Quick Answer: Why Does An Axon Collateral Ascend The Spinal Cord?

Why does the sensory homunculus appear distorted in the face and hands?

The reason for the distorted appearance of the homunculus is that the amount of cerebral tissue or cortex devoted to a given body region is proportional to how richly innervated that region is, not to its size.

The homunculus is like an upside-down sensory or motor map of the contralateral side of the body..

What are the major spinal cord tracts?

The four main plexuses are the cervical, brachial, lumbar and sacral.

What are the three sensory pathways?

A somatosensory pathway will typically consist of three neurons: primary, secondary, and tertiary.In the periphery, the primary neuron is the sensory receptor that detects sensory stimuli like touch or temperature. … The secondary neuron acts as a relay and is located in either the spinal cord or the brainstem.More items…

What part of the body does the lumbar spine control?

These lumbar vertebrae (or lumbar bones) contain spinal cord tissue and nerves which control communication between the brain and the legs. Damage to the lumbar spinal cord subsequently affects the hips and groin area, and may impact the lower abdominal muscles and thigh flexion as well.

What are the two major somatosensory pathways?

The somatosensory system consists of the two main paired pathways that take somatosensory information up to the brain: the medial lemniscal or posterior pathway, and the spinothalamic or anterolateral pathway. The somatosensory pathways are made up of a relay of four neurons.

What are ascending and descending pathways?

Ascending pathway: A nerve pathway that goes upward from the spinal cord toward the brain carrying sensory information from the body to the brain. In contrast, descending pathways are nerve pathways that go down the spinal cord and allow the brain to control movement of the body below the head.

What is the descending pathway?

The descending tracts are the pathways by which motor signals are sent from the brain to lower motor neurones. … The motor tracts can be functionally divided into two major groups: Pyramidal tracts – These tracts originate in the cerebral cortex, carrying motor fibres to the spinal cord and brain stem.

What is the difference between sensory and somatosensory?

As adjectives the difference between sensory and somatosensory. is that sensory is of the senses or sensation while somatosensory is (biology) of or pertaining to the perception of sensory stimuli produced by the skin or internal organs.

Which special sense is the most complex?

visionThere is a seemingly easy answer to this question: It is because vision is our most important and most complex sense.

What is the function of ascending tracts of the spinal cord?

Ascending and descending spinal tracts are pathways that carry information up and down the spinal cord between brain and body. The ascending tracts carry sensory information from the body, like pain, for example, up the spinal cord to the brain.

What is the ascending pain pathway?

The pathway that goes upward carrying sensory information from the body via the spinal cord towards the brain is defined as the ascending pathway, whereas the nerves that goes downward from the brain to the reflex organs via the spinal cord is known as the descending pathway.

What are the ascending pathways?

The ascending tracts refer to the neural pathways by which sensory information from the peripheral nerves is transmitted to the cerebral cortex. In some texts, ascending tracts are also known as somatosensory pathways or systems.

What are the major ascending sensory tracts?

Figure 14.5. 1 – Ascending Sensory Pathways of the Spinal Cord: The dorsal column system and spinothalamic tract are the major ascending pathways that connect the periphery with the brain. The trigeminal pathway carries somatosensory information from the face, head, mouth, and nasal cavity.

What protects the spinal cord?

The brain and spinal cord are protected by bony structures — the skull and spinal column. Meninges are membranes that cover and protect the brain and spinal cord.

What is the function of spinal nerves?

Spinal nerves, considered part of the peripheral nervous system, generally refer to mixed spinal nerves, which carry motor, sensory, and autonomic information between the brain and spinal cord and the rest of the body.

How are the two pathways different?

How are the two pathways different? In the first pathway activated nerve cells transmit touch to signals through the spinal cord and back to muscle cells, triggering muscles to move away from the source of pain. In the second pathway activated nerve cells transmit touch signals through the spinal cord to the brain.

How are spinal nerves attached to the spinal cord?

Each spinal nerve is attached to the spinal cord by two roots: a dorsal (or posterior) sensory root and a ventral (or anterior) motor root. The fibers of the sensory root carry sensory impulses to the spinal cord —pain, temperature, touch and position sense (proprioception)—from tendons, joints and body surfaces.

What is the gray commissure of the spinal cord?

The grey commissure is a thin strip of grey matter that surrounds the central canal of the spinal cord and, along with the anterior white commissure, connects the two halves of the cord. It comprises lamina X in the Rexed classification.

How many pairs of spinal nerves do humans have?

The spinal nerves consist of 31 symmetrical pairs of nerves that connect the spinal cord to the periphery. There are 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal nerves.

How do you appreciate the role of spinal cord in nervous system?

The brain and spinal cord are your body’s central nervous system. The brain is the command center for your body, and the spinal cord is the pathway for messages sent by the brain to the body and from the body to the brain.

What are the 4 processes of nociception?

There are four major processes: transduction, transmission, modulation, and perception. Transduction refers to the processes by which tissue-damaging stimuli activate nerve endings.