Nervous System Flashcards
Cranial nerves
Leaving the brain and supplying the head and neck except the vagus nerve which supplies the head, neck, thorax and abdomen
Autonomic nerves
Contains some nerve fibres from the brain, majority of nerves arise from the spinal cord and supply smooth muscle in the internal organs, blood vessels, gland in epithelial and skin and cardiac muscles.
Spinal nerves
Leaving the spinal cord and supplying the body, wall and limbs
How many pairs of cranial nerves ?
12
Where do the cranial nerves arise from?
Brain
Structure of cranial nerves?
Similar to spinal nerves but don’t have distinct dorsal or ventral roots
How do the cranial nerves leave the cranial cavity
Various foramina or fissures
Varying Functions of cranial nerves
- some convey only sensory (afferent) fibers = organ to brain
- some convey only motor (efferent) fibres = brain to muscles or glands
- some convey both sensory and motor fibres =mixed nerves
Olfactory (I)
- entirely sensory nerve
- carries info about smell or olfaction from the nerve fibres in the mucous membrane lining the nasal cavities to the olfactory bulbs of the brain
Optic (II)
- entirely sensory
- carries in for about sight from each eye to brain. Some of the nerve fibres leaving the eye cross over at optic chiasma on ventral surface of forebrain and travel to cerebral hemisphere on opposite sides.
2 nerves considered extensions of CNS. Rather then PNS
Olfactory and optic
Oculomotor (III), trochlear (IV), Abducens ( VI)
- all motor nerves
- carry info from brain to extrinsic muscles of eye. Brings about small and delicate movement of eye
Trigeminal (V)
- mixed nerve
- carries sensory info from skin around the eye and face to provide motor impulses to the muscles of mastication I.e masster.
- supplies the tensor muscles of the eardrum and the tensor muscles of soft palate
Glossopharyngeal (IX)
- mixed nerve
- carries sensory fibres including taste from caudal 1/3 of the surface of the tongue and pharynx,
- motor fibres to the muscles of the pharynx and soft palate
Vagus ( X)
- mixed nerve
- longest cranial nerve in body
Arises from medulla oblongata and splits into numerous named branches which supply the head and neck and thoracic and abdominal viscera. - Carries more sensory then motor fibres
- one of 4 carrying parasympathetic fibres (often referred to as parasympathetic nerve)
- carries :
- somatic sensory fibres from pharynx and larynx
- somatic motor fibres to muscles of the larynx and pharynx
- visceral parasympathetic motor fibres to muscle of heart and other thoracic and abdominal viscera
- viper also after net fibres from smooth muscles and glands of the thoracic and upper abdominal organs.
Assessors (XI)
- motor
- may be called spinal assessors nerve
- Supplies motor fibres to muscles of the neck and shoulder
Hypoglossal (XII)
- motor nerve
- muscles of the tongue and hyoid apparatus
Facial nerve (VII)
- mixed
- carries motor fibres to muscles of facial expressions, the muscles associated with movement of ears, lips and skin around eyes
- supplies sensory fibres to ear canal and rostrum 2/3 of tongue
Dermatomes
Area of skin supplies by an individual nerve
Vestibulocochlear (VIII)
- sensory
- carries in for to brain from inner ear
- concerning balance from the semicircular canals in the inner ear m vestibular branch
Cerebrum
- divided into left and right hemispheres
- left controls RHS of body
- Right controls LHS of body
- hemispheres deeply folded to increase SA and allow nutrients via cerebrospinal fluid (CSF)
FUNCTIONS:
- receive sensory info, interprets, links to previous associations and sends a voluntary actions using msk systems
- site of complex facilities e.g learning, reasoning, intellangce
Thalamus
- located deep in the tissue of the posterior forebrain
FUNCTIONS:
- process info from the sense organs and relay to cerebral cortex
Hypothalamus
- located ventral to the thalamus or base of forebrain
FUNCTIONS:
- link between endocrine systems by synthesising and secreting hormones that are stored within pituitary glands
- controls autonomic NS by coordinating sweating, shivering, vasodilation, sleep, sex
- maintain homeostasis e.g thermoregulagion, osmoregulation by controlling thirst and hunger senses in the brain
Midbrain
- short length of brain lying between the forebrain and hindbrain
FUNCTIONS:
- pathway for fibers between fore and hind brains
- controls hearing, vision and aspects of body movement.
Pons
- lies ventral to the cerebellum
- forms a bridge of nerve fibers between central hemisphere
FUNCTIONS:
- contains centres that control respiration
Cerebellum
- lies dorsal surface of hindbrain
- Receives sensory info from muscles and ears
FUNCTIONS:
- controls balance and coordination- works with cerebrum to control balance and movement
- regulates and coordinates posture, body movements
