1. STRUCTURE OF THE NERVOUS SYSTEM Flashcards
What are the two main divisions of the nervous system?
- Central Nervous System (CNS)
2. Peripheral Nervous System (PNS)
What are the two main divisions of the peripheral nervous system?
- Autonomic Nervous System - involuntary control such as heart rate, breathing & digestion
- Somatic Nervous System - voluntary control of locomotion, skin, joints, skeletal muscle
What are the two divisions of the autonomic nervous system?
- Parasympathetic - rest & digest
2. Sympathetic - fight or flight
What are the functions of the brain?
- The brain is the most complex organ and has both basic & complex functions
- Basic = breathing, organ functions & movement
- Complex - thought, emotion & behaviour
What are the three regions of the brain?
- FOREBRAIN
- Telencephalon
- Diencephalon - BRAIN STEM
- Midbrain
- Pons
- Medulla Oblongata - CEREBELLUM
What comprises the forebrain?
- Telencephalon (cerebrum)
- Diencephalon
What comprises the brain stem?
- Midbrain
- Pons
- Medulla Oblongata
What are the 4 axes of the brain?
- ANTERIOR-POSTERIOR - front (anterior) & back (posterior)
- DORSAL-VENTRAL - dorsal (top) & ventral (bottom)
- ROSTRAL-CAUDAL - rostral (nose) & caudal (tail)
- INFERIOR-SUPERIOR - inferior (below) & superior (above)
What are the three planes of the brain?
- CORONAL - divides brain into anterior (front) & posterior (back), also known as a frontal section
- HORIZONTAL - divides brain into superior (above) & inferior (below)
- SAGGITAL - divides the brain into left & right hemispheres
*What is the hippocampus & it’s functions?
- Hippocampus is a region of the cerebral cortex found in the temporal lobe. It’s functions are:
1. Learning
2. Memory formation & retrieval
3. Regulation of HPA
Give an example of a clinical case that involved hippocampal dysfunction?
- Clive Wearing contracted a virus which affected his hippocampus
- He suffered anterograde & retrograde amnesia
What are the cranial nerves?
- The cranial nerves are 12 pairs of nerves that arise from the brain stem & carry out various functions
What is cranial nerve 1 & what does it do?
- Cranial nerve 1 is the OLFACTORY NERVE
- It is a SPECIAL SENSORY nerve involved in the sensation of olfaction (smell)
What is cranial nerve 2 & what does it do?
- Cranial nerve 2 is the OPTIC NERVE
- It is a SPECIAL SENSORY nerve involved in the sensation of vision
What is cranial nerve 3 & what 2 functions does it have?
- Cranial nerve 3 is the OCULOMOTOR NERVE
- It has MOTOR functions
1. Movement of the eye & eyelid
2. Parasympathetic control of pupil size
*What structures does cranial nerve 3 innervate?
- CN III innervates the Superior, inferior & medial rectus & the inferior oblique (Simi)
SIM - R, I - O - SUPERIOR RECTUS & INFERIOR RECTUS - moving the eye upwards & downwards
- INFERIOR OBLIQUE moving the eye outwards & downwards, MEDIAL RECTUS - moving the eye inwards to control pupil size
*What is cranial nerve 4 & what does it do/what does it innervate?
- Cranial nerve 4 is the TROCHLEAR NERVE
- It has motor function & is involved in the movement of the eye
- CN IV innervates the SUPERIOR OBLIQUE, moving the eye outwards & upwards
What is cranial nerve 5 & what 2 functions does it have?
- Cranial nerve 5 is the TRIGEMINAL NERVE
- It has both sensory & motor functions
1. Sensation of touch to the face
2. Motor control of muscles involved in mastication or chewing
What is cranial nerve 6 & what does it do/what does it innervate?
- Cranial nerve 6 is the ABDUCENS NERVE
- It is a motor nerve, involved in the lateral movement of the eye
- Cranial nerve 6 innervates LATERAL RECTUS
**What is cranial nerve 7 & what 2 functions does it have?
- Cranial Nerve 7 is the FACIAL NERVE
- The Facial nerve has both sensory & motor functions
1. Movement of muscles involved in facial expression
2. Sensation of taste in the anterior tongue
What is cranial nerve 8 & what does it do?
