Vertebrae and Spinal Cord Flashcards
How many bones in the vertebral column?
33 Bones in the vertebral column
How many bones in the Cervical spine?
7
How are C1 and C2 so unique structurally when compared to other vertebrae?
No disc between them and no real vertebral body, they are very thin
Structure of C1
“atlas” is ringed shape and has two lateral masses that articulate with the occipital condyles of the skull base, thereby supporting the head
Dens of C2
C2 dens is held in place by the transverse ligament of C2, the axis, and allows rotation of the head around the dens.
Joint between C1 and C2
Between the C1 and C2 is the atlanto-axial joint, which allows flexion and extension and lateral tilting of the head. It has two facet joints and a “dens” (odontoid process). 50% of all neck motion occurs here.
Transverse foramen of C1-C6 important for what
vertebral artery
Foramen of C7?
C7 only has tiny foramina for tiny veins
Joint of luschka?
C3 - C6 are called uncovertebral joints or “joints of Luschka” that are beveled edges at the lateral edges of the disc joints
How many thoracic vertebrae?
12
Articular processes for cervical vertebrae?
Articular processes are just about horizontal to allow for flexion, extension, and some lateral flexion. Rotation is restricted
Articular processes for thoracic vertebrae?
T1 - T10 have coronally oriented articular processes that allow rotation and some lateral flexion
Most injured vertebrae?
T12 is the transitional vertebra between the stiff thoracic and mobile lumbar. Most frequently fractured vertebra
How many lumbar vertebrae?
5
Shape of lumbar vertebrae?
Kidney shaped
Why do lumbar vertebrae have suck thick bodies?
Bear weight
Order of largest foramen
Cervical Lumbar Thoracic
How many vertebrae in sacrum
5 fused
Purpose of Sacrum?
Transmits weight of body to pelvic girdle, wider in females
Sacral canal
Houses terminal roots of the cauda equina
Sacral foramina
Four paired openings on the dorsal and ventral surfaces with the filum terminale running through
filum terminale
a tender flexible strand that attaches the bottom of the spinal cord to the coccyx at the lower end of the vertebral column.
Filum terminale is an extension of what layer of the spinal cord?
Pia mater
How many vertebrae in the coccyx
4 fused vertebrae
Primary curve?
Kyphosis - Our first spinal curve
Secondary curve?
As infants begin to raise their heads, the cervical lordosis appears
Lumbar lordotic curve develops when?
With upright posture as a child, the lumbar lordotic curve develops
Symphyseal joints?
The intervertebral discs between the vertebral bodies
How much of the height of the spinal cord is discs?
20-25%
Nucleus pulposus
Gelatinous central mass of the disc. Highly elastic - located posteriorly with the annulus fibrosis
Annulus fibrosis
Outer portion of the disc - Made of fibrocartilage and is avascular
Zygopophyseal joints
facet joints. Synovial joints between the articulating processes of adjacent vertebrae.
Zygopophyseal joints movements
They permit the gliding movements between the articulating processes of adjacent vertebrae. They permit gliding movements between vertebrae during lateral flexion and extension and iwth twisting movements
Ligaments of the spine
ALL PLL Flavum Supraspinous Interspinous Nuchal
ALL
Anterior longitudinal ligament - Strong band covering the anterolateral aspects of vertebral bodies and discs. Prevents hyperextension
PLL
Posterior longitudinal ligament - Narrower and weaker, runs within the vertebral canal along the posterior surface of vertebral bodies and discs. This prevents hyperflexion
Ligamentum Flavum
Also called the yellow ligament. Part of the posterior wall of the vertebral canal
Supraspinous ligament
Cord-like, connects the spinous processes of C7 to sacrum
Interspinous ligaments
Run between the spinous processes of adjacent vertebrae
Nuchal ligament
Continuation of the supraspinous ligament, runs from C7 to the external occipital protuberence
Extrinsic muscles of the back
Trapezius Latissimus Dorsi Levator Scapulae Rhomboids
Intrinsic muscles of the back. Superficial
Splenius
Nerve supply of splenius
Posterior Rami of C3 and C4
Action of splenius
Lateral bending and extension of the head and neck
Intermediate intrinsic muscles of the back
Iliocostalis Longissimus Spinalis
Action of the intermediate intrinsic muscles of the back
Extend and laterally bend the spine at their respective levels
Spinal cord and contents
The part of the CNS housed in the vertebral canal, which also contains meninges which are protective coverings, and connective tissue, fat, and blood vessels
Where does the spinal cord begin?
Begins at the medulla oblongata and passes downward through the foramen magnum of the occipital bone of the skull
Termination of the spinal cord?
Termination taper is called the conus medullaris
What vertebra does the cord end typically?
In embryos, the spinal cord runs the length of the vertebral canal, but the spine grows faster than the cord. At birth the cord ends at L4-5 region. In adults it ends at the L1-L2 vertebral disc
Cauda Equina
At the terminus of the spinal cord, lumbar and sacral spinal nerve roots are the longest. Roots descend inferiorly to corresponding intervertebral foramina. This collection of roots forms the cauda equina, and it lies distal to the L2 vertebra in the adult
Enlargements of the spinal cord?
