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Lacrimal Nerve
The lacrimal nerve is the smallest of the three main branches of the ophthalmic nerve (CN V1) (itself a branch of the trigeminal nerve (CN V)). It enters the orbit outside the common tendinous ring and passes forward along the side wall of the orbit. It provides sensory innervation to the skin and both surfaces of conjunctiva at the lateral portion of the upper eyelid. It also receives a parasympathetic secretomotor communicating branch for the lacrimal gland which it conveys to the gland. Structure Origin The lacrimal nerve branches from the ophthalmic nerve immediately before traveling through the superior orbital fissure to enter the orbit. At the superior portion of the lateral wall of the orbit, it also receives a secretomotor communicating parasympathetic branch from the zygomaticotemporal nerve for the lacrimal gland. Course It enters the orbit through the superior orbital fissure outside (lateral to) the common tendinous ring, coursing lateral to the front ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ocular Muscles
The extraocular muscles, or extrinsic ocular muscles, are the seven extrinsic muscles of the eye in humans and other animals. Six of the extraocular muscles, the four recti muscles, and the superior and inferior oblique muscles, control movement of the eye. The other muscle, the levator palpebrae superioris, controls eyelid elevation. The actions of the six muscles responsible for eye movement depend on the position of the eye at the time of muscle contraction. The ciliary muscle, pupillary sphincter muscle and pupillary dilator muscle sometimes are called intrinsic ocular muscles or intraocular muscles. Structure Since only a small part of the eye called the fovea provides sharp vision, the eye must move to follow a target. Eye movements must be precise and fast. This is seen in scenarios like reading, where the reader must shift gaze constantly. Although under voluntary control, most eye movement is accomplished without conscious effort. Precisely how the integration between ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Frontal Nerve
The frontal nerve is the largest branch of the ophthalmic nerve (V1), itself a branch of the trigeminal nerve (CN V). It supplies sensation to the skin of the forehead, the mucosa of the frontal sinus, and the skin of the upper eyelid. It may be affected by schwannoma. Structure The frontal nerve is a branch of the ophthalmic nerve (V1), itself a branch of the trigeminal nerve (CN V). The frontal nerve branches immediately before entering the superior orbital fissure. In then travels superolateral to the annulus of Zinn between the lacrimal nerve and inferior ophthalmic vein. After entering the orbit it travels anteriorly between the roof periosteum and the levator palpebrae superioris. Midway between the apex and base of the orbit it divides into two branches, the supratrochlear nerve and supraorbital nerve. Functions The two branches of the frontal nerve provide sensory innervation to the skin of the forehead, mucosa of the frontal sinus (an air sinus), and the skin of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eyelid
An eyelid ( ) is a thin fold of skin that covers and protects an eye. The levator palpebrae superioris muscle retracts the eyelid, exposing the cornea to the outside, giving vision. This can be either voluntarily or involuntarily. "Palpebral" (and "blepharal") means relating to the eyelids. Its key function is to regularly spread the tears and other secretions on the eye surface to keep it moist, since the cornea must be continuously moist. They keep the eyes from drying out when asleep. Moreover, the blink reflex protects the eye from foreign bodies. A set of specialized hairs known as lashes grow from the upper and lower eyelid margins to further protect the eye from dust and debris. The appearance of the human upper eyelid often varies between different populations. The prevalence of an epicanthic fold covering the inner corner of the eye account for the majority of East Asian and Southeast Asian populations, and is also found in varying degrees among other populat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lacrimal Gland
