Medical Anatomy: Lecture 2

name the different regions of the vertebral column

• cervical

• thoracic

• lumbar

• sacral

• coccygeal

name the numbered regions of the vertebrae

1. spinous process

2. transverse process

3. superior articular facet

4. superior articular process

5. vertebral foramen

6. body

7. spinal cord location

8. lamina

9. pedicle

10. vertebral arch

where do spinal nerves pass through

intervertebral foramen

what are the first 2 cervical vertebrae called and what makes them unique

C1 ( atlas)

• large superior articulating facet for joint with cranium

C2 (axis)

• additional posterior process called “dens” which allows head to swivel

• atlanto-axial joint movement

features of cervical vertebrae

• small size

• spinous process has bifid tip

• transverse foramen (space for vertebral arteries)

features of thoracic vertebrae

• medium size

• elongated spinous process

• costal facets for rib joints

features of lumbar vertebrae

• large size

• rounded spinous process

sacrum

• 5 fused vertebrae

• sacral promontory

• auricular surface (articulates with pelvis)

coccyx

3-4 fused tiny vertebrae

lumbosacral joint

• intervertebral disc between L5 and sacrum

• facet joint between L5 inferior articulating facets and sacral superior articulating facets

sacroiliac (SI) joint

• sacral auricular surface and auricular surface of ilium

intervertebral discs; articulation, structural type, functional type, & movements

• vertebral bodies of adjacent vertebrae

• cartilaginous

• amphiarthrosis

• extension, flexion, lateral flexion of vertebral column

facet joints; articulation, structural type, functional type, & movements

• superior & inferior articulating processes of adjacent vertebrae

• synovial

• diarthrosis

• rotation, extension, flextion, lateral flexion of the vertebral column

atlanto-occipital joint; articulation, structural type, functional type, & movements

• superior articulating facets of atlas and occipital condyles of occipital bone

• synovial

• diathrosis

• extension, flexion or the head, slight lateral flexion

atlantoaxial; articulation, structural type, functional type, & movements

• anterior arch of atlas and dens of axis

• synovial

• diarthrosis

• head rotation

sacroiliac; articulation, structural type, functional type, & movements

• auricular surface of ilium to auricular surface of sacrum

• synovial

• diarthrosis

• nutation (sacral flexion) & counternutation (sacral extension)

nervous system

neural communication by electrical and chemical signals that are rapid and cause immediate responses

responsible for voluntary, involuntary movements, reflexes, learning, memory, & emotions

central nervous system (CNS)

• brain

• spinal cord

peripheral nervous system (PNS)

• nerves & receptors outside of the brain and spinal cord

name the 2 nervous systems

sensory and motor

sensory nervous system

detects stimuli and transmits infromation from receptor to the CNS

somatic sensory

sensory input form the receptors of the 5 sense and proprioceptors

visceral sensory

sensory input from receptors of internal organs and blood vessels

motor nervous system

initiates and transmits information from the CNS to effectors

somatic motor

motor output to skeletal muscle

autonomic motor

motor output to cardiac muscle, smooth muscle, and glands

autonomic

organ, gland regulation

• sympathetic

• parasympathetic

neurons

• electrical cells that transmit the signals through the nervous system

  • directional flow of electrical activity

  • action potentials are the long distance signals

name the numbered structures of the neuron

1. dendrites

2. cell body

3. axon hillock

4. axon

5. myelin sheath

6. synaptic knobs

synapses

connection points between 2 neurons or between a neuron and a muscle, gland, or other cell

glia

supportive cells within the central and peripheral nervous system

myelin sheath

• external wrapping around the axon that insulates and increases the speed of electrical transmission

• myelin makes the axon appear white

white matter

myelinated axons

• tracts

  • bundles of axons in the CNS

• nerves

  • bundles of axons in the PNS

tracts with white matter

bundles of axons in the CNS

nerves with white matter

bundles of axons in the PNS

gray mater

non-myelinated axons

• nuclei

  • cell bodies in the CNS

• ganglia

  • cell bodies in the PNS

nuclei with gray matter

cell bodies in the CNS

ganglia with gray matter

cell bodies in the PNS

nerve

bundles of axons in the peripheral nervous system traveling to/from the CNS

reflex

• simplest, fastest pathways

• input, integration, output

sensory pathways

• inputs processed within multiple CNS regions

motor pathways

• outputs regulated by multiple CNS regions

afferent

• brings sensory information from the outside world into the body

receptors

• sense the stimulus

sensory neurons

• transmit the signals into the nervous system

sensory ganglion

• group of sensory neuron cell bodies outside of the CNS

sensory fibers

• bundle of axons within a nerve that carry sensory information toward the CNS

somatic sensory pathway

• dorsal horn

• dorsal root

• dorsal root ganglion

• spinal nerve

• somatic sensory receptors (tactile receptors, proprioceptors)

visceral sensory pathway

• dorsal horn & lateral horn

• dorsal root

• dorsal root ganglion

• spinal nerve

• visceral sensory receptors (baroreceptor, chemoreceptor)

somatic effectors

• anterior horn

• anterior root

• spinal nerve

• somatic effector (skeletal muscle)

autonomic effector

• anterior & lateral horn

• anterior root

• spinal nerve

• preganglion synapse on postganglion

• postganglion reach the effector organs (cardiac muscle, smooth muscle, gland)

efferent

• motor control is efferent output from the nervous system

• motor commands are sent to move muscles and related structures

motor fibers

• bundle of axons within a nerve that carry motor information from CNS toward skeletal muscle

motor neurons

• transmit the motor commands from the CNS to skeletal muscle

what do autonomic pathways do

• regulate the organs

• central nervous system control

2 major divisions of the CNS

sympathetic

• fight or flight

parasympathetic

• rest and digest

two-neuron chains

• autonomic pathways have 2 neuron chain in the PNS

• pre-ganglionic neuron exits the CNS

• post-ganglionic neuron signals directly to the organ

ganglion

a group of autonomic cell bodies outside of the CNS

parasympathetic nervous system

• cranial nerves (C3, C7, C9, C10)

