Regional Anatomy of the Trunk LE Fall 2024

Regional Anatomy of the Trunk

Posterior Muscles of the Thorax

  • Trapezius

    • Fiber Regions and Actions:

      • Superior fibers: Elevation of scapula

      • Middle fibers: Retraction of scapula

      • Inferior fibers: Depression of scapula

    • Motor Innervation: Accessory CN XI

  • Latissimus Dorsi

    • Actions: Extension of arm, adduction of arm, medial rotation of arm

  • Rhomboid Major

    • Actions: Elevation of scapula, retraction of scapula

  • Rhomboid Minor

    • Actions: Elevation of scapula, retraction of scapula

  • Levator Scapulae

    • Action: Elevation of scapula

  • Erector Spinae Group

    • Action: Extension of vertebral column

    • Groups:

      • Iliocostalis group (most lateral)

      • Longissimus group (lateral to spinalis)

      • Spinalis group (most medial)

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Posterior Neck and Abdominal Wall Muscles

Neck Muscles

  • Splenius Capitis

    • Actions: Ipsilateral neck rotation, extension of neck

  • Semispinalis Capitis

    • Action: Extension of neck

Abdominal Wall Muscles

  • Rectus Abdominis

    • Action: Flexion of trunk

    • Key Structures:

      • Tendinous intersection (inscription)

      • Anterior rectus sheath

      • Posterior rectus sheath

      • Linea alba

  • Transversus Abdominis

    • Action: Compresses abdominal wall during forced exhalation

  • External Oblique

    • Action: Flexion of trunk

  • Internal Oblique

    • Action: Flexion of trunk

  • Quadratus Lumborum

    • Action: Extension of trunk

  • Psoas Major and Iliacus

    • Both have the action: Flexion of thigh

Muscles of the Lower Extremity

Gluteal Muscles

  • Gluteus Maximus

    • Actions: Extension of thigh, lateral rotation of thigh, abduction of thigh

  • Gluteus Medius

    • Actions: Abduction of thigh, medial rotation of thigh

  • Gluteus Minimus

    • Actions: Abduction of thigh, medial rotation of thigh

  • Piriformis

    • Action: Lateral rotation of thigh

Arteries and Veins

  • Abdominal Aorta (unpaired)

    • Begins at diaphragm

    • Branches:

      • Celiac trunk (unpaired)

      • Superior mesenteric artery (unpaired)

      • Inferior mesenteric artery (unpaired)

      • Renal arteries & veins (Right drains into inferior vena cava, Left drains into left renal vein)

      • Gonadal artery & veins (Right drains into inferior vena cava, Left drains into left renal vein)

      • Common iliac artery and veins (merge to form inferior vena cava)

Lower Extremity Anatomy

Anatomical Terminology

  • Dorsiflexion: Foot movement upwards toward the shin

  • Plantar Flexion: Foot points away from leg e.g., standing on tiptoes

  • Eversion: Sole of foot moves away from the median plane

  • Inversion: Sole of foot moves towards median plane

Posterior Thigh Muscles (Hamstrings)

  • Biceps Femoris

    • Actions: Flexion of leg, lateral rotation of leg, extension of thigh

    • Innervation: Tibial nerve & common fibular nerve

  • Semitendinosus

    • Actions: Extension of thigh, flexion of leg, medial rotation of leg

    • Innervation: Tibial nerve

  • Semimembranosus

    • Actions: Extension of thigh, flexion of leg, medial rotation of leg

    • Innervation: Tibial nerve

Anterior and Lateral Thigh Muscles

  • Tensor Fasciae Latae

    • Actions: Abduction of thigh, medial rotation of thigh

  • Sartorius

    • Actions: Flexion and lateral rotation of thigh, flexion of leg, abduction of thigh

    • Innervation: Femoral nerve

Quadriceps Femoris Group

  • Rectus Femoris

    • Actions: Flexion of thigh, extension of leg

    • Innervation: Femoral nerve

  • Vastus Lateralis, Medialis, Intermedius

    • Action: Extension of leg

    • Innervation: Femoral nerve

Posterior Leg Muscles

  • Gastrocnemius

    • Actions: Flexion of leg, plantar flexion of foot

    • Innervation: Tibial nerve

  • Soleus

    • Actions: Plantar flexion of foot

    • Innervation: Tibial nerve

  • Flexor Digitorum Longus

    • Actions: Plantar flexion of foot, flexion of toes 2-5

    • Innervation: Tibial nerve

  • Flexor Hallucis Longus

    • Actions: Plantar flexion of foot, flexion of hallux

    • Innervation: Tibial nerve

  • Tibialis Posterior

    • Actions: Plantar flexion of foot, inversion of foot

    • Innervation: Tibial nerve

Lateral and Anterior Leg Muscles

  • Fibularis Longus

    • Action: Eversion of foot

    • Innervation: Common fibular nerve

  • Fibularis Brevis

    • Action: Eversion of foot

    • Innervation: Common fibular nerve

  • Tibialis Anterior

    • Action: Dorsiflexion of foot, inversion of foot

    • Innervation: Common fibular nerve

Nerves to the Lower Extremity

  • Femoral Nerve: Anterior thigh muscles

  • Obturator Nerve: Medial thigh muscles

  • Sciatic Nerve: Comprises Tibial and Common Fibular nerves

Arteries and Veins of the Lower Extremity

  • External Iliac Artery and Vein

  • Femoral Artery and Vein

  • Popliteal Artery and Vein

  • Great Saphenous Vein: Drains into femoral vein

  • Anterior Tibial Artery: Branch of popliteal artery

  • Dorsalis Pedis Artery: Continuation of anterior tibial artery

  • Posterior Tibial Artery: Branch of popliteal artery

Final Notes

  • Remember to label all anatomical structures accurately during practical.

  • Always refer to the lab manual for terminology and procedural guidance.