BackBIO107 Lab Practicum 2 Study Guide: Muscular, Nervous, and Special Senses Systems
Study Guide - Smart Notes
Tailored notes based on your materials, expanded with key definitions, examples, and context.
Muscular System
Microscopic Anatomy and Organization of Muscle Tissue
The muscular system consists of three main types of muscle tissue, each with distinct structural and functional characteristics.
Skeletal Muscle: Voluntary, striated muscle attached to bones; responsible for body movement.
Cardiac Muscle: Involuntary, striated muscle found only in the heart; responsible for pumping blood.
Smooth Muscle: Involuntary, non-striated muscle found in walls of hollow organs; controls movements like peristalsis.
Key microscopic structures include:
Motor Unit: A motor neuron and all the muscle fibers it innervates.
Axon Terminal: The end of a motor neuron that forms a synapse with a muscle fiber.
Neuromuscular Junction: The site where a motor neuron communicates with a muscle fiber.
Example: Skeletal muscle fibers are multinucleated and show clear striations under the microscope, while smooth muscle cells are spindle-shaped and lack striations.
Gross Anatomy of the Muscular System
Muscles are organized by region and function. Identification of major muscles is essential for understanding movement and anatomical relationships.
Head: Epicranius, Orbicularis oculi, Zygomaticus, Orbicularis oris, Buccinator, Masseter, Temporalis
Neck: Platysma, Sternocleidomastoid, Digastric, Mylohyoid
Thorax & Shoulder: Pectoralis major/minor, Serratus anterior, Deltoid
Abdominal Wall: Rectus abdominis, External/Internal oblique, Transversus abdominis
Back: Trapezius, Latissimus dorsi, Teres major, Rhomboid major, Erector spinae
Rotator Cuff: Supraspinatus, Infraspinatus, Teres minor, Subscapularis
Upper Extremity: Triceps brachii, Biceps brachii, Brachialis, Brachioradialis
Forearm (Anterior): Flexor carpi radialis, Palmaris longus, Flexor carpi ulnaris, Flexor digitorum superficialis
Forearm (Posterior): Extensor carpi radialis longus/brevis, Extensor digitorum, Extensor carpi ulnaris
Lower Extremity: Iliopsoas, Sartorius, Adductors, Pectineus, Gracilis, Tensor fasciae latae, Gluteus maximus/medius
Thigh (Anterior): Quadriceps femoris (Rectus femoris, Vastus lateralis/medialis/intermedius)
Thigh (Posterior): Hamstrings (Biceps femoris, Semitendinosus, Semimembranosus)
Leg: Triceps surae (Gastrocnemius, Soleus), Fibularis longus, Tibialis anterior, Extensor digitorum longus
Example: The quadriceps femoris group is responsible for knee extension, while the hamstrings flex the knee.
Nervous System
Neurophysiology of Nerve Impulses
Nerve impulses are electrical signals transmitted by neurons. The process involves changes in membrane potential and the movement of ions across the neuronal membrane.
Resting Membrane Potential: The voltage difference across the membrane when the neuron is at rest, typically around .
Action Potential: A rapid change in membrane potential that propagates along the axon.
Key Steps: Depolarization (Na+ influx), Repolarization (K+ efflux), Hyperpolarization.
Equation:
Example: The sodium-potassium pump ( out, in) maintains the resting membrane potential.
Spinal Cord, Spinal Nerves, and the Autonomic Nervous System
The spinal cord is a major pathway for information traveling between the brain and peripheral nerves. It contains both gray and white matter and is organized into horns and columns.
White Columns: Bundles of myelinated axons.
Gray Horns: Dorsal (sensory), Ventral (motor), Lateral (autonomic).
Roots: Dorsal root (sensory), Ventral root (motor).
Spinal Nerve: Formed by the union of dorsal and ventral roots.
Cauda Equina: Bundle of spinal nerves at the lower end of the spinal cord.
Conus Medullaris: Terminal end of the spinal cord.
Example: The dorsal root ganglion contains cell bodies of sensory neurons.
Plexuses and Peripheral Nerves
Plexuses are networks of nerves that innervate specific regions of the body. Each plexus gives rise to major peripheral nerves.
Plexus | Peripheral Nerve | Innervates |
|---|---|---|
Cervical | Phrenic nerve | Diaphragm |
Brachial | Axillary nerve | Deltoid & teres minor |
Brachial | Musculocutaneous nerve | Biceps brachii & brachialis |
Brachial | Median nerve | Flexors of anterior forearm |
Brachial | Ulnar nerve | Flexor carpi ulnaris |
Brachial | Radial nerve | Triceps brachii & extensors of forearm |
Lumbar | Femoral nerve | Quadriceps femoris & sartorius |
Lumbar | Obturator nerve | Adductors of thigh |
Sacral | Sciatic nerve | Hamstrings, gastrocnemius & soleus |
Sacral | Common fibular nerve | Fibularis longus, extensor digitorum longus & tibialis anterior |
Example: Injury to the phrenic nerve can result in paralysis of the diaphragm.
Gross Anatomy of the Brain and Cranial Nerves
The brain is divided into several regions, each with specific functions. Identification of these structures is essential for understanding neuroanatomy.
