Muscles of the Head - Muscle Directory

Definitions

Muscle - name of the muscle
Origin (Proximal Attachment) - attachment point that does NOT move when contracting- usually a bone.
Insertion (Distal Attachment) - attachment point that does move during contraction- usually a bone.
Innervation - describes nerve distribution to the specific muscle
Blood Supply - describes arterial structures that supply muscle

Head Muscles List

• Scalp and Eyelid
  • Occipitalis
  • Frontalis
  • Orbicularis Oculi
  • Corrugator Supercilii
  • Depressor Supercilii
• Extraocular - Controls Movement of Eye
  • Superior Rectus
  • Inferior Rectus
  • Medial Rectus
  • Lateral Rectus
  • Levator Palpebrae Superioris
  • Superior Tarsal
  • Superior Oblique
  • Inferior Oblique

Occipitalis 
The lateral portion of the superior nuchal line of the occipital bone.

Distal attachment
Galea aponeurotica (aponeurosis of the epicranium).

Innervation
Posterior auricular branch of the facial nerve (cranial nerve VII).

Blood supply
Branches from the occipital artery.

Primary action
1. Pulls the scalp posteriorly.
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Frontalis
Proximal attachment
Galea aponeurotica (aponeurosis of the epicranium).

Distal attachment
By right and left bellies from the skin of the eyebrow, with fibers extending down to interdigitate with orbicularis oculi and procerus.

Innervation
Temporal branch of the facial nerve (cranial nerve VII).

Blood supply
Supraorbital branch from the ophthalmic artery.

Primary actions
1. Wrinkles the skin of the forehead.

2. Elevation of the eyebrows
Agonists: none
Antagonists: corrugator supercilii, orbicularis oculi, and procerus

Secondary action
3. Assists with elevation of the upper eyelid.
Agonist: levator palpebrae superioris
Antagonist: orbicularis oculi, palpebral portion
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Orbicularis Oculi
Proximal attachment
Palpebral part: to the medial palpebral ligament and adjacent bone on the medial side of the orbit.
Orbital part: to a slip of bone adjacent to the orbit on the orbital process of the frontal bone, to the frontal process of the maxilla, and to the medial palpebral ligament between the two bony areas.

Distal attachment
Palpebral part: into the skin of the eyelids, blending with levator palpebrae superioris and continuing on to the lateral palpebral raphe.
Orbital part: into the skin surrounding the orbit and blending with adjacent facial muscles.

Innervation
Temporal and zygomatic branches of the facial nerve (cranial nerve VII).

Blood supply
Branches from the ophthalmic artery.

Primary actions
1. Closes the eyelids.

2. Depression of the eyebrows (Anim)
Agonists: corrugator supercilii and procerus
Antagonist: frontalis and levator palpebrae superioris
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Corrugator Supercilii
Proximal attachment
Medial superciliary arch.

Distal attachment
Skin of the middle of the eyebrow.

Innervation
Temporal and zygomatic branches of the facial nerve.

Blood supply
Branches of the superficial temporal artery.

Primary action
1. Depression of the eyebrows (Anim)
Agonists: orbicularis oculi and procerus
Antagonists: frontalis
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Depressor Supercilii
Proximal attachment
medial orbital rim

Distal attachment
medial aspect of bony orbit

Primary Action
depression of eyebrow 
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Superior Rectus
Origin
The superior rectus muscle is slightly larger than the other recti muscles. It arises from the upper part of the common tendinous ring, above and lateral to the optic foramen. Some fibers also arise from the dural sheath of the optic nerve.

Insertion
The fibers pass forwards and laterally, at an angle of about 25 degrees to the median plane of the eye in the primary position, to insert into the upper part of the sclera about 8 mm from the limbus. The insertion of the superior rectus muscle is slightly oblique, the medial margin being more anterior than the lateral margin.

Nerve supply
The superior division of the oculomotor nerve supplies the muscle. This nerve enters the inferior surface of the muscle.

Vasculature
The arterial supply is derived both directly from the ophthalmic artery and indirectly from its supra-orbital branch.

Action
Superior rectus moves the eye so that the cornea is directed upwards (elevation) and medially (adduction). To obtain upward movement alone, the muscle must function with the inferior oblique muscle. The superior rectus muscle also causes intorsion of the eye, i.e. medial rotation. Because a check ligament extends from the muscle to the levator palpebrae superioris muscle, elevation of the cornea also results in elevation of the upper eyelid.
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Inferior Rectus
Origin
Inferior rectus arises from the common tendinous ring, below the optic canal. It runs along the orbital floor in a similar direction to superior rectus, i.e. forwards and laterally.

Insertion
The muscle inserts obliquely into the sclera below the cornea, 6 mm from the limbus.

Nerve supply
A branch of the inferior division of the oculomotor nerve innervates the inferior rectus muscle. This branch enters the superior surface of the muscle.

Vasculature
The arterial supply is derived from the ophthalmic artery and from the infra-orbital branch of the maxillary artery.

Action
The principal activity of inferior rectus is to move the eye so that the cornea is directed downwards (depression). The muscle also causes the cornea to deviate medially. To obtain downward movement alone, the muscle must function with the superior oblique muscle. The inferior rectus muscle is responsible for extorsion of the eye, lateral rotation. A check ligament passes from the inferior rectus muscle to the inferior tarsal plate of the eyelid. This causes the lower eyelid to be slightly depressed when the inferior rectus muscle contracts.
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Medial Rectus
The medial rectus muscle is slightly shorter than the other recti muscles, but is said to be the strongest.

Origin
It arises from the medial part of the common tendinous ring. In addition, some fibers arise from the dural sheath of the optic nerve. It passes horizontally forwards along the medial wall of the orbit, below the superior oblique muscle.

Insertion
It inserts into the medial surface of the sclera, approximately 5.5 mm from the limbus and slightly anterior to the other recti muscles.

Nerve supply
A branch from the inferior division of the oculomotor nerve supplies this muscle. This branch enters the lateral surface of the muscle.

Vasculature
The arterial supply is derived from the ophthalmic artery.

Actions
The medial rectus muscle moves the eye so that the cornea is directed medially (adducted). The two medial recti muscles acting together are responsible for convergence.
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Lateral Rectus
Origin
This muscle arises from the lateral part of the common tendinous ring. It bridges the superior orbital fissure. Some fibers also arise from a spine on the greater wing of the sphenoid.

Insertion
The fibers pass horizontally forward along the lateral wall of the orbit to insert into the lateral surface of the sclera, about 7 mm from the limbus.

Nerve supply
Lateral rectus receives its nerve supply from the abducent nerve. This nerve enters the medial surface of the muscle.

Vasculature
The artery to this muscle arises from the ophthalmic artery directly and/or from its lacrimal branch.

Action
Contraction of the lateral rectus muscle moves the eye so that the cornea is directed laterally (abducted).

Pathology

Acquired paralysis of this muscle indicates possible damage to the VI cranial nerve (abducent), which supplies it.
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