Lower plexuses Flashcards
Where do rr. anteriores of lumbar, sacral and coccygeal region exit the vertebrae?
- L: through foramina intervertebralia
- S1-4: through foramina sacralia anteriora
- S5 + Co1: through hiatus sacralis
Which nerves contribute to plexus lumbosacralis?
Location in relation to hip joint?
- plexus lumbalis: rr. anteriores T12 - L4
- truncus lumbosacralis: rr. anteriores L4 - 5, connect both plexuses
- plexus sacralis: rr. anteriores L4 - S5, Co1
→ nn. of plexus lumbalis ventral to hip joint, nn. of plexus sacralis dorsal to hip joint
List all 7 branches of plexus lumbalis and their spinal origin.
- rr. musculares (T12 - L4)
- n. iliohypogastricus (L1)
- n. ilioinguinalis (L1)
- n. genitofemoralis (L1 - 2)
- n. cutaneus femoralis lateralis (L2 - 3)
- n. femoralis (L2 - 4)
- n. obturatorius (L2 - 4)
rr. musculares not shown, 2 - 7 = cf. above
Which mm. are innervated by rr. musculares of plexus lumbalis?
Where do they originate from?
T12 - L4
- m. iliopsoas
- m. quadratus lumborum
- mm. intertransversarii laterales lumborum (autochthonal back mm.)
What are common features of n. iliohypogastricus and n. ilioinguinalis?
- originate from L1
- innervate caudal parts of mm. abdominales + overlying skin
Nerve?
Pathway + function.
n. iliohypogastricus (L1)
dorsally to kidney on m. quadratus lumborum, pierces, then runs btw m. transversus abdominis and m. obliquus internus abdominis, 3 branches
- rr. musculares → m. transversus abd. + obliquus internus abd.
- r. cutaneus lat. → lat. hip
- r. cutaneus ant. → mons pubis
13
Nerve?
Pathway + function.
n. ilioinguinalis (L1)
dorsally to kidney on m. quadratus lumborum, pierces, then runs btw m. transversus abdominis and m. obliquus internus abdominis, then through canalis inguinalis to labia maj./scrotum
→ caudal parts of mm. abdominales + sensory innervation of uppermost parts of labia maj./scrotum
Nerve?
Pathway + function.
n. genitofemoralis (L1 - 2)
below n. ilioinguinalis/hypogastricus, pierces m. psoas, then bifurcates into 2 branches:
- r. genitalis (cf. own card)
- r. femoralis (cf. own card)
Nerve?
Pathway + function.
r. genitalis n. genitofemoralis
runs in spermatic cord/lig. teres uteri to scrotum/labia majores
→ m. cremaster, sensory innervation of scrotum/labia majora + upper medial part of thigh
1a
Nerve?
Pathway + function.
n. femoralis n. genitofemoralis
runs below lig. inguinale in lacuna vasorum of hiatus saphenus to surface
→ sensory innervation of upper ventral region of thigh
1b
Pointing at 2 different sections of the same nerve.
Which nerve is it?
Pathway + function.
n. cutaneus femoralis lateralis (L2 - 3)
runs on m. iliopsoas downwards, emerges medially to SIAS through lacuna musculorum, then changes direction in right angle, pierces fascia lata
→ sensory innervation of lat. side of thigh
12
Nerve?
Pathway + function.
n. femoralis (L1 - 4)
btw m. psoas and iliacus down to lacuna musculorum lat. to v./a. femoralis, reaches down to thigh, then branches into
- 2 rr. cutanei ant. in fascia lata → ventral thigh
- rr. musculares → m. iliopsoas, pectineus, sartorius, quadriceps fem.
- n. saphenus (cf. own card) → medial side of calf, knee
<u>REMEMBER:</u> IVAN - inside, vein, artery, nerve
1 = rr. cutanei ant., 2 = n. saphenus
5.
