Which Muscle Contracts When You Open Your Eye

The upper right and upper oblique muscles attach to the top of the eye. The lower right and lower inclined position attach to the underside of the eye. The lateral right and the median right fix the sides furthest from the nose and closest to the nose. Despite the upper inclination that belongs to the cone, it takes an indirect path before joining the other EOM to the tin ring; The SO attaches to the top of the eye, passes through a fibrous ring called a “trochlea”, and then converges with the other MOE (see Figure 1). Four of the 6 extraocular muscles control movement in the cardinal directions: north, east, south, west (or up, right, bottom, left). The other 2 out of 6 extraocular muscles are responsible for counteracting head movements and adjusting eye movements accordingly. There is orbital fat that surrounds the sides and back of the eye, which cushions it, allows it to move more freely, and works to protect blood vessels and nerves as they pass through the back of the orbit. The orbicularis oculi muscle can also contract involuntarily in benign essential blepharospasm. This can severely affect a person`s ability to perform activities of daily living, such as reading and driving, as the person has trouble keeping their eyes open to see properly. Periodic chemodergivation of the orbicularis oculi muscle with botulinum toxin injections can significantly relieve symptoms. [7] [8] Damage to the smooth circle of pursuit: Damage to the temporal eye field results in deficits in the ability to fix objects and track them. Attempts to attach to a target are undermined by severe instability and eye wandering. Tracking movements are jerky rather than smooth when you try to follow an object moving in one direction (ipsilateral to) the side of the lesion.

Note that the smooth tracking circuit involves a double intersection and the temporal eye field controls ipsilateral eye movements (i.e., the right cortex controls smooth rightward tracking). If the temporal eye field is damaged, both eyes can follow a visual target in an ipsilesional direction; however, does so with the voluntary saccadic cycle. That is, if the frontal cortical eye fields are intact, the eyes can be moved voluntarily (guided jerks) in the direction of an object of interest ipsilateral to the deficiency. In this case, however, the movements will be jerky, unlike eye movements in smooth tracking. The pursuit of visual targets opposite the lesion proceeds smoothly. » Look to the right (Dextroversion): You already know that the lateral right adheres to the side of the eye that is furthest from the nose. Since muscles can only contract, it makes perfect sense for the LR to turn the eye away from the nose. So if you look to the right, the LR of the right eye causes the right rotation in orbit. The movement of the eyes away from the nose is called abduction.

The orbicularis oculi muscle receives its blood from the branches of the facial artery and the superficial temporal artery (which are branches of the external carotid artery), as well as from the ophthalmic artery (which is a branch of the internal carotid artery). Muscles move in response to nerve impulses carried by the base of the brain (brain stem) of three cranial nerves called oculomotor (or nerve III), trochlear nerve (or iv nerve) and abducens (or vi nerve). The trochlear nerve annoys the upper oblique muscle, the abducens nerve annoys the right latalis muscle and the oculomotor nerve annoys the other four as well as the lifting (or lifting) muscle of the upper eyelid. The accommodation response includes many structures involved in the pupil lumen response and, with the exception of the pretectal zone and supraococomotor region, damage to both pathways leads to frequent symptoms. The most common complaint affecting the coping response is its loss with aging (i.e., presbyopia). Remember that presbyopia is most often due to structural changes in the lens that hinder the response of lens imaging. Cranial nerve damage: Damage to the cranial nerves can lead to sensory and motor symptoms. Sensory loss would affect the sensations that the cranial nerve normally mediates (for example. B taste of the front two-thirds of the tongue and somatic sensations of the skin of the ear – if the facial nerve is damaged). Motor loss can be severe (i.e. A loss of inferior motor neuron leading to total paralysis) when the cranial nerve contains all the motor axons that control the muscles of the normally innervated area. You have just learned the six cardinal directions by examining Figure 2.

All these movements are “attached”, meaning that EOM works together in both eyes to move the eyes in the same direction at the same time; What one eye does, the other eye does automatically. For example, if something draws your eye to the left and your left eye moves quickly to focus the scene, you don`t need to consciously and separately tell your right eye to move to the left. Since this direction of view (“left”) is an attached eye movement, both eyes react. The lacrimal part is a small thin muscle, about 6 mm wide and 12 mm long, located behind the median palpebral ligament and lacrimal sac. It originates from the posterior crest and the adjacent part of the orbital surface of the lacrimal bone and divides behind the tear sac into two briefs, high and low, which are introduced into the upper and lower median tarsi of the puncta lacrimalia; Sometimes he is very indistinct. The organicularis lacrymal facilitates the tear pump in the lacrimal sac. [4] We have already seen the pairings (although without the agonist/antagonist terminology) when we look at both eyes in our discussion of cardinal directions (Figures 3 – 10). The following table summarizes the pairs of agonists when both eyes are considered a reference: the median rectus or muscles on the side of the nose move the eyes inward; When they work at the same time, they converge or cross their eyes. The lateral right or temporal lateral muscles move the eyes outward; When working at the same time, they diverge or look out. When they move the eyes from side to side – their main function – they work as a team so that normal movements are fluid and coordinated. For example, to look to the right, the nasal lateral muscle (middle right) of the left eye and the external muscle (right lateral) of the right contract; Their opposites (or antagonists) – the left and right lateral recti medials – relax.

Figure 8.1 The extraocular muscles of the right eye and their effects. Antagonistic actions draw the eye in opposite directions, while synergistic actions draw the eye in the same direction. The orbicularis oculi muscles orbit the eyes and are located just below the skin. Some parts of this muscle act to open and close the eyelids and are important muscles in facial expression. The orbicularis oculi muscle closes the eyelids and helps pump tears from the eye into the nasolacrimal canal system. The orbital section of Orbicularis oculi is more likely to be involved in the voluntary closure of the eyelid, such as winking and forced compression. The preseptal section is involved in both voluntary forced closure and involuntary blinking of the eye and closing of the eyelids during sleep. The pretarsal section is more involved in involuntary blinking of the eye and keeps the eyelids closed during sleep. Figure 7.6 The accommodation pathway includes the afferent limb, which includes the entire visual pathway; upper motor control structures encompassing an area of the visual association cortex and the supraococomotor zone; and the efferent limb, which includes the oculomotor nuclei and the ciliary ganglion. .