EXTRAOCULAR MUSCLES Flashcards
1
Q
SPIRAL OF TILLAUX
A
- rectus muscles pass through tenon’s capsule + insert into the sclera
- muscles insert at different distances from the cornea
- insertion pattern is a spiral with medial rectus closest to the cornea (5.5mm) + superior rectus furthest away (7.4mm)
2
Q
TENON’S CAPSULE
A
- bulk of orbital fascial system
- forms envelope in which the eyeball moves
- fuses post. with optic nerve sheath
- fuses ant. with inter-muscular septum
3
Q
ANNULUS OF ZINN
A
- ring of fibrous tissue surrounding optic nerve (ophthalmic artery + vein)
- all EOM arise from here except IO
- cone shaped structure behind eye
4
Q
TROCHLEA
A
- loop of fibrous tissue that SO tendon passes through
- exerts pressure used in pulley system
5
Q
ORIGIN OF INFERIOR OBLIQUE
A
behind lacrimal fossa
6
Q
ORIGIN OF SUPERIOR OBLIQUE
A
lesser wing of sphenoid bone
7
Q
SUPERIOR OBLIQUE CN
A
trochlear nerve (IV)
8
Q
WHERE DO OBLIQUES INSERT INTO?
A
posterior aspect of sclera
9
Q
THICK FIBRES
A
- striated muscle
- singly innervated
- motor end plate
- fast + slow twitch fibres
- all or none contraction
10
Q
THIN FIBRES
A
- striated muscle
- multiply innervated (many branches, 1 nerve)
- en grappe end plate
- slow sustained (tonic)
- graded contraction
11
Q
MOTION OF EYE
A
X axis - nasal -> temporal
Y axis - anterior -> posterior
Z axis - superior -> inferior
12
Q
SACCADES
A
eye movement - quick jumps
13
Q
SMOOTH TRACKING
A
combined head + eye tracking
14
Q
WHAT INNERVATES THE LATERAL RECTUS?
A
abducens - cranial nerve VI
15
Q
WHAT DOES CRANIAL NERVE III INNERVATE?
A
(oculomotor nerve)
- levator palpebrae
- superior rectus
- medial rectus
- inferior rectus
- inferior oblique
