The Vertebral Column And Segmental Innervation Of The Limbs Flashcards
In the cervical spinal cord, where do spinal nerves emerge?
Spinal nerves emerge through foremen superior to the corresponding vertebral levels
In the non-cervical spinal cord, where do spinal nerves emerge?
Spinal nerves emerge through foremen inferior to the corresponding vertebral levels
How many bones form the vertebral column?
33
What are the functions of the vertebral column?
Provides centre of gravity of body
Provides attachments for bones (both axial and appendicular)
Supports head and ribs, anchors axial skeleton
Provides attachments for trunk muscles (for posture)
Protection and passage of the spinal cord- allows segmental nerves to leave or join the cord at specific points to supply their targets
Describe the foetal vertebral column
Only has Primary Curvature - figure of C shape, concave anteriorly.
This is retained throughout life in the thoracic and sacral parts.
What is kyphosis?
Exaggerated primary curvature of the vertebral column
Describe the development of the vertebral column from a foetus to a young adult
The c-shaped column opens up to elongate.
1st posterior concavity (cervical) forms when the child lifts its head, 2nd posterior concavity (lumbar) spine opens up when child begins to crawl and walk.
What is lordosis?
Exaggerated secondary curvature
Describe the vertebral column in a young adult
Has 4 distinct curvatures (figure of s shape, sinusoidal profile)
Has 2 anterior concavities which are continuations of primary curvature, in the thoracic and sacral sections.
Has 2 posterior concavities = secondary curvatures in the cervical and lumbar sections
Describe the changes that occur to the vertebral column in old age?
Secondary curvature starts to disappear, vertebral column returns to its original shape in foetus: full continuous primary curvature re establishes, vertebral column closes up again.
How many discrete single vertebrae and fused vertebrae are there?
24 discrete single vertebrae capable of individual movement
9 vertebrae are fused to give 2 innominate structures, 5= sacrum and 4= coccyx
Where does the spinal cord start and end?
Starts where the medulla of the brain ends at the Conus Medullaris.
Ends where it tapers into the Filum Terminale ligament at about L2/L3.
What parts make up the neural/vertebral arch?
Spinous process in centre, transverse processes on the sides.
Lamina = area between transverse and spinous processes
Pedicle = area between body and transfers processes
Articulate processes at junctions of pedicle and Lamina. 1 above and 1 below on each side, strengthened by liamentum flavum.
What are the 2 main parts of a Vertebra?
The Vertebral Body and the Vertebral (neural) Arch
What are facet joints?
The joints between the neural arches, prevent anterior displacements of all the vertebrae.
Describe the structure of intervertebral discs
Peripheral region = the Annulus Fibrosus, made up of annular bands with varying orientations (outer bands are collagenous and inner bands are fibro-cartilaginous)
Central region = the Nucleus Pulposus, jelly like with high osmotic pressure to act as a water reservoir for the disc. Changes in size throughout the day and with age. Centrally located in infant,mposterior in adults.
Where are intervertebral discs found?
Separating successive vertebrae from C2 to S1
What are the functions of intervertebral discs?
They are responsible for the flexibility of the vertebral column
Act as a shock absorber
They are wedge shaped in the lumbar and thoracic levels (thickest anteriorly) which accounts for the secondary curvature of the spine
What is a slipped disc?
When the Nucleus Pulposus herniates through the the Annulus Fibrosus, leading to compression of the spinal segmental nerves.
What is Degenerative Annular disease?
Degeneration of the annulus fibrosis. Leads to marginal osteophytosis
Describe the Anterior Longitudinal Ligament of the spine
A strong flat ligament that extends from the anterior tubercle of the atlas to the front of the upper part of the sacrum. Broadens as it passes downwards.
It attaches to the periosteum of the vertebral bodies but is free over the intervertebral discs.
Describe the Posterior Longitudinal Ligament of the spine
Extends from C2 to the canal of the sacrum. Continues above C2 as the ‘membrana tectoria’. Narrows as it passes downwards.
Has serrated margins, broadest over the intervertebral discs, narrows over the vertebral bodies.
Attached to the vertebral discs, free over the vertebral bodies.
Name the ligaments of the vertebral column
Ligamentum Flava
Supraspinous ligament
Interspinous ligament
Ligament Nuchae
Where do the Ligamentum Flava attach?
They join the laminae of adjacent vertebrae. High level of elastic fibres, stretched by flexion of the spine.