Pathway + function.
n. saphenus
branch of n. femoralis, enters canalis adductorius together w/ a./v. femoralis, pierces septum intermusculare vastoadductorium, runs to medial side of calf w/ v. saphena magna, gives off branches
- r. infrapatellaris → knee
- rr. cutanei cruris medialis → medial side of calf
Nerve?
Pathway + function.
n. obturatorius (L2 - 4)
runs behind m. psoas along wall of lesser pelvis, leaves it through foramen obturatum, gives off branch to m. obturatorius ext., then bifurcation into
- r. anterior → m. adductor long., brev. gracilis, pectineus, sensory inn. of medial part of thigh
- r. posterior → m. adductor magnus
Which spinal nerve segment connects plexus lumbalis and plexus sacralis in order to form together plexus lumbosacralis?
L4
Which spinal nerve segments form plexus sacralis?
Through which structure do all the fibers pass?
L4 - S3
→ fibers leave through foramen ischiadicus major
NOTE: 5 and 6 are not considered part of plexus sacralis
Which branches (incl. single muscular branches) are given off by plexus sacralis?
What is their spinal origin)
in craniocaudal direction, 4 m. + 4 nerves
-
muscular branches to
- m. obturatorius int.
- mm. gemelli
- m. piriformis
- m. quadratus femoris
- n. gluteus sup. (L4 - S1)
- n. gluteus inf. (L5 - S2)
- n. cutaneus femoris post. (S1 - 3)
- n. ischiadicus (L4 - S3)
Nerve?
Spinal origin?
Pathway + function.
n. gluteus sup. (L4 - S1)
leaves through foramen suprapiriforme together w/ vasa glutea sup., runs branches to mm.
→ m. gluteus med., min. + m. tensor fasciae latae
Nerve?
Spinal origin?
Pathway + function.
n. gluteus inf. (L5 - S2)
leaves through foramen infrapiriforme, runs to m.
→ m. gluteus max.
Nerve?
Spinal origin?
Pathway + function.
n. cutaneus femoris post. (S1 - 3)
through foramen infrapiriforme w/ … (cf. own card), then beneath m. gluteus max. to subcutis, there giving off branches (see below), continues to mid of dorsal thigh
- nn. clunium inferiores → caudal gluteal region
- rr. perineales → perineum - scrotum/labia majora
nn. clunium inf. on picture just cranial to n. cutaneus fem. post.
Nerve?
Spinal origin?
Pathway + function.
n. ischiadicus (L4 - S3)
through foramen infrapiriforme, first covered by m. gluteus max., then m. biceps femoris, in most cases (88%) bifurcates into n. tibialis and n. peroneus communis after 2/3 of thigh, BUT: can bifurcate earlier, still perceived as one nerve bc covered by same epineurium
→ knee flexors, all mm. of calf, foot + sensory innervation of calf + foot (exc. medially)
1
Nerve?
Spinal origin?
Pathway + function.
n. peroneus communis (L4 - S2)
- branch of n. ischiadicus, runs lateralyl to n. tibialis on dorsal side of knee flexors
- gives off cutaneus branches at level of popliteal fossa
- runs laterally around caput fibula
- enters compartmentimentum cruris laterale + bifurcates into terminal branches n. peron. prof., superf.
→ mm. peronei, extensors of foot, digits + sensory innervation of parts of calf, dorsum of foot
NOTE: n. ischiadicus = L4 - S3
Which branches are given off by n. peroneus communis?
Where?
in craniocaudal direction, 3 branches
- n. cutaneus surae: in popliteal fossa
- 2 terminal branches: in compartimentum cruris lat.
- n. peroneus superf.
- n. peroneus prof.
4 = n cut. surae lat., 7 = n. per. prof., 8 = n. per. sup.
Nerve?
Pathway + function.
n. cutaneus surae lat.
branch of n. peroneus comm., originates in popliteal fossa, gives off r. communicans to anastomose w/ n. cutaneus surae med., form n. suralis
→ sensory innervation of lateral calf
4 = n. cut. surae lat., 5 = r. comm., 6 = n. suralis
Nerve?
