Muscle Anatomy and Classification Quiz

Connective Tissues Surrounding Muscles

• Epimysium: Encases the entire muscle
• Perimysium: Surrounds fascicles (bundles of muscle fibers)
• Endomysium: Wraps individual muscle fibers

Muscle Classification

• Fusiform muscles: Thick in the middle, tapered at the ends
• Parallel muscles: Uniform width, fascicles aligned

Muscles Acting on the Thigh

• Anterior muscles of the thigh: Quadriceps femoris (extends the knee)
  • Rectus femoris
  • Vastus lateralis
  • Vastus medialis
  • Vastus intermedius
• Posterior gluteal muscles:
  • Gluteus maximus (extends and abducts the thigh)
  • Gluteus medius (abducts and medially rotates the thigh)
  • Gluteus minimus (abducts and medially rotates the thigh)

Muscles Acting on the Leg

• Anterior compartment muscles: Dorsiflex the foot and extend the toes
• Posterior compartment muscles: Plantar flex the foot and flex the toes

Muscle Attachments and Innervation

• Quadriceps femoris: Attaches to the anterior inferior iliac spine and tibial tuberosity
• Hamstrings: Attach to the ischial tuberosity and bones of the leg
• Tibialis anterior: Attaches to the lateral condyle of the tibia and medial cuneiform
• Gastrocnemius: Attaches to the femur and calcaneus via the Achilles tendon

Muscle Injuries

• Pitcher’s arm: Inflammation at the attachments of the wrist flexors
• Blocker’s arm: Abnormal calcification in the lateral margin of the forearm
• Shin splints: Pain in the crural region caused by tendinitis of the tibialis posterior and inflammation of the periosteum
• Tennis elbow: Inflammation at the attachment of extensor carpi muscles that attach to the lateral epicondyle

Nervous System

• Functions: Sensory perception, integration, and motor planning
• Subdivisions:
  • Central nervous system (CNS): Brain and spinal cord
  • Peripheral nervous system (PNS): Nerves and ganglia

Synapses

• Axodendritic synapse: Axon to dendrite
• Axosomatic synapse: Axon to neurosoma (cell body)
• Axoaxonic synapse: Axon to axon

Spinal Cord

• Functions: Transmits signals between the brain and the body, coordinates reflexes
• Surface Anatomy:
  • Regions: Cervical, Thoracic, Lumbar, Sacral
  • Enlargements: Cervical, Lumbosacral
  • Medullary cone: Conical end of the spinal cord
  • Cauda equina: Collection of nerve roots at the end of the spinal cord
  • Terminal filum: Fibrous extension from the conus medullaris
• Cross-Sectional Anatomy:
  • Fissure/Sulcus: Anterior median fissure, Posterior median sulcus
  • Central canal: Runs down the center, Contains cerebrospinal fluid (CSF)
• Gray matter: Contains very few myelinated axons, Has two posterior (dorsal) horns and two anterior (ventral) horns
• White matter: Contains myelinated axons
  • Columns (funiculi): Posterior (dorsal), lateral, and anterior (ventral)
    • Tracts (fasciculi): Located within the columns
• Ascending Tracts: Carry sensory info to the brain
• Descending Tracts: Carry motor info from the brain

Nerves and Ganglia

• Nerve: Several axons wrapped by connective tissue
  • Epineurium: Wraps the entire nerve
  • Perineurium: Wraps a fascicle of axons
• Ganglion: Collection of neuron cell bodies outside the CNS

Brain Meninges

• Dura Mater: Tough, outer layer, epidural space
• Arachnoid Mater: Transparent, middle layer, contains CSF, arachnoid granulations
• Pia Mater: Delicate, inner layer

Ventricles and Cerebrospinal Fluid (CSF)

• Ventricles: Fluid-filled chambers in the brain
  • Lateral ventricles (2)
  • Third ventricle (1)
  • Fourth ventricle (1)
  • Central Canal of Spinal Cord
• CSF: Clear, colorless liquid
  • Production: By choroid plexus (ependymal cells) within the ventricles
  • Flow: Within ventricles, down canals, and within subarachnoid space
  • Absorption: Back into blood at superior sagittal sinus by arachnoid granulations
• Functions: Provides buoyancy, protection, and chemical stability for the brain

Brainstem

• Components:
  • Midbrain
  • Pons
  • Medulla oblongata
• Pons:
  • Anterior aspect: Contains longitudinal and transverse fascicles
  • Posterior aspect: Contains peduncles that attach to cerebellum
• Midbrain:
  • Tectum (posterior aspect): Tectal plate (corpora quadrigemina) - four bulges consisting of superior and inferior colliculi
• Medulla oblongata:
  • Location: Extends from the pons to the foramen magnum
• Functions:
  • Pons: Contains tracts between the spinal cord and brain/cerebellum
  • Midbrain: Substantia nigra (degenerates leading to Parkinson’s)
  • Medulla oblongata: Contains cardiac center, vasomotor center, respiratory center

Diencephalon

• Components:
  • Thalamus: "Sensory gateway to the cerebral cortex." All sensory input except for smell goes through here.
  • Hypothalamus: Controls autonomic functions (heart rate, body temperature, hunger, thirst), endocrine control (pituitary gland)
  • Epithalamus: Contains pineal gland (secretes melatonin)

Test your knowledge on the connective tissues surrounding muscles, the classification of different muscle types, and the muscles acting on both the thigh and leg. This quiz covers important structures including epimysium, perimysium, and key muscle groups like the quadriceps and gluteal muscles.