Spinal Cord – Flashcards

- Conducts sensory impulses from body to brain - Conducts motor impulses from brain to body - Controls reflex activities

- Duramater is subdural space filled with interstitial fluid - Arachnoid mater is subarachnoid space filled with cerebrospinal fluid - Pia mater

- Flattened cylinder 42-45cm long, 2 cm diameter - Lies within the spinal canal - Extends from the foramen magnum to L4 in newborn, to L1 in adults. - Growth of cord stops at age 5

- Because people get taller

enlargement in spinal cord in cervical region, a lot of information the spinal cord has to handle and work it has to do in that region

nerves of pelvis and lower limbs

- Cone shaped end of the spinal cord (where the spinal cord ends).

-Dorsal, ventral roots of lowest spinal nerves

- Thread like extension of pia mater - stabilizes spinal cord in the spinal canal

Crescent shaped projection of gray matter within the spinal cord where sensory neurons enter the spinal cord

somatic motor neurons whose axons exit the cord via ventral roots

a thin strip of gray matter that surrounds the central canal of the spinal cord and, along with the anterior white commissure, connects the two halves of the cord.

(only in thoracic regions)

conveys two-point discrimination, vibratory and proprioceptive senses

Ventral white matter

the white matter of the spinal cord lying on either side between the anterior median fissure and the ventral root.

- Contains sensory fibers

- Contains motor vibers

Roots

- Contains cell bodies of sensory neurons

- Highways for sensory and motor information (sensory tracts ascend, motor tracts descend)

- In anterior part of the spinal cord - Impulses travel from spinal cord to thalamus

- Pyramidal (corticospinal) - Extrapyramidal tracts

- Dorsal Columns - Spinothalamic - Spinocerebellar

- Propioception - Discriminative Touch - Two point discrimination - Pressure - Vibration

- Pain, temperature, crude touch, deep pressure

- Unconscious propioception - Sensing balance

- Precise, voluntary movements

- "programmed" automatic movement - Co-ordinate gross movements and visual reflexes

- Regions in the CNS that relay impulses from sensory to motor neurons

- Fast, predictable, automatic responses to environmental changes

- Spinal cord serves as an integrating center for spinal reflexes

- Stretch Reflex - Tendon Reflex - Flexor (withdrawal) reflex - Crossed extensor reflex

- Monosynaptic reflex - Prevents over-stretching injury

- Golgi tendon organs activated when tendon stretched. - Muscle relaxes - Antagonistic muscle contracts - Prevents tendon damage

- Post synaptic reflexes

- Draws limb away from painful stimulus - Pain signals activate motor fibers in several spinal cord segments - >1 muscle group activated to lift foot

- Extends contralateral limb to maintain balance - Pain signals to contralateral spinal cords - Contralateral extensors contract, flexors relax - Contralateral limb extends to support body

- Protection - minimizes duration of exposure to noxious stimuli - Maintain posture, balance - Co-ordination

- Branch from spinal cord and emerge through intervertebral foramina = small holes - Mixed nerves (contain sensory and motor fibers)

- Epineurium - Perineurium - Endoneirum

31 pairs of Spinal Nerves

Spinal Nerves

Dorsal and Ventral rami

- Complex network of nerves - Switchbox for ventral rami of spinal nerves - Found in cervical, brachial, lumbar and sacral regions - s.n. T2-T12 don't form plexuses

- Ventral Rami of Spinal Nerves C1 to C5 - Innervates skin and muscles of the head and neck, and superior shoulders and chest.

Keeps the diaphragm alive

- Ventral rami of spinal nerves C5 to T1 - Innervate shoulder and upper limb - Roots merge to form superior, middle, and inferior trunks - Trunks merge to form lateral, posterior and medial cords - Most nerves branch from cords

Deltoid innervation

Forearm Innervation

Posterior of the arm

Supply the anterior muscles of the arm

- Ventral Rami of Spinal Nerves L1 to L4 - Innervates abdominal wall, external genitals and anterior-medial thigh - Femoral Nerve

- Ventral rami of Spinal Nerves L4 to S4 - Innervates buttocks, perineum and part of lower limb - Sciatic Nerve

- Area of skin supplied by one spinal nerve - Overlap of dermatones prevent loss of sensation if one spinal nerve is damaged (must block/cut 3 adjacent spinal nerves to induce local anesthesia)