Cerebrum: Largest part, responsible for higher functions.
Longitudinal Fissure: Divides the two cerebral hemispheres.
Central Sulcus: Separates frontal and parietal lobes.
Lobes: Frontal, Parietal, Temporal, Occipital.
Primary Somatosensory Area: Postcentral gyrus.
Primary Motor Area: Precentral gyrus.
Olfactory Bulbs, Optic Nerve/Chiasma: Sensory input for smell and vision.
Infundibulum, Pituitary Gland: Endocrine functions.
Mammillary Body, Midbrain, Pons, Medulla Oblongata: Brainstem structures.
Pineal Gland, Corpora Quadrigemina (Superior/Inferior Colliculi): Visual and auditory reflexes.
Arbor Vitae: Cerebellar white matter.
Corpus Callosum: Connects cerebral hemispheres.
Thalamus, Hypothalamus: Sensory relay and homeostasis.
Cerebellum: Coordination and balance.
Ventricles: Lateral, Third, Fourth; contain cerebrospinal fluid.
Example: The medulla oblongata controls vital functions such as heart rate and respiration.
Cranial Nerves
There are twelve pairs of cranial nerves, each with specific sensory and motor functions. They pass through distinct foramina in the skull.
Number | Name | Passage | Sensory | Motor | Parasympathetic |
|---|---|---|---|---|---|
I | Olfactory | Cribriform foramina | Smell | -- | -- |
II | Optic | Optic canal | Vision | -- | -- |
III | Oculomotor | Superior orbital fissure | -- | Eye muscles | Iris and lens |
IV | Trochlear | Superior orbital fissure | -- | Superior oblique | -- |
V | Trigeminal | V1-V3 | Facial sensation | Mastication | -- |
VI | Abducens | Superior orbital fissure | -- | Lateral rectus | -- |
VII | Facial | Internal acoustic meatus | Taste (ant. 2/3) | Facial expression | Lacrimal, sublingual, submandibular glands |
VIII | Vestibulocochlear | Internal acoustic meatus | Hearing/equilibrium | -- | -- |
IX | Glossopharyngeal | Jugular foramen | Taste/sensation (post. 1/3) | Tongue/pharynx | Parotid gland |
X | Vagus | Jugular foramen | Taste/sensation (post. 1/3), organs | Pharynx/larynx, organs | Organs of thorax/abdomen |
XI | Accessory | Jugular foramen | -- | SCM, trapezius | -- |
XII | Hypoglossal | Hypoglossal canal | -- | Tongue | -- |
Mnemonic for Names: On Occasion Our Trusty Truck Acts Funny Very Good Vehicle AnyHow
Mnemonic for Functions: Some Say Money Matters But My Brother Says Big Brains Matter More (S = sensory, M = motor, B = both)
Special Senses
Anatomy of the Visual System
The eye is a complex organ responsible for vision. Its anatomy includes several layers and structures that focus and detect light.
Sclera: Tough, white outer layer.
Cornea: Transparent front part; refracts light.
Lens: Focuses light onto the retina.
Retina: Contains photoreceptors (rods and cones).
Choroid: Vascular layer; provides nutrients.
Optic Nerve: Transmits visual information to the brain.
Ciliary Body: Controls lens shape.
Iris: Regulates pupil size.
Macula Lutea: Area of sharpest vision.
Vitreous Humor: Gel filling the eye.
Cell types in the retina:
Rods & Cones: Photoreceptors for dim and color vision.
Bipolar Cells: Intermediate neurons.
Ganglion Cells: Their axons form the optic nerve.
Example: The ophthalmoscope is used to examine the interior of the eye, including the retina and optic disc.
Anatomy of the Ear: Hearing and Equilibrium
The ear is divided into external, middle, and inner regions, each with specialized structures for hearing and balance.
Auricle (Pinna): Collects sound waves.
External Acoustic Meatus: Ear canal.
Tympanic Membrane: Eardrum; vibrates in response to sound.
Ossicles: Malleus, Incus, Stapes; transmit vibrations.
Oval and Round Windows: Openings to the inner ear.
Cochlea: Contains the organ of Corti; responsible for hearing.
Vestibule and Semicircular Canals: Balance and equilibrium.
Pharyngotympanic Tube: Equalizes pressure.
Vestibulocochlear Nerve: Transmits auditory and equilibrium information.
Key cochlear structures:
Scala Vestibuli, Scala Tympani: Perilymph-filled chambers.
Cochlear Duct: Contains endolymph and the organ of Corti.
Basilar and Tectorial Membranes: Support hair cells.
Hair Cells: Sensory receptors for sound.
Example: The otoscope is used to examine the external ear and tympanic membrane.
Summary Table: Major Systems and Structures
System | Main Structures | Function |
|---|---|---|
Muscular | Skeletal, Cardiac, Smooth muscles | Movement, posture, heat production |
Nervous | Brain, Spinal cord, Nerves | Coordination, communication, reflexes |
Special Senses | Eye, Ear | Vision, hearing, equilibrium |
Additional info: This guide expands on lab identification lists by providing academic context, definitions, and examples for each major structure and system. For detailed physiology, refer to PhysioEx activities and lab manual pages as indicated in the original lab list.
