Anatomy of Back, Spine and Spinal Cord Flashcards
What are the extrinsic muscles of the back?
Rhomboids, trapezius, levator scapulae and latissimus dorsi = attach back to pectoral girdle and move upper limb
Where are the intrinsic back muscles located?
Entirely within the back = maintain back posture and move the spine
What are the two groups of intrinsic back muscles?
Erector spinae = superficial
Transversospinalis = deep
What are some features of erector spinae?
3 vertical muscle groups located lateral to the spine
Low back pain may be due to erector spinae strain
What is the inferior attachment of erector spinae?
Common tendon attaches to sacrum and iliac crest
Where do individual muscle fibres of erector spinae attach superiorly via a tendon?
Either a rib (between angles and tubercles), transverse process of a vertebra or a spinous process of a vertebra
Where is transversospinalis located?
Located within the groove between the transverse and spinous processes
Where do the individual muscles fibres of transversospinalis attach between?
A vertebra and the skull
A vertebra and a rib
One vertebra and another
Sacrum and a vertebra
What is the nerve supply to the intrinsic muscles of the back?
Segmental nerve supply as per dermatome/myotome pattern
Posterior rami branches
What are the functions of the intrinsic muscles of the back?
Help maintain posture
Support the spine
Extend the spine
What happens when erector spinae contracts?
Bilateral contraction = extension of spine
Unilateral contraction = lateral flexion of spine
What muscles are involved in flexion of the spine?
Psoas major and rectus abdominis
What are the typical features of the cervical vertebrae?
Transverse foramen, bifid spinous process and triangular vertebral foramen
What are some features of C1 (atlas)?
No body or spinous process
Has posterior arch and superior arch instead
What are some features of C2 (axis)?
Has odontoid process
Projects superiorly from body
What is the first vertebrae palpated in most people?
C7 = vertebrae prominens
What are the atlanto-occipital joints?
Synovial joints with loose capsule = between the occipital condyles and the superior articular facets of atlas
What movements do the atlanto-occipital joints allow?
Flexion and extension of the neck
A 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 axis
1 between anterior arch of atlas and odontoid process of axis
What are some features of the atlanto-axial joint?
All articulations are synovial
Main movement is rotation
What are the categories of dislocation for cervical vertebrae?
Stage 1 = flexion sprain
Stage 2 = anterior subluxation, 25% translation
Stage 3 = 50% translation
Stage 4 = complete dislocation
What level does the spinal cord end?
At L2
Where does the subarachnoid space end?
At the level of S2
What does the cauda equina consist of?
All L2-5 spinal nerve roots descending towards their respective intervertebral foraminae
Where is the safest place to insert the needle when giving spinal or epidural anaesthetic?
Where subarachnoid space surrounds the cauda equina (not the spinal cord)
Where vertebrae aren’t fused
At what level is the needle usually inserted for giving spinal or epidural anaesthetic?
L3/4 interspace
In what situation should a lumbar puncture never be performed?
In cases of raised ICP
What structures does the needle pass through when giving spinal anaesthetic?
Supraspinous ligament, interspinous ligament, ligamentum flavum, epidural space, dura mater, arachnoid mater, finally reaches subarachnoid space
What structures does the needle pass through when giving epidural anaesthetic?
Supraspinous ligament, interspinous ligament, ligamentum flavum, epidural space
Where is local anaesthetic injected when giving caudal anaesthesia?
Into the sacral hiatus to anaesthetise the sacral spinal nerve roots of the cauda equina
What is a laminectomy used for?
To access the spinal canal = posterior exposure of spinal cord and/or spinal roots
What occurs in a laminectomy?
Removal of one or more spinous processes and the adjacent lamina = relieves pressure on spinal cord or nerve roots
What can a laminectomy be used to treat?
Tumour, herniated disc or bone hypertrophy
