The Muscular System Muscles of the Head and Neck
Muscles of Facial expression common nerve supply via Cranial nerve 7 *(facial)
Occipitofrontalis two bellies, one central tendon. Each belly performs a different
Frontalis belly controls movement of eyebrows fascia around eyes.
Occipitalis belly draws scalp backwards.
Orbicularis Oculis surrounds eye, called the ‘winking’ muscle.
Zygomaticus (major and minor grouped) attach around mouth, ‘smiling’ muscle.
Obicularis Oris ‘kissing’ muscle.
Depressor Anguli Oris attaches from corner of chin (mandibular angle) to corner of
mouth. Called the ‘frowning’ muscle.
Platysma originates on the pectoralis major, reaches to mandible. Called the ‘shaving’
muscle men when they shave contract this muscle to tighten skin around neck.
Buccinator serves other functions, not just subject to facial expression. Called the
‘whistling’ muscle, there are two of them, and they are not contracted simultaneously;
one contracts first.
Facial Nerve (VII)
Arises in brainstem
Enters through internal acoustic meatus
Exits via the styloidmastoid foramen
5 main branches
Bell’s Palsy refers to damage of the facial nerve, resulting in a droopy appearance. Some
of the muscles of facial expression lose functioning.
Muscles of Mastication
Masseter named for its size. Attaches from zygomatic down to angle of
mandible. Contraction of this muscle closes the jaw.
Temporalis originates off of temporal bone. Moves underneath zygomatic
process. Inserts onto coronoid processes on mandible.
The above muscles are innervated by the mandibular branch of the Trigeminal nerve.
There are three branches of cranial nerve 5, the first branch is the Opthlamic nerve,
second is the maxillary nerve (goes through rotundrum), and third is the Mandibular
nerve (innervating the masseter and the temporalis muscles)
Buccinator largely responsible for moving cheeks inward, as well as sideto
side. Allows you to put food between your molars for proper chewing. Innervated
by the facial nerve. Deeper Layers
Two pterygoid muscles arise from the pterygoid plate of the sphenoid bone.
o Lateral pterygoid muscle runs from the lateral pterygoid process to the
temporal mandibular joint. When it contracts it pulls the jaw forward
o Medial pterygoid stems off of process of sphenoid bone but moves
downwards to angle of mandible (on inside of bone). Moves jaw side
to side. Assists the buccinator in keeping food in molars. Delicate
movements not abrupt.
Muscles of the Tongue (Glossus)
Intrinsic muscles of tongue important to speech & chewing not prime moves of jaw.
Styloglossus Stoyloid process down to glossus (underneath tongue). During
contraction, it moves tongue towards styloid processes retraction & slight
Hyloglossus Runs from hyoid bone to bottom of tongue. Draws sides of
Genioglossus Innerside of mandible to underside of tongue. Contracts and
brings tongue forwards.
Those three muscles are innervated by the Hypoglossal cranial nerve (7).
Palatoglossus important role in gag reflex. Soft palate to underside of
tongue. Pushes tongue against soft palate (roof of mouth).
The palatoglossus muscle is the only glossus muscle innervated by the vagus nerve.
Extrinsic Muscles of the Eye
Trochlear Nerve innervation