Dermatomes, Myotomes Flashcards
Define Neural Level anatomically and clinically
Anatomical: Each neural segment of the CNS
Clinical: Lowest caudal level of fully intact sensation and motor function
What does the neural tube contain
Contains precursor cells of the nervous system
What does a single dermatomyotome develop in association with?
How do they take their nerve supply with them from the neural tube
A specific neural level
A spinal nerve
Define Dermatome
An area of skin supplied by a single spinal nerve
What do you call the blood vessels in the epineurium
Vasa Nervorum
What does a spinal nerve consist of?
What does it split into?
How does this branch re-enter the spinal canal and what does it supply
- Dorsal and Ventral nerve roots
- Dorsal and Ventral Rami, Meningeal branch re-enters through intervertebral foramen.
Supplies the vertebrae, ligaments of the spinal column as well as blood vessels and meninges
What is each vertebra is derived from?
What does the spinal cord run through
What do the spinal nerves leave the canal through
Parts of 2 adjacent somites
Vertebral foramen
Intervertebral foramina
Where does the spinal cord begin and end
Begins at Medulla Oblongata, ends at the Conus Medullaris
What is the Cauda Equina, where does it originate?
A bundle of spinal nerve roots from the L2 through to Coccygeal nerve pairs, originating in the Conus Medullaris
How many pairs of Cervial roots, and vertebrae are there?
What does this result in?
What is the exception
8 pairs of cervical nerve roots
7 pairs of cervical vertebrae
Cervical nerve roots exit above their corresponding vertebrae, except C8, which emerges between the C7 and T1 Vertebrae
From T1 vertebra downwards, where does the nerve root exit in comparison to the vertebrae
Nerve roots exit below the corresponding vertebrae
Where do the Sacral nerve roots exit from
Where do the S5 and Coccygeal nerve roots exit from
Sacral nerve roots- Exit through sacral foramina
Exit via the sacral hiatus
Compare the Ventral and Dorsal Rami
- What is supplied by each
- Size
- Ventral supplies muscles and skin of upper and lower limbs + Lateral and ventral trunk
Dorsal supplies muscles and skin of dorsal trunk - Dorsal- Very small
Ventral- Large
What is the meninges?
Name the 3 layers in the order you cut when entering body
Membranous coverings of brain and spinal cord
Dura mater
Arachnoid mater
Pia mater
The T1-L2 nerves give off a what?
What do all spinal nerves receive?
Give off a White Ramus Communicans
Receive a Grey Ramus Communicans
What does the dorsal ramus divide into
What does it supply
Medial and lateral branches
A narrow strip of muscle and skin in line with the intervertebral Foramen
What do the anterior rami of C5-T1 and L1-S5 supply?
Which nerve networks do they each enter
Muscles and skin of upper limbs- C5 to T1; Brachial plexus
Muscles and skin of lower limbs- L1 to S5; Lumbosacral plexus
On the anterior trunk, why are C4 and T2 adjacent to each other?
C5-T1 enter brachial plexus to supply upper limbs, so no distribution on trunk
What is an axial line?
Does functional overlap extend across one of these
What does it mark
The junction of 2 Dermatomes supplied from discontinuous spinal levels
NO
Marks the Centre of either the ventral/ dorsal compartments of the limb
What is an Axial Border
Compare limb rotation of a fetus
At the Margins of the limbs, and mark the borders of the anterior and posterior compartments
Upper limbs rotate laterally by 90 degrees
Lower limbs rotate medially by 90 degrees
How many routes can the axons from a single spinal nerve take through the brachial plexus, how many peripheral nerves can it emerge in
Axons from a single spinal nerve can follow multiple different routes through the plexus and emerge in several peripheral nerves
Define Myotome
What is a motor unit
- The group of muscle fibres supplied by a single spinal nerve
- A single motor neuron and the skeletal muscle fibres it innervates
What upper limb movement is caused by the C5 spinal nerve
Shoulder abduction and external rotation
What 3 upper limb movements are caused by the C6 spinal nerve
Elbow Flexion
Wrist extension
Supination
