Anat 07

• The nervous system is the control center that allows the body to react to the environment, stores, integrates, and initiates all appropriate response to information it receives.
• The nervous system functions as a sensory system, an integrative system, and a motor system.
• Cn X also includes the dorsal and ventral vagal trunks, the dorsal and ventral vagus branches, and the celiac branch.
• Cn X is the majority of the cranial parasympathetic outflow, including the vagus nerve, which is responsible for functions such as heart rate, blood pressure, and digestion.
• The nervous system is divided into the Central Nervous System (CNS) and the Peripheral Nervous System (PNS).
• The Central Nervous System (CNS) consists of the brain and spinal cord.
• The Peripheral Nervous System (PNS) consists of all the nerve processes connecting to the central nervous system consisting of cranial and spinal nerves.
• The Somatic (Voluntary) Nervous System carries voluntary information from the CNS to the skeletal muscles along cranial and spinal nerves.
• The Autonomic (Involuntary, Vegetative) Nervous System carries involuntary information from the CNS to smooth muscle, cardiac muscle, and glands of the body along cranial nerves and spinal nerves.
• The Autonomic (Involuntary, Vegetative) Nervous System is strictly regarded as an efferent system.
• The Sensory (Afferent) System conducts sensory (afferent) information from the periphery to the CNS.
• The Motor (Efferent) System conducts information from higher to lower levels of the CNS (via upper motor neurons) and from the CNS to the periphery (via lower motor neurons).
• The Neuron is the basic anatomic unit of the nervous tissue, composed of a cell body with its processes, the dendrites (conduct impulses toward the cell body) and axons (conduct impulses away from the cell body).
• The Central Nervous System consists of the gross section of the brain and the spinal cord, which are made up of white matter characterized mainly of tracts or fasciculi containing phospholipids and gray matter cell bodies of the nerve cells.
• In the cerebral hemispheres and cerebellum, the gray substance is located in the main periphery as cortex; whereas the white substance is chiefly central.
• Cauda Equina refers to the structure formed by nerve roots leaving the caudal part of the spinal cord, travelling caudally to reach their exit from the vertebral canal.
• Functional components carried by peripheral nerve fibers include General Somatic Afferent (GSA), General Visceral Afferent (GVA), General Somatic Efferent (GSE), and General Visceral Efferent (GVE).
• The cranial nerves include the Olfactory nerve (Cn I), Optic nerve (Cn II), Oculomotor nerve (Cn III), Trochlear nerve (Cn IV), Trigeminal nerve (Cn V), Abducent nerve (Cn VI), Facial nerve (Cn VII), and Vestibulocochlear nerve (Cn VIII).
• Transverse section of the spinal cord includes the Central canal, a small perforation at the central mass of gray substance, Median fissures, grooves along the length of the dorsal and ventral surfaces of the spinal cord, Horns, or Columns, in the gray substance, Dorsal horn, composed of somatic and visceral afferent neurons, Ventral horn, composed of somatic and visceral efferent neurons, Funiculi, in the white substance, dorsal, lateral, and ventral.
• The Cranial Nerves are twelve pairs of nerves attached to the brain, in the brain stem, and they leave the cranial cavity through foramina to reach the head, neck, and body cavities.
• The Peripheral Nervous System (PNS) is composed of the Cranial nerves, Spinal nerves, and the Peripheral portion of the Autonomic Nervous System.
• Dorsal and ventral median fissures are grooves along the length of the dorsal and ventral surfaces of the spinal cord.
• According to function, the cranial nerves are either motor (M), sensory (S), or mixed (Mi) nerves.
• The seven functional types of fibers of peripheral nerves are Aα, Aβ, Aγ, Bα, Bβ, Bγ, and Bδ.
• The Peripheral Nervous System (PNS) also carries the Special Visceral Efferent (SVE), Special Visceral Afferent (SVA), and Special Somatic Afferent (SSA) in addition to the first four functional types of fibers.
• The postganglionic neuron innervates the visceral structures, smooth muscles and cardiac muscles.
• Examples of ganglia associated with sympathetic nervous system include Cranial cervical ganglion, Middle cervical ganglion, Cervicothoracic (stellate) ganglion, Sympathetic trunk ganglia, and Trunk ganglia.
• Common peroneal nerve branches include Superficial peroneal and Deep peroneal Motor nerves, which innervate craniolateral muscles of the crus and Sensory nerves that innervate the skin of the craniolateral crus and dorsal foot.
• Terminal (intramural) ganglia are the ganglia of the parasympathetic division located close to or in the wall of the organs they innervate.
• The Autonomic Nervous System is a two-neuron that has its cell body in the brain or spinal cord (preganglionic motor neuron) in synapse with ganglia (postganglionic neuron).
• Parasympathetic Division has its cell bodies in the brain and sacral segment of the spinal cord and slows the heart rate and increases motility of the GI tract, causing the live and let-live response.
• Examples of parasympathetic nerves include Cranial nerves, which carry parasympathetic preganglionic motor fibers, and Pelvic nerve, which carries sacral outflow.
• Cranial nerves include Cn III, which constricts the pupil and accommodates the lens of the eye, Cn VII, which innervates mandibular and sublingual salivary glands, Cn IX, which innervates parotid salivary gland and zygomatic salivary gland, and Cn X, which innervates abdominal organs.
• Sympathetic Division has its cell bodies in the thoracolumbar segment of the spinal cord and its activation dilates the pupils, increases the heart rate, opens the lung’s airways, decreases gut motility, dilates the blood vessels in skeletal muscles, increases glucose in the blood, and erects hair on the back, causing the fight or flight response.
• Sacral Branches (Rami) include Pudendal nerve, which innervates internal and external genitalia, rectum, perineal area, and S1-S3; Caudal rectal nerve, which innervates anus.
• The brain is contained within the cranial cavity of the skull and develops embryologically from the neural tube and three cerebral vesicles: Prosencephalon, Telencephalon, and Diencephalon.
• Cranial Nerve X, or Vagus nerve, is the longest and widest distributed of the cranial nerves.
• The auditory, acoustic or statoacoustic nerve is also known as CN IX.
• Cranial Nerve II, or Optic nerve, sends signals from the eye to the brain.
• Cranial Nerve III, or Oculomotor nerve, controls the muscles responsible for eye movement.