Bio 22 LAB – Miss Kim Beltran-Benjamin Mia Allyanna A. Fernandez Term 1, AY 2014-2015 College of Public Health, BS Public Health

EXERCISE 12: NERVOUS SYSTEM

A. Central Nervous System

Parts and function of the frog’s CNE.

Part Remarks Telencephalon - L: anterior portion of the brain and rostral to the midbrain

- F: Motor function (movement), interpretation of sensory impulses Diencephalon - L: between optic lobes behind, posterior to the cerebral hemispheres

- F: directs sense impulses throughout the body, equilibrium or balance, eye movement (vision), respiration

Mesencephalon - “Midbrain” - F: reflex activities of the spinal cord, eye movement/pupil dilation, body movement

Cerebellum or Metencephalon

- F: balance, cardiac reflexes, circulation, fine muscle movement

Medulla Oblongata or Myencephalon

- F: breathing, conduction pathway of nerve tracts, digestion

Spinal Cord - F: pathway to the brain of sensory stimuli, seat of reflex action Olfactory Lobes - F: sense of smell

Optic Lobes - F: certain optic ventricles which communicate with each other and with the 3rd and 4th ventricles through the small aqueduct of Sylvius.

Optic Chiasma - Part of the brain where the optic nerves (CN II) partially cross. - L: bottom of the brain immediately below the hypothalamus - F: Crucial to sight, left and right optic nerves intersect at the chiasm. One-half of

each nerve's axons enter the opposite tract at this location, making it a partial decussation

Infundibulum - the hollow conical process of gray matter - F: connects the pituitary gland to the hypothalamus

Pituitary Body - F: master gland

B. Peripheral Nervous System

Spinal Nerves of the Frog o Spinal Nerves

- 10 pairs (left and right); arise from the spinal cord and distributes to the limbs and trunk; emerge between vertebrae

- Each spinal nerve is attached to the spinal cord by 2 roots: Dorsal sensory root and Ventral sensory root Cranial Nerves of the Frog o Cranial Nerves – 10 pairs (left and right); extends from the lateral surfaces of the brain to the parts of the body

I Olfactory Sensory nerves - Area of Focus: Nasal

- F: receives impulse from the nasal epithelium II Optic Sensory nerves - Area of Focus: Retina, eyes

- F: receives impulse from the retina from the ganglion cells

III Oculo-Motor Motor nerves - Area of Focus: - F: superiorly uplifting eyelid, superiorly rotating eyeball,

construction of pupil on the exposure to light and operating several eye muscles

IV Trochlear Motor nerves - Area of Focus: - F: supplies to the midbrain and performs the function of

handling the eye muscles and turning the eye V Trigeminal Sensory, Motor - Area of Focus:

- F: a type of largest cranial nerve in all and performs many sensory functions related to nose, eyes, tongue and teeth

- a) ophthalmic, b) maxillary and c) mandibular nerve VI Abducens Motor nerves - Area of Focus:

- F: supplies to the pons and perform function of turning eye laterally

VII Facial Motor nerves - Area of Focus: face (found over the brain stem) - F: Responsible for different types of facial expressions.

This also performs some functions of sensory nerve by supplying information about touch on face and senses of tongue in mouth.

a) Palatine – root of buccal cavity, b) Hyomandibular – tongue, muscles of the lower jaw

VIII Auditory Sensory nerves - Area of Focus: Ear - F: Receive impulse from the ear

IX Glossopharyngeal Sensory, Motor - Area of Focus: - F: carries sensory information from pharynx and some

portion of tongue and palate (temperature, pressure and other related facts). It also covers some portion of taste buds and salivary glands. Motor functions: helping in swallowing food.

X Vagus or Pneumogastric Sensory, Motor - Area of Focus: area of pharynx, larynx, esophagus, trachea, bronchi, some portion of heart and palate

- F: constricting muscles, tasting ability

B.1. Histology of the Spinal Cord

Dura Mater - Tough membrane lining the outermost portion of the cord

Pia Mater - Inner vascular membrane that adheres closely to the spinal cord

Arachnoid - Middle membrane

White Matter - Outer mass; myelinated - White Commisures – oblique crossing of the medullated fibers

Gray Matter - Made up of nerve cell bodies, portion of dendrites and axons, and unmyelinated fibers. - Gray Commisures – connects the gray matter on two sides a. Dorsal Ventral Horns or cornua – two each forming the wings of the Gray matter b. Central Canal – central cavity of the Gray matter c. Ependymal Cells – cells lining the canal

Dorsal Fissure - An extremely narrow vertical wall on the mid-dorsal side of the spinal cord

Ventral Fissure - Deeper and wider than the dorsal fissure - Separates the right and left columns of the white matter