• pelvic splanchnic nerves (S2, S3, S4)

• long pre-ganglionic axons

• terminal ganglia within organs

sympathetic nervous system

• lateral horns T1-L2 to sympathetic trunk

• cervical ganglia

• thoracic, lumbar, sacral splanchnic nerves

• abdominal ganglia

• short pre-ganglionic axons

• prominent ganglia near the spine

spinal cord

• protected by the vertebrae within the spinal canal

• part of the CNS

• foramen magnum ——> L1/L2

• anchored laterally by denticulate ligaments and inferiorly by filum terminale

name the spinal cord meninges and other spaces in order of out to in

• wall of vertebrae

• epidural space

• dura mater

• arachnoid mater

• subarachnoid space (filled with CSF)

• pia mater

what space does a lumbar puncture needle reach?

needle is inserted into the subarachnoid space to get a sample of CSF fluid

what space does an epidural needle reach?

epidural needle stays in the epidural space before the dura matter

name the gross features of the spinal cord

• cervical

• thoracic

• lumbar

• sacral

• coccygeal

• conus medullaris

• cauda equina

• filum terminale

cauda equina

• the spinal cord ends at L1/L2

• lumbar and sacral parts of the spinal cord end much higher than their vertebrae send nerves below through cauda equina

sectional anatomy of the spinal cord

white matter:

• posterior, lateral, anterior funiculus

gray matter:

• posterior, lateral, anterior horns

• central canal

• posterior median sulcus

• anterior median fissure

spinal nerves

• combined sensory, motor, and autonomic nerve roots that exit the spinal canal via the intervertebral foramen

rami

• spinal nerve branches

• form nerve plexuses

posterior ramus

innervate deep muscles and skin of the back

anterior ramus

innervate anterior and lateral portions of the trunk, upper limbs, and lower limbs

rami communicantes

• between the spinal nerves and the sympathetic trunk ganglia of the sympathetic trunk

how to number spinal nerves

• cervical spinal nerves exit above corresponding cervical vertebrae

• C8 spinal nerve exits above T1

• thoracic, lumbar, sacral, coccygeal spinal nerves exit below corresponding vertebrae

cervical plexus

• spinal nerves C1-C4

  • innervate anterior neck muscles, skin of the neck, and parts of the head and shoulders

• phrenic nerves C3, C4, C5

  • innervate the diaphragm

brachial plexus

• spinal nerves C5-T1

  • innervate the pectoral girdle and the entire upper limb of one side

  • roots, trunks, divisions, cords, branches (richard tucker drinks cold beer)

thoracic nerves

• no plexus

• T1-T11 anterior rami form intercostal nerves (between adjacent ribs)

• T12 isubcostal nerve

lumbosacral plexus: lumbar

• spinal nerves L1-L4

  • anterior division

    • includes obturator nerve

  • posterior division

    • includes femoral nerve

lumbosacral plexus: sacral

• spinal nerves L4/5, S1-S4

• includes sciatic nerve

deep back muscles of the vertebral column

action:

• vertebral extension, lateral flexion of the spine

innervation:

• dorsal rami of spinal nerves

erector spinae muscles

lateral to medial

1. iliocostalis group

2. longissimus group

3. spinalis group

transversospinalis muscles

1. multifidus

2. semispinalis

3. rotatores

action:

• vertebral extension

• lateral flexion or rotation of the spine

quadratus lumborum

origin:

• 12th rib; transverse process of lumbar vertebrae

insertion:

• iliac crest

innervation:

• T12-L4 spinal nerves

action:

• spinal extension, lateral flexion, depresses rib 12

serratus posterior

• serratus posterior superior

• serratus posterior inferior

both extend, laterally rotate the spine, and stabilize posture

trapezius

action:

• elevation, superior rotation of the scapula (superior), retraction of the scapula (middle), depression of the scapula (inferior)

origin:

• occipital bone, ligamentum nuchae, spinous processes of C7-T12

insertion:

• clavicle, acromion and spine of scapula

innervation:

• CN XI accessory nerve

test: “shrug your shoulders”

latissimus dorsi

action:

• extension, adduction, medial rotation of the arm

origin:

• spinous processes of T7-T12, ribs 8 to 12, iliac crest, thoracolumbar fascia

insertion:

• intertubercular sulcus of the humerus

innervation:

• thoracodorsal nerve (C6-C8)

vertebral landmarks

• vertebra prominens: C7

• iliac crest (intercristal line): palpated near L3/L4 and imaging at L4/L5

what muscles border the triangle of ausculatation

• trapezius

• latissimus dorsi

• rhomboid major