Cervical Lumbosacral
Cervical Enlargement
Extends from C4 - T1 segments of the spinal cord. Ventral rami from these levels form the brachial plexus which innervates the upper limbs
Lumbosacral enlargement
Extends from T11 - S1 segments of the spinal cord; corresponding nerves innervate the lower limbs and form the lumbar and sacral plexuses
C3 nerve
Diaphragm for breathing
C4 nerve
Diaphragm for breathing and shoulder shrug
C5 nerve
Deltoid, biceps
C6 nerve
Wrist extension
C7 nerve
Triceps
C8 nerve
Hands and fingers
T1
Hands and fingers
Chest muscles innervated by what?
T2 - T5 exclusively Also T6-T8
Abdominal muscles innervated by what
T9 - T12 exclusively Also T6 - T8
Hip muscles
L1 - L2
L3
Knee straighten
L4
Knee and ankle muscles
L5
Ankle and toe muscles
Anal and bladder sphincters innervated by what?
S2 - S5
Points the foot
S1
What are meninges?
Associated spaces. They include dura mater, arachnoid mater, and pia mater. They sheath and support the spinal cord
Dura mater
Tough, durable, outermost covering (membrane) of the spinal cord. It forms a long tube called the dural sac and extends a short distance into the intervertebral foramen with the dorsal and ventral nerve roots as the dural root sleeves, then blends with the epineurium (outermost coating) of the nerve
Dural sac?
extends from the foramen magnum to the level of the 2nd sacral vertebrae, encasing the spinal cord and cauda equina and anchored by the filum terminale.
Epidural space
lies between the bony wall of the vertebral canal and dura mater. It contains the internal vertebral plexus of veins, fat, and the loose connective tissue that supports them
Subdural space
This is a potential space between the dura mater and the arachnoid mater. Not usually occupied by anything
Arachnoid mater
Delicate, filamentous, avascular middle layer (covering) of the spinal cord that is connected to the pia mater by delicate strands of connective tissue called arachnoid trabeculae. It ensheaths the cauda equina and lines dural sac and dural sheaths.
Arachnoid mater on a cadaver looks like what?
These are spiderweb-like and can be seen in a cadaver
Subarachnoid space
Between arachnoid mater and the pia mater. Filled with CSF when you are alive that puts pressure on the arachnoid mater which then rests against the duramater.
What are you hitting with a lumbar puncture?
you are tapping a space called the lumbar cistern, which is an enlargement of the subarachnoid space distal to the conus medullaris
Pia mater
Innermost, transparent layer made up of connective tissue. It encloses a network of blood vessels and covers the spinal roots and blood vessels. Cannot be detached from the spinal cord.
Denticulate ligament
20-22 saw-like ligaments that extend between the pia mater and the inner surface of the dura mater along each lateral “seam” of the cord. They seaparate the ventral from the dorsal roots and extend from the foramen magnum to the T12-L1 vertebrae
Anterior spinal arteries
Formed by segmental branches from the aorta that run the length of the spinal cord in the anterior mdeian fissure. They supply the anterior ⅔ of the spinal cord
Posterior spinal arteries
Small branches of vertebral arteries. They run the length of the spinal cord on either/both sides of the dorsal medican sulcus and anastamose with the anterior spinal arteries, supplying the posterior ⅓ of the spinal cord
Radicular arteries
Small arteries that supply the nerve roots, some reaching through the intervertebral foramina to reach the spinal cord
Anterior and posterior segmental medullary arteries
Provide segmental blood supply to the spinal cord from branches of the aorta
The Great Anterior Segmental Medullary Artery
Largest of the segmental vessels. Arises from the left interior intercostals or superior lumbar artery. This provides the main blood supply to the anterior ⅔ of the caudal spinal cord
Paraplegia
paralysis from the waist down
What is a common cause of paraplegis as related to blood flow?
Blockage of blood flow through the Great Anterior Segmental Medullary Artery
Where do the anterior and posterior spinal veins drain to?
the internal vertebral venous plexus which lies within the epidural space
Epidural anesthesia/injections
Insert anesthetics into the epidural space usually at L4/5 via the caudal canal (sacral hiatus)
Spinal stenosis
Narrowing of the spinal canal and/or intervertebral foramen - Combination of DDD (Degenerative Disc Disease), osteoarthritis and/or hypertrophy of spinal ligaments
Effect of spinal stenosis?
Leads to pain, radiculopathy and limping. Pain worse with standing, better with sitting
Treatment for spinal stenosis
Surgical decompression
Herniated disc
Tearing of the disc anulus with nucleosus pulposus material filling the void in the posterior lateral direction.
- Conus medullaris
- Filum Terminale
- Cauda Equina
Nerve plexus
Formed by the interlacing of nerves or nerve fibers by means of numerous communicating branches or fibers
Dermatome
Myotome
All muscles derived from one somite and innervated by one segmental spinal nerve
