Anatomy of Back, Spine and Spinal Cord

Question 1

What are the extrinsic muscles of the back?

Answer 1

Rhomboids, trapezius, levator scapulae and latissimus dorsi = attach back to pectoral girdle and move upper limb

Question 2

Where are the intrinsic back muscles located?

Answer 2

Entirely within the back = maintain back posture and move the spine

Question 3

What are the two groups of intrinsic back muscles?

Answer 3

Erector spinae = superficial

Transversospinalis = deep

Question 4

What are some features of erector spinae?

Answer 4

3 vertical muscle groups located lateral to the spine

Low back pain may be due to erector spinae strain

Question 5

What is the inferior attachment of erector spinae?

Answer 5

Common tendon attaches to sacrum and iliac crest

Question 6

Where do individual muscle fibres of erector spinae attach superiorly via a tendon?

Answer 6

Either a rib (between angles and tubercles), transverse process of a vertebra or a spinous process of a vertebra

Question 7

Where is transversospinalis located?

Answer 7

Located within the groove between the transverse and spinous processes

Question 8

Where do the individual muscles fibres of transversospinalis attach between?

Answer 8

A vertebra and the skull
A vertebra and a rib
One vertebra and another
Sacrum and a vertebra

Question 9

What is the nerve supply to the intrinsic muscles of the back?

Answer 9

Segmental nerve supply as per dermatome/myotome pattern

Posterior rami branches

Question 10

What are the functions of the intrinsic muscles of the back?

Answer 10

Help maintain posture
Support the spine
Extend the spine

Question 11

What happens when erector spinae contracts?

Answer 11

Bilateral contraction = extension of spine

Unilateral contraction = lateral flexion of spine

Question 12

What muscles are involved in flexion of the spine?

Answer 12

Psoas major and rectus abdominis

Question 13

What are the typical features of the cervical vertebrae?

Answer 13

Transverse foramen, bifid spinous process and triangular vertebral foramen

Question 14

What are some features of C1 (atlas)?

Answer 14

No body or spinous process

Has posterior arch and superior arch instead

Question 15

What are some features of C2 (axis)?

Answer 15

Has odontoid process

Projects superiorly from body

Question 16

What is the first vertebrae palpated in most people?

Answer 16

C7 = vertebrae prominens

Question 17

What are the atlanto-occipital joints?

Answer 17

Synovial joints with loose capsule = between the occipital condyles and the superior articular facets of atlas

Question 18

What movements do the atlanto-occipital joints allow?

Answer 18

Flexion and extension of the neck

A little lateral flexion and rotation

Question 19

What are the 3 articulations of the atlanto-axial joint?

Answer 19

2 between the inferior articular facets of atlas and superior articular facets of axis
1 between anterior arch of atlas and odontoid process of axis

Question 20

What are some features of the atlanto-axial joint?

Answer 20

All articulations are synovial

Main movement is rotation

Question 21

What are the categories of dislocation for cervical vertebrae?

Answer 21

Stage 1 = flexion sprain
Stage 2 = anterior subluxation, 25% translation
Stage 3 = 50% translation
Stage 4 = complete dislocation

Question 22

What level does the spinal cord end?

Answer 22

At L2

Question 23

Where does the subarachnoid space end?

Answer 23

At the level of S2

Question 24

What does the cauda equina consist of?

Answer 24

All L2-5 spinal nerve roots descending towards their respective intervertebral foraminae

Question 25

Where is the safest place to insert the needle when giving spinal or epidural anaesthetic?

Answer 25

Where subarachnoid space surrounds the cauda equina (not the spinal cord) Where vertebrae aren't fused

Question 26

At what level is the needle usually inserted for giving spinal or epidural anaesthetic?

Answer 26

L3/4 interspace

Question 27

In what situation should a lumbar puncture never be performed?

Answer 27

In cases of raised ICP

Question 28

What structures does the needle pass through when giving spinal anaesthetic?

Answer 28

Supraspinous ligament, interspinous ligament, ligamentum flavum, epidural space, dura mater, arachnoid mater, finally reaches subarachnoid space

Question 29

What structures does the needle pass through when giving epidural anaesthetic?

Answer 29

Supraspinous ligament, interspinous ligament, ligamentum flavum, epidural space

Question 30

Where is local anaesthetic injected when giving caudal anaesthesia?

Answer 30

Into the sacral hiatus to anaesthetise the sacral spinal nerve roots of the cauda equina

Question 31

What is a laminectomy used for?

Answer 31

To access the spinal canal = posterior exposure of spinal cord and/or spinal roots

Question 32

What occurs in a laminectomy?

Answer 32

Removal of one or more spinous processes and the adjacent lamina = relieves pressure on spinal cord or nerve roots

Question 33

What can a laminectomy be used to treat?

Answer 33

Tumour, herniated disc or bone hypertrophy