| Inbound Relationships | Type | Active | Source | Characteristic | Refinability | Group | 
| Entire base of skull | Is a | True | Base of skull structure | Inferred relationship | Existential restriction modifier |  | 
| Bone structure of cranial fossa | Is a | True | Base of skull structure | Inferred relationship | Existential restriction modifier |  | 
| Excision of base of skull in anterior cranial fossa | Procedure site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 2 | 
| Excision of base of skull in middle cranial fossa | Procedure site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 2 | 
| Excision of base of skull in posterior cranial fossa | Procedure site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 2 | 
| Intracranial hemorrhage co-occurrent and due to closed fracture of base of skull | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Intracranial injury co-occurrent and due to closed fracture of base of skull | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Intracranial hemorrhage co-occurrent and due to open fracture of base of skull | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Open fracture of base of skull with intracranial injury | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Excision of base of skull | Procedure site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Fracture of base of skull | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Closed fracture of base of skull without intracranial injury | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Closed fracture of base of skull with subarachnoid, subdural AND/OR extradural hemorrhage | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Cerebral laceration AND contusion co-occurrent and due to open fracture of base of skull | Finding site | True | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Open fracture of base of skull with subarachnoid, subdural AND/OR extradural hemorrhage | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Open fracture of base of skull without intracranial injury | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Cerebral laceration AND/OR contusion co-occurrent and due to closed fracture of base of skull | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Plain X-ray base of skull | Procedure site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Closed fracture base of skull without intracranial injury | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Closed fracture base of skull with intracranial injury | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Open fracture base of skull without mention of intracranial injury | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Open fracture base of skull with intracranial injury | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Closed fracture of base of skull without mention of intracranial injury, unspecified state of consciousness | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Closed fracture of base of skull without mention of intracranial injury, with loss of consciousness of unspecified duration | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Closed fracture of base of skull without mention of intracranial injury, with concussion, unspecified | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Closed fracture of base of skull with intracranial injury, unspecified state of consciousness | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Closed fracture of base of skull with intracranial injury, with loss of consciousness of unspecified duration | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Closed fracture of base of skull with intracranial injury, with concussion, unspecified | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Open fracture of base of skull without mention of intracranial injury, unspecified state of consciousness | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Open fracture of base of skull without mention of intracranial injury, with loss of consciousness of unspecified duration | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Open fracture of base of skull without mention of intracranial injury, with concussion, unspecified | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Open fracture of base of skull with intracranial injury, unspecified state of consciousness | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Open fracture of base of skull with intracranial injury, with loss of consciousness of unspecified duration | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Open fracture of base of skull with intracranial injury, with concussion, unspecified | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Fracture of base of skull NOS | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Closed fracture of base of skull without mention of intracranial injury, with no loss of consciousness | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Closed fracture of base of skull without mention of intracranial injury, with less than 1 hour loss of consciousness | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Closed fracture of base of skull without mention of intracranial injury, with 1-24 hours loss of consciousness | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Closed fracture of base of skull without mention of intracranial injury, with more than 24 hours loss of consciousness and return to pre-existing conscious level | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Closed fracture of base of skull without mention of intracranial injury, with more than 24 hours loss of consciousness without return to pre-existing conscious level | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Closed fracture of base of skull with intracranial injury, with no loss of consciousness | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Closed fracture of base of skull with intracranial injury, with less than 1 hour loss of consciousness | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Closed fracture of base of skull with intracranial injury, with 1-24 hours loss of consciousness | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Closed fracture of base of skull with intracranial injury, with more than 24 hours loss of consciousness and return to pre-existing conscious level | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Closed fracture of base of skull with intracranial injury, with more than 24 hours loss of consciousness without return to pre-existing conscious level | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Open fracture of base of skull without mention of intracranial injury, with no loss of consciousness | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Open fracture of base of skull without mention of intracranial injury, with less than 1 hour loss of consciousness | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Open fracture of base of skull without mention of intracranial injury, with 1-24 hours loss of consciousness | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Open fracture of base of skull without mention of intracranial injury, with more than 24 hours loss of consciousness and return to pre-existing conscious level | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Open fracture of base of skull without mention of intracranial injury, with more than 24 hours loss of consciousness without return to pre-existing conscious level | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Open fracture of base of skull with intracranial injury, with no loss of consciousness | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Open fracture of base of skull with intracranial