Session 5 MSK

Question 1

The neural tube contains the

Answer 1

Precursor cells of the nervous system

Question 2

What happens in an 18 day embryo

Answer 2

• Influence of notochord
• Neural tube invaginate to form neural groove
• Neural folds fuse at midline
• Neural tube formed

Question 3

What has happened by 24 day stage

Answer 3

Cephalon head and caudal tail ends of neural tube have closed

Question 4

What happens from day 20 onwards-

Answer 4

paired Somites (primitive segments) appear

Question 5

What happens by day 30

Answer 5

Embryo has approx 34-35 pairs of Somites that begin to differentiate as soon as they are formed

Question 6

What happens during the 4th week after fertilisation

Answer 6

Each Somite differentiates into the sclerotome, (ventral- gives rise to vertebrae and ribs), dermatomyotome (dorsal and forms dermis via dermatomes) and muscle tissue via the myotomes

Question 7

Dermatomyotomes develop in association with

Answer 7

A specific neural level of spinal cord and take nerve supply with them from neural tube as spinal nerve

Question 8

Skin and muscle derived from a single dermatomyotome have a

Answer 8

Common spinal nerve supply

Question 9

What is a dermatome

Answer 9

An area of skin supplied by a single spinal nerve

Question 10

Landmarks of Foerster dermatome map

Answer 10

T4/T5- nipped
T10- umbilicus
L1- groin

Question 11

What is a neuron

Answer 11

An electrically excitable cell that receives, processes and transmits information through chemical and electrical signals

Question 12

Within the nerve, each axon is surrounded by a layer of connective tissue called

Answer 12

Endometrium

Question 13

Structure within endoneurium

Answer 13

• Endonurial fliud
• Axons are bundled into fascicles and surrounded by perineurium connective tissue
• Fascicles grouped together and surrounded by epineurium
• Vasa nervorum

Question 14

What is a spinal nerve

Answer 14

A mixed nerve that carries motor, sensory and autonomic signals between body and spinal cord

Question 15

What does dorsal nerve root do

Answer 15

Transmits sensory fibres from the sensory receptors to the spinal cord, afferent

Question 16

What does ventral nerve root do

Answer 16

Carried motor and autonomic fibres leaving spinal cord, efferent

Question 17

Spinal nerves key points

Answer 17

31 pairs, numbered according to level of vertebral column they emerge from. Short and exist briefly as they pass through intervertebral foramen

Question 18

Each vertebra is derived from

Answer 18

Parts of 2 adjacent Somites

Question 19

Spinal cord runs through

Answer 19

Vertebral foramen, multiple vertebra foramina form spinal canal

Question 20

Spinal nerves leave spinal canal through

Answer 20

Gaps between vertebrae knows as intervertebral foramina

Question 21

Spinal cord commences at

Answer 21

Inferior margin of medulla oblongata, base of brain stem

Question 22

Spinal cord ends at

Answer 22

Conus medullaris at L2

Question 23

Spinal cord is shorter than

Answer 23

Vertebral canal

Question 24

What is below conus medullaris

Answer 24

Cauda equina

Question 25

How many pairs of cervical spine roots and cervical vertebrae

Answer 25

8 and 7

Question 26

Significance of difference in cervical spine roots and vertebrae number

Answer 26

Cervical spinal roots emerge above the corresponding vertebral body with the exception of the 8th, C8, which emerges between C7 and T1 (above T1)

Question 27

Exit of nerve roots in thoracic vertebra

Answer 27

From T1, each corresponding nerve root exits inferior to vertebral body

Question 28

Sacral nerve roots exit through the

Answer 28

Sacral foramina and the S5 and first coccygeal nerve roots exit via the sacral hiatus

Question 29

What happens to spinal nerves after emerging through intervertebral foramen

Answer 29

Divides into rami. Posterior ramus supplies deep muscles and skin of the dorsal trunk. Anterior ramus supplies muscles and skin of upper and lower limbs and lateral and ventral trunk. Larger.

Question 30

What is meningeal branch

Answer 30

Each spinal nerve gives one off that re-enters spinal canal through intervertebral foramen (to supply ligaments, vertebra, blood vessels and meninges)

Question 31

Spinal nerves from T1-L2 all give off

Answer 31

White ramus communicans (pre ganglionic sympathetic nerve) which enters the sympathetic trunk via adjacent paravertebral ganglion

Question 32

All spinal nerves receive

Answer 32

Grey ramus communicans from adjacent paravertebral ganglion (unmyelinated)

Question 33

What is a dermatome

Answer 33

An area of skin in which sensory nerves derive from a signal spinal nerve root (anterior rami from upper and lower limbs)

Question 34

Posterior rami divide again into

Answer 34

Medial and lateral branches that supply back (in line with intervertebral Foramen)

Question 35

What does functional overlap between adjacent dermatomes mean

Answer 35

If a single spinal nerve is damaged, the area of anaesthesia will be smaller than you think

Question 36

Functional overlap does not extend across

Answer 36

An axial line

Question 37

What is an axial line

Answer 37

Junction of two dermatomes supplied from discontinuous spinal levels

Question 38

The developing upper and lower limbs…

Answer 38

Rotate in opposite directions and to different degrees

Question 39

What marks pre-axial and post-axial border in upper limb

Answer 39

Pre - cephalic vein | Post- basillic vein

Question 40

What marks the pre-axial and post-axial border in lower limb

Answer 40

Great saphenous vein - pre | Small saphenous vein- post

Question 41

Anterior rami of C5-T1 enter the

Answer 41

Brachial plexus to supply muscles and skin of upper limb

Question 42

Anterior rami of L1-S5 enter the

Answer 42

Lumbosacral plexus to supply the muscles and skin of lower limb

Question 43

Peripheral nerves generally contain fibres from

Answer 43

More than 1 spinal nerve (hence skin supplied by a single peripheral nerve does not correspond to the dermatome map)

Question 44

A dermatome may be supplied by

Answer 44

Multiple peripheral nerves as fibres may enter multiple different peripheral nerves

Question 45

What is a myotome

Answer 45

group of muscle fibres supplied by a single spinal nerve

Question 46

What is a motor unit

Answer 46

Single motor neuron and the skeletal muscle fibres it innervates

Question 47

Myotomes of lower limb

Answer 47

``` L2- hip flexion L3- hip extension L4- ankle dorsiflexion L5- great toe extension S1- ankle plantar flexion S2- great toe flexion ```

Question 48

What is Hilton’s law

Answer 48

The nerves supplying the muscles moving the joint also supply the joint capsule and the skin overlying insertions of the muscles

Question 49

What is the neural level

Answer 49

Lowest level of fully intact sensation and motor function

Question 50

L2 dermatome includes territory from

Answer 50

- Obturator nerve - Femoral nerve - Lateral cutaneous nerve of thigh (And Genitofemoral nerve L1-2)

Question 51

What are peripheral nerve territories

Answer 51

Areas of skin supplied by the peripheral nerves branches of brachial plexus in upper lumb and lumbosacral plexus in lower limb Often overlap sections of multiple dermatomes