The lacrimal glands are paired exocrine glands, one for each eye, found in most terrestrial vertebrates and some marine mammals, that secrete the aqueous layer of the tear film. In humans, they are situated in the upper lateral region of each orbit, in the lacrimal fossa of the orbit formed by the frontal bone. Inflammation of the lacrimal glands is called dacryoadenitis. The lacrimal gland produces tears which are secreted by the lacrimal ducts, and flow over the ocular surface, and then into canals that connect to the lacrimal sac. From that sac, the tears drain through the lacrimal duct into the nose. Anatomists divide the gland into two sections, a palpebral lobe, or portion, and an orbital lobe or portion. The smaller ''palpebral lobe'' lies close to the eye, along the inner surface of the eyelid; if the upper eyelid is everted, the palpebral portion can be seen. The orbital lobe of the gland, contains fine interlobular ducts that connect the orbital lobe and the palpe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orbital Septum
In anatomy, the orbital septum (palpebral fascia) is a membranous sheet that acts as the anterior (frontal) boundary of the orbit. It extends from the orbital rims to the eyelids. It forms the fibrous portion of the eyelids. Structure In the upper eyelid, the orbital septum blends with the tendon of the levator palpebrae superioris, and in the lower eyelid with the tarsal plate. When the eyes are closed, the whole orbital opening is covered by the septum and tarsi. Medially it is thin, and, becoming separated from the medial palpebral ligament, attaches to the lacrimal bone at its posterior crest. The medial ligament and its much weaker lateral counterpart, attached to the septum and orbit, keep the lids stable as the eye moves. The septum is perforated by the vessels and nerves which pass from the orbital cavity to the face and scalp. Clinical significance Orbital septum supports the orbital contents located posterior to it, especially orbital fat. The septum can be w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lacrimal Artery
The lacrimal artery is an artery of the Orbit (anatomy), orbit. It is a branch of the ophthalmic artery. It accompanies the lacrimal nerve along the upper border of the lateral rectus muscle, travelling forward to reach the lacrimal gland. It supplies the lacrimal gland, as well as Extraocular muscles, two rectus muscles of the eye, the Eyelid, eyelids, and the conjunctiva. Structure Origin The lacrimal artery is normally a branch of the ophthalmic artery and represents one of its largest branches. Its origin occurs near the optic foramen, optic canal. It usually branches off the ophthalmic artery just after the ophthalmic artery's entry into the Orbit (anatomy), orbit. It can rarely arise before the ophthalmic artery enters the optic canal. Course and relations The lacrimal artery accompanies the lacrimal nerve along the upper border of the lateral rectus muscle. It travels anterior-ward to supply the lacrimal gland. Branches and distribution The lacrimal artery suppli ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lateral Rectus Muscle
The lateral rectus muscle is a muscle on the lateral side of the eye in the orbit. It is one of six extraocular muscles that control the movements of the eye. The lateral rectus muscle is responsible for lateral movement of the eyeball, specifically abduction. Abduction describes the movement of the eye away from the midline (i.a. nose), allowing the eyeball to move horizontally in the lateral direction, bringing the pupil away from the midline of the body. Structure The lateral rectus muscle originates at the lateral part of the common tendinous ring, also known as the annular tendon. The common tendinous ring is a tendinous ring that surrounds the optic nerve and serves as the origin for five of the seven extraocular muscles, excluding the inferior oblique muscle. The lateral rectus muscle inserts into the temporal side of the eyeball. This insertion is around 7 mm from the corneal limbus. It has a width of around 10 mm. Nerve supply The lateral rectus is the only musc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trochlear Nerve
The trochlear nerve (), ( lit. ''pulley-like'' nerve) also known as the fourth cranial nerve, cranial nerve IV, or CN IV, is a cranial nerve that innervates a single muscle - the superior oblique muscle of the eye (which operates through the pulley-like trochlea). Unlike most other cranial nerves, the trochlear nerve is exclusively a motor nerve ( somatic efferent nerve). The trochlear nerve is unique among the cranial nerves in several respects: * It is the ''smallest'' nerve in terms of the number of axons it contains. * It has the greatest intracranial length. * It is the only cranial nerve that exits from the dorsal (rear) aspect of the brainstem. * It innervates a muscle, the superior oblique muscle, on the opposite side (contralateral) from its nucleus. The trochlear nerve decussates within the brainstem before emerging on the contralateral side of the brainstem (at the level of the inferior colliculus). An injury to the trochlear nucleus in the brainstem will result i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Common Tendinous Ring
