinian corpuscles (deep pressure) and Meissner’s corpuscles (light touch).
- Taste: Located on the tongue, the taste buds within the papillae contain gustatory cells that detect taste.
- Smell: Olfactory epithelium located in the nasal cavity contains olfactory receptors that send signals to the olfactory bulb.
- Hearing: The cochlea in the inner ear contains the Organ of Corti, which has hair cells that detect sound vibrations.
- Sight: The retina in the eye contains rods and cones for detecting light and color.
- Equilibrium: The semicircular canals and vestibule (saccule and utricle) in the inner ear detect balance and spatial orientation.
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- Lacrimal gland: Produces tears.
- Lacrimal canals (canaliculi): Drain tears from the eyes to the lacrimal sac.
- Lacrimal sac: Collects tears from the canaliculi.
- Nasolacrimal duct: Drains tears into the nasal cavity.
- Palpebrae (eyelids): Protect and lubricate the eyes.
- Lacrimal caruncle: Small, pink structure at the inner corner of the eye.
- Conjunctiva: Transparent mucous membrane covering the sclera.
- Sclera: White outer layer.
- Cornea: Transparent front part, helps focus light.
- Choroid: Vascular, pigmented layer.
- Ciliary body: Controls lens shape.
- Iris: Colored part of the eye, controls pupil size.
- Pupil: Opening that allows light into the eye.
- Lens: Focuses light onto the retina.
- Anterior Segment: Filled with aqueous humor, nourishes the cornea and lens.
- Posterior Segment: Filled with vitreous humor, helps maintain eye shape.
- Retina: Contains rods and cones for vision.
- Optic nerve: Carries visual information to the brain.
- Fovea centralis: Area of sharpest vision.
- Blind spot (Optic disc): Where the optic nerve exits the eye, no photoreceptors.
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- Pinna (Auricle): Collects sound.
- Ear canal (External acoustic meatus): Transmits sound to the tympanic membrane.
- Tympanic membrane (Eardrum): Vibrates in response to sound.
- Ossicles (Malleus, Incus, Stapes): Amplify sound vibrations and transmit them to the oval window.
- Cochlea: Contains the Organ of Corti, which detects sound.
- Vestibule (Saccule and Utricle): Detects gravity and linear acceleration.
- Semicircular Canals: Detect rotational movement and balance.
- Vestibulocochlear Nerve: Transmits hearing and balance information to the brain.
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- Skin: Protects internal organs, regulates temperature, and contains receptors for touch.
- Tongue: Facilitates taste and aids in digestion and speech.
- Nasal Cavity: Warms, moistens air, and detects odors via the olfactory epithelium.
- Eye: Detects light, processes visual information, and allows for sight.
- Ear: Detects sound and maintains balance and equilibrium.
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- Epidermis, Dermis, Hypodermis: Layers that protect the body, regulate temperature, and contain sensory receptors.
- Pacinian Corpuscles: Detect deep pressure.
- Meissner’s Corpuscles: Detect light touch.
- Stratified Squamous Epithelium: Provides protection.
- Papillae: House taste buds.
- Taste Buds: Contain taste receptors.
- Ganglion Cells: Neurons that form the optic nerve.
- Bipolar Cells: Transmit signals from photoreceptors to ganglion cells.
- Rods and Cones: Detect light and color.
- Choroid: Pigmented, vascular layer.
- Sclera: Outer fibrous layer.
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- Scala Vestibuli: Transmits sound vibrations to the cochlear duct.
- Scala Tympani: Transmits vibrations from the cochlea to the round window.
- Cochlear Duct (Scala Media): Contains the Organ of Corti.
- Organ of Corti: Detects sound vibrations via hair cells.
- Vestibular, Basilar, and Tectorial Membranes: Play a role in the transmission of sound within the cochlea.
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- Papillae: Fungiform, filiform, and circumvallate.
- Taste Buds: Located within papillae, detect taste.
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- Olfactory Bulb: Processes smell information.
- Olfactory Epithelium: Contains smell receptors.
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- Pinna (Auricle): Collects sound.
- Ear Canal (External Acoustic Meatus): Transmits sound to the tympanic membrane.
- Tympanic Membrane: Vibrates in response to sound.
- Ossicles (Malleus, Incus, Stapes): Amplify sound vibrations.
- Oval and Round Windows: Transmit sound vibrations into the inner ear.
- Auditory Tube (Eustachian Tube): Equalizes pressure in the middle ear.
- Vestibulocochlear Nerve: Transmits sound and balance information to the brain.
- Semicircular Canals: Detect rotational movement.
- Vestibule: Detects gravity and linear acceleration.
- Cochlea: Contains the organ of Corti for sound detection.
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