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Biological: Behavioural genetics · Evolutionary psychology · Neuroanatomy · Neurochemistry · Neuroendocrinology · Neuroscience · Psychoneuroimmunology · Physiological Psychology · Psychopharmacology (Index, Outline)
| Iris dilator muscle | ||
|---|---|---|
 | ||
| Iris, front view. (Muscle visible but not labeled.) | ||
| The upper half of a sagittal section through the front of the eyeball. ("Radiating fibers" labeled near center.) | ||
| Latin | musculus dilatator pupillae | |
| Gray's | subject #225 1013 | |
| Origin: | ||
| Insertion: | ||
| Blood: | ||
| Nerve: | superior cervical ganglion (sympathetics) | |
| Action: | dilates pupil | |
| Antagonist: | iris sphincter muscle | |
| Dorlands/Elsevier | m_22/12548821 | |
The iris dilator muscle (pupil dilator muscle, pupillary dilator, radial muscle of iris, radiating fibers), is a smooth muscle[1] of the eye. It is innervated by the sympathetic system, which acts by releasing noradrenaline, which acts on α1-receptors.[2]. Thus, when presented with a threating stimuli that activates the fight-or-flight response, this innervation dilates the iris, thus temporarily letting more light reach the retina.
It has the opposite effect to the iris sphincter muscle
Additional images[]
See also[]
References[]
- ↑ jneurosci.org Muscarinic and Nicotinic Synaptic Activation of the Developing..
- ↑ Rang, H. P. (2003). Pharmacology, Edinburgh: Churchill Livingstone. Page 163
External links[]
- Description of function at tedmontgomery.com
- Slide at mscd.edu
- Dictionary at eMedicine dilator+pupillae+muscle
- Histology at Boston University 08010loa
scalp/eyelid: occipitofrontalis (occipitalis, frontalis) - orbicularis oculi - corrugator supercilii - depressor supercilii
extraocular: levator palpebrae superioris - superior tarsal - rectus (superior, inferior, medial, lateral) - oblique (superior, inferior) - intraocular: ciliary - iris dilator - iris sphincter
ear: auriculares - temporoparietalis - stapedius - tensor tympani
nose: procerus - nasalis (dilatator naris) - depressor septi nasi - levator labii superioris alaeque nasi
mouth: levator anguli oris/depressor anguli oris - levator labii superioris/depressor labii inferioris - zygomaticus (major, minor) - mentalis - buccinator - orbicularis oris - risorius
mastication: masseter - temporalis - pterygoid (lateral, medial)
tongue: extrinsic (genioglossus - hyoglossus - chondroglossus - styloglossus) intrinsic (superior longitudinal - inferior longitudinal - transversus - verticalis)
soft palate: levator veli palatini - tensor veli palatini - musculus uvulae - palatoglossus - palatopharyngeus
pharynx: pharyngeal constrictor (inferior, middle, superior) - stylopharyngeus - salpingopharyngeus
larynx: cricothyroid - posterior cricoarytenoid - lateral cricoarytenoid - arytenoid - thyroarytenoid
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