The Ocular Appendages
The eyebrows: The eyebrows lie at the junction of the forehead and the upper lid. Several muscles of facial expressions are inserted into the skin permitting movement of the eyebrows. - Raising of the eyebrows is accomplished by contracting the frontalis muscle. - lowering the eyebrows by contracting the orbital part of orbicularis oculi. - Drawing the eyebrows medially by contracting the corrugator supercilli muscle. All these muscles are supplied by the seventh cranial nerve (facial nerve).
The eyebrows receive an arterial supply from the Supraorbital and supratrochlear branches of the ophthalmic artery. The corresponding veins drain into the angular vein and so enter the facial vein. The lymphatic drainage of the lateral end is into the superficial parotid nodes and from the medial end into the Submandibular nodes.
The eyelids
The lateral angle of the eye is directly in contact with the eyeball, whereas the medial rounded angle lies about 6mm medially from the eyeball. Here the two eyelids are separated by a small triangular space, the lacus lacrimalus, in the center of which is a small, pinkish elevation, the caruncula lacrimalus.
An eyelid is a thin fold of skin and muscle that covers and protects the eye.
The upper eyelid is larger and more mobile than the lower.
The eyelids meet at the medial and lateral angles (or canthi).
The palpebral fissure is the elliptical opening between the two eyelids
About 5 mm from the medial angle there is a small elevation, the papilla lacrimalus. On the summit of the papilla is a small hole, the punctum lacrimale.
A grayish line or slight sulcus can sometimes be seen running along the eyelid margin between the eyelashes and the openings of the tarsal glands(meibomian glands), this represents the line between the anterior portion of the eyelid formed by the skin and orbicularis oculi muscle and the posterior portion formed by the tarsus and the conjunctiva.
Structure of the eyelid
04. Orbital septum and tarsal plate
01. Skin
02. Subcutaneous tissue
05. Smooth muscle
06. Conjunctiva
3. striated muscle fibers of the orbicularis oculi
From superficial to deep, each eyelid consists
1-The skin
2- Subcutaneous tissue
It is very thin and easily folds.
Microscopic examination of the skin shows many small hairs with sebaceous glands and small sweat glands
It is very loose and rich in elastic fibers. In whites, it is almost devoid of fat
3-Orbicularis oculi
It is a flat, elliptical muscle that surrounds the orbital margin extending onto the temporal region and cheek (orbital part) it also extends into the eyelids (palpebral portion and further behind the lacrimal sac (lacrimal portion). It is composed of striated muscle.
The palpebral portion of the orbicularis oculi muscle consists of thin bundles of fibers that arise from the medial palpebral ligament; then these fibers sweep laterally across the eyelids and interlace at the lateral palpebral raphe .
Nerve supply
Temporal and zygomatic branches of the facial nerve.
4- Orbital septum and tarsal plate
The fibrous framework of the eyelids is formed by a membranous sheet, the orbital septum. It is continuous with the periosteum (preiorbita).
The orbital septum acts as a diaphragm between the anterior and posterior part of the orbit so it prevents spread of the inflammation fluid and the blood between the anterior and posterior part of the orbit.
The tarsal plate consists of the dense fibrous tissue and gives the eyelids firmness and shapes
The tarsal plate of the upper eyelid is much larger than the lower and is crescent shaped; each tarsus is approximately 29 mm long and 1 mm thick. The upper tarsus measures around 10 mm in the center and gradually narrows towards its ends, and the lower one measures around 5 mm in height at the center and gradually narrows towards its end.
The tarsal glands (Meibomian glands) are embedded within the substance of the tarsal plate, they are about 20 to 25 in each lid arranged in a single row .
5-Smooth muscle
The function of the superior tarsal muscle is to raise the upper lid and assist the striated muscle of the levator palpebrae superioris.
The function of the inferior tarsal muscle is to lower the lower lid .
Paralysis of the smooth muscle results in drooping of the upper lid (ptosis).
