The term âshoulder instabilityâ is used to refer to the inability to maintain the humeral head in the glenoid fossa.The ligamentous and muscle structures around the glenohumeral joint, under non-pathological conditions, create a balanced net joint reaction force. The relevant structures are listed below.
Definition of synapse. : the point at which a nervous impulse passes from one neuron to another.
Synapses are composed of three main parts: 1  The presynaptic ending that contains neurotransmitters. 2  The synaptic cleft between the two nerve cells. 3  The postsynaptic ending that contains receptor sites.