Flashcards in Sacral And Coccygeal Plexuses Deck (115):
Through which opening do the posterior primary rami of S1-S4 travel through?
The four posterior sacral foramina
Through which opening does the S5 posterior ramus travel through?
In which direction do the sacral posterior rami decrease in size?
From superior to inferior
Which of the sacral posterior primary rami divide into medial and lateral branches?
What do the medial branches of S1-S3 posterior primary rami supply?
What do the lateral branches of the posterior primary rami of S1-S3 supply?
Skin over the buttocks (combined with branches from L5 and S4)
What is the supply of the posterior primary rami of S4 and S5 and their union with the coccygeal posterior rami?
Skin over the coccyx
What travels through the anterior sacral foramina?
Anterior primary rami of S1-S4
Which sacral anterior primary ramus travels through the sacral hiatus?
There are usually how many sacral sympathetic ganglia that form the communication with the sympathetic trunk?
Three or four
The anterior primary ramus of each sacral nerve will receive what kind of information via a gray ramus communicans?
Postganglionic sympathetic fibers
What forms the sacral plexus?
Anterior primary rami of L4, L5, S1-S3, part of S4
What forms the lumbosacral trunk?
L4 and L5
The sacral plexus forms on the anterior surface of what muscle?
When do the nerve roots of the sacral plexus divide into anterior and posterior divisions?
Shortly after exiting their IVF/sacral foramen
What fibers are contained in the nerve to the quadratus femoris and gemellus inferior?
L4, L5, and S1
The nerve to the quadratus femoris and gemellus inferior leaves the pelvis through what opening?
Greater sciatic foramen
The muscles supplied by the nerve to the quadratus femoris and gemellus inferior share what common action?
Lateral rotation and adduction of the thigh
What fibers are contained in the nerve to the obturator internus and gemellus superior?
L5, S1, S2
The nerve to the obturator internus and gemellus superior leaves the pelvis through what opening?
Greater sciatic foramen
The nerve to the obturator internus and gemellus superior re-enters the pelvis through what opening to supply what muscle?
Lesser sciatic foramen, obturator internus
The muscles that are supplied by the nerve to the obturator internus and gemellus superior share what common action?
Lateral rotation and abduction of the thigh
What fibers are contained in the pudendal nerve?
S2, S3, and S4
What is the course of the pudendal nerve?
Leaves pelvic cavity through greater sciatic foramen, arches around the ischial spine and into the perineum via lesser sciatic foramen
Then, through the pudendal canal inferior to the pubic symphysis to reach dorsal side of penis or clitoris
What branches of the pudendal nerve come off within the pudendal canal?
Inferior rectal nerves, perineal nerve, dorsal nerve of penis/clitoris
The superior and inferior gluteal nerves are named in reference to what muscle?
The inferior rectal nerves carry sensory information from what locations?
Skin around the anus and the inferior 2/3 of the anal canal
What is the motor supply of the inferior rectal nerves?
External anal sphincter
Which branch of the perineal nerve has motor supply? Which has sensory supply?
Motor - deep branch
Sensory - superficial branch
What muscles are supplied by the deep branches of the perineal nerve?
External anal sphincter, bulbospongiosus, ischiocavernosus, superficial transverse perineus
What do the superficial branches of the perineal nerve supply?
Males - posterior scrotum, urethral mucosa, bulb of penis
Females - labium majus, external urethral orifice, and vestibule
What muscles are supplied by the dorsal nerve of the penis/clitoris?
Deep transverse perineus, urethral sphincter muscles
The dorsal nerve of the penis/clitoris carries sensory fibers from what location?
Males - corpus cavernosum, glans penis, skin covering penis
Females - corpus cavernosum, clitoris
What supplies the levator ani and coccygeus muscles?
Individual muscular branches off the sacral plexus in fibers from S4
The pelvic splanchnic nerves contain fibers from what nerves?
S2, S3, and S4
What are the branches from the posterior division of the sacral plexus?
