Ch 10 Appendicular Muscles: Lower Limbs LAB

Overview of Muscles of the Hip and Thigh

• Introduction

  • Understanding the evolution of human locomotion and anatomy

  • Connection between human muscle anatomy and four-legged animals

Muscles of the Medial Thigh

• Muscles Included

  • Psoas Major

  • Origin: Lumbar vertebrae

  • Function: Hip flexion

  • Iliacus Muscle

  • Origin: Iliac fossa of the pelvis

  • Function: Part of the iliopsoas, assists in hip flexion

• Iliopsoas Group

  • Combination of the iliacus and psoas major

  • Inserts onto the lesser trochanter of the femur

  • Action: Flexion of the hip when muscle contraction pulls leg upward

• Medial Thigh Muscles

  • Purpose: Movement of the leg toward the midline (adduction)

  • Key Muscles:

  • Adductor Longus

    • Function: Adducts the thigh

  • Adductor Magnus

    • Function: Adducts the thigh

  • Adductor Brevis

    • Function: Adducts the thigh

• Explanation of Medial and Anterior Positions

  • Recognition of anatomical orientations (anterior vs. posterior) using pelvic landmarks like the sacrum and symphysis pubis

  • Adductor Longus: Anterior most strap, prominent in movement

  • Gracilis: Starts at symphysis pubis, pulls to medial femur and tibia, aiding in thigh adduction

Lateral Thigh Muscles

• Muscle Group Introduction

  • Involved in hip abduction movements

  • Use of the iliotibial band (ITB) for muscle attachments

• Tensor Fasciae Latae

  • Description: Primary muscle that pulls on the ITB, aids in abduction

  • Function: Contraction felt when abduction movements are performed, stabilizes hip joint

• Gluteus Maximus and Medius

  • Largest muscle in the body, essential for maintaining upright posture

  • Gluteus Medius: Essential for abducting the hip

Posterior Thigh Muscles (Hip and Knee)

• Gluteus Maximus

  • Description: Thick muscle, key player in bipedal posture

  • Evolutionary perspective on muscle size differences between bipeds and quadrupeds

• Piriformis Muscle

  • Located near the sciatic nerve

  • Clinical relevance regarding sciatica due to compression of the nerve

• Hamstring Muscles

  • Crossing both the hip and knee joints

  • Muscles:

  • Biceps Femoris: Lateral aspect, flexes knee, extends hip

  • Semitendinosus and Semimembranosus: Medial, assist with the same actions as they cross both joints

Anterior Thigh Muscles

• Quadriceps Group

  • Description: Composed of four muscles

  • Key Muscles:

  • Rectus Femoris: Crosses both hip and knee joints, flexes hip, extends knee

  • Vastus Lateralis: Lateral muscle, assists in extending the knee

  • Vastus Medialis: Medial muscle, assists in extending the knee

  • Vastus Intermedius: Deep muscle, assists in the extension of the knee

  • Combined tendon work into the patella, which further pulls at the tibia

Lower Leg Muscles

• Compartments of the Lower Leg

  • Three compartments: Anterior, Lateral, and Posterior

Anterior Compartment Muscles

• Extensor Digitorum Longus

  • Function: Extends toes

• Tibialis Anterior

  • Function: Dorsiflexion and inversion of the foot

Lateral Compartment Muscles

• Fibularis Longus and Brevis

  • Function: Eversion of the foot

Posterior Compartment Muscles

• Gastrocnemius

  • Description: Upper portion, two bellies, attaches to the Achilles tendon

  • Function: Plantarflexion of the ankle

• Soleus

  • Description: Located beneath gastrocnemius, involved in stability during standing

Key Anatomical Concepts

• Importance of muscle origin and insertion in understanding function

• The unique abilities of muscles that cross multiple joints

• Clinical Considerations

  • Sciatica: Caused by irritation of the piriformis muscle on the sciatic nerve

  • Avulsion fractures in lateral ankle sprains

• Evolutionary Aspect

  • Differences in muscle development and function in different species due to lifestyle

• Muscle Function Testing: Ability to assess strength and actions of these muscles via movement and palpation.