Topic 9: Nerve Supply of the Lower Limb Flashcards
The Nervous System
- Bodies control centre+ communication network
- Senses changes, interprets changes and responds to changes
- Highly specialised cells (neurons) that are designed to transmit information around the body
o Sensory neurons transmit information about conditions inside and outside the body
o Motor neurons transmit information that controls the activity of muscles and glands - Glial/ support cells provide protection and nutrition
The Central Nervous System
- Brain and co-located structures
- Spinal cord
All protected by bones of the axial skeleton
The Peripheral Nervous System (PNS)
- Nerves that connect the CNS to the peripheral structures e.g. skin, muscle, glands
- cranial nerves
- spinal nerves
Cranial Nerves
o Nerves that emerge directly from the brain/ brainstem
o 12 pairs, named and numbered
o Supply the musculoskeletal structures of the head and neck
o Supply the viscera of the thorax and abdomen
Spinal Nerves
o Nerves that emerge from the spinal cord
o 31 pairs, each numbered according to the place where it emerges from the spinal cord and vertebral column
8 cervical, 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal
o Supply the structures of the trunk wall + limbs
- E.g. spinal nerve
Spinal Nerve Formation
- Spinal cord- cut in cross section, part of the CNS
- Sensory Neurons enter at the back of SC
- The spinal nerve then divides into a dorsal (posterior) ramus, and a ventral (anterior) ramus
- motor and sensory neurons = grouped together in the spinal nerve
- motor neurons leave from the front of SC
Ventral Ramus
- distributed to the muscles of the anterior + lateral trunk, and the corresponding skin
- also distributed into the limbs to supply the muscles and skin there
Dorsal Ramus
Distributed to the muscles of the back, and the skin covering those muscles
Sensory Distribution
- To skin – sensation e.g. hot, cold, pain, touch, pressure
- To joints – sensation of joint position (proprioception)
o General rule for supply of joints – ‘where a nerve supplies a muscle that moves a particular joint, that nerve will also supply that joint’.
Motor Distribution
To muscles:
- turns the muscle on, makes it contract (might be concentric, isometric, or eccentric dependent on task requirements)
To glands:
- (usually) increases secretion from gland
- e.g. supply to sweat glands produces sweating
Sensory Pathways
- Touch hot object (pain receptors in skin) –> impulse travels down arm–> dendrite of afferent neuron –> axon of afferent neuron –> cell body of interneuron - spinal cord
Motor Pathways
Sensory impulse has been processed by CNS–> cell body of efferent neuron –> axon of efferent neuron –> muscle contracts and withdraws part being stimulated
Ventral Rami form plexi
Cervical Plexus
C1234, supplies structures in the neck and the diaphragm
Brachial Plexus
C5678, T1
Supplies the upper limbs
Lumbar Plexus
L1234
Supplies the lower limb
Lumbosacral plexus
L45, S123
Supplies the lower limb
Lumbar Plexus nerve inclusions
Genitofemoral, lateral femoral cutaneous, femoral, obturator
Lumbosacral Plexus nerve inclusions
Lumbosacral trunk, posterior femoral cutaneous, sciatic
Femoral Nerve Root Value
L234
Femoral Nerve motor distribution
iliacus, pectineus, sartorius, quad group
Femoral Nerve sensory distribution
- Skin of anterior and medial thigh
2. knee and hip joints
Saphenous nerve (cutaneous branch of femoral) root value
none as it branches off the femoral nerve
Obturator Nerve Root value
L234
Saphenous nerve (branch of femoral) motor distribution
none
Saphenous nerve (branch of femoral) sensory distribution
Skin of the medial knee+ leg to base of great toe
Obturator Nerve Motor Distribution
Pectineus, add brev, add long, 1/2 of add mag, obt ext, gracilis
Root value definition
where the nerve originates in the SC
Obturator Nerve Sensory Distribution
Skin of medial thigh
Lateral Femoral Cutaneous nerve root value
none (why?)
Is it because it comes off the fem vein?
Lateral Femoral Cutaneous nerve motor distribution
none
Lateral Femoral Cutaneous nerve sensory distribution
skin of the lateral thigh
Genitofemoral nerve root value
none
Genitofemoral Nerve motor distribution
none
genitofemoral nerve sensory distribution
skin of the medial thigh, skin of the external genitalia
Muscular branches nerve motor distribution
iliacus & psoas major
LUMBOSACRAL PLEXUS
Posterior Femoral Cutaneous nerve root value
XXX
Posterior Femoral Cutaneous nerve motor distribution
none
Posterior Femoral Cutaneous nerve sensory distribution
skin of posterior thigh and leg to mid calf
Superior gluteal nerve root value
XXX
Superior gluteal nerve motor distribution
gluteus Medius and minimus, TFL
Superior gluteal nerve sensory distribution
hip joint
Inferior gluteal nerve root value
XXX
Inferior gluteal nerve motor distribution
gluteus maximus
Inferior gluteal nerve sensory distribution
none
Muscular branches nerve root value
XXX
Muscular branches nerve motor distribution
external rotators except obt ext