PHYSIOLOGY

• Lower limb


  • Similar to upper limb in basic structure
  • Formerly used for locomotion
  • Has a girdle (hip or shoulder)
  • Has 3 main segments: proximal, middle, distal
• Evolution of erect or plantigrade posture in man


  Upper and lower limbs have become specialized in different directions to meet new functional needs
• Upper limb


  • Specialized for prehension and free mobility
• Lower limb


  • Specialized for support and locomotion
  • Attains stability at the cost of some mobility
• Lower limbs are bulkier and stronger than upper limbs
• Lower limb development


  • Rotates medially through 90 degrees, so preaxial/tibial border faces medially and extensor surface faces forwards
• Upper limb development


  • Rotates laterally through 90 degrees, so preaxial/radial border faces laterally and extensor surface faces backwards
• Antigravity muscles in lower limb

  • Much better developed than upper limb
  • Gluteus maximus, extensor of hip
  • Quadriceps femoris, extensor of knee
  • Gastrocnemius and soleus, plantar flexors of ankle
• Certain diseases like varicose veins and Buerger's disease occur specifically in the lower limb
• Developmental deformities of the foot like talipes equinovarus are more common than those of the hand
• Parts of the lower limb

  • Gluteal region
  • Thigh
  • Leg or Crus
  • Foot or Pes
• Hip bone


  • Made up of 3 fused elements: ilium, pubis and ischium
  • Two hip bones form the hip girdle which articulates with the sacrum
• Bony pelvis


  Includes two hip bones, sacrum and coccyx
• Hip joint


  Articulation between hip bone and femur
• Gluteal region


  Overlies the side and back of the pelvis, includes the hip and buttock
• Foot or Pes


  • Has an upper dorsal surface and a lower sole/plantar surface
  • Sole is homologous with the palm of the hand
• Inguinal region


  Junction of thigh and anterior abdominal wall
• Gluteal fold


  Upper limit of the thigh posteriorly
• Scalp


  The part of the head that extends from the super ciliary arches or the supraorbital margin anteriorly to the external occipital protuberance as well as superior nuchal lines posteriorly, and laterally continues inferiorly to the zygomatic arch
• Scalp


  • Multilayered structure
  • Layers: skin, connective tissue (dense), aponeurotic layer, loose connective tissue, pericraniume
• Skin


  Outer layer of the scalp, similar to skin throughout the body with the exception that hair is present on a large amount of it
• Connective tissue (dense)


  Deep to the skin, anchors the skin to the third layer and contains the arteries, veins, and nerves supplying the scalp
• Aponeurotic layer


  Deepest layer of the first three layers, consists of the occipitofrontalis muscle with a frontal belly anteriorly, an occipital belly posteriorly, and an aponeurotic tendon-the epicranial aponeurosis (galea aponeurotica) connecting the two
• Loose connective tissue


  Separates the aponeurotic layer from the pericranium and facilitates movement of the scalp proper over the calvaria
• Pericranium


  Deepest layer of the scalp, the periosteum on the outer surface of the calvaria
• Occipitofrontalis muscle


  • Moves the scalp, wrinkles the forehead, and raises the eyebrows
  • Frontal belly innervated by temporal branches of the facial nerve [VII]
  • Posterior belly innervated by the posterior auricular branch
• Sensory innervation of the scalp

  1. Anterior to the ears and vertex: Branches of the trigeminal nerve [V]

  2. Posterior to the ears and vertex: Branches from spinal cord levels C2 and C3
• Branches of the trigeminal nerve [V] supplying the scalp anterior to the ears and vertex


  • Supratrochlear nerve
  • Supra-orbital nerve
  • Zygomaticotemporal nerve
  • Auriculotemporal nerve
• Branches of the cervical nerves supplying the scalp posterior to the ears and vertex

  • Great auricular nerve
  • Lesser occipital nerve
  • Greater occipital nerve
  • Third occipital nerve
• Arteries supplying the scalp

  • Branches from the ophthalmic artery: Supratrochlear and supra-orbital arteries
  • Branches from the external carotid artery: Superficial temporal, posterior auricular, and occipital arteries
• Lymphatic drainage of the scalp

  Generally follows the pattern of arterial distribution, draining to occipital nodes and upper deep cervical nodes
• Epicranial aponeurosis


  • Clinically important, superficial scalp wounds do not gape and the margins of the wound are held together
  • Deep scalp wounds gape widely when the epicranial aponeurosis is lacerated in the coronal plane due to the pull of the frontal and occipital bellies of the occipitofrontalis muscle
• Loose connective tissue layer

  • The danger area of the scalp, pus or blood spreads easily in it
  • Infection in this layer can pass into the cranial cavity through emissary veins
  • Infection cannot pass into the neck or spread laterally beyond the zygomatic arches
• Black eyes can result from an injury to the scalp and/or the forehead due to the frontalis inserting into the skin and subcutaneous tissue and not attaching to the bone
• Ecchymosis, or purple discoloration, can result from an injury to the scalp and/or the forehead