What is the function of the anatomical structure indicated by the blue arrow in the image below?
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Options:
explanation: The image shows a lateral view of the thoracic wall, with a dissection of the external intercostal muscles of one of the intercostal spaces, showing the muscle layers underneath. The muscles indicated by the blue arrow are orientated obliquely, forward and upward, so they are the internal intercostal muscles, which lie directly underneath the external intercostal muscles. The internal intercostals are implicated in forced expiration and work by depressing the lower ribs and increasing the pressure in the thoracic cavity. The external intercostals work by elevating the ribs and decreasing the pressure in the thoracic cavity during inspiration.
name: Contributes to forced expiration by elevating the ribs and decreasing the pressure in the thoracic cavity
label: d
answer: no
explanation: The image shows a lateral view of the thoracic wall, with a dissection of the external intercostal muscles of one of the intercostal spaces, showing the muscle layers underneath. The muscles indicated by the blue arrow are orientated obliquely, forward and upward, so they are the internal intercostal muscles, which lie directly underneath the external intercostal muscles. The internal intercostals are implicated in forced expiration and work by depressing the lower ribs and increasing the pressure in the thoracic cavity. The resting inspirator movements are performed by the diaphragm.
name: Contributes to resting inspiratory movements
label: e
answer: no
explanation: The image shows a lateral view of the thoracic wall, with a dissection of the external intercostal muscles of one of the intercostal spaces, showing the muscle layers underneath. The muscles indicated by the blue arrow are orientated obliquely, forward and upward, so they are the internal intercostal muscles, which lie directly underneath the external intercostal muscles. The internal intercostal muscles are implicated in forced expiration and work by depressing the lower ribs and increasing the pressure in the thoracic cavity.
name: Contributes to forced expiration by depressing the lower ribs and increasing the pressure in the thoracic cavity
label: a
answer: yes
explanation: The image shows a lateral view of the thoracic wall, with a dissection of the external intercostal muscles of one of the intercostal spaces, showing the muscle layers underneath. The muscles indicated by the blue arrow are orientated obliquely, forward and upward, so they are the internal intercostal muscles, which lie directly underneath the external intercostal muscles. The internal intercostals are implicated in forced expiration, not forced inspiration and work by depressing the lower ribs and increasing the pressure in the thoracic cavity.
name: Contributes to forced inspiration by depressing the lower ribs and increasing the pressure in the thoracic cavity
label: b
answer: no
explanation: The image shows a lateral view of the thoracic wall, with a dissection of the external intercostal muscles of one of the intercostal spaces, showing the muscle layers underneath. The external intercostals are implicated in forced inspiration, elevating the ribs and decreasing the pressure in the thoracic cavity. The muscles indicated by the blue arrow are orientated obliquely, forward and upward, so they are the internal intercostal muscles, which lie directly underneath the external intercostal muscles. The internal intercostals are implicated in forced expiration and work by depressing the lower ribs and increasing the pressure in the thoracic cavity.
name: Contributes to forced inspiration by elevating the ribs and decreasing the pressure in the thoracic cavity
label: c
answer: no

Correct answer: a