Anatomy Flashcards
What are 2 components of CNS?
- brain
- spinal cord
What 3 components make up the PNS?
- spinal nerves
- cranial nerves
- autonomic nerves
What is the difference between a nucleus and a ganglion?
Nucleus is a collection of nerve cell bodies in the CNS
Ganglion is a collection of nerve cell bodies in the PNS
What is a multipolar neuron and where is its cell body?
- has 2 or more dendrites
- cell body is in CNS
What is a unipolar neuron and where is its cell body?
- single process comes from cell body that splits into dendrite and axon
- cell body in PNS
What type of neurons are the motor neurones of skeletal muscle and autonomic nervous system?
Multipolar
What are unipolar neurons also known as in the body?
Sensory or pseudounipolar neurons
What is the difference between a tract and a nerve?
- Tract is a collection of axons in the CNS
- Nerve is a collection of axons in the PNS
What are single modality and mixed modality nerves?
Single modality nerve has only one type of nerve axons in it e.g. parasympathetic only
Mixed modality nerves carry multiple types of axons
Most nerves are single modality nerves and tracts tend to consist of multiple modality nerves. True/false?
False.
Most nerves mixed modality and tracts are mostly single modality.
How many pairs of spinal nerves are there and how many of these are cervical?
- 31 pairs
- 8 cervical
At which point are the nerves that exit the spine actually only known as spinal nerves?
At the intervertebral foramen
Cervical spinal nerves C1-C8 are named according to the vertebrae sitting above them while the rest are named according to vertebrae below. True/false?
True
What parts of the body do the posterior and anterior rami supply?
- Posterior rami supplies the posterior
- Anterior rami supplies the anterolateral
Which roots do sensory axons enter spinal cord and which roots do motor axons exit?
- Sensory axons enter posterior (dorsal) roots, rootless and horn
- Motor axons exit anterior horn, rootless and roots
Rami are single modality nerves. True/false?
False, they are mixed modality.
What is a dermatome?
Area of skin supplied with sensory innervation from single spinal nerve
What is a myotome?
Group of skeletal muscles supplied with moron
innervation from single spinal nerve
What do the nipple and umbilicus mark in terms of the dermatome map?
- Nipple marks T4 segment
- Umbilicus marks T10 segment
What areas do C2-C4 innervate?
-posterior scalp, neck and shoulder
What spinal nerves innervated upper limb?
C5-T1
What spinal nerves innervate lower limb, gluteal region and perineum?
L2-Co1
To have complete anaesthesia in dermatome innervation, how many spinal nerves need to be damaged?
At least 3. If only 1 damaged you’ll have reduced sensation. Need 3 because there is overlap of dermatomes
What are axial lines in dermatome map on limbs?
Areas of no overlap of dermatomes (goes down middle of each limb)
What branch of spinal nerves form nerve plexuses?
Anterior rami
What are the spinal nerves forming cervical plexus?
C1-C4
What are the spinal nerves forming brachial plexus?
C5-T1
What are the spinal nerves forming lumbar plexus?
L1-L4
What are the spinal nerves forming sacral plexus?
L5-S4
What is the dorsal root ganglion?
It’s the ganglion in the dorsal root where cell bodies of sensory axons synapse
What are 3 common typical features of cervical vertebrae?
- Transverse foramen
- bifid spinous process
- triangular shaped foramen
Vertebral arteries pass through C1-C7 transverse foramen. True/false?
False - pass through C1-C6, don’t pass through on C7, accessory veins tend to pass through on C7
What 2 features does the atlas (C1) vertebra not have?
- no body
- no spinous process
- has posterior and anterior arch instead
What is the extra feature that the axis (C2) vertebra has?
Odontoid process
What is atypical about C7? (2)
- vertebrae prominens (has long spinous process)
- sometimes doesn’t have transverse foramen
What are the two parts of the Atlanta-occipital synovial joints?
- occipital condyles
- superior articulate facets
What movements occur at the Atlanto-occipital joints?
- flexion and extension of neck
- little lateral flexion and rotation
What are the 3 articulations of the Atlanto-axial joint?
- 2 between the inferior articular facets of atlas and superior articular facets of the axis
- 1 between the anterior arch of the atlas and odontoid process of the axis
What is the main movement of the Atlanto-axial joint?
Rotation
How might the spinal cord escape without being damaged in instances of slight dislocation of cervical vertebrae?
Cervical vertebral canal is quite large
What is Stage I in cervical vertebral dislocation?
Flexion sprain
What is Stage II in cervical vertebral dislocation?
Anterior subluxation, 25% translation
What is Stage III in cervical vertebral dislocation?
50% translation
What is Stage IV in cervical vertebral dislocation?
Complete dislocation
What does sacrum have instead of intervertebral foraminae for spinal nerves to pass through?
anterior and posterior sacral foraminae for anterior and posterior rami
What is the sacral hiatus?
Opening at the end of the sacral canal
What are the cauda equina made up of?
Nerve roots
At what vertebral level does subarachnoid space end?
S2
At what vertebral level should spinal and epidural anaesthetic be inserted?
L3/L4
Why can you not perform a lumbar puncture in cases of raised ICP?
Because pressure change when removing CSF can cause a herniation in brain
What is the order of layers spinal anaesthetic has to pass through from supraspinous ligament inwards?
- supraspinous ligament
- interspinous ligament
- ligamentum flavum
- epidural space
- dura mater
- arachnoid mater
- subarachnoid space
What is the name of the clinical condition in which the epidural venous plexus veins are damaged and what can this cause?
- epidural haematoma
- can cause compression of the spinal cord or cauda equina
Where is caudal anaesthesia injected into?
Into sacral hiatus
What are 2 main uses of laminectomy?
- access spinal cord
- relieve pressure on spinal cord/nerve roots
