202 NeuroAnatomy Flashcards
What does SCALP stand for?
Skin, Connective Tissue, Aponeurosis, Loose Connective Tissue, Periosteum
What innervates the scalp?
Trigeminal nerve and spinal cutaneous nerves
What are the three layers of the meninges?
Dura Mater (endosteal and meningeal layers), Arachnoid Mater, Pia Mater
What is the role of the meninges?
Protection, support network for blood vessels, form a fluid-filled cavity to cushion and nourish the brain
What supplies the Dura Mater?
CN V, X, C 1-3 and sympathetic nerves, blood from middle meningeal artery
Name prominent folds and function of meningeal layer of dura mater.
All restrict movement of brain.
Falx Cerebri- Separates cerebral hemispheres.
Tantorium Cerebelli- Separates cerebellar hemispheres from cerebral hemispheres
falx cerebelli- separates cerebellar hemispheres
What does damage to the middle meningeal artery cause?
extradural/epidural haematoma
What is a cause of a headache?
Dura sensitivity to stretching
What can a lesion on the temporal lobe cause?
tentorial herniation (temporal lobe herniates and pushes down)
What is the arachnoid mater?
thin avascular layer between dura and pia, loosely applied with projections
Name two noteworthy items about the arachnoid mater
Arachnoid granulations transport CSF from brain to venous system, all structures passing to brain pass through subarachnoid space
What is an advantage of CSF around the bottom of the brain?
Cranial Nerves are not crushed by the bones of the skull, and brain essentially floats.
Describe the pia mater.
Delicate vascular layer, includes cerebral artery entering brain carry sheath of pia mater, invested in gyri/sulci, difficult to see
What is missing from the spinal cord meninges?
endosteal layer of the dura mater
What is leptomeningitis?
Infection and inflammation of the arachnoid and pia mater (leptomeninges), may enter subarachnoid space and into blood (septicaemia)
Where are the dural sinuses and what to they do?
They sit between the dural fold and drain blood and CSF from brain via cerebral veins
Where does all brain’s blood eventually drain?
From veins of skull and scalp to dural sinuses to internal jugular vein and into neck
Describe the structure of the dural sinuses
thick-walled endothelium with no valves or smooth muscle
What mainly supplies the brain?
Internal Carotid Artery and Vertebral Artery
Where does the internal carotid artery enter the skull?
Carotid Canal
What is the Circle of Willis?
Anastomoses of the vertebral artery and the internal carotid artery
What are the terminal branches of arteries to the brain?
Anterior cerebral artery and middle cerebral artery
What happens to the vertebral arteries?
They pass within the cervical vertebrae and enter foramen magnum, where they unite to form basilar artery, which splits into 2 posterior cerebral arteries
Describe the circle of willis
2 anterior cerebral arteries (with and anterior communicating artery). on each side, it connects to internal carotid artery to posterior communicating artery to posterior cerebral artery to basilar artery
What does the anterior cerebral artery supply?
superior surfaces of the brain and frontal pole
What does the middle cerebral artery supply?
lateral surfaces of the brain and temporal pole
What does the posterior cerebral artery supply?
inferior surfaces of the brain and occipital pole
Where does the spinal cord start and extend to?
From below the medull to about L1
What tethers the spinal cord to the coccyx?
Terminal Filum
What is the normal englargement and narrowing of the spinal cord called?
cervical enlargement, lumbosacral enlargement, and conus medullaris (Inferior end)
How many sections does each part of the spine have?
C7 (8 nerves), T12, L5, S6 (5 nerves), Coccygeal nerve
Which spinal roots are afferent and which are efferent?
Ventral- Efferent (exit, motor), Dorsal- Afferent (into, sensory)
What does the inner core of the spinal cord look like?
Neuronal cell bodies, H shaped, Ventral, lateral (only in thoracic segment), and dorsal horns
What does the outer core of the spinal cord look like?
Myelinated axons, white columns/tracts or funiculi
What is projected form the lateral horn?
Ascending and Descending Preganglionic sympathetic neurons
Which tracts carry sensory and motor information?
Long ascending tracts carry afferent sensory info, and long descending tracts carry efferent motor info
What is the significance of tracts to/from cerebral hemispheres being crossed?
left cerebral hemisphere controls right side of the body and vice-versa
What is information ascending from within the body? joints, muscles, tendons, etc
proprioceptive
What is information ascending from outside the body? pain, temperature, touch, etc
exteroceptive
What are the basic parts of an ascending neuronal circuit?
First order neuron primary sensory- enters spinal cord via dorsal root. Second order neuron ascends spinal cord or brainstem. Third order neuron projects to cerebral cortex.
What pathway provides your mind an image of what the body is doing?
dorsal column-medial lemniscus pathway
What are the types of first-order neurons?
