Anatomy

• The nervous system consists of nervous tissues and nervous organs.
• The nervous system has sensory, integrative, and motor functions.
• The nervous system is organized anatomically into the Central Nervous System (CNS) which includes the brain and spinal cord, and the Peripheral Nervous System (PNS) which includes nerves, ganglia, and sensory receptors.
• The Peripheral Nervous System (PNS) is functionally divided into the Sensory/Afferent division which brings information of the internal and external environment to the CNS, and the Motor/Efferent division which carries motor commands from the CNS to effectors.
• The Motor/Efferent division of the Peripheral Nervous System (PNS) is further divided into the Somatic nervous system (SNS) which sends motor commands to skeletal muscle, and the Autonomic nervous system (ANS) which sends motor commands to smooth muscle, cardiac muscle, and glands.
• The human brain constitutes 2% of body mass and is continuous with the spinal cord via the foramen magnum.
• The brain is covered by meninges.
• Cerebrum, Cerebellum, Diencephalon, and Brainstem are the four parts of the brain.
• 3rd ventricle is located in the brain.
• Cerebral aqueduct is located in the brain.
• Parts of the cerebellum include R and L cerebellar hemispheres, which are connected by vermis, and Anterior, posterior and flocculonodular lobes.
• Gray matter is located in the cortex of the brain.
• Dura mater, Arachnoid mater, and Pia mater are the three layers of meninges that cover the brain.
• Cerebellum is inferior to the cerebrum, posterior to medulla and pons, and attaches to brain stem via cerebellar peduncles.
• Interventricular foramen is located in the brain.
• Cerebrum is the largest part of the brain and is divided into cerebral hemispheres which are connected by corpus callosum and are covered by meninges.
• White matter is located in the subcortex of the brain.
• Parts of the brain include frontal lobe, parietal lobe, occipital lobe, temporal lobe, and insula.
• Lateral ventricles are located in the brain.
• 4th ventricle is located in the brain.
• Types of ganglia include dorsal root ganglia, paravertebral ganglia/Sympathetic chain, prevertebral ganglia/Collateral ganglia, and terminal ganglia.
• The endoneurium, perineurium and epineurium are parts of the nerve fibres.
• Nerve fibres can be myelinated or unmyelinated.
• Sensory receptors will be discussed in general and special senses.
• Cranial nerves can be classified into sensory (Olfactory nerve, Optic nerve), mixed nerve, and general and specific fibres.
• Spinal nerves and cranial nerves are types of nerves.
• Spinal nerves have 31 pairs (C, T, L, S, C) and are composed of nerve roots which are anterior/ventral for efferent/motor fibers and posterior/dorsal for afferent/sensory fibers.
• The nerve roots unite laterally to form spinal nerves, which divide into anterior ramus and posterior ramus.
• Ganglia are capsulated and contain satellite cells around each cell body.
• The anterior rami branch and anatomose repeatedly to form nerve plexuses such as cervical, brachial, lumbar, sacral and coccygeal plexus.
• Nerve fibres can be classified into afferent and efferent fibres, somatic and visceral fibres, or general and specific fibres.
• Cranial nerves have 12 pairs (I - XII) and arise primarily from the base of brain.
• Ascending tracts consist of 1, 2, 3 neurons.
• Descending tracts in the spinal cord are motor and consist of upper and lower motor neurons.
• Ascending tracts in the spinal cord are sensory and consist of first, second and third order neurons.
• Cervical spinal nerves are located in the posterior median sulcus.
• Cervical enlargement is located in the anterior median fissure.
• Gray matter is H-shaped, with a gray commissure on the dorsal, lateral and ventral horns.
• Coccygeal nerve (Co 1 ) is located in the filum terminale (in coccygeal ligament).
• Descending tracts consist of upper and lower motor neurons.