Give 2 different reasons why two muscles that act across the same side of the same joint are not necessarily redundant? Explain your reasons in detail and give at one real example that illustrates each reason.
Question 2. : Relate their structure of a neuron to the anatomy of the cerebral cortex and spinal cord. Be sure to discuss the locations of soma, axons, dendrites, and supportive cells in each area. "
This is cheating. HUman anatomy at trent university
Question 1: Reasons why two muscles that act across the same side of the same joint are not necessarily redundant:
Reason 1: Different roles in movement
Even though two muscles act across the same joint, they may have different roles in movement. This means that each muscle contributes to different aspects of the overall movement, making them non-redundant. One muscle may be responsible for the primary action, while the other muscle provides secondary or fine-tuning movements.
Example: Biceps brachii and brachialis in elbow flexion
In the case of elbow flexion, the biceps brachii and brachialis muscles both act across the elbow joint. However, they have distinct roles in this movement. The biceps brachii is the primary muscle responsible for flexing the elbow, while the brachialis provides additional support and strength to the movement. Despite both muscles contributing to elbow flexion, their roles are not redundant.
Reason 2: Different functions in stabilizing the joint
Muscles not only produce movement at a joint but also contribute to joint stability. Two muscles acting across the same joint may have different functions in stabilizing the joint, making them non-redundant. One muscle may primarily stabilize the joint in one plane of movement, while the other muscle stabilizes it in a different plane or provides overall joint support.
Example: Rotator cuff muscles in the shoulder
In the shoulder joint, there are four rotator cuff muscles: supraspinatus, infraspinatus, teres minor, and subscapularis. Although they all act across the shoulder joint, each muscle has a unique role in stabilization. The supraspinatus primarily helps with abduction of the arm, the infraspinatus and teres minor help with external rotation, and the subscapularis helps with internal rotation. These muscles work together to stabilize the shoulder joint in various movements, highlighting their non-redundancy.
Question 2: Relationship between the structure of a neuron and the anatomy of the cerebral cortex and spinal cord:
The structure of a neuron plays a crucial role in the functioning of the cerebral cortex and spinal cord. Understanding the locations of soma, axons, dendrites, and supportive cells in each area is key to understanding the overall organization and function of the nervous system.
Cerebral Cortex:
The cerebral cortex is the outermost layer of the brain and is responsible for higher cognitive functions. It is composed of a vast number of neurons organized into six layers. The structure of a neuron within the cerebral cortex includes:
1. Soma (cell body): The soma is located within the cerebral cortex and contains the nucleus, which houses the genetic material of the neuron.
2. Dendrites: Dendrites are branched extensions stemming from the soma. They receive signals from other neurons and transmit them to the soma for processing.
3. Axons: Axons are long, slender extensions of the neuron that transmit electrical signals away from the soma to other neurons or target cells. In the cerebral cortex, axons can extend over long distances, connecting different parts of the brain.
4. Supportive cells: The cerebral cortex is supported by glial cells, such as astrocytes and oligodendrocytes. Astrocytes provide nourishment and support to neurons, while oligodendrocytes produce myelin, a substance that insulates axons and facilitates faster signal transmission.
Spinal Cord:
The spinal cord is a long, cylindrical structure that runs within the spinal column. It serves as a communication pathway between the brain and the rest of the body, relaying sensory and motor signals. The structure of a neuron within the spinal cord includes:
1. Soma (cell body): The soma of spinal cord neurons is located within the grey matter, which forms the central core of the spinal cord.
2. Dendrites: Dendrites extend from the soma and receive sensory information from the peripheral nerves, such as touch, temperature, and pain signals.
3. Axons: Axons of spinal cord neurons transmit motor commands from the brain to muscles and glands, as well as relay sensory information from the peripheral nerves to the brain. Axons within the spinal cord are bundled together in the white matter, forming tracts that carry signals up and down the spinal cord.
4. Supportive cells: The spinal cord is supported by glial cells, specifically astrocytes and Schwann cells. Astrocytes provide support, while Schwann cells produce myelin sheaths around axons in the peripheral nervous system, facilitating signal transmission.
Overall, the structure of neurons in the cerebral cortex and spinal cord is intricately connected to their specific functions in information processing and transmission within the nervous system.