Lecture 4: Spinal Cord And Spinal Nerves Flashcards
Describe how the spinal cord is enclosed by meninges
Also label slide on pg 7
-spinal dura sac terminates at S2
-dural root sleeve covers nerve rootless and becomes continuous with the epineurium of spinal nerves
-film terminal projection of pia mater covered in dura mater anchors spinal cord to the coccyx
Slide 7
Think about that slice through the medulla oblongata on slide 4 and label the different sections of it and what there functions are.
Also label the diagrams of the middle medulla oblongata and caudal medulla oblongata on slides 5 and 6
4th ventricle White matter containing nuclei CN 8-11 Medial leminiscus- which is pathway that carries sensory info from the gracilis and cuneate nuclei to the thalamus Inferior olivary nucleus Corticospinal tract
Describe the location of the spinal cord
Slide 9
- continuation of medulla oblongata
- projects through the vertebral canal for protection
- extend from foremen magnum to lower boarder of L1 (adults), L3 (children)
- terminates caudally as conus medullaris (bottom of it looks like a cone)
Why are there enlargements through the spinal cord? And we’re are they?
-cervical (C5-T1) and lumbosacral (L1-S2) enlargements.
Enlargements because extra nerves go through the extremities. Need lots of neurons to come out there
-ie due to increase numbers of motor neurons and inter neurons going to upper and lower extremities
What is the blood supply of the spinal cord?
Spinal arteries
- 1 anterior spinal arteries
- 2 posterior spinal arteries
The subclavian branches of into vertebral arteries then spinal arteries branch of them
Slide 12
Reinforced by segmental medullary arteries
What are the attachments of the spinal cord? And what is they’re function?
Suspend and anchor cord within the dural sac.
Arise from pia mater
1. Denticulate ligaments - are located in the pia mater of spinal cord. They attach the pia mater to the arachnoid and dura maters. Providing stability to the spinal cord. Slide 14
2. Filum terminal - is a delicate strand of fibrous tissue, about 20cm, proceeding downward from apex of conus medullaris. It gives it longitudinal support. Slide 16
3. Spinal nerve roots
What are spinal cord segments?
Portion of the spinal cord giving rise to the rootlets and roots that ultimately form one bilateral pair of spinal nerves
Slide 17
Label the internal morphology of the spinal cord on slide 21
Yep
What are the different areas of grey matter in the spinal cord and what are each of there functions?
Posterior horn contains sensory interneurons.
Lateral horn contains preganglionic sympathetic neurons -only from T1-L3
Anterior horn contains cell bodies if large motor neurons that supply the skeletal muscle.
Slide 22
Efferent motor axons project from_____grey horn through the _____nerve rootlets to mixed spinal nerve and in to the effector muscles.
Afferent sensory axons project from ____ through mixed spinal nerves back to the ____root and into the CNS
Efferent motor axons project from__anterior___grey horn through the __ventral___nerve rootlets to mixed spinal nerve and in to the effector muscles.
Afferent sensory axons project from _skin/joints___ through mixed spinal nerves back to the __dorsal__root and into the CNS
Memorise the muscle stretch reflexes on slide 25 Reflex: Biceps Brachioradialis Triceps Knee-jerk (patellar) Ankle-jerk (Achilles) What are there principal cord segments and the peripheral nerve that translates it?
Slide 25
Describe the knee jerk reflex
Tapping the ligament activates muscle spindles in the quads. Afferent impulses from the spindles travel in the femoral nerve to the L2-L4 segments of the spinal cord .
From here, efferent impulses are transmitted via motor fibres in the femoral nerve to the quadriceps, resulting in a jerk-like contraction of the muscle and extension of the leg at the knee.
Label all of the funiculi on slide 27,28, 29,30
What is the function of the dorsal fasciculi
Mainly ascending primary after eat fibres from mechanoreceotors of body to CNS. Dorsal column fibres synapse in nucleus gracilis or nucleus cuneatus in the caudal medulla.
Ascending tracts slide 34
Concerned with sensory function. Convey information from trunk and limbs to the brain.
1. Anterior spinothalamic tract
Conveys light touch sensation
• ASCENDING tract. Conveys information about pain and temperature.
• 1st order neuron sense pain/temperature and end in posterior horn.
• 2nd order neurons cross the midline and form the spinothalamic tract that ascends to the VPL nucleus of the thalamus.
• 3rd order neurons project to somatosensory cortex (postcentral gyrus)
- Lateral spinothalamic tract
Conveys itch, pain & temperature - Anterior spinocerebellar tract
Unconscious co-ordination of motor activities.
• Convey afferent impulses from
muscles/tendons/joints to the CEREBELLUM.
