Overview
This lecture covers the major muscles involved in movements of the hand, forearm, face, and scalp, as well as their specific functions and anatomical locations.
Muscles of the Hand
- Thenar group: three muscles at the base of the thumb control thumb movement.
- Hypothenar group: three muscles at the palm's side and base of little finger control little finger motion.
Muscles of the Forearm and Wrist
- Brachialis: located in the upper arm, under biceps, flexes forearm at elbow.
- Brachioradialis: between upper arm and forearm, flexes the forearm.
- Flexor digitorum: side muscle in forearm, flexes fingers.
- Extensor digitorum: extends from elbow to back of forearm, extends fingers.
- Flexor carpi ulnaris: above ulna, flexes and moves wrist inward.
- Flexor carpi radialis: above radius, flexes and moves wrist outward.
- Extensor carpi radialis: middle of forearm, extends and abducts wrist.
Muscles of the Scalp and Head
- Epicranius: all structures above cranium, includes muscles, skin, and aponeuroses.
- Occipitofrontalis: broad muscle formed by two muscles joined by aponeuroses tendon.
- Occipitalis: at nape of neck, draws scalp back.
- Temporalis: above the ear.
- Auricularis anterior: in front of the ear.
- Auricularis posterior: behind the ear.
Muscles of the Face
- Corrugator: between eyebrows, draws them in and downward.
- Levator palpebrae superioris: above eyelids, raises the eyelid.
- Orbicularis oculi: circles eye socket, closes eyelid.
- Procerus: between eyebrows, draws brows down, wrinkles area between brows and upper nose.
- Nasalis: across bridge of nose, opens nostrils, wrinkles bridge of nose.
- Orbicularis oris: circles mouth, contracts and wrinkles lips (kissing/whistling).
- Levator labii superioris: above upper lip (three parts), raises nostrils and upper lip (distaste expression).
Key Terms & Definitions
- Thenar group — muscles at thumb base controlling thumb movement.
- Hypothenar group — muscles at little finger base controlling its movement.
- Brachialis — upper arm muscle under biceps, flexes forearm.
- Brachioradialis — muscle between upper arm and forearm, flexes forearm.
- Epicranius — structures above cranium including muscle, skin, and aponeuroses.
- Occipitofrontalis — broad muscle over skull, moves scalp.
- Corrugator — face muscle between eyebrows, draws brows downward.
- Levator labii superioris — muscle above upper lip, raises upper lip and nostrils.
Action Items / Next Steps
- Review the location and function of each muscle group.
- Memorize key muscle functions for exam preparation.