Nerve to piriformis, superior and inferior gluteal nerves, perforating cutaneous nerve
What fibers are contained in the nerve to the piriformis?
S1 and S2
The sacral spinal nerves descend inside the dura to form what structure?
Much of the cauda equina
How can one test for damage to the obturator nerve by analyzing muscle weakness?
See if patient can adduct hip and if weak on one side, obturator nerve is likely to be compromised.
(if bilateral, more of a systemic issue)
How many gray rami communicans can be seen among the sacral spinal nerves?
5 (one for each)
What fibers are contained in the superior gluteal nerve?
L4, L5, and S1
What is the course of the superior gluteal nerve?
Leaves pelvis through greater sciatic foramen, superior to the piriformis, and splits into superior and inferior branches
Which muscles are supplied by the superior branches of the superior gluteal nerve?
Gluteus medius and minimus
What muscles are supplied by the inferior branches of the superior gluteal nerve?
Gluteus medius, minimus, and tensor fascia lata
What fibers are contained in the inferior gluteal nerve?
L5, S1, and S2
What is the course of the inferior gluteal nerve?
Leaves pelvis through greater sciatic foramen, inferior to piriformis, innervates gluteus maximus
What muscle is supplied by the inferior gluteal nerve?
What fibers make up the perforating cutaneous nerve?
S2 and S3
Why is it called the perforating cutaneous nerve?
It travels through the sacrotuberous ligament
The perforating cutaneous nerve ultimately reaches what location?
Lower medial aspects of the buttocks
The perforating cutaneous nerve can also be formed by a branch off of what other nerve?
Pudendal nerve (or could be absent)
What nerves are formed by branches of both the anterior and posterior divisions of the sacral plexus?
Posterior cutaneous nerve of the thigh and sciatic nerve
What forms the posterior cutaneous nerve of the thigh?
Anterior divisions of S2 and S3 and posterior divisions of S1 and S2
What is the course of the posterior cutaneous nerve of the thigh?
Leaves pelvis through greater sciatic foramen and descends through posterior thigh and inferior to the leg to communicate with the sural nerve
What is the supply of the posterior cutaneous nerve of the thigh?
Skin on the posterior and medial thigh
What is the largest nerve in the human body?
What is the approximate diameter of the sciatic nerve?
The sciatic nerve is a combination of which two nerves?
Common fibular (more lateral) and tibial nerves (more medial)
What fibers make up the sciatic nerve?
Anterior divisions of L4-S3 and posterior divisions of L4-S2
What covers both nerves of the sciatic nerve as it exits the pelvis?
What is the course of the sciatic nerve?
Exits pelvis through greater sciatic foramen below piriformis muscle
Travels inferior on posterior aspect of adductor magnus
Splits into common fibular and tibial components
When does the sciatic nerve USUALLY split into the common fibular and tibial nerves?
Approximately 2/3 of the way to the knee
Which is more lateral: common fibular or tibial nerve?
Common fibular nerve
The common fibular nerve is composed of what fibers?
In the thigh, the common fibular nerve gives off a branch to supply what muscle?
Biceps femoris (short head)
What is the course of the common fibular nerve after it separates from the tibial nerve?
Runs around lateral aspect of the fibula
Gives off articular branch upon reaching the anterolateral aspect of leg
An articular branch to which joint is given off of the common fibular nerve?
What are the two sensory branches given off of the common fibular nerve?
Lateral sural cutaneous nerve and fibular communicating branch
Where are the two sensory branches of the common fibular nerve given off?
Lateral aspect of the popliteal fossa
What does the lateral sural cutaneous nerve supply?
Skin on lateral aspect of the leg
When does the fibular communicating branch form the sural nerve?
After combining with the medial sural cutaneous nerve
The common fibular nerve divides into what two nerves as it enters the leg?
Superficial and deep fibular nerves
The superficial fibular nerve travels inferior in between what two structures down to the dorsum of the foot?
Fibularis longus and fibula
What muscles are supplied by the superficial fibular nerve?
