Lecture Notes on Arm Muscles

Introduction

• Overview of arm muscles and their functions.

Pectoralis Major

• Location: Superficial muscle in the chest.
• Functions:
  • Flexes arm at shoulder joint.
  • Adducts at shoulder joint.
  • Medial rotation at shoulder joint.

Deltoid Muscle

• Structure: Three heads (anterior, middle, posterior).
• Functions:
  • General function: Abduction at the shoulder joint.
  • Anterior head: Flexion at the shoulder joint.
  • Lateral head: Abduction.
  • Posterior head: Extension at the shoulder joint.

Trapezius and Supraspinatus

• Trapezius: Superficial muscle covering deeper muscles.
• Supraspinatus:
  • Location: Sits in the supraspinous fossa.
  • Function: Abduction at the shoulder joint.

Infraspinatus and Teres Minor

• Infraspinatus:
  • Function: Lateral rotation (external rotation) of the arm.
• Teres Minor:
  • Function: Lateral rotation.
  • Synergists: Infraspinatus.

Teres Major

• Functions:
  • Extension at the shoulder joint.
  • Medial rotation.
  • Antagonist to infraspinatus and teres minor.

Subscapularis

• Location: Anterior side of scapula in the subscapular fossa.
• Function: Medial rotation.

Latissimus Dorsi

• Functions:
  • Extension at the shoulder joint.
  • Medial rotation.
  • Adduction.
  • Synergist with teres major and subscapularis.

Coracobrachialis

• Location: Attaches at the coracoid process.
• Functions:
  • Flexion at the shoulder joint.
  • Adduction at the shoulder joint.
  • Synergist to latissimus dorsi and teres major.

Biceps Brachii

• Structure: Two heads (short and long).
• Functions:
  • Flexion at the elbow.
  • Supination of the palm.

Brachialis

• Function: Flexion of the forearm.
• Synergist: Biceps brachii.

Triceps Brachii

• Structure: Three heads (lateral, long, medial).
• Function: Extension at the elbow.
• Antagonist: Biceps brachii and brachialis.

Anconeus

• Function: Assists in extension at the elbow.

Forearm Muscles (Extensor Side)

• Brachioradialis: Flexion of the forearm.
• Extensor Carpi Radialis Longus and Brevis: Extends the wrist.
• Extensor Digitorum: Extends the digits.
• Extensor Digiti Minimi: Extends the digits.
• Extensor Carpi Ulnaris: Extends the wrist.

Forearm Muscles (Flexor Side)

• Pronator Teres: Pronates the palm.
• Flexor Carpi Radialis and Ulnaris: Flexes the wrist.
• Palmaris Longus: Flexes the wrist.
• Flexor Digitorum Superficialis: Flexes the digits and wrist.
• Flexor Pollicis Longus: Flexes the pollex.
• Flexor Digitorum Profundus: Flexes the digits.
• Supinator: Supinates the palm.

Thenar Muscles

• Opponens Pollicis
• Abductor Pollicis Brevis
• Flexor Pollicis Brevis

Hypothenar Muscles

• Opponens Digiti Minimi
• Abductor Digiti Minimi
• Flexor Digiti Minimi

Conclusion

• Overview of the muscles discussed and their roles in arm movement.