Fasciculus Gracilis (Medial, information from lower limb) and Fasciculus Cuneatis (Lateral, information from upper limb). Uncrossed longest neurons in body.
Where do first order neurons synapse on second order neurons in the dorsal column-medial lemniscus pathway?
medulla, fasciculus gracilis on nucleus gracilis and fasciculus cuneatis on nucleas cuneatis
What 3 things happens to second-order neurons in medulla in the dorsal column-medial lemniscus pathway?
Cross over to form medial lemniscus, ascend to thalamus, synapsed onto third-order neurons
In what condition do you find ipsilateral lesions an what do they cause?
Multiple sclerosis, loss of tactile discrimination and proprioception on same side as lesion if in the dorsal column medial-lemniscus pathway, opposite side if on the spinothalamic pathway
How can you test for ipsilateral lesions?
Romberg’s Sign: severe swaying on standing with eyes closed/feet together
What is the pain, temperature and crude touch pathway?
spinothalamic tract, sacral fibres lateral, cervical fibres medial
What do first order neurons do in the spinothalamic tract?
Enter dorsal horn and form tract of Lissauer, run up or down 1-2 segments, synapse in dorsal root with second-order neurons
What do second order neurons do in the spinothalamic tract?
Cross in dorsal horn, ascend to enterolateral column to thalamus
What is different about the spinocerebellar tracts and what do they do?
Unconscious muscle proprioception for smooth motor coordination. Only two neurons, not three, uncrossed (no need because left cerebellum controls right side of body and vice versa)
What is the posterior spinocerebellar tract? Describe its neurons.
information from lower limb muscle spindles. First order neurons synapse in dorsal horn, and second order neurons ascend in lateral column to cerebellum (very fast)
What is the cuneocerebellar tract?
information from upper limb muscle spindles
What do you see in ipsilateral lesions in posterior spinocerebellar tract?
Uncoordinated lower limb muscular activity on same side. Rarely damaged in isolation.
What is the great voluntary motor pathway for all skeletal muscles and where does it run?
Corticospinal tract, 2 neurons in circuit. Pass through pyramids of medulla. Upper motor neuron from cerebral cortext to ventral horn. Lower motor neurons from entral horn to skeletal muscles.
Where does the corticospinal tract cross and what does this mean?
80% Cross in spinal cord (pyramids of decussation), most medial aspects of cortex control most distal muscles (feet) and most lateral aspects control most proximal and upper limbs.
What symptoms do you see in upper motor neuron disease and what is it caused by?
Spastic paralysis (increased muscle tone), overactive tendon reflexes, no significant muscle atrophy. Opposite side if above pyramids, same side if below. After stroke.
What is motor neuron disease?
Degeneration of the motor neurons
What causes lower motor neuron disease and what symptoms do you see?
Flaccid paralysis (no muscle tone), no tendon reflexes, Muscle atrophy. Caused by defects in the SMN1 gene (spinal muscular neuron disease).
What is ALS?
Lou Gehrig’s Disease/Amyotrophic Lateral Sclerosis, progressive muscle weakness atrophy but mind intact, SOD1 gene
What symptoms are seen in ALS?
Initially appear in limbs or bulbar signs, upper neuron symptoms cause spasticity, short life span (~5 years to respiratory failure), selectively affects lower and upper motor neurons
What is an example of a descending neuronal tract that does not pass through the pyramids?
Reticulospinal tract, regulates ventral horn motor ativity (inhibits and facilitates), important for posture and locomotion.
What do the superior and inferior colliculi help with?
superior colliculis for vision, inferior colliculis for hearing
Name the voluntary tracts and what they’re useful for.
Rubrospinal (activate flexor muscles in arms), Corticospinal
Name the involuntary tracts and what they’re useful for.
Reticulospinal (Activate extensor muscles in arms and legs, also lateral vestibulospinal), Tectospinal (control head and neck movements, also medial vestibulospinal), Vestibulospinal
In GCS state, stiff with bent arms, clenched fists, and legs held out straight, arms bent in toward the body and wrists and fingers bent and held on the chest. What does this represent?
Dcorticate posturing, lesion above red nucleus
In GCS state, arms and legs held straight out, toes pointed down, head and neck arched back. What does this represent?
Decerebrate posturing, lesion below the red nucleus
Name 4 roles the cerebellum has.
Maintenance of balance and posture, coordination of voluntary movements, motor learning, cognitive functions
Why is the cerebellum the great comparator?
It compares movement intended to movement actually happening and can send a correction signal to correct planning of movements.
How many lobes does the cerebellum have and what are they?
3: anterior, posterior, and flocculonodular lobes.
How do the lobes of the cerebellum communicate with the brain stem?
Via the cerebellar peduncles: Superior, middle, inferior
What inputs into the cerebellum?
Vestibulocerebellum into flocculus, spinocerebellum into vermis (medial), cerebrocerebellum into lateral hemispheres
