Is the motor homunculus in the primary motor cortex?
The primary motor cortex lies anterior to the central sulcus. As with the postcentral sensory gyrus, a motor homunculus indicates the areas of cortex controlling different muscle groups (Fig. 35.10). The size of the region in the homunculus represents the number of motor units in the innervated muscles.
Which part of the cortex would be considered Agranular?
Agranular cortex: Areas of the cerebral cortex lacking a distinct layer 4, typically related to a paucity or lack of stellate cells. In mice, essentially all cortical areas anterior and medial to the somatosensory (barrel) cortex are agranular. Frontal cortex is defined as areas 4, 6, 8, 10, and 11 (Caviness, 1975 ).
What is a motor homunculus?
The motor homunculus is a topographic representation of the body parts and its correspondents along the precentral gyrus of the frontal lobe. While the sensory homunculus is a topographic representation of the body parts along the postcentral gyrus of the parietal lobe.
What does the supplementary motor cortex do?
The supplementary motor area (SMA) is a part of the primate cerebral cortex that contributes to the control of movement. It is located on the midline surface of the hemisphere just in front of (anterior to) the primary motor cortex leg representation. In monkeys the SMA contains a rough map of the body.
What is a homunculus sensation and motor?
Motor and sensory homunculus are two areas that show neurological connections that associate the brain, nerves and spinal cord. Motor homunculus is the imaginary map of neurological connections based on motor processing. Sensory homunculus is the imaginary map of neurological connections based on sensory processing.
What is my homunculus?
This map is different than a simple picture of your body. For example, a small portion of cortex is devoted to your arm, while a very large portion is dedicated to your hand and fingers. This odd map, corresponding body part to touch sensitivity, is called a homunculus, Latin for “little man”.
Why is motor cortex Agranular?
The motor cortex is also known as the agranular cortex because of the masking (attenuation) of the granular layers, particularly the inner granular layer. It occupies most of the frontal lobe and exerts control over the axial and appendicular muscles.
Which leukocytes are Agranular?
both lymphocytes and monocytes are agranular leukocytes. Monocytes fight bacteria, viruses, and fungi. The are the biggest type of white blood cell. They are formed in the bone marrow.
What is the function of the somatosensory cortex?
The primary somatosensory cortex is responsible for processing somatic sensations. These sensations arise from receptors positioned throughout the body that are responsible for detecting touch, proprioception (i.e. the position of the body in space), nociception (i.e. pain), and temperature.
What happens if supplementary motor cortex is damaged?
Supplementary motor area (SMA) syndrome is defined as temporary paralysis and mutism following damage to the SMA. Although paralysis induced by SMA syndrome is severe during the acute phase, recovery usually occurs within relatively short periods and rarely results in a permanent deficit.
Does the primary motor cortex homunculus represent the activity of individual muscles?
Movements of individual muscles are correlated with activity from widespread parts of the primary motor cortex. Similarly, stimulation of small regions of primary motor cortex elicits movements that require the activity of numerous muscles. Thus, the primary motor cortex homunculus does not represent the activity of individual muscles.
Why is the motor cortex also called the agranular cortex?
The motor cortex is also known as the agranular cortex because of the masking (attenuation) of the granular layers, particularly the inner granular layer. It occupies most of the frontal lobe and exerts control over the axial and appendicular muscles.
Is the dorsolateral area connected to the primary motor cortex?
The dorsolateral area is interconnected to the supplementary motor and premotor cortices but not the primary motor cortex. It is also connected to the frontal eye field (area 8) rostral part of the cingulate gyrus as well as the cerebellum and the superior colliculus.
How does the motor cortex affect the tectospinal tract?
Motor cortex output can alter some of the descending pathways. Therefore, in combination with the corticospinal tract’s direct cortical innervation of alpha nerve cells, the accompanying cortical efferent routes regulate the other descending tracts: The corticotectal tract enables the cortex to influence the tectospinal tract.