Chapter 16 Flashcards
What are the two functions of the spinal cord?
pathway for sensory and motor impulses
responsible for reflexes
How many longitudinal depressions does a spinal cord have?
two
Longitudinal depressions
the posterior (or dorsal) median sulcus, dips internally on the posterior surface the anterior (or ventral) median fissure, is observed on its anterior surface
Cervical region
the superior-most region of the spinal cord
continuous with the medulla oblongata
contains neurons whose axons form the cervical spinal nerves
Thoracic region
lies inferior to the cervical region
thoracic spinal nerves are attached
Lumbar region
shorter segment of the spinal cord
contains the neurons for the lumbar spinal nerves
Sacral region
lies inferior to the lumbar region
contains the neurons for the sacral spinal nerves
Coccygeal region
most inferior “tip” of the spinal cord.
one pair of coccygeal spinal nerves arises
What is the conus medullaris?
The tapering inferior end of the spinal cord
What does the conus medullaris mark?
it marks the official “end” of the spinal cord proper
How many pairs are spinal nerves does the spinal cord have?
31 pairs of spinal nerves
The 31 pairs connect to….
CNS to muscles, receptors, and glands.
How many cervical nerves does the spinal cord have?
8 (C1–C8)
How many thoracic nerves does the spinal cord have?
12 (T1-T12)
How many lumbar nerves does the spinal cord have?
5 (L1-L5)
How many sacral nerves does the spinal cord have?
5 (S1-S5)
How many coccygeal nerve does the spinal cord have?
1 (Co)
The grey matter resembles a….
Letter H or Butterfly
Grey Matter is subdivided into what 4 components?
anterior horns
lateral horns
posterior horns
the gray commissure
How does a spinal nerve form?
anterior root + posterior root = intervertebral foramen
Each spinal nerve is associated with the…..
Vertebra of the same number
What is a Dermatomes?
specific segment of skin supplied by a single spinal nerve
What does the anterior (ventral) ramus supply?
supply anterior and lateral regions of the neck, trunk, and all regions of the limbs
What does the posterior (dorsal) ramus supply?
supply back/posterior of neck and trunk, contain both sensory and motor neurons
What is nerve plexuses?
A network of interweaving anterior rami of spinal nerves.
What principal plexuses?
cervical plexuses, brachial plexuses, lumbar plexuses, and sacral plexuses
Cervical plexus
C1-C4
Brachial plexus
C5-T1
Lumbar plexus
L1-L4
Sacral plexus
L4-S4
Why is stimulus required?
to initiate a response to sensory input
What does a rapid response require?
few neurons be involved and synaptic delay be minimal
What does a muscle and a nerve makeup?
a myotomes
C3-5
Supply the diaphragm (mostly C4)
C5
C5 also supplies bicep and deltoid
C6
Bends the wrist back and rotates the arm
C7
Straightens the elbow and wrist; pronates wrist
C8
Bends the finger
T1
Spreads the fingers and supplies small muscles of the hand
T1-T12
supplies the chest wall and abdominal muscles
T10- L2
Psychogenic erections (thought controlled)
L2
Bends the hip
L1-L4
Thigh flexion
L2, L3, L4
Extension of leg at the knee and Thigh ADDuction
L4, L5, S1
Thigh ABDuction, Dorsiflexion of foot, extension of toes
L4, L5, S1, S2
Flexion of leg at the knee (hamstrings)
L5, S1 , S2
Extension of leg at the hip (gluteus maximus)
Plantar flexion of foot
Flexion of toes
S2, S3 , S4
Control a man’s ability to have an erection and Ejaculation
S3- S5
supply the bladder, bowel and sex organs and the anal and other pelvic muscles
What is ipsilateral? (Touching HOT)
when both the receptor and effector organs of the reflex are on the same side of the spinal cord
What is contralateral? (Steeping on SHARP)
when the sensory impulses from a receptor organ cross over through the spinal cord to activate effector organs in the opposite limb
What is the simplest of reflexes?
Monosynaptic reflexes (ex. Reflex Hammer)
What does Golgi tendon reflex do?
Prevents skeletal muscles from tensing excessively.
Golgi Tendon
protects the muscle and tendon from excessive tension damage