Describe the Supraspinous ligaments
Joins tips of adjacent spinous processes. Made of strong fibrous tissue. Lax in extended spine, drawn taut in flexion to mechanically support the vertebral column.
Describe the interspinous ligament
Joins spinous processes along their adjacent borders. Made of weak sheets of fibrous tissue, fuse with the supraspinous ligaments.
Only well developed in the lumbar region
Describe the ligament Nuchae and give some of its functions
Runs from the occipital protuberance at the back of the skull to the thoracic spinal ligaments. It’s attached to all the cervical vertebrae at the spinous processes.
Maintains secondary curvature of the cervical spine, helps the cervical spine support the head and provides a site if attachment for neck and trunk muscles.
Describe the structure of the Atlas
The atlas is the first cervical vertebrae C1.
Widest cervical vertebrae, lacks a vertebral body and a spinous process.
Superior articular surface articulates with the skull (atlanto-occipital joint).
Articulates with the dens of the Axis inferiorly (atlanto-axial joint). Fused with the Axis anteriorly.
Describe the structure of the Axis
The second cervical vertebra C2, the strongest cervical vertebrae.
Has a wide bifid spinous process, lacks transverse processes but has rugged lateral material.
The Dens (odontoid process) prevents horizontal displacement of the axis.
Fractures and dislocates in hanging
Describe the structure of Cervical Vertebrae
Smallest of the discrete vertebrae. Have a bifid spinous process (not C7). Short transverse processes. Have oval transverse foramen in the transverse processes = Foramen Transversarium, vertebral artery passes through here (except C7). Large vertebral foramen.
Describe the structure of thoracic vertebrae
Intermediate in size, increase in size from the top downwards.
Has facets on the sides of the transverse processes that articulate with the tubercles of the ribs (not T1/T2).
Has facets on the side of the body that articulate with the head of the rib.
Has a larger vertebral body and smaller, circular vertebral foramen.
Describe the structure of the lumbar vertebrae
The largest of the discrete vertebrae.
Lack foramen or facets on the transverse processes, lack facets on the side of the body.
Vertebral foramen is small and triangular.
What is scoliosis?
Sideways curvature of the spine. Can results from unbalanced muscle tone of the trunk mussels between the right and left sides.
What injuries is the cervical spine susceptible to?
Whiplash
Sports injuries
Which intervertebral discs are susceptible to herniation?
L4/L5 and L5/S1 intervertebral discs
Where does the upper limb receive its nerve supply from?
Cervical spinal segments C5-T2 of the spinal cord. Ventral Ramus of each segment
Where does the lower limb receive its nerve supply from?
Receives all nerve supply from spinal cord segments L1-S4.
Form the Lumbar Plexus and Sacral Plexus.
Where is the lumbar plexus and what spinal nerves is it formed from?
The anterior rami of spinal nerves L1-L4
Forms behind the psoas major, nerves emerge medially and laterally to the psoas major
Name the six major branches of the lumbar plexus, superior to inferior
Iliohypogastric nerve Ilioinguinal nerve Genitofemoral nerve Lateral Cutaneous nerve of the thigh Obturator nerve Femoral nerve
Where is the sacral plexus and what spinal nerves is it formed from?
On the surface of the posterior pelvic wall, anterior to the pisiformis muscle.
Formed by the anterior rami of spinal nerves L4-5 (the lumbosacral trunk) and S1-4
Name the 5 major branches of the sacral plexus, superior to inferior
Superior gluteal nerve Inferior gluteal nerve Sciatic nerve Posterior cutaneous nerve of the thigh Pudendal nerve
Define dermatome
An area of skin supplied by sensory nerve fibres from a single spinal nerve that corresponds to a specific neural level.
What are axial lines on the limbs?
The junction between 2 dermatomes that are supplied by discontinuous spinal levels.
The limbs have both anterior and posterior axial lines which mark out boundaries between flexor and extensor components of the limb.
Describe the sensory supply and dermatomes of the upper limb
Sensory supply is C4-T2 C4= shoulder C5= radial side of arm C6= radial side of forearm and thumb C7= the hand C8= little finger and ulnar side of forearm T1= ulna side of arm T2= skin of axilla
What spinal nerve roots form the musculocutaneous nerve?
C5, C6, C7
What spinal nerve roots form the axillary nerve?
C5, C6
What spinal nerve roots form the median nerve?
C6, C7, C8, T1
What spinal nerve roots form the radial nerve?
C5, C6, C7, C8, T1
What spinal nerve roots form the ulnar nerve?
C8, T1
