Anatomy and Physiology Quiz

Sciatica and Foot Conditions

• Sciatica: pain along the distribution of the sciatic nerve, which is the largest nerve in the body
• Dorsiflexion of the foot plus eversion results in a condition called calcaneovalgus
• Foot drop: plantar flexed and inverted, a condition called equinovarus

Injuries to the Brachial Plexus

• Injury to the superior roots of the brachial plexus (C5-C6): Erb-Duchenne palsy (waiter's tip position)
• Injury to the radial nerve: wrist drop - inability to extend the wrist and fingers
• Median nerve palsy: numbness, tingling, and pain in the palm and fingers
• Ulnar nerve palsy: inability to abduct or adduct fingers, resulting in claw hand
• Injury to the long thoracic nerve: winged scapula - the arm cannot be abducted beyond the horizontal position

Autonomic Nervous System (ANS)

• Controls involuntary actions, such as heart rate, respiratory rate, and blood pressure
• Divided into:
  • Sympathetic: supports exercise of emergency actions, "fight-or-flight" responses
  • Parasympathetic: takes care of "rest-and-digest" activities
  • Enteric: controls secretions and movements of the digestive tract unconsciously

Nervous Tissue

• Formed of two types of cells:
  • Neurons (nerve cells)
  • Neuroglia or Glia cells (supporting cells)
• No extracellular matrix in nervous tissue
• Space between cells is called neuropil and is formed of the processes of both neurons and glia cells and some fluid
• Mature neurons cannot divide and are replaced by fibrous tissue if damaged

Neurons

• Functional unit of the nervous system, consisting of:
  • Cell body
  • Axon
  • Dendrites
• Have the capacity to produce action potentials
• Electrical excitability

Cerebellum

• Second-largest part of the brain
• Located inferior to the occipital lobe and posterior to the brainstem
• Separated from the brainstem by the 4th ventricle
• Functions:
  • Coordinates movement
  • Maintains balance on the same side of the body
  • Smooths and coordinates contractions of skeletal muscles
  • Regulates posture and balance

Brainstem

• Connects the diencephalon with the spinal cord
• Formed of three parts: midbrain, pons, and medulla oblongata
• Contains several important control centers and the origin of several cranial nerves
• Relays between the cerebrum and cerebellum

Peripheral Nervous System

• Cranial Nerves:
  • Olfactory (I): olfaction (smelling)
  • Optic (II): vision (sight)
  • Oculomotor (III): supply intrinsic and extrinsic muscles of the eye
  • Trochlear (IV): supply extrinsic muscle of the eye
  • Trigeminal (V): carries sensation from scalp and face, and supplies muscles of mastication
  • Abducent (VI): supply extrinsic muscle of the eye
  • Facial (VII): supply muscles of facial expression, carry taste sensations, and secretions of tears and saliva
  • Vestibulocochlear (VIII): hearing and equilibrium
  • Glossopharyngeal (IX): supply various muscles, carry taste sensation, and secretions of parotid saliva
  • Vagus (X): supplies various muscles and carries various sensations
  • Accessory (XI): supply sternocleidomastoid and trapezius muscles
  • Hypoglossal (XII): supply intrinsic muscles of the tongue (except palatoglossus)
• Spinal Nerves:
  • 31 pairs of mixed nerves (sensory and motor)
  • Cervical (C1-C8), thoracic (T1-T12), lumbar (L1-L5), sacral (S1-S5), and coccygeal (C0)
  • A spinal nerve gives off two main branches: anterior ramus and posterior ramus
• Cervical Plexus:
  • Formed of anterior rami of C1-C4
  • The phrenic nerve (C3,4,5) is an important nerve arising from this plexus, supplying the diaphragm
• Brachial Plexus:
  • Formed of anterior rami of C5,6,7,8, and T1
  • Supplies the shoulders and upper limbs
  • Important nerves arising from this plexus include:
    • Axillary
    • Musculocutaneous
    • Radial
    • Median
    • Ulnar
• Lumbar Plexus:
  • Formed of anterior rami of L1-L4
  • Femoral and obturator nerves arise from this plexus
• Sacral Plexus:
  • Formed of anterior rami of L4-L5 and S1-S4
  • Supplies the buttocks, perineum, and lower limbs