Muscle Anatomy Overview

Muscle Anatomy and Identification

• Semitendinosus

  • Function: Hamstring muscle involved in knee flexion and hip extension.
  • Origin: Ischial tuberosity.
  • Insertion: Medial surface of the tibia at the pes anserinus.

• Gracilis

  • Function: Adducts thigh, flexes knee.
  • Origin: Inferior ramus of pubis.
  • Insertion: Medial surface of the tibia at the pes anserinus.

• Subscapularis

  • Function: Internal rotation of the humerus and stabilization of the shoulder.
  • Origin: Subscapular fossa of the scapula.
  • Insertion: Lesser tubercle of the humerus.

• Semimembranosus

  • Function: Hamstring muscle that assists in knee flexion and hip extension.
  • Origin: Ischial tuberosity.
  • Insertion: Posterior part of the medial condyle of the tibia.

• Sartorius

  • Function: Flexes, abducts, and externally rotates the hip; flexes the knee.
  • Origin: Anterior superior iliac spine (ASIS).
  • Insertion: Medial aspect of the proximal tibia at the pes anserinus.

• Masseter

  • Function: Primary muscle of mastication (chewing), elevates the mandible.
  • Origin: Zygomatic arch.
  • Insertion: Angle and ramus of the mandible.

• Vastus Intermedius

  • Function: Extends the knee.
  • Origin: Anterior and lateral surfaces of the femur.
  • Insertion: Quadriceps tendon to patella and tibial tuberosity via the patellar ligament.

• Brachioradialis

  • Function: Flexes forearm at the elbow joint.
  • Origin: Lateral supracondylar ridge of the humerus.
  • Insertion: Styloid process of the radius.

• Supraspinatus

  • Function: Abducts the arm and stabilizes the shoulder joint.
  • Origin: Supraspinous fossa of the scapula.
  • Insertion: Greater tubercle of the humerus.

• Brachialis

  • Function: Flexes the elbow joint.
  • Origin: Distal half of the anterior surface of the humerus.
  • Insertion: Coronoid process and tuberosity of the ulna.

• Infraspinatus

  • Function: External rotation of the arm and stabilization of the shoulder joint.
  • Origin: Infraspinous fossa of the scapula.
  • Insertion: Greater tubercle of the humerus.

• Adductor Magnus

  • Function: Adducts the thigh and assists in hip extension.
  • Origin: Ischial and pubic rami, and ischial tuberosity.
  • Insertion: Linea aspera of the femur and adductor tubercle.