Anatomy Flashcards
what are the two main types of neurones?
multipolar
unipolar
what is the difference between multipolar neurones and unipolar neurones?
multipolar = most common, 2 or more dendrites, all motor neurones and their cell body is in CNS
unipolar = double process, sensory, their cell body is in PNS
what is the difference between motor and sensory neurones?
motor (efferent) = impulse moves towards body wall, body cavity or organ
sensory (afferent) = impulse moves towards brain
what is a group of nerve cell bodies in the CNS called and how is this named differently in the PNS?
CNS - nucleus
PNS - ganglion
a nerve is a bundle of what?
axons
this is called a tract in the CNS
tracts tend to be of a “single modality” - what does this mean?
all axons contained within it have the same job
ie somatic motor/sensory, special sensory etc
what is meant by “mixed modality” nerves?
axons for somatic motor and sensory and sympathetic all together in one nerve
what cranial nerves connect to CNS in forebrain?
CNI and CNII
what cranial nerves connect to CNS via the midbrain?
CN III and IV
where does CNV connect to the CNS?
pons
what cranial nerves connect to the CNS at the pons-medullary junction?
VI, VII and VIII
which of CNIX, X, XI and XII does not connect to CNS at medulla?
CNXI - connects at spinal cord
(cause spinal accessory nerve lol)
spinal nerves are actualy very small - true or false?
true
they are only found in the intervertebral foraminae as on one side they are rootlets/roots or rami on the opposite side
what do the anterior and posterior rami supply?
anterior - anterolateral body wall
poserior - posterior body wall
are roots and rootlets single or mixed modality?
single
posterior root/rootlets = somatosensory
- all sensory axons pass from the spinal nerve into posterior root then posterior rootlets then into posterior horn of spinal cord
anterior root/rootlets = somatomotor
- all motor axons pass from anterior horn of spinal cord into anterior rootlets then into the anterior root then into the spinal nerve
are spinal nerves and rami single or mixed modality?
mixed - anterior and posterior roots come together and mix forming spinal nerve
what is the name given to the swelling on the posterior (or dorsal) root and what does it contain?
dorsal root ganglion - contains collection of cell bodies
rami supply what in their segment of the body?
sensory supply to area
somatic motor supply to skeletal muscles
sympathetic supply to the skin and to the smooth muscle of arterioles
what is a dermatome?
area of skin supplied with sensory innervation from a single spinal nerve (eg T4 = nipple level)
what is a myotome?
skeletal muscles supplied with motor innervation from a single spinal nerve
myotomes lie under the corresponding spinal nerve dermatome - true or false?
false - not always the case
eg C3,4,5 dermatome = shoulder and upper arm
but myotome = diaphragm
dermatomes for spinal nerves can overlap - true or false?
true
why is dermatome overlap a clinical issue?
if a patient experiences a symptom (eg numbness / tingling) in a specific dermatome then we must contemplate that nerves in the adjacent dermatome may also be damaged
what dermatome levels mark the nipple and umbilicus?
T4 = nipple
T10 = umbilicus
roughly describe what each segment of spinal nerves innervates (ie cervical, thoracic etc)?
cervical = upper limbs, posterior head and neck
thoracic = thorax
lumbar = anterior of lower limbs
sacral = posterior of lower limbs
what makes up a nerve plexus?
anterior rami
what anterior rami make up each plexus?
cervical = C1-C4
brachial = C5-T1
lumbar = L1-L4
sacral = L5-S4
it is possible for more than one named cutaneous nerve to pass through one dermatome - true or false?
true eg lateral cutaneous nerve of thigh, femoral nerve and obturator nerve all pass through L2 dermatome
between what spinal level does sympathetic outflow leave the spinal cord?
T1-L2
what extra horns are found in the spinal cord where sympathetics or sacral parasympathetics leave?
lateral horns (on edge of grey matter in spianl cord)
what 4 ways are used by sympathetics to leave spinal cord?
1) signal ascends sympathetic chain before synapsing
2) signal synapses on same spinal level it leaves
3) signal descends sympathetic chain before synapsing
4) passes through sympathetic chain without synapsing, passes onto splanchnic nerves and then synapses onto viscera
what term is used to describe parasympathetic outflow and why is this?
craniosacral outflow
cranial nerves III, VII, IX and X
sacral spinal nerves
what is the role of the extrinsic back muscles?
attach to back of pectoral girdle (outwith back) and move the upper limb
what is the role of the intrinsic muscles within the back and what is the two groups?
muscles which attach within the spine which maintain back posture and move spine
2 groups = erector spinae (superficial - located lateral to spine) and transversospinalis (deep - located within grooves between transverse and spinous processes)
lower back pain may be due to the strain of which muscle?
erector spinae
what nerves supply the extrinsic vs the intrinsic muscles?
extrinsic = anterior rami
intrinsic = posterior rami
identify an axial image of erector spinae in context of transversospinalis?
