Compendium 9 Flashcards
Explain divisions of the spinal cord
Divided into cervical, thoracic, lumbar, sacral and coccygeal regions
Diameter changes from top to bottom- enlargements in cervical region and lumbar/sacral region that correspond with nerves that supply limbs
Cervical- supply nerves to arms
Lumbar/sacral- supply nerves to legs
Explain structure of the spinal cord
Starts at foramen magnum ends at 1st or 2nd lumbar vertebrae
Pointy end called CONUS MEDULLARIS which finishes at 2nd lumbar vertbrae
Very end region called CAUDA EQUINA which are branches of spinal nerves extending from lumbar/sacral enlargement and conus medullaris (occurs as spinal cord shorter than vertebral canal)
What are meninges
Connective tissue covering brain and spinal cord for protection, to hold CSF and to form partitions in the skull
Explain meninges layers in spinal cord
Duramata: outermost, thickest, toughest layer- as move deeper into spine there is subdural space that contains serous fluid
Arachnoid mata: thin, fine, loose, elastic - followed by subarachnoid space consigning CSF and blood vessels
Pia mata: tense, contains many blood vessels which tightly surround brain and spinal cord
Explain the structure of nerves in PNS
Axon (can be myelinated) covered by connective tissue layer called ENDONERIUM
A bunch of these is called a NERVE FASCICLE
Connective tissue surrounding one fascicle is called PERINERIUM
Outermost layer surrounding a bunch of fascicles is called EPINERIUM
Connective tissue provides strength and protection
How are spinal nerves organised
31 pairs arise, only 39 vertebral bones
Top half:
8 cervical nerves (7 bones)
8 thoracic nerves (including remaining 4 thoracic nerves- 12 bones)
Bottom half: Remaining 4 thoracic nerves 5 lumbar nerves (5 bones) 5 sacral nerves (5 bones) 1 coccygeal nerve (5 fused bones= 1 bone)
First cervical nerve come out on top of first vertebral bone (C1 on top of bone 1, C2 on top of bone 2)
C8 comes out on top of 1st thoracic bone therefore only 7 cervical bones)
From now on spinal nerves come under corresponding bone (T1 under bone 1)
What are the major parts of the brain
Forebrain: cerebrum, diencephalon
Mid brain
Hindbrain: pins, medulla oblongata, cerebellum
Midbrain, points, medulla oblongata form BRAIN STEM
What is the purpose of the brain stem
Sits under diencephalon
Connects spinal cord to rest of brain
Describe medulla oblongata
Directly connects to spinal cord at foramen magnum
Autonomic reflex centre maintaining body homeostasis
Contains groups of cells:
-cardiovascular centre: heart rate and force, blood vessel diameter
-respiratory centre: rate and depth of breathing
-other reflexes such as vomiting, swallowing, sneezing, coughing, hiccuping
Describe pons
Superior to medulla oblongata
Bridges different parts of brain to allow for communication
Contains conduction tracts running in 2 different directions: longitudinal tracts (spinal cord to higher brain centres) and transverse tracts (cerebrum to cerebellum)
Contains sleep centre which regulates rapid eye movement when sleeping
Also part of respiratory centre (works with medulla)
Describe midbrain
Smallest part of stem
Receives visual, auditory and tactile sensory input and generates reflex movements of head, eyes and body
Controls eyeball movements
Describe cerebellum
Outer grey matter, inner white matter
Highly convoluted
Communications with all of brain stem to control locomotion in association with cerebrum (coordinated movement)
Controls fine motor control e.g. Muscles in wrists, fingers, etc.
Controls posture and balance
Describe diencephalon
Contains thalamus (largest part), subthalamus, epithalamus and hypothalamus Grey matter
Describe thalamus of diencephalon
Paired structure
Sensory relay centre: relays info to cerebrum (sensory information goes here before cerebrum- all senses besides smell)
Regulates mood, memory and strong emotions
Describe hypothalamus of diencephalon
Made up of different parts
Maintain homeostasis via endocrine system
Regulates heart rate, digestive activities, sex drive and sexual pleasure
Controls muscles in swallowing, body temp
Regulates mods, motivation, emotions
Regulates sleep wake cycle
Describe cerebrum
Most superficial part of brain
Made up of elevated tissue and folds called GYRI and has grooves within called SULCI
Deep grooves called FISSURES
Left and right hemisphere divided by LONGITUDINAL FISSURE - hemisphere connected by bundle of fibres called corpus callosum
LATERAL FISSURE and CENTRAL SULCUS divide hemispheres into lobes
What are the lobes of the cerebrum
Frontal: voluntary motor function, motivation, planning, aggression, sense of smell, regulation emotional mood and behaviour
Parietal lobe: receives most sensory input except hearing, smell, taste, and vision (pain, temp, touch, ect.)
Occipital: receives and process visual input
Temporal: smell and heating input and has role in memory
Insula: located deep inside behind lateral fissure- taste information
How are the lobes in the cerebrum separated
Lateral fissure separates frontal lobe from rest of cerebrum
Central sulcus separates frontal lobe from parietal lobe
Also precentral gyrus (fold in front of central sulcus in frontal lobe) for primary somatic motor control -particularly fine voluntary movements
Postcentral gyrus/primary somatosensory cortex (fold behind central sulcus in parietal lobe) receives somatic sensory input from receptors in skeletal muscles, joints, tendons and processes it (pain, pressure)
It is first synapses in thalamus before transmitted here
Grey and white matter of cerebrum
Grey matter = outer
Where consciousness is formed
Allows us to communicate, remember, understand, ect.
White matter = inner/deep
Communication between cerebral areas and cortex and lower CNS structures
What is the limbic system
Runs through medial aspect of hemispheres and diencephalon
Runs around border of corpus callosum
Group of structures that have role in memory, developing new neurological pathways and control emotion and emotional gestures
Describe meninges layers of the brain
Dura mata: outermost, fibrous connective tissue that contains the following:
- periosteal dura: connects to bony skull and also meningeal dura (deeper) which continues with the dura mata of the spinal cord
- some parts of brain contain these two layers and have a dural venous sinus which contain veins that collect blood that nourishes brain and also dural folds which are connective tissue partitions extending deep into brain which hold brain in place and stop excessive movement
- if no sinus then two layers fuse together
- between whole dura mata and next layer there is subdural space with serous fluid
Arachnoid mata: similar structure to in spinal cord- followed by subarachnoid space with CSF and blood vessels
Pia mata: very small blood vessels sit tightly over brain surface
Describe the ventricles of the brain
Brain has 4 ventricles that are continuous with each other and are lined with ependymal cells
Largest= lateral ventricle which is paired and extends into each hemisphere
4th is brain stem which is continuous with central canal of spinal cord
These spaces are where CSF is produced
Describe cerebrospinal fluid
Most produced by choroid plexus which in brain is specialised ependymal cells and support tissue
Protects brain from trauma and provides buoyancy (brain floats which reduces feeling of its weight and takes pressure off structures underneath)
Similar to plasma but less proteins, different ionic concentrations
Some CSF comes from water and solutes in blood moving through ventricles
Provides nutrients to brain and spinal cord
Circulates through ventricles, central canal of spinal cord and subarachnoid space
Cilia of cells help to circulate CSF
Describe cranial nerves
12 pairs arise from brain
Emerge directly out of brain and carry info from brain to body and back to brain
Can be sensory motor and or parasympathetic functions