Fibularis longus and fibularis brevis
What compartment of the leg is supplied by the superficial fibular nerve? What is their common action?
Lateral compartment, plantar flexor muscles (everters)
The superficial fibular nerve splits into what nerves for its sensory supply?
Medial and intermediate dorsal cutaneous nerves
What is the supply of the medial and intermediate dorsal cutaneous nerves?
Skin over the dorsum of the foot except for the skin between the first two toes
The deep fibular nerve runs inferiorly along what muscle as it reaches the foot?
The deep fibular nerve supplies what group of muscles? What is their common action?
Anterior compartment of the leg, extensor muscles
What muscles are supplied by the deep fibular nerve?
Tibialis anterior, extensor digitorum longus, extensor digitorum brevis, extensor hallucis longus, extensor hallucis brevis, fibularis tertius
What is the sensory supply of the terminal branch of the deep fibular nerve?
Skin between the first two toes
What type of gait can be see with damage to the common fibular nerve?
What forms the tibial nerve?
Fibers from L4-S3
Which is more medial: common fibular or tibial nerve?
Which is larger: common fibular or tibial nerve?
What muscles are supplied by tibial nerve fibers (even when still combined with common fibular nerve)?
Biceps femoris (long head), semitendinosus, semimembranosus, adductor magnus
What do the long head of the biceps femoris, semitendinosus, and semimembranosus all have in common?
Same origin (ischial tuberosity)
Which supplies the short head of the biceps femoris: common fibular or tibial nerve? The long head?
Short head - common fibular nerve
Long head - tibial nerve
What branches are given off of the tibial nerve in the popliteal fossa?
Articular branches, muscular branches, popliteal branch
What does the articular branch given off of the tibial joint supply?
What muscles are supplied by the muscular branches given off of the tibial nerve in the popliteal fossa?
Popliteus, gastrocnemius (both heads), soleus, and plantaris
The popliteal branch of the tibial nerve gives rise to what nerve?
Interosseous nerve of the leg
The interosseous nerve of the leg continues inferior along the posterior surface of what structure?
The interosseous nerve of the leg carries sensory information from what locations?
Tibial periosteum, ankle, and tibiofibular joints
What branches are given off of the tibial nerve in the leg?
Muscular branches sensory branches
What muscles are supplied by the muscular branches of the tibial nerve that are given off in the leg?
Flexor digitorum longus, flexor hallucis longus, tibialis posterior
What is the name of the sensory branches that are given off of the tibial nerve in the leg?
Medial calcaneal branches
What is supplied by the medial calcaneal branches of the tibial nerve?
Skin over the medial heel
The tibial nerve travels around what osseous structure to the plantar surface of the foot?
What are the two terminal branches of the tibial nerve (in the foot)?
Medial and lateral plantar nerves
What is supplied by the medial plantar nerve?
Abductor hallucis, flexor digitorum brevis, flexor hallicus brevis
After supplying three muscles of the foot, what does the medial plantar nerve divide into?
Common plantar digital nerves
What is the motor supply for the common plantar nerves?
Lumbricals 1 and 2
What is the sensory supply for the common plantar digital nerves?
Skin between toes (by way of proper plantar digital nerves)
What does the lateral plantar nerve divide into?
Superficial and deep branches
What is the supply of the superficial branch of the lateral plantar nerve?
Skin around 5th digit
What is the supply of the deep branch of the lateral plantar nerve?
Adductor hallucis, flexor digiti minimi brevis, abductor digiti mimini, quadratus plantae, lateral lumbricals, interossei muscles
What group of muscles can be paralyzed with damage to the tibial nerve?
Damage to what nerve can result in the "hammer toes" appearance?
The "claw foot" appearance is seen with damage to what nerve?
What forms the coccygeal plexus?
Anterior rami of S4, S5, and Co1 nerves
What nerves are given off of the coccygeal plexus?
The anococcygeal nerves carry sensory information from what locations?
Skin adjacent to the coccyx and anus
How many white rami communicans are there in the sacral area?