Capsule of Ténon
Encyclopedia
The fascia bulbi is a thin membrane which envelops the eyeball from the optic nerve
to the limbus
, separating it from the orbital fat and forming a socket in which it moves.
Its inner surface is smooth, and is separated from the outer surface of the sclera
by the periscleral lymph space
.
This lymph space is continuous with the subdural
and subarachnoid cavities, and is traversed by delicate bands of connective tissue which extend between the fascia and the sclera.
The fascia is perforated behind by the ciliary vessels and nerves, and fuses with the sheath of the optic nerve and with the sclera around the entrance of the optic nerve
.
In front it adheres to the conjunctiva
, and both structures are attached to the ciliary region of the eyeball.
The structure was named after Jacques-René Tenon
(1724–1816), a French surgeon and pathologist.
The sheath of the Obliquus superior is carried as far as the fibrous pulley of that muscle; that on the Obliquus inferior reaches as far as the floor of the orbit, to which it gives off a slip.
The sheaths on the recti are gradually lost in the perimysium
, but they give off important expansions.
The expansion from the Rectus superior blends with the tendon of the Levator palpebrae; that of the Rectus inferior is attached to the inferior tarsus.
The expansions from the sheaths of the Recti lateralis and medialis are strong, especially that from the latter muscle, and are attached to the zygomatic bone and lacrimal bone respectively.
As they probably check the actions of these two Recti they have been named the medial and lateral check ligaments.
Charles Barrett Lockwood
described a thickening of the lower part of the fascia bulbi, which he named the 'suspensory ligament of the eye'. It is slung like a hammock below the eyeball, being expanded in the center, and narrow at its extremities which are attached to the zygomatic and lacrimal bone
s respectively.
, a small fold of conjunctiva is lifted off the eyeball and an incision made. A blunt, curved cannula is passed through the incision into the periscleral lymph space
and a volume of local anaesthetic solution is instilled. The advantages are a reduced risk of bleeding and of penetration of the globe, compared to peribulbar and retrobulbar approaches. Akinesia (paralysis of the external eye muscles) may be less complete, however.
Optic nerve
The optic nerve, also called cranial nerve 2, transmits visual information from the retina to the brain. Derived from the embryonic retinal ganglion cell, a diverticulum located in the diencephalon, the optic nerve doesn't regenerate after transection.-Anatomy:The optic nerve is the second of...
to the limbus
Corneal limbus
The corneal limbus is the border of the cornea and the sclera . The limbus is a common site for the occurrence of corneal epithelial neoplasm....
, separating it from the orbital fat and forming a socket in which it moves.
Its inner surface is smooth, and is separated from the outer surface of the sclera
Sclera
The sclera , also known as the white or white of the eye, is the opaque , fibrous, protective, outer layer of the eye containing collagen and elastic fiber. In the development of the embryo, the sclera is derived from the neural crest...
by the periscleral lymph space
Periscleral lymph space
The periscleral lymph space is the space between the outer surface of the sclera and the inner surface of the Capsule of Ténon of the eye. This lymph space is continuous with the subdural and subarachnoid spaces, and is traversed by fine bands of connective tissue.-References:*...
.
This lymph space is continuous with the subdural
Subdural space
The subdural space is an artificial space created by the separation of the arachnoid mater from the dura mater as the result of trauma, pathologic process, or the absence of cerebrospinal fluid as seen in a cadaver. In the cadaver, due to the absence of cerebrospinal fluid, the arachnoid mater...
and subarachnoid cavities, and is traversed by delicate bands of connective tissue which extend between the fascia and the sclera.
The fascia is perforated behind by the ciliary vessels and nerves, and fuses with the sheath of the optic nerve and with the sclera around the entrance of the optic nerve
Optic nerve
The optic nerve, also called cranial nerve 2, transmits visual information from the retina to the brain. Derived from the embryonic retinal ganglion cell, a diverticulum located in the diencephalon, the optic nerve doesn't regenerate after transection.-Anatomy:The optic nerve is the second of...
.
In front it adheres to the conjunctiva
Conjunctiva
The conjunctiva covers the sclera and lines the inside of the eyelids. It is composed of rare stratified columnar epithelium.-Function:...
, and both structures are attached to the ciliary region of the eyeball.
The structure was named after Jacques-René Tenon
Jacques-René Tenon
Jacques-René Tenon was a French surgeon who was born near the town of Joigny.-Biography:He studied medicine in Paris, where one of his instructors was Jacques-Bénigne Winslow . For several years he was associated with the Salpêtrière, and in 1757 attained the chair of pathology of the College of...
(1724–1816), a French surgeon and pathologist.
Relations to extraocular muscles
It is perforated by the tendons of the ocular muscles, and is reflected backward on each as a tubular sheath.The sheath of the Obliquus superior is carried as far as the fibrous pulley of that muscle; that on the Obliquus inferior reaches as far as the floor of the orbit, to which it gives off a slip.
The sheaths on the recti are gradually lost in the perimysium
Perimysium
Perimysium is a sheath of connective tissue that groups muscle fibers into bundles or fascicles.Recent advances in muscle physiology suggest that the perimysium plays a role in transmitting lateral contractile movements...
, but they give off important expansions.
The expansion from the Rectus superior blends with the tendon of the Levator palpebrae; that of the Rectus inferior is attached to the inferior tarsus.
The expansions from the sheaths of the Recti lateralis and medialis are strong, especially that from the latter muscle, and are attached to the zygomatic bone and lacrimal bone respectively.
As they probably check the actions of these two Recti they have been named the medial and lateral check ligaments.
Charles Barrett Lockwood
Charles Barrett Lockwood
Charles Barrett Lockwood was a British surgeon and anatomist who practiced surgery at St. Bartholomew's Hospital in London. Lockwood was a member of the Royal College of Surgeons....
described a thickening of the lower part of the fascia bulbi, which he named the 'suspensory ligament of the eye'. It is slung like a hammock below the eyeball, being expanded in the center, and narrow at its extremities which are attached to the zygomatic and lacrimal bone
Lacrimal bone
The lacrimal bone, the smallest and most fragile bone of the face, is situated at the front part of the medial wall of the orbit. It has two surfaces and four borders.-Lateral or orbital surface:...
s respectively.
Sub Tenon's block for ophthalmic surgery
Local anaesthetic may be instilled into the space between Tenon's capsule and the sclera to provide anaesthesia for eye surgery, principally cataract surgery. After applying local anaesthetic drops to anaesthetise the conjunctivaConjunctiva
The conjunctiva covers the sclera and lines the inside of the eyelids. It is composed of rare stratified columnar epithelium.-Function:...
, a small fold of conjunctiva is lifted off the eyeball and an incision made. A blunt, curved cannula is passed through the incision into the periscleral lymph space
Periscleral lymph space
The periscleral lymph space is the space between the outer surface of the sclera and the inner surface of the Capsule of Ténon of the eye. This lymph space is continuous with the subdural and subarachnoid spaces, and is traversed by fine bands of connective tissue.-References:*...
and a volume of local anaesthetic solution is instilled. The advantages are a reduced risk of bleeding and of penetration of the globe, compared to peribulbar and retrobulbar approaches. Akinesia (paralysis of the external eye muscles) may be less complete, however.