Wk3 Neurology

Ventral

anterior

Dorsal

posterior

Ramus

singular

Rami

plural

Ganglion

collection of nerve cell bodies

Peripheral NS made up of

somatic and autonomic

Somatic ns

peripheral nerves

Autonomic ns

sympathetic and parasympathetic

spinal nerves

PNS. Mixed- carry sensory info to CNS and motor info out of CNS. 31 pairs. C1 (highest, exits above cervical veterbrae), rest exit below veterbrae

CNS and PNS recovery

CNS has limited/no ability to recover, PNS has greater ability to recover

Spinal cord terminates at

~L2, called the conus medullaris

Most superficial layer of spinal cord

border between CNS and PNS, outside of that is PNS. Some peripheral nerves are inside canal and dural sac

Between vertebrae

fibral cartilage for shock absorption

Motor neuron cell body

inside CNS

Sensory neuron cell body

inside PNS, cell body dorsal root ganglion

Cell body made up of

grey matter

Myelin sheaths made up of

white matter

Schwann cells

regen myelin sheath, only in PNS

Somatic

provides sensory and motor information to all body at conscious level

Autonomic

controls function of body not under conscious control, autonomic reflexes, visceral function and pain

Sensory information

touch, pain, position sensation

Motor information

innervates skeletal muscles for voluntary and reflective movements

Efferent

convey neural impulses from CNS to effector organs (muscles and glands). Form anterior (ventral) nerve root of spinal nerve

Afferent

convey neural impulses to the CNS from the sensory receptors in various parts of body. Form posterior (dorsal) nerve root of spinal nerve

Nerves

bunched together vasicles

Epineurium

covers nerve

Perineurium

surrounds fasicle

Fascicle

made up of peripheral (myelinated) nerve fibres which are lined by endoneurium

Axon to muscle fibres

one axon covers many nerve fibres. Fine motor control, more nerves.

Neuromuscular junction

Motor nerve fibre attaches to muscle fibres

Fascia

covers nerve fibres

Ventral roots

anterior. Formed by rootlets. motor

Dorsal root

posterior. Formed by rootlets. Sensory. Moves towards brain

Splits of spinal nerve

dorsal ramus and ventral ramus

Ventral gray horn

ventral rootlets emmerge from, taking motor information to effectors. Gray matter.

Dorsal gray horn

sensory information lead into horn by dorsal rootlets by dorsal ganglion. Gray matar

Intervertebral foramen

bony part gap. Where spinal nerves exit

Dorsal ramus

mixed. Innovates skin on posterior aspect of body and deep instrinsic back muscles

Ventral ramus

innovates structures on anterior and lateral aspects of body and contributes to plexuses in every region but thoracic. mixed

Epidural fat

outside spinal cord

Spinal reflex eg

flexor (withdrawal) reflex

Internuncials/interneurons

connect neurons and act as medium of communication. May ascend or descend cord and stimulate motor fibres at diff levels depending on what innovates the muscle. Connects motor and sensory in spinal reflex.

Neural plexus

an intertwining network of nerves derived from several spinal nerves that give rise to peripheral nerves that supply the structures of arm or leg

Plexus

formed by ventral rami. Cervical, brachial, lumbar, sacral, coccygeal

Thoracic region supplied

not by plexus, supplied segmentally

Advantage of plexus

if one nerve is damaged (if theres compression), it can receive info from other nerves. Backup system.

Hypoaesthesia

numb

Paraesthesia

abnormal sensation, Pins and needles, tingling

Lumbosacral plexus

six main nerves. Femoral nerve, lateral femoral cutaneous nerve, obturator nerve

Lumbar plexus

superior nerves, lateral femoral cutaneous from L2 and L3, femoral nerve from L2, L3, L4, obturator nerve from L2, L3, L4, accessory obturator from L3 and L4

Femoral nerve innervates

hip flexors (iliacus, pectineus, sartorius) quadriceps/knee extensors (rectus femoris, vastus lateralis, vastus medialis, vastus intermedius, articularis genu)

What femoral nerve targets general

anterior hip and thigh

Obturator nerve innervates

hip adductors- adductor longus, adductor brevis, adductor magnus gracilis, obturator externus

Obturator nerve targets general

medial thigh

Femoral nerve branches into

saphenous nerve (medial leg)

Saphenous nerve

terminal cutaneous branch of femoral nerve

Obturator cutaneous supply

Obturator neuropathy

pregnancy- pressure within pelvis. Stretched during surgery- within pelvis. Entrapment due to adductor muscles. AFL and rugby- running with turning and twisting

Sacral plexus

sciatic nerve from L1, L5, S1, S2, S3, S4. superior gluteal L4 L5 S1 (dorsal). inferior gluteal L5, S1, S2 (dorsal). Posterior femoral cutaneous S1 S2 S3. pudendal nerve from S2, S3, S4

Sacral plexus

lies in pelvis. Formed from lumbosacral trunk (L4 and L5) and ventral rami of S1-S4

Sciatic nerve

innervates hamstrings (semitendinosis, semimembranosus, biceps femoris (long and short head), adductor magnus

Sciatic nerve targets generally

posterior thigh

Dermatomal map

gives singular levels of spinal cord. Pattern recognition. For one pinch. Stems from embryological development

Dermatome

a dermatome is a unilateral area of skin supplied by a single spinal nerve