Functions of the Spinal Cord
• Transmit
• Transmit
• Integrate
Brain Spinal Cord Periphery
Sensory Info
Motor Commands
Ascending tracts
Descending tracts
Fasciculus gracilisDorsalwhitecolumn
Fasciculus cuneatus
Dorsalspinocerebellar tract
Lateralspinothalamic tract Ventral spinothalamictract
Ventral whitecommissure
Lateralcorticospinal tract
Lateralreticulospinal tract
Ventral corticospinaltract
Medialreticulospinal tract
Rubrospinaltract
Vestibulospinal tractTectospinal tract
Ventralspinocerebellartract
Transmitting Information
Receptor
Sensory neuron
Integration center
Motor neuron
Effector
Spinal cord(in cross section)
Interneuron
Stimulus
Skin
1
2
3
4
5
Integration - Reflexes
Spinal Cord Protected by
Bone
Meninges
Cerebrospinal fluid
Bony Protection
Meninges 3 Membranes surrounding the spinal cord
Pia materArachnoid materDura mater
Meninges Basic Arrangement
Spinal Cord
Pia mater
Arachnoid mater
Dura mater
Subarachnoid spaceEpidural space
CSF
Produced from blood by specialized capillaries (choroid plexuses) in the brain
Functions:1. Support2. Protect3. Buffer
Spinal Cord Anatomy
Foramen magnum – L1
CervicalnervesC
1 – C
8
ThoracicnervesT
1 – T
12
LumbarnervesL
1 – L
5
Sacral nervesS
1 – S
5
Coccygeal nerve Co1
31 spinal nerve pairs
31 spinal segments
C2C3
C4
C5T1
T2
T2T3T4T5
C6
C8C7 C7
C6
T6
T7T8T9
T10
T11
T12L1
S2S3
L1
L2
L3
L4
L5
L2
L3
L4
L5
S1
C5
C6
C8
T2
C5
C6
S1
C2
C3
C4C5C6C7C8
C8 C8
C7 C7
T1T2T3T4T5T6T7T8T9
T10
T11T12
L1L2
L3
S1
L5S2
S1
S1
S3
S2 S1S2
S4S5
L5L5
L4L5L5
L4
C6 C6
C5
L4
L3
L2
L1
L4
Dermatomes
Spinal Cord Anatomy
Conus Medullaris & Cauda Equina
Filum Terminale
Spinal Cord – Cross Sectional Anatomy
White Matter – Myelinated axons
Gray Matter – SomataDendritesUnmyelinated axons
Dorsal column
Central canal
Graycommissure Dorsal horn Gray
matterLateral horn
Ventral hornVentral columnLateral column
Whitecolumns
Spinal Cord – Cross Sectional Anatomy
Ascending tracts
Descending tracts
Fasciculus gracilisDorsalwhitecolumn
Fasciculus cuneatus
Dorsalspinocerebellar tract
Lateralspinothalamic tract Ventral spinothalamictract
Ventral whitecommissure
Lateralcorticospinal tract
Lateralreticulospinal tract
Ventral corticospinaltract
Medialreticulospinal tract
Rubrospinaltract
Vestibulospinal tractTectospinal tract
Ventralspinocerebellartract
Spinal Cord – Cross Sectional Anatomy
White Matter – Organized into columns and tracts
Spinal Cord – Cross Sectional AnatomyGray Matter Organization
Somaticsensoryneuron
Dorsal root (sensory)
Dorsal root ganglion
Visceralsensory neuron
Somaticmotor neuron
Spinal nerve
Ventral root(motor)
Ventral horn(motor neurons)
Dorsal horn (interneurons)
Visceralmotorneuron
Interneurons receiving input from somatic sensory neurons
Interneurons receiving input from visceral sensory neurons
Visceral motor (autonomic) neurons
Somatic motor neurons
Fascicle
Epineurium
Perineurium
Endoneurium
AxonMyelin sheath
Basic Structure of a Nerve
Spinal Nerve AnatomyVentral and Dorsal Roots
Ventral and Dorsal Rootlets
Dorsal Root Ganglion
Spinal Rami
Dorsal ramus
Ventralramus
Dorsal ramus
Motor and sensory signals to/from the posterior trunk
Ventral ramus
Motor and sensory signals to/from the anterior trunk and limbs
Ventral ramus
Rami communicantes – carrying autonomic nerve fibers
All ventral rami(Except T2-T12)
Form Interlaced bundles of nerve fibers
Nerve Plexuses
4 major plexuses
Cervical PlexusBrachial PlexusLumbar PlexusSacral Plexus
Primarily serve the limbs
C1
C2
C3
C4
C5
Segmentalbranches
Lesser occipitalnerveGreater auricularnerve
Ansa cervicalis
Phrenic nerve
Supraclavicularnerves
Transversecervical nerve
Ventralrami:
Ventral rami
Cervical PlexusMostly cutaneous nerves
Axillary
Musculo-cutaneous
Radial
Ulnar
C4
C5
C6
C7
C8
T1
Brachial Plexus Supplies the upper limb
Gives rise to several important nerves
Axillary Nerve
Carries sensory info from the shoulder region and motor commands to the deltoid muscle.
Musculocutaneous NerveCarries sensory info from the lateral arm and motor commands to the biceps brachii and brachialis muscles.
Radial Nerve
Carries sensory info from the posterior arm and motor commands to the triceps brachii, wrist extensors and brachioradialis muscles.
Ulnar Nerve
Carries sensory info from the palm and the medial hand/fingers and sends motor commands to the wrist flexors and intrinsic hand muscles.
Obturator
Femoral
Obturator
Femoral
Lumbar Plexus
L1
L2
L3
L4
L5
Supplies much of the lower limb
Part of the lumbosacral plexus
Gives rise to several important nerves
Femoral NerveCarries sensory info from much of the thigh, leg, and foot and sends motor commands to quadriceps femoris muscles.
Obturator NerveCarries sensory info from the thigh and sends motor commands to adductor muscles.
Pudendal
Sciatic
L4
L5
S1
S2
S3
S4
S5
Co1
Superiorgluteal
Inferiorgluteal
Sacral Plexus
Superior gluteal
Inferior gluteal
Pudendal
Sciatic
Supplies much of the pelvis, thigh, and leg
Part of the lumbosacral plexus
Gives rise to several important nerves
Sciatic NerveCarries sensory info from the skin of much of the lower limb and sends motor commands to hamstring muscles as well as other muscles of the lower leg and feet.
Sciatic
Gluteal NervesPrimarily send motor commands to adductor muscles of the thigh and to the gluteus maximus.
Superior gluteal
Inferior gluteal
Pudendal NerveCarries sensory info from the external genitalia and supplies motor commands to the external urethral and anal sphincters.