GLOSSARY

The muscles of the head are a group of skeletal muscles in the head region involved in facial expression, chewing, eye movement, and tongue movement.

Main Groups

• Muscles of facial expression: such as the orbicularis oculi, orbicularis oris, zygomaticus, and frontalis; unlike most muscles, they attach to the skin and are supplied by the facial nerve (cranial nerve VII).
• Muscles of mastication: the masseter, temporalis, and the two pterygoid muscles; supplied by the mandibular branch of the trigeminal nerve (cranial nerve V).
• Extraocular muscles: six muscles for precise movement of the eyeball.
• Tongue muscles: for speech and swallowing.

Characteristics

The facial muscles have very small motor units, allowing subtle expressions.

Relevance to Sport and Clinical Application

• Bell’s palsy: sudden paralysis of one side of the face due to facial-nerve dysfunction.
• Jaw clenching: in strength sports such as weightlifting, jaw clenching may slightly aid force (concurrent activation potentiation) but places high stress on the teeth and jaw joint; a mouthguard in contact sports prevents dental injury.
• Extraocular muscles: rapidly tracking a ball in tennis and baseball depends on the coordination of these muscles.