if the erector spinae contracts bilaterally then the spine extends but what occurs if it contracts unilaterally?
lateral flexion
why do vertebrae get larger towards the lumbar region and then progressively smaller again?
larger to bear more weight until the weight is transferred to hip bones
what curves of the spine are secondary (ie not present from birth, they have adapted to new functions of spine)?
cervical and lumbar lordosis
describe the structure of a typical vertebra?
where are spinal nerves found and where is the spinal cord found in relation to the vertebrae?
spinal nerves = intervertebral foramen
spinal cord = vertebral foramen
what is the role of intervertebral discs and describe the difference between the outer ring and inner pulp?
weight bearing, strength and small amounts of movement at each disc
outer fibrous ring (annulus fibrosus) = provides strong bond
inner soft pulp (nucleus pulposus) = up to 90% water in newborns, flexibility and protection
what ligaments are found on the outside of vertebral body and what is their role?
posterior longitudinal ligament (narrow and weak, prevents over-flexion of spine)
anterior longitudinal ligament (broad and strong, prevents over-extension of spine)
what ligament connects the adjacent laminae posterior to the spinal cord?
ligamentum flavum
where are the supraspinous ligament and interspinous ligament found?
supraspinous = connects tips of spinous processes (strong)
interspinou ligament = connects adjacent spinous processes (weak)
thwt are the common typical features of a cervical vertebrae?
transverse foramen
bifid spinous process
triangular shapes vertebral foramen
C1 (atlas) does not have a body or spinous process - true or false?
true - body is donated to a C2 as odontoid process
has a posterior arch and anterior arch instead
why is C7 important?
first palpable spinous process in 70% of people
how does C1 atlas connect to the base of the skull?
atlanto-occipital joints = between the occipital condyles and the superior articular facets of the atlas
these are synovial joints with loose capsule for maximum movement
what movements does the atlanto-occipital joint allow?
flexion and extension of neck
a little lateral flexion and rotation
identify the components of a lateral C-spine radiograph?
what are the four stages of cervical vertebrae dislocation?
stage I - flexion sprain
stage II - anterior subluxation, 25% translation
stage III - 50% translation
stage IV - complete dislocation
how many articulations are part of the atlanto-axial joint?
3 - all synovial
2 are between the inferior articular facets of the atlas and the superior articular facets of the axis
1 between the anterior arch of the atlas and odontoid process of the axis
what is the main function of the atlanto-axial joint?
rotation
C1 disappears on a radiograph as it has no spinous process - true or false?
false - the posterior arch appears like a spinous process would
it is easier to fracture cervical vertebrae than dislocate them - true or false?
false - much easier to dislocate them
sometimes they will reduce by themselves
what nerves pass through the anterior and posterior sacral foraminae?
rami of spinal nerves
what is the cauda equina made up of?
nerve roots from L2 -> CO1 descending to their intervertebral foramen at their level
why is it safer to perform an epidural or LP at the level of the cauda equina (below L2)?
no damage to spinal cord
nerve roots more likely to move out of way of needle
where does the spinal cord begin and end?
begins at foramen magnum (C1 - continuous with medulla oblongata)
ends around vertebral level L1/2 (Co segment of spinal cord)
what can result from an epidural or lumbar puncture which damages the venous plexus in the epidural fat?
epidural haematoma which can compress the spinal cord
what layer of meninges needs to be reached during a lumbar puncture?
subarachnoid space containing CSF for extraction
what is a laminectomy?
removal of one or more spinous processes and the adjacent lamina
used to access spinal canal / relieve pressure on spinal cord or nerve roots caused by tumour, herniated disc or bone hypertrophy
the posterior rami supply a strip of skin where?
centrally down the back and posterior neck (C2-C8)
what plexuses are formed by the anterior rami?
cervical plexus
brachial plexus
lumbar plexus
sacral plexus
give examples of named nerves from the anterior rami which supply the trunk wall?
state the difference between a spinal nerve and a named nerve?
spinal nerve = contains axons originating from one spinal cord level (eg C5 spinal nerve)
named nerve = contains axons originating from one or more spina cord levels supplying a particular area (eg musculocutaneous nerve - C5, 6, 7)
explain how the area of innervation of femoral nerve crosses 3 true dermatomes?
femoral nerve contains axons that connect via spinal nerve roots L2, 3 and 4 with spinal cord segments L2, 3 and 4
this means that the area of cutaneous innervation of the femoral nerve crosses 3 true dermatomes - those of L2, L3 and L4 spinal nerves
what is the “nerve point” of neck?
where the sensory nerves of cervical plexus converge and pass from superficial to deep fascia
this occurs at midpoint of posterior border of SCM
what is the clinical significance of T1 and T2 anterior rami?
important for referred pain from the myocardium
what supplies the anatomical snuff box?
cutaneous branches of the radial nerve