- Cranial nerve 8 is the VESTIBULAR-COCHLEAR/AUDITORY-COCHLEAR
- Involved in hearing & balance
- Sensory nerve
**What is cranial nerve 9 & what are it’s 4 functions?
- Cranial nerve 9 is the GLOSSOPHARYNGEAL NERVE
- Both motor & sensory function
1. Detects blood pressure changes of the aorta
2. Parasympathetic control of the salivary gland
3. Sensation of taste in the posterior tongue
4. Movement of muscles in the throat
What is cranial nerve 10 & what 3 functions does it have?
- Cranial nerve 10 is the VAGUS NERVE
- The VAGUS nerve has both sensory & motor functions
1. Parasympathetic control of the heart, lungs & abdominal muscles
2. Sensation of pain in the viscera
3. Movement of muscles of the throat
What is cranial nerve 11 & what does it do?
- Cranial nerve 11 is the SPINAL ACCESSORY nerve
- It has motor function
- It’s involved in the movement of the muscles of the throat & neck
*What is cranial nerve 12 & what does it do?
- Cranial nerve 12 is the HYPOGLOSSAL NERVE
- It has motor function
- It’s involved in the movement of the tongue in swallowing & speech
What are three structures involved in the protection of the brain?
- MENINGES
- VENTRICULAR SYSTEM
- VASCULATURE SYSTEM
What is the meninges?
- The meninges describes the three membranous layers that cover the brain & spinal cord to prevent direct contact with overlying bone
What are the three layers of the meninges?
- DURA MATER - Outermost, superficial layer which forms a tough inelastic layer
- ARACHNOID MATER
- PIA MATER - Deepest layer of meninges
What is the sub-dural & sub-arachnoid space?
- SUB-DURAL = in between the dura & arachnoid mater
- SUB-ARACHNOID = in between the arachnoid & pia mater
What are the three functions of the meninges?
- Protection of the brain & spinal cord
- Passageway of the CSF for the ventricular system
- Support of the cerebral & spinal arteries for the vasculature system
*What is the ventricular system of the brain?
- The ventricular system comprises of a series of interconnected CSF filled spaces that lie at the core of the forebrain & brain stem
- The ventricular system is made up of 3 ventricles, containing the choroid plexus which is responsible for CSF production
What are the three ventricles of the ventricular system?
- LATERAL VENTRICLE - paired structures that arise from the third ventricle, surrounded by the two cerebral hemispheres
- THIRD VENTRICLE
- FOURTH VENTRICLE - extends from the cerebral aquaduct
What are the functions of the ventricular system?
- Protection of the brain & spinal cord
- Buoyancy regulation, CSF reduces the net weight & pressure
- Transport of nutrients & removal of waste by the CSF
What are the two pairs of arteries that supply blood to the brain?
- INTERNAL CAROTID ARTERIES branching from the common carotid
- VERTEBRAL ARTERIES branching from the subclavian artery
*What is the anterior & posterior circulation of the brain?
- ANTERIOR CIRCULATION is derived from the internal carotid & supplies the forebrain (telencephalon & diencephalon)
- POSTERIOR CIRCULATION is derived from the vertebral arteries & supplies the brain stem, cerebellum & the upper spinal cord
Describe the branching of the vertebral arteries in the circle of Willis?
- The vertebral arteries converge to form the BASILAR ARTERY
- The basilar artery branches into the right & left POSTERIOR CEREBRAL ARTERIES and the SUPERIOR CEREBELLAR ARTERIES
- The posterior cerebral arteries branch into posterior communicating arteries which connect the anterior & posterior circulation
Describe the branching of the internal carotid arteries
- The INTERNAL CAROTID ARTERY branches into the MIDDLE CEREBRAL ARTERIES & ANTERIOR CEREBRAL ARTERIES
- The anterior cerebral arteries are connected by the anterior communicating arteries