The common tendinous ring, also known as the annulus of Zinn or annular tendon, is a ring of fibrous tissue surrounding the optic nerve at its entrance at the apex of the orbit. It is the common origin of the four recti muscles of the group of extraocular muscles. It can be used to divide the regions of the superior orbital fissure. The arteries surrounding the optic nerve form a vascular structure known as the circle of Zinn-Haller, or sometimes as the ''circle of Zinn''. The following structures pass through the tendinous ring (superior to inferior): * Superior division of the oculomotor nerve (CNIII) * Nasociliary nerve (branch of ophthalmic nerve) * Inferior division of the oculomotor nerve (CNIII) * Abducens nerve The abducens nerve or abducent nerve, also known as the sixth cranial nerve, cranial nerve VI, or simply CN VI, is a cranial nerve in humans and various other animals that controls the movement of the lateral rectus muscle, one of the extraocula ... (CNVI) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Superior Orbital Fissure
The superior orbital fissure is a foramen or cleft of the skull between the lesser and greater wings of the sphenoid bone. It gives passage to multiple structures, including the oculomotor nerve, trochlear nerve, ophthalmic nerve, abducens nerve, ophthalmic veins, and sympathetic fibres from the cavernous plexus. Structure The superior orbital fissure is usually 22 mm wide in adults, and is much larger medially. Its boundaries are formed by the (caudal surface of the) lesser wing of the sphenoid bone, and (medial border of the) greater wing of the sphenoid bone. Contents The superior orbital fissure is traversed by the following structures: * (superior and inferior divisions of the) oculomotor nerve (CN III) * trochlear nerve (CN IV) * lacrimal, frontal, and nasociliary branches of ophthalmic nerve (CN V1) * abducens nerve (CN VI) * superior ophthalmic vein and superior division of the inferior ophthalmic vein * sympathetic fibres from the cavernous nerve plex ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zygomaticotemporal Nerve
The zygomaticotemporal nerve (zygomaticotemporal branch, temporal branch) is a cutaneous ( sensory) nerve of the head. It is a branch of the zygomatic nerve (itself a branch of the maxillary nerve (CN V2)). It arises in the orbit and exits the orbit through the zygomaticotemporal foramen in the zygomatic bone to enter the temporal fossa. It is distributed to the skin of the side of the forehead. It also contains a parasympathetic secretomotor component for the lacrimal gland which it confers to the lacrimal nerve (which then delivers it to the gland). Structure Origin The zygomaticotemporal nerve is a branch of the zygomatic nerve. Course It passes along the lateral wall of the orbit in a groove in the zygomatic bone. It passes through the zygomaticotemporal foramen of the zygomatic bone to emerge (at the anterior portion of) the temporal fossa. In the temporal fossa, it passes superior-ward between the two layers of the temporal fascia, between the temporal bone an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trigeminal Nerve
In neuroanatomy, the trigeminal nerve (literal translation, lit. ''triplet'' nerve), also known as the fifth cranial nerve, cranial nerve V, or simply CN V, is a cranial nerve responsible for Sense, sensation in the face and motor functions such as biting and chewing; it is the most complex of the cranial nerves. Its name (''trigeminal'', ) derives from each of the two nerves (one on each side of the pons) having three major branches: the ophthalmic nerve (V), the maxillary nerve (V), and the mandibular nerve (V). The ophthalmic and maxillary nerves are purely sensory, whereas the mandibular nerve supplies motor as well as sensory (or "cutaneous") functions. Adding to the complexity of this nerve is that Autonomic nervous system, autonomic nerve fibers as well as special sensory fibers (taste) are contained within it. The motor division of the trigeminal nerve derives from the Basal plate (neural tube), basal plate of the embryonic pons, and the sensory division originates in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