injury, with less than 1 hour loss of consciousness | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Open fracture of base of skull with intracranial injury, with 1-24 hours loss of consciousness | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Open fracture of base of skull with intracranial injury, with more than 24 hours loss of consciousness and return to pre-existing conscious level | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Open fracture of base of skull with intracranial injury, with more than 24 hours loss of consciousness without return to pre-existing conscious level | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Excision of base of skull | Procedure site - Direct | True | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Plain X-ray base of skull | Procedure site - Direct | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Closed fracture of base of skull | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Intracranial hemorrhage co-occurrent and due to open fracture of base of skull | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Open fracture of base of skull with intracranial injury, with concussion, unspecified | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Plain X-ray base of skull | Procedure site - Direct | True | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Intracranial hemorrhage co-occurrent and due to closed fracture of base of skull | Finding site | True | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Open fracture of base of skull with intracranial injury | Finding site | True | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Intracranial hemorrhage co-occurrent and due to open fracture of base of skull | Finding site | True | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Fracture of base of skull NOS | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Open fracture of base of skull without mention of intracranial injury, with loss of consciousness of unspecified duration | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Open fracture of base of skull with intracranial injury, unspecified state of consciousness | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Closed fracture of base of skull with intracranial injury, with more than 24 hours loss of consciousness without return to pre-existing conscious level | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Closed fracture of base of skull with intracranial injury, with more than 24 hours loss of consciousness and return to pre-existing conscious level | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Open fracture of base of skull with intracranial injury, with loss of consciousness of unspecified duration | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Open fracture of base of skull without intracranial injury | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Closed fracture of base of skull without mention of intracranial injury, with no loss of consciousness | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Open fracture of base of skull without mention of intracranial injury, with more than 24 hours loss of consciousness and return to pre-existing conscious level | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Closed fracture of base of skull without mention of intracranial injury, with more than 24 hours loss of consciousness and return to pre-existing conscious level | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Closed fracture of base of skull with intracranial injury, with 1-24 hours loss of consciousness | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Open fracture of base of skull without mention of intracranial injury, with 1-24 hours loss of consciousness | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Open fracture of base of skull without mention of intracranial injury, with less than 1 hour loss of consciousness | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Basilar skull invagination | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Open fracture of base of skull without mention of intracranial injury, with more than 24 hours loss of consciousness without return to pre-existing conscious level | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Open fracture of base of skull with intracranial injury, with 1-24 hours loss of consciousness | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Closed fracture of base of skull without mention of intracranial injury, with concussion, unspecified | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Closed fracture of base of skull without mention of intracranial injury, with loss of consciousness of unspecified duration | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Closed fracture of base of skull without mention of intracranial injury, with more than 24 hours loss of consciousness without return to pre-existing conscious level | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Closed fracture of base of skull with intracranial injury, with less than 1 hour loss of consciousness | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Closed fracture of base of skull with intracranial injury, with no loss of consciousness | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Closed fracture of base of skull with subarachnoid, subdural AND/OR extradural hemorrhage | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Open fracture of base of skull without mention of intracranial injury, with no loss of consciousness | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Cerebral laceration AND/OR contusion co-occurrent and due to closed fracture of base of skull | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Open fracture base of skull without mention of intracranial injury | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Open fracture of base of skull with intracranial injury, with more than 24 hours loss of consciousness without return to pre-existing conscious level | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Open fracture of base of skull with intracranial injury, with more than 24 hours loss of consciousness and return to pre-existing conscious level | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Closed fracture of base of skull with intracranial injury, unspecified state of consciousness | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Closed fracture of base of skull with intracranial injury, with loss of consciousness of unspecified duration | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Closed fracture of base of skull with intracranial injury, with concussion, unspecified | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Platybasia | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Open fracture of base of skull without mention of intracranial injury, unspecified state of consciousness | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Closed fracture of base of skull without mention of intracranial injury, with 1-24 hours loss of consciousness | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Closed fracture of base of skull without mention of intracranial injury, with less than 1 hour loss of consciousness | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Closed fracture of base of skull without intracranial injury | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Fracture of base of skull | Finding site | True | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 | 
| Open fracture of base of skull without mention of intracranial injury, with concussion, unspecified | Finding site | False | Base of skull structure | Inferred relationship | Existential restriction modifier | 1 |