Answer:
The answer is B: All the muscle cells innervated by a single motor neurorn.
Explanation:
It is called a motor unit, all muscle fibers that are innervated by a motor neuron cell. A motor neuron cell can establish contact with up to 150 muscle fibrils, which when activated causes their simultaneous contraction, therefore, all the muscle fibers of a motor unit contract and relax at the same time.
Complete question with options:
Dorsal rami_________
A) contain cell bodies of sensory neurons.
B)unite to form plexuses in the cervical, brachial, lumbar, and sacral regions.
C)are the structures to which the rami communicantes are attached.
D)branch from spinal nerves to innervate the deep/intrinsic muscles of the back.
E)are the structure that lead to the sympathetic trunk ganglia.
Answer:
Dorsal rami branch from spinal nerves to innervate the deep/intrinsic muscles of the back. The correct option is D.
Explanation: the dorsal rami branches off from the spinal nerve at the posterior aspect hence its also called posterior rami.
Dorsal rami transmits;
-visceral motor,
-somatic motor, and
-sensory information to and from the skin and muscles of the back. Therefore is it is traumatised or severe during an accident or surgery respectively, it will cause numbness at the muscle of the back.
B. Simple columnar epithelium
SCE is in all skin, lung, and blood vessel walls.
1. spine and sacrum
2. atlas and axis
3. intervertebral discs
4. nucleus pulposus
