PERIPHERAL NERVOUS SYSTEM Flashcards
Posterior ramus (plural rami) Dorsal branch
Posterior division of spinal nerve
Posterior Nerve roots are sensory (tickle back of your spine you can feel it)
Anterior ramus (ventral branch)
Anterior division of spinal nerve
Anterior nerve roots are involved in motor function
Plexus (latin meaning for braid)
Branching network of nerves/vessels
Ganglion
Nerve cell cluster/ group of nerve bodies in the autonomic nervous system/sensory system
Afferent
Input of nerve fibres (recieve information)
Efferent
Output of nerve fibres (motor supply)
Dura
Thick outer meningeal layer attached to skull
Arachnoid
Layer containing arachnoid spaces/ blood brain barrier for exchange between blood and CSF
Pia
Protective layer directly over the brain and continues down the spinal cord
White ramus communicans
Preganglionic sympathetic nerve tract fibres from the spinal cord
Grey ramus communicans
Postganglionic nerve fibres for sympathetic tract
What spinal nerve roots is the brachial plexus supplied by?
- 5 spinal nerve roots arise from C5-T1 (C5,C6,C7,C8,T1)
- Gives rise to 5 major peripheral nerves
What are the 5 major peripheral nerves which carry motor and sensory fibres to the upper limb?
- Radial Nerve
- Axillary Nerve
- Ulnar Nerve
- Median Nerve
- Musculo-cutaneous Nerve
What does the radial nerve innervate?
- Triceps brachii, extensor muscles of forearm and brachioradialis
- supplies posterior portion of the upper limb for extension
Fall asleep on your arm and wake up with dead arm = radial nerve
What does the axillary nerve innervate?
innervates axillary region and runs to deltoid + teres major (nerve is short and thin)
What does the ulna nerve innervate?
Innervates the flexor carpi ulnaris, medial two bellies of flexor digitorum profundus, intrinsic hand muscles (except for thenar muscles and lumbricals of the hand)
supplies muscles of the forearm for flexion and also intrinsic muscles of the hand
What does the median nerve innervate?
Flexor in the forearm except flexor carpi ulnaris (1st and 2nd lumbrical muscles)
located in the middle, passes through the carpal tunnel, supplies the intricate hand muscles, flexion
What does the musculo cutaneous nerve innervate?
Innervates the coracobrachialis and biceps brachii
Where are the peripheral nerves vulnerable to damage?
Axilliary nerve = within the axilla
Radial nerve = as it winds around the shaft of the humerus
Ulnar nerve = as it passes behind the medial epicondyle of the humerus
Median nerve = deep to the flexor retinaculum in the wrist
What are the eight spinal roots which supply the lower limb?
Where does the lumbar plexus branch within and what does it supply?
What is the rest of the lower limb supplied by?
- Lower limb is supplied is by eight spinal nerve roots (L1 to S3)
- Contribute to lumbar and sacral plexuses
- The lumbar plexus L1-L4 branches within the psoasas major muscle (hip flexor muscle) and supplies the anterior and medial compartments of the thigh
- The rest of the limb is supplied by the sacral plexus S1-S3 ( which includes the lumbosacral trunk L4-L5)
At what division do the different plexuses arise from?
- Lumbar plexus (L1-L4)
- Lumbosacral plexus (L4/L5)
- Sacral plexus (S1-S3)
What happens to the spinal cord after L1/L2?
The spinal cord changes to the cauda equina
Important as at the level of the pelvic crest is where there is a safe zone and you are able to access CSF through lumbar puncture around L3 and L4
What are the major branches of the lumbosacral plexus?
What do they supply?
- Femoral (quadriceps) –lumbar plexus
- Obturator (adductor muscles)- lumbar plexus
- Tibial (hamstrings, calf muscles)- sacral plexus
- Common fibular/peroneal (anterior leg)- sacral plexus
What nerves are part of the lumbar plexus?
- Femoral (quadriceps) –lumbar plexus
- Obturator (adductor muscles)- lumbar plexus
What nerves are part of the sacral plexus?
- Tibial (hamstrings, calf muscles)- sacral plexus
- Common fibular/peroneal (anterior leg)- sacral plexus
What does the femoral and obturator nerve innervate?
Femoral nerve = Quadriceps on the anterior aspect of the thigh
Obturator nerve = Muscles on the medial aspect of the thigh are innervated by obturator for adduction
What does the sciatic nerve split into?
- Common fibular
- Tibial
What does the tibial branch of the sciatic nerve innervate?
The tibial branch of the sciatic nerve supplies the posterior thigh (hamstring) muscles. Also, it supplies the soleus and gastrocnemius (calf muscles). Their common tendon is the Achilles tendon.
What does the pudendal nerve innervate?
The pudendal nerve originates from the sacral plexus (S2-S4) and provides innervation to the perineum, anal and urethral sphincters, penis and clitoris.
