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CRANIAL NERVES

Definition

  • Cranial Nerves: Nerves that originate in the brain and control various functions in the head, neck, and other parts of the body.

Memory Trick for Cranial Nerves

  • Mnemonic: Some Say Marry Money But My Brother Says Big Brains Matter Most.
  • Nerves List:
    • CNI: Olfactory - SENSORY
    • CNII: Optic - SENSORY
    • CNIII: Oculomotor - MOTOR
    • CNIV: Trochlear - MOTOR
    • CNV: Trigeminal - BOTH
    • CNVI: Abducens - MOTOR
    • CNVII: Facial - BOTH
    • CNVIII: Vestibulocochlear - SENSORY
    • CNIX: Glossopharyngeal - BOTH
    • CNX: Vagus - BOTH
    • CNXI: Accessory - MOTOR
    • CNXII: Hypoglossal - MOTOR

Functions and Tests of Cranial Nerves

CN I: Olfactory
  • Function: Sense of smell
  • Test: Have patient identify smell of a substance with eyes closed.
  • Normal Response: Able to correctly identify smell.
CN II: Optic
  • Function: Vision
  • Test: Snellen chart standing 20 feet away, covering one eye at a time.
  • Normal Response: Able to read with each eye and both eyes together.
CN III: Oculomotor
  • Function: Upward eye movement and pupillary reflex.
  • Test: Use a penlight to check light reaction and finger for accommodation.
  • Normal Response: Pupils constrict equally when brought towards nose and when exposed to light.
CN IV: Trochlear
  • Function: Downward and medial eye movements.
  • Test: Use a penlight and move it medially and downwards.
  • Normal Response: Able to move eyes down and medially.
CN V: Trigeminal
  • Function: Facial sensation and chewing.
  • Tests:
    • Sensory: Use sharp and dull side of a pen to check sensation with eyes closed.
    • Motor: Ask patient to clench teeth with resistance.
  • Normal Response: Can distinguish between sharp and dull; can open mouth against resistance and bite.
CN VI: Abducens
  • Function: Lateral or sideward eye movements.
  • Test: Use a penlight and move it sideways.
  • Normal Response: Able to move eyes laterally.
CN VII: Facial
  • Function: Facial movement and taste.
  • Tests:
    • Sensory: Taste test on the anterior tongue (sweet and salty).
    • Motor: Ask patient to smile, raise eyebrows, close eyes, puff out cheeks.
  • Normal Response: Able to distinguish taste; able to perform facial expressions without difficulty.
CN VIII: Vestibulocochlear
  • Function: Hearing and sense of balance.
  • Tests:
    • Hearing: Whisper near patient's ear.
    • Balance: Ask patient to walk across the room and back.
  • Normal Response: Can hear clearly in both ears; able to stand and walk upright while maintaining balance.
CN IX: Glossopharyngeal
  • Function: Throat sensation, swallowing, salivation.
  • Tests:
    • Sensory: Taste test on the posterior tongue (sour and bitter).
    • Motor: Have patient say “ahhhh”.
  • Normal Response: Able to distinguish taste; uvula rises symmetrically upon saying “ahhhh.”
CN X: Vagus
  • Function: Digestion, heart rate, respiratory rate, immune system, swallowing.
  • Test: Use tongue blade to touch posterior pharynx to test gag reflex; swallowing assessment.
  • Normal Response: Gag reflex assessed followed by swallow without difficulty.
CN XI: Accessory
  • Function: Shoulder and neck movement.
  • Test: Shrug shoulders and turn head side to side against resistance.
  • Normal Response: Able to shrug shoulders and turn head to each side without difficulty.
CN XII: Hypoglossal
  • Function: Tongue movement.
  • Test: Ask the patient to protrude tongue and move it in different directions.
  • Normal Response: Able to move tongue without difficulty.

ENDCRINE SYSTEM OVERVIEW

Definition

  • The endocrine system is made up of glands and organs that secrete hormones to maintain homeostasis throughout the body.

Major Glands and Their Functions

1. Hypothalamus
  • Function: Regulates hunger, thirst, sleep, and body temperature.
  • Hormones Released: GHRH, CRH, GnRH, TRH.
2. Pineal Gland
  • Function: Regulates sleep-wake cycles.
  • Hormones Released: Melatonin.
3. Pituitary Gland (Master Gland)
  • Function: Controls other endocrine glands and regulates growth, blood pressure, and reproduction.
  • Hormones Released:
    • Anterior Pituitary: TSH, ACTH, LH, FSH, GH, Prolactin.
    • Posterior Pituitary: Oxytocin, ADH.
4. Thyroid Gland
  • Function: Regulates metabolism and plays a key role in growth and development.
  • Hormones Released: T4, T3, Calcitonin.
5. Parathyroid Glands
  • Function: Regulates calcium balance.
  • Hormones Released: PTH.
6. Adrenal Glands
  • Function: Triggers stress response and regulates various bodily functions.
  • Hormones Released:
    • Adrenal Medulla: Epinephrine, Norepinephrine.
    • Adrenal Cortex: Cortisol, Aldosterone.
7. Pancreas
  • Function: Regulates blood sugar levels.
  • Hormones Released: Insulin, Glucagon.
8. Gonads (Ovaries and Testes)
  • Function: Regulates sexual function and traits.
  • Hormones Released:
    • Ovaries: Estrogen, Progesterone.
    • Testes: Testosterone.
9. Thymus
  • Function: Regulates immune system development.
  • Hormones Released: Thymosin, Thymopoietin.

ENDOCRINE DISORDERS

Types of Disorders and Their Causes

1. Diabetes Insipidus
  • Cause: Not enough ADH being released; leads to excessive urination and thirst.
2. Diabetic Ketoacidosis (DKA)
  • Cause: Complication of Type 1 Diabetes; characterized by high blood sugar and ketone formation.
3. Addison's Disease
  • Cause: Insufficient cortisol and aldosterone production; symptoms include low blood pressure and skin darkening.
4. Hypothyroidism
  • Cause: Low production of T3 and T4 hormones; symptoms include fatigue, weight gain, and cold intolerance.
5. Hyperthyroidism
  • Cause: Overproduction of T3 and T4; symptoms include weight loss and nervousness.
6. Cushing's Syndrome
  • Cause: Overproduction of cortisol; symptoms include moon face and obesity.
7. Type I and Type II Diabetes Mellitus
  • Type I: Autoimmune destruction of beta cells; insulin production loss.
  • Type II: Insulin resistance, usually associated with obesity.

IMPORTANT HORMONES

  1. Growth Hormone (GH): Stimulates growth of body tissues.
  2. Thyroxine (T4): Controls metabolism.
  3. Insulin: Lowers blood sugar levels.
  4. Glucagon: Raises blood sugar levels.
  5. Adrenaline: Emergency hormone; increases heart rate and energy.
  6. Cortisol: Manages stress and regulates metabolism.
  7. Aldosterone: Regulates sodium and water balance.
  8. Estrogen: Female secondary sexual characteristics and regulates menstrual cycle.
  9. Progesterone: Maintains pregnancy.
  10. Testosterone: Male secondary sexual characteristics and sperm production.
  11. Oxytocin: Stimulates milk ejection during lactation and uterine contractions.

RELATIONSHIP BETWEEN ENDOCRINE AND NERVOUS SYSTEM

  • The endocrine system uses hormonal messengers for communication, resulting in slower but longer-lasting effects compared to the rapid, immediate response of the nervous system using chemical and electrical signals.