Clinical notes on EOM
✅ MR (medial rectus EOM)
• Origin: Annulus of Zinn
• Ms length: 40 mm
• Tendon length: 3.6 mm
• Insertion: 5.5 from
✅ LR (lateral rectus EOM)
• Origin: Annulus of Zinn
• Ms length: 40 mm
• Tendon length: 8.4 mm
• Insertion: 6.9 mm from limbus
✅ SR (superior rectus EOM)
• Origin: Annulus of Zinn
• Ms length : 41 mm
• Tendon length: 5.4 mm
• Insertion: 7.7 mm from limbus
✅ IR (Inferior rectus EOM)
• Origin: Annulus of Zinn
• Ms length: 40 mm
• Tendon length: 5.0 mm
• Insertion: 6.5 mm from limbus
✅ SO (superior oblique EOM)
• Origin: Sphenoid
• Ms length: 32 mm
• Tendon length: From 10mm pre-trochlea
• Insertion : Posterior superotemporal
✅ IO (iinferior oblique EOM)
• Origin: Orbital floor
• Ms Length: 34 mm
• Tendon length: Minimal
• Insertion : posterior temporal
In other words from EOM:
✅ The longest : LR ( 48.4 mm)
✅ shortest : IO ( almost 34 mm)
✅ anterior origin: IO
✅ posterior origin : SO, IR,SR,MR, LR
✅ Anterior insertion : SR,LR,MR,IR
✅ posterior insertion: SO, IO
✅ nearest to limbus:MR( 5.5 mm)
✅farthest from limbus: SR ( 7.7 mm)
✅ longest tendon: SO ( 10 mm)
✅ Shortest tendon: IO ( almost no tendon)
✅ 3 rd nerve supply: IR , SR, MR ,IO
✅ 6th nerve supply: LR
✅ 4th nerve supply : SO
✅ elevators : SR,IO
✅depressors : IR, SO
✅ abductors : LR ,SO, IO
✅ Adductors : MR , SR, IR
✅ intorters : SO, SR
✅extorters : IO, IR
EOM PowerPoint presentation:
- EXTRAOCULAR MUSCLES Dr.Lhacha Wangdi (Resident), Department of Ophthalmology JDWNRH
- Learning objectives 1. Physiology of ocular movement 2. Anatomy of extra ocular muscles (EOM) 3. Clinical correlates
- Outline 1. Gross anatomy of EOM 2. Physiology of extra ocular movement 3. Perimuscular connective tissue 4. Microscopic anatomy of EOM 5. Law of ocular movements
- introduction Extraocular muscle (EOM) plays vital role in visual system 1. Provides static adjustment of binucular alignment necessary to enable BSV and steropsis 2. Precise dynamic movements to acquire and maintain visual targets Fibers of EOMs are mesodermal in origin and Perimuscular Connective tissues are neural crest in origin
- Extraocular muscles 7 extraocular muscles 1. Lateral rectus 2. Medial rectus 3. Superior rectus 4. Inferior rectus Levator Pelpebrae Superioris Two oblique musclesFour Rectus muscles 5.Superior oblique 6.Inferiro Oblique
- Muscle cone The rectus muscle forms the muscle cone within the orbit with apex at their origin and base at their penetration of tenon’s capsule. Each muscle is surrounded by fibrous capsule which are attached by thin continuous membrane called intermuscular septum Intermuscular septum divides orbital fat pad into extraconal fat and intraconal fat which help to maintain cushioning effects. Intermuscular septum fuses with tenon 3mm from the limbus Fibrous capsule Intermuscular septum Intraconal fat Extraconal fat Muscle cone
- The fascia bulbi The tenon capsule/fascia bulbi is an envelope of elastic fibrous connective tissue Form protective covering and the site of attachment of EOM Tenon capsule fuses with optic nerve sheath posteriorly and anteriorly with intermascular septum, 3 mm posterior to the limbus. EOM penetrates the tenon capsule 10 mm posterior to their insertion Tenons are divided into anterior and posterior parts Tenon capsule 10mm
- Muscle pulley As the EOM penetrates the tenon capsule the connective tissue forms the sleeves around the muscles creating muscle pulleys. Discrete rings of dense collagen tissue encircling EOM & are about 2mm length Pulley redirects the muscle and acts as functional origin it also prevents displacement of muscle during movement Because of pulley mechanism muscle are inflect at the insertion forming angle with the orbital axis. muscle pulley Pulley Angle
EOM (extraocular muscles) videos:
EOM Extraocular Muscles | Eye Anatomy – YouTube
The anatomy of the extraocular muscles – YouTube
Actions of the ocular muscles – YouTube
Extra Ocular Muscles Explained 3d Medical animation
Clinical notes on EOM
