Outermost, tough connective tissue covering the spinal cord. Extends to the level of the 2nd sacral vertebra where it ends by forming a sheath around the filum terminale.

Surrounds and protects the spinal cord.

Numerous fine strands of delicate connective tissue that become continuous with the pia mater.

Terminates with dura at S2.

Subarachnoid space - between arachnoid and pia mater, contains CSF. CSF acts as the "shock absorber" and maintains the CNS in a constant pressure environment.

Adheres closely to spinal cord and to nerve rootlets.

Forms filum terminale and denticulate ligaments.

Triangular extensions of the pia that project laterally between the dorsal and ventral roots.

Attach to inner surface of the dura, playing a role in stabilizing the position of the spinal cord.

Lumbar cistern

(Spinal Tap)

Subarachnoid space btwn L2 and S2.

Preferred site to withdraw CSF b/c spinal cord is absent and the nerve roots of the cauda equina are mobile.

Needle usually introduced at L3/L4 (adult) or L4/L5 (child). L4 = iliac crest level.

Path: Skin->superficial fascia->surapsinous ligament-> interspinous ligament->ligamentum flavum->epidural space->dura->subdural space->arachnoid->subarach.

Meningitis - an inflammation of the meningeal coverings of the brain and/or spinal cord, usually the result of a fungal, bacterial or viral infection.

Diagnosis confirmed by obtaining CSF via spinal tap.

Consists of the processes of somatic sensory neurons and visceral afferent.

Transmit sensations such as temperature, touch, pain, pressure into the spinal cord as the result of stimulation of their highly specialized cutaneous receptors, located on the skin.-->exteroreceptors.

Neural crest cells and alar plate join together.

Axons of Preganglionic sympathetic motor (efferent) and

somatic motor. Cell bodies in gray mater.

These transmit impulses or information out of the spinal cord that will elicit activity in a specific skeletal muscles.

Embryology: Neural crest cells and basal plates

at L2.

Tip of spinal cord

Dorsal and ventral roots of the lumbar and sacral nerves.

Bath and float in CSF.

Cell bodies of sensory neurons.

Located outside dura mater.

In intervertebral foramen.

Derived from regularly arranged clusters of neural crest cells that migrate dorsally and laterally.

Somatic motor and sensory fibers and postganglionic sympathetic.

Supply bone, muscles, skin of anterior thoracic and abdominal wall.

Innervate skeletal muscle derived from segmentally arrange somites.

Bigger than dorsal rami.

Mix of somatic sensory and motor fibers and postganglionic sympathetic fibers.

Supply to bones, muscles, skin of posterior neck and trunk.

Smaller than ventral.

Also called Intercostal nerve. 

Network of valveless veins that course along the spine and provide a route for venous metastases of cancer cells from distal locations to spine and other organs located proximal (lungs and brain).

1. Single Longitudinal Anterior spinal artery

and 2 longitudinal posterior spinal arteries.

2. Paired dorsal spinal arteries

These are derived from branches of vertebral, deep cervical, intercostal and lumbar arteries.

Infection or inflammation of the dorsal root ganglion. 

Specific area of skin supplied by visceral afferent fibers with cell bodies in the affected dorsal root ganglion is reddened and has small lesions.

Geographically defined area of skin supplied by cutaneous branches of both ventral and dorsal rami of all spinal nerves.

"Referred pain" – somatic/visceral afferent relay info to same segment of spinal cord. Visceral afferent pain in heart sent back to spinal cord at same spot as exteroreceptors, somatic sensory cutaneous branches of chest and left arm (T1-T4/5).

Congenital condition - incomplete (bifid) formation of the vertebral arch in lumbosacral region. 

Types:

1. Occulta - Marked by patch of hair (L4-S1)

2. Meningocele - meninges/arachnoid ballooning out

3. Meningomyelocele - herniation of meninges and spinal cord has floated out of vertbral canal. Pulls whole spinal cord inferiorly at base of brain, stopping flow of CSF and infant would have hydrocephaly (water of the brain).

Ancephaly

(Cranio)rachischisis totalis

Defect in the neural tube is restricted to the cranial area. 

Failure of entire neural tube to close or form results in this. And lack boney structure and brain.

Not compatible with life.

Ancephaly = "without head"

Important embryological principle.

Interaction btwn 2 populations of cells. One group will go along specific pathway because near inducting group of cells.

Occurs as result of lack of ganglia of preganglionic parasympathetics within walls of large intestine and subsequent absence of peristalsis.

Newborns and constipated and have distended abdomens. 

Clusters of neural crest cells that fail to become part of the adrenal medulla may persis in a para-adrenal location organized as catecholamine-producing tumor.

Affected individuals present with transient episodes of high bp accompanied by severe headaches, heart palpitations and extreme nervousness.

1. Flexion - following rapid deceleration (head-on-collision)  Compression of anterior portion of vertebral body.

2. Vertical compression - diving accident. Burst fracture, when body and arch of vertebra are crushed. Bone particles sent into vertebral canal/spinal cord. Can result in quadripeligia. (usually C4,5)

3. Hyperextension - Rear end collision. Fracture of one or both sides of vertebral arch, again boney fragments sent. Tear drop fracture -due to escessive strain on anterior longitudinal ligament.