Locking of the knee joint : summary

Locking of the knee joint

•      Medial rotation of the femur on tibia during terminal phase of extension (last 30° of extension )

•      It is brought about by quadriceps femoris

•      Locked knee becomes absolutely rigid

•      All ligaments are taut

•      Function: locking of the joint bring the joint into close packed

•      Clinical anatomy :

•      True Knee Locking: True locking at the knee is where the knee gets physically stuck and you physically can't move the knee for a period of time.

•      True knee locking is caused by a mechanical block where something gets caught inside the joint, preventing movement.  Cause: menisci tear , loose body

•      True locking is fairly rare and typically occurs as you move the knee into full extension, i.e. towards being fully straight.

•      Pseudo Knee Locking: Pseudo knee locking is much more common than true locking.

•      Here, knee movement is limited by temporary by muscle spasming as the body tries to protect itself in response to pain. Ex: inflammation , swelling etc

•       

Anatomy of Lumbar splanchnic nerve

Lumbar splanchnic nerve

It is the peripheral nerves of sympathetic nervous system

Location of preganglionic neuron : Its pre-ganglionic neurons are located in the  lateral horn of gray matter of Lumbar 1,2 spinal cord segment

Sympathetic ganglion : Its preganglionic fibres do not synapse with corresponding sympathetic ganglion . these fibres only pass through sympathetic ganglion 1,2.

Collateral ganglion : The pre-ganglionic sympathetic fiber of lumbar splanchnic nerve synapse with post ganglionic neuron located in the Inferior mesenteric ganglion

Nerve fibers convey by  lumbar splanchnic nerves : they convey two types of fibres

1.      they convey pre-ganglionic sympathetic fibres also known as general visceral efferent fibers which innervate smooth muscle cells

2.       They also convey general visceral afferent fibers which collect sensory information from  pelvic viscera and passage through the

·          inferior mesenteric ganglion,

·         sacral splanchnic nerve then

·         sympathetic and dorsal root ganglion

Plexus : they take part in the formation of inferior mesenteric plexus which is situated near the inferior mesenteric artery

They also form superior hypogastric plexus which situated near the bifurcation of abdominal

Function: Innervate pelvic viscera and vasculature

 

Anatomy of Sacral splanchnic nerve

Sacral splanchnic nerve

It is the peripheral nerves of sympathetic nervous system

Its pre-ganglionic neurons are located in the  lateral horn of gray matter of Lumbar 1,2 spinal cord segment

Pre-ganglionic fibre descend through sympathetic ganglion and leave sympathetic ganglion at the level of Sacral 1-5 . They do not synapse with sympathetic ganglion .

The pre-ganglionic sympathetic fiber of sacral splanchnic nerve synapse with post ganglionic neuron located in the Inferior mesenteric ganglion

So sacral splanchnic nerves convey pre-ganglionic sympathetic fibres also known as general visceral efferent fibres. They also convey general visceral afferent fibers which collect sensory information of pelvic viscera and passage through the inferior mesenteric ganglion sacral splanchnic nerve and sympathetic and dorsal root ganglion

They take part in the formation of  Inferior hypogastric plexus

Functions :

The inferior hypogastric plexus is a plexus of nerves that supplies the viscera of the pelvic cavity. The inferior hypogastric plexus gives rise to the prostatic plexus in males and the uterovaginal plexus in females

Celiac ganglion : easy and brief discussion

Celiac ganglion  :

The celiac ganglia /coeliac ganglia are two large irregularly shaped masses of nerve tissue in the upper abdomen. 

They are  the largest ganglia  in the Autonomic nervous system

They are sometimes referred to as the semilunar ganglia or the solar ganglia.

•       The upper part of  each ganglion is joined by the greater splanchnic nerve, while the lower part, glion, receives the lesser splanchnic nerve and gives off the greater part of the renal plexus. 

The upper part of each ganglion is joined by the greater splanchnic nerve, while the lower part, which is segmented off and named the aorticorenal ganglion, receives the lesser splanchnic nerve and gives off the greater part of the renal plexus

•       Greater splanchnic nerve contain preganglionic fibre arises from the preganglionic neuron located in the thoracic 5-9 spinal cord segments 

•       Lesser  splanchnic nerve contain preganglionic fibre arises from the preganglionic neuron located in the thoracic 10-11 spinal cord segments

•       Celiac ganglion situated just lateral to the celiac trunk at the level of T12 & L 1 vertebra

•       The aorticorenal ganglia may be located anywhere in the general area of the junction of the renal arteries with the aorta.

•       These ganglia were found to be partly fused with the celiac ganglion in 4% on the right side and in 12% on the left.

•       All three thoracic splanchnic nerves (greater, lesser, and least) may have rami which terminate in the aorticorenal ganglia.

•       The least splanchnic terminated in the aorticorenal ganglion more often than the other nerves when the ganglion was located inferior to the renal artery. 

•       It is situated anterior to the crura of the diaphragm

•       It lies medial to supra renal gland

•       above the upper border of the body of pancreas

they innervate most of the digestive tract.

•       These ganglia contain neurons whose postganglionic axons innervate

•       the stomach,

•       liver,

•       gallbladder,

•       spleen,

•       kidney,

•       small intestine, and

•       the ascending and transverse colon.

•       They directly innervate the ovarian theca and secondary interstitial cells and exert an indirect action on the luteal cells. 

•       Summary of celiac ganglion

1. Postganglionic sympathetic neuron 

2. Pre and post ganglionic sympathetic fibres : preganglionic sympathetic neurons are located in the lateral horn of gray matter of spinal cord > ventral root of spinal nerve > trunk of spinal nerve > white rami communicans > sympathetic ganglion (no synapse ) > greater or lesser splanchnic nerve > celiac ganglion > synapse with post ganglionic neuron > post ganglionic fibres innervate abdominal viscera 

3. General visceral afferent fibres : general visceral afferent fibres collect sensory information from abdominal viscera > greater or lesser splanchnic nerve > sympathetic ganglion > white rami communicans > spinal nerve trunk > dorsal root of spinal nerve > dorsal root ganglion > posterior horn of spinal cord