Muscle Anatomy, Contractions, and Testing

Identifying Muscles and Types of Contractions

Calf Muscles (Gastrocnemius and Soleus)

• Gastrocnemius:
  • To feel the medial or lateral head, point toes inward or outward, respectively.
• Anterior Tibialis:
  • Walking on heels primarily contracts the anterior tibialis.
  • This action causes dorsiflexion, lifting the foot upwards.
  • Walking on heels engages the anterior tibialis in an isometric contraction.

Types of Muscle Contractions

• Concentric Contraction: Muscle shortens while generating force (e.g., standing on toes).
• Eccentric Contraction: Muscle lengthens while generating force (e.g., slowly lowering from standing on toes).

Stretching the Calf Muscles

• Gastrocnemius and Soleus Stretch:
  • Lift the toes and lean into the stretch to feel it in the calf muscles.
  • Adjusting the angle of the foot (toes inward or outward) can target different parts of the gastrocnemius.
• Anterior Tibialis Stretch:
  • Sit with one leg crossed over the other.
  • Apply overpressure by pushing down on the big toe.
  • This action stretches the anterior tibialis.

Studying Muscles

• Use flashcards or mimic motions in a group setting to remember muscle actions and locations.

Extensor Carpi Ulnaris & Radiated Radialis

• Apply overpressure to the hand while extending it to feel the extensors contract.
• Be cautious with pressure to avoid issues if carpal problems exist
• Flexor Tendons: Flip the hand over to check flexor tendons.

Biceps and Triceps

• Biceps:
  • Long head biceps: typical bicep curl.
• Triceps:
  • Push against resistance to feel the triceps firing.
• Brachioradialis:
  • Flip the arm over to emphasize brachioradialis.
  • The muscle belly goes over the joint.
  • Assess the line of pull when testing or observing muscle engagement, focusing on flexion vs extension.

Shoulder Muscles

• Supraspinatus:
  • Important for overhead throwers due to its role in internal rotation and horizontal flexion.
• Deltoids:
  • Anterior Deltoid: Activated during forward punching motions.
  • Medial Deltoid: Engaged during lateral fly exercises.
  • Posterior Deltoid: Activated by drawing the arm back.
• Subscapularis:
  • Internal rotation is a key function; often a culprit in tendonitis for overhead athletes because of tendons fitting in small space through which inflammation may cause further irritation to the area
• Serratus Anterior:
  • Causes protraction of the shoulder blade.
  • Activated when punching forward.
• Rhomboids:
  • Responsible for retraction (squeezing the shoulder blades together).
  • Often sore due to poor posture and prolonged overstretching.
  • Strengthening exercises help counteract this.
• Pectoralis Muscles:
  • Pec Major: Two heads (clavicular and sternal).
    • Clavicular head: Involved in bringing the arm inwards.
    • Sternal Head: Engaged when moving towards the opposite hip due to the muscle's diagonal pull.

Manual Muscle Testing

• Vastus Medialis Oblique (VMO):
  • Patient sits on a table with the knee at 90 degrees.
  • Apply slight resistance above the ankle and have the patient extend the leg.
  • Assess for pain and strength, comparing bilaterally.
• Hamstrings:
  • Standing: Patient performs a curl while the tester resists the motion.
  • Concentric: Patient brings heel to buttock; tester resists the motion.
  • Eccentric: Tester straightens the leg while the patient resists.
• Medial Deltoid:
  • Patient elevates arm to the side; tester applies downward pressure while the patient resists.
  • This tests both the supraspinatus and medial deltoid.
• Biceps:
  • Brake Test: Patient performs a curl through the full range of motion, and the tester applies resistance to assess strength and stability.
  • Isometric Contraction: Tester holds the patient's arm in a flexed position and resists any movement to assess the bicep's ability to maintain the contraction.

Additional Notes on Manual Muscle Testing

• Always ensure the patient has no injuries before testing.
• Bilateral comparison is crucial for identifying weaknesses or potential injuries.
• If a significant strength difference exists, consider the possibility of an injury.
• Be cautious with pressure, especially when testing potentially weak areas.
• Dominant sides may exist, but significant weakness on one side compared to the other can indicate an issue.