Which of the following extraocular muscles originate at the orbital rim?

rectus muscles
Extraocular Muscles The four rectus muscles (each about 3–4 cm long) originate from the annulus of Zinn at the orbital apex, which is contiguous with the dura surrounding the optic nerve and the periorbita.

Which muscle originates from the anterior of orbit?

Each of the rectus muscles originates posteriorly at the Annulus of Zinn and courses anteriorly along the orbital walls until it reaches its insertion point.

What is unique about the extraocular muscles?

Extraocular Muscles: Extraocular Muscle Anatomy The EOMs are quite distinct from noncranial skeletal muscles. They have one of the fastest contraction rates, the smallest motor units, and contain amongst the smallest myofiber cross-sectional areas.

Which muscles originate from the annulus of Zinn?

The annulus of Zinn is a dense, fibrous ring of connective tissue located at the apex of the orbit that is the origin of four of the six extraocular muscles – the superior rectus, inferior rectus, lateral rectus, and medial rectus.

Which cranial nerves innervate extraocular muscles?

The extraocular muscles are innervated by lower motor neurons that form three cranial nerves: the abducens, the trochlear, and the oculomotor (Figure 20.3).

What are the extraocular muscles of the orbit?

The 4 extraocular muscles that control eye movement in the cardinal directions (along with their functions) are the superior rectus, inferior rectus, lateral rectus and medial rectus muscles.

Are the extraocular muscles smooth or skeletal?

Extraocular muscles are among the fastest and most fatigue-resistant skeletal muscles. Their highly specialized function, to move a sensory organ, the eyeball, is reflected in their specific MHC content and the multiplicity of fiber types.

Which extraocular muscle does not arise from the tendinous ring of the orbit?

The superior oblique is one of the two noteworthy oblique extraocular muscles. These muscles are unique in that they do not originate from the common tendinous ring, have an angular attachment to the eyeball, and they attach to the posterior aspect of the eyeball.

Is the levator Palpebrae Superioris in extraocular muscle?

Six of the extraocular muscles control movement of the eye and the other muscle the levator palpebrae controls eyelid elevation….Movements.

What type of muscles are extraocular muscles?

Anatomical terms of muscle The extraocular muscles, are the seven extrinsic muscles of the human eye. Six of the extraocular muscles control movement of the eye and the other muscle the levator palpebrae controls eyelid elevation.

Where to do the extraocular muscles originate?

The extraocular muscles mostly originate at the annulus of Zinn , at the back of the eye socket . This is a fibrous ring that surrounds the optic nerve. The only muscle that doesn’t originate at this point is the inferior oblique which originates at the orbital floor.

What muscles are around the eye?

The orbicularis oculi muscle is a ringlike band of muscle, called a sphincter muscle, that surrounds the eye. It lies in the tissue of the eyelid and causes the eye to close or blink. At the same time, it compresses the nearby tear gland, or lacrimal gland, aiding the flow of tears over the surface of the eye.

What are the muscles of the eye and their functions?

There are six muscles responsible for the different movements of both eyes. They are the lateral, medial, inferior, and superior rectus, and the inferior and superior oblique muscles. Each one of these extraocular muscles has specific functions which allow each eye to move in certain directions.

What is extraocular movement?

The extraocular muscles are the six muscles that control movement of the eye and one muscle that controls eyelid elevation ( levator palpebrae ). The actions of the six muscles responsible for eye movement depend on the position of the eye at the time of muscle contraction.