The smooth muscle forms the superior and inferior tarsal muscles
Ocular Appendages
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Transcript
The Ocular Appendages
The eyebrows: The eyebrows lie at the junction of the forehead and the upper lid. Several muscles of facial expressions are inserted into the skin permitting movement of the eyebrows. - Raising of the eyebrows is accomplished by contracting the frontalis muscle. - lowering the eyebrows by contracting the orbital part of orbicularis oculi. - Drawing the eyebrows medially by contracting the corrugator supercilli muscle. All these muscles are supplied by the seventh cranial nerve (facial nerve).
The eyebrows receive an arterial supply from the Supraorbital and supratrochlear branches of the ophthalmic artery. The corresponding veins drain into the angular vein and so enter the facial vein. The lymphatic drainage of the lateral end is into the superficial parotid nodes and from the medial end into the Submandibular nodes.
The eyelids
The lateral angle of the eye is directly in contact with the eyeball, whereas the medial rounded angle lies about 6mm medially from the eyeball. Here the two eyelids are separated by a small triangular space, the lacus lacrimalus, in the center of which is a small, pinkish elevation, the caruncula lacrimalus.
An eyelid is a thin fold of skin and muscle that covers and protects the eye. The upper eyelid is larger and more mobile than the lower. The eyelids meet at the medial and lateral angles (or canthi). The palpebral fissure is the elliptical opening between the two eyelids
About 5 mm from the medial angle there is a small elevation, the papilla lacrimalus. On the summit of the papilla is a small hole, the punctum lacrimale.
A grayish line or slight sulcus can sometimes be seen running along the eyelid margin between the eyelashes and the openings of the tarsal glands(meibomian glands), this represents the line between the anterior portion of the eyelid formed by the skin and orbicularis oculi muscle and the posterior portion formed by the tarsus and the conjunctiva.
Structure of the eyelid
04. Orbital septum and tarsal plate
01. Skin
02. Subcutaneous tissue
05. Smooth muscle
06. Conjunctiva
3. striated muscle fibers of the orbicularis oculi
From superficial to deep, each eyelid consists
1-The skin
2- Subcutaneous tissue
It is very thin and easily folds. Microscopic examination of the skin shows many small hairs with sebaceous glands and small sweat glands
It is very loose and rich in elastic fibers. In whites, it is almost devoid of fat
3-Orbicularis oculi
It is a flat, elliptical muscle that surrounds the orbital margin extending onto the temporal region and cheek (orbital part) it also extends into the eyelids (palpebral portion and further behind the lacrimal sac (lacrimal portion). It is composed of striated muscle.
The palpebral portion of the orbicularis oculi muscle consists of thin bundles of fibers that arise from the medial palpebral ligament; then these fibers sweep laterally across the eyelids and interlace at the lateral palpebral raphe .
Nerve supply
Temporal and zygomatic branches of the facial nerve.
4- Orbital septum and tarsal plate
The fibrous framework of the eyelids is formed by a membranous sheet, the orbital septum. It is continuous with the periosteum (preiorbita).
The orbital septum acts as a diaphragm between the anterior and posterior part of the orbit so it prevents spread of the inflammation fluid and the blood between the anterior and posterior part of the orbit.
The tarsal plate consists of the dense fibrous tissue and gives the eyelids firmness and shapes
The tarsal plate of the upper eyelid is much larger than the lower and is crescent shaped; each tarsus is approximately 29 mm long and 1 mm thick. The upper tarsus measures around 10 mm in the center and gradually narrows towards its ends, and the lower one measures around 5 mm in height at the center and gradually narrows towards its end.
The tarsal glands (Meibomian glands) are embedded within the substance of the tarsal plate, they are about 20 to 25 in each lid arranged in a single row .
5-Smooth muscle
The function of the superior tarsal muscle is to raise the upper lid and assist the striated muscle of the levator palpebrae superioris. The function of the inferior tarsal muscle is to lower the lower lid . Paralysis of the smooth muscle results in drooping of the upper lid (ptosis).
The smooth muscle forms the superior and inferior tarsal muscles