• VENTRAL spinocerebellar tract fibres ascend CONTRA- & IPSILATERALLY to enter cerebellum through SUPERIOR CEREBELLAR PEDUNCLE.
• DORSAL spinocerebellar tract fibres ascend IPSILATERALLY and enter cerebellum through INFERIOR CEREBELLAR PEDUNCLE.
Slide 40 - Posterior spinocerebellar tract
- Fasciculus cuneatus
• Carries fibres conveying conscious PROPRIOCEPTION and FINE CUTANEOUS TOUCH from the UPPER LIMB.
• Only present in spinal cord segments C5-T1. - Fasciculus gracilis
Spinocerebellar tracts
39
Unconscious co-ordination of motor activities.
• Convey afferent impulses from
muscles/tendons/joints to the CEREBELLUM.
• VENTRAL spinocerebellar tract fibres ascend CONTRA- & IPSILATERALLY to enter cerebellum through SUPERIOR CEREBELLAR PEDUNCLE.
• DORSAL spinocerebellar tract fibres ascend IPSILATERALLY and enter cerebellum through INFERIOR CEREBELLAR PEDUNCLE.
Stimulation of muscle spindles travel via the 1st order neuron into the spinal cord via dorsal root into gracilis fasciculus. The axon ascend for a number of segments before terminating in clarks colum.
2nd order neurons arising in clarks colum enter the ipsilateral dorsal spinal cerebellar tract.The 2nd order neuron continues to take the impulse up towards the medulla oblongata via the dorsal cerebellar tract, it then travels up to the inferior cerebellar peduncle and carries the impulse to the appropriate area of the cerebellar cortex
Anterior spinocerebellar enters through ________superior peduncle.
Posterior spinocerebellar enters through ______peduncle.
Slide40 view pic important
Anterior spinocerebellar enters through superior cerebellar peduncle.
Posterior spinocerebellar enters through inferior cerebellar peduncle.
What happens when you get destruction of the dorsal column?
loss of proprioception and kinesthesia.
ATAXIA (incoordination of muscular activity)
Slide 41
Summary of sensory pathways
Proprioception, vibration, light touch ascend through dorsal column.
• Pain and temperature information ascend through anterolateral pathways.
• Decussate before passing through brainstem in medial lemniscus then on to thalamus and terminate in primary somatosensory cortex.
Descending tracts slide 43
Concerned with motor function. Convey information from higher motor centres to motor neurons in spinal cord. 1. Anterior corticospinal tract 2. Lateral corticospinal tract 3. Rubrospinal tract 4. Reticulospinal tract 5. Vestibulospinal tract 6. Tectospinal tract
How does information travel between the PNS and CNS?
Don’t know frand, will have to find out
Anatomy of the spinal nerve Slide 51 and 5. How many pairs of spinal nerves? Dorsal and ventral rootlets unite in? Emerge from? Spinal nerves are apart of the \_\_\_\_\_ nervous system
- 31 pairs of spinal nerves.
- Dorsal (sensory, afferent) & ventral (motor, efferent) rootlets unite in dural root sleeve.
- Emerge from intervertebral foramina.
- Part of PNS
Contain axons of:
• General somatic afferent • General somatic efferent • General visceral afferent • General visceral efferent
fibres
What is a dermatome?
- Area of skin supplied by a SINGLE spinal nerve (coming from single spinal cord segment).
- Somites = sclerotome (bone), myotome (muscle), dermatome (skin).
- Each spinal nerve retains it relationship with its somite during development.
What is the spinal level of these important dermatomes? • Upper arm (lateral surface): • Thumb: • Middle finger: • Little finger: • Nipple: • Umbilicus: • Big toe: • Heel: • Back of thigh:
- Upper arm (lateral surface): C5
- Thumb: C6
- Middle finger: C7
- Little finger: C8
- Nipple: T4
- Umbilicus: T10
- Big toe: L5
- Heel: S1
- Back of thigh: S2
Lesions of spinal cord and peripheral nerves
• Dorsal root lesions will lead to __________
• Ventral root lesions will lead to __________
Lesions of spinal cord and peripheral nerves
• Dorsal root lesions will lead to sensory disturbances in dermatomes.
• Ventral root lesions will lead to motor disturbances = weakness (paresis) because muscles usually receive innervation from several segments.
Spinal nerve root irritation
• Pain in affected dermatome. • Sensory losses in affected dermatome. • Motor deficits in “indicator” muscles. • Reflexes associated with affected segment are diminished or absent.
Learn slide 59 indicator muscles
Yep
What happens when you get a loss of dorsal column function
loss of proprioception and kinesthesia.
ATAXIA (incoordination of muscular activity)
Makes us uncoordinated coz were not getting that info that’s needed