Pathway + function.
n. peroneus superficialis
terminal branch of n. peroneus comm., runs btw 2 mm. peronei down to dorsum of foot, bifurcates into n. cutaneus dorsalis medialis, intermedius
→ mm. peronei + sensory innervation of dorsum of foot
8 = n. per. sup., 2 = sens. inn.
Nerve?
Pathway + function.
n. peroneus prof.
terminal branch of n. peroneus communis, pierces septum intermusculare, enters extensor compartment , runs downwards btw m. tibialis ant., m. extensor hallucis long. together w/ a. tibialis ant. to dorsum of foot, then sensory branch
→ all extensors (m. tibialis ant., extensor hallucis long., brev., extensor digitorum long., brev.) + sensory innervation of halfs of 1. and 2. toe
7 = n. per. prof., 3 = sens. innervation
Which nerves give off nn. digitales dorsales pedis?
Function?
- n. cutaneus dorsalis medialis
- n. cutaneus dorsalis intermedius
- n. fibularis profundus
→ sensory innervation ofskin of digits till middle phalanges (terminal phalanges inn. by plantar nn.)
2 = n. cutaneus dors. med./intermed., 3 = n. peron. prof.
Nerve?
Spinal origin?
Pathway + function.
n. tibialis (L4 - S3)
- branch of n. ischiadicus, runs medially to n. peroneus comm. on dorsal side of knee flexors
- continues straight pathway of n. ischiadicus, submerges btw heads of m. gastrocnemius, downwards btw m. soleus and deep flexors together w/ a. tibialis post.
- runs together w/ tendons of deep flexors below malleolus medialis to plantar side of foot
- terminal branches n. plantars med., lat.
→ ALL flexors of ancle, digits, plantar foot mm. + sensory innervation of lat. side around ancle, plantar side of foot
<u>NOTE:</u> n. ischiadicus = L4 - S3, hence all its fibers
Which branches are given off by n. tibialis?
Where?
in craniocaudal direction, “5” branches
- rr. musculares to flexors in calf
- n. interosseus cruris on membrana interossea
- n. cutaneus surae med. in fossa poplitea
- 2 terminal branches at malleolus med.
- n. plantaris med.
- n. plantaris lat.
3 = n. cut. sur. med., 4 = n. suralis, 5 = rr. musc., 6 = n. plant. med., 7 = plant. lat., n. int. cruris not shown
Nerve?
Which nerve does it eventually form?
Pathway + function.
n. cutaneus surae med.
from n. tibialis, together w/ v. saphena parva running down on calf, anastomosis w/ r. communicans of n. cutaneus surae med. to form
- n. suralis → area around lat. malleolus
- then gives off rr. calcanei → heel
- eventually becomes n. cutaneus dorsalis lat. → lat. side of foot
pathway: 3 = n. cut. surae med., 4 = n. suralis<br></br>inn: 1 = n. suralis, 2 = rr. calcanei
Nerve?
Pathway + branches.
n. plantaris medialis
terminal branch of n. tibialis, gives off branches
- rr. musculares
- 3 nn. digitales plantares communes
→ n. medianus
What is the function of plantaris med.?
resembles n. medianus of foot, hence:
-
motor innervation via rr. musculares
- m. abductor hallucis
- med. head of m. flexor hallucis brevis
- m. flexor digitorum brevis
- m. lumbricalis I
-
sensory innervation via nn. digit plant. comm.
- medial 3,5 toes on plantar side
- terminal phalanges
3
Nerve?
Pathway + function.
n. plantaris lat.
terminal branch of n. tibialis, originates at level of malleolus, runs to lat. side of sole, bifurcates into r. superficialis, profundus
→ n. ulnaris of foot
What is the function of n. plantaris lat.?
resembles n. ulnaris of foot, hence:
-
r. superficialis
→ 3 nn. digitales plantares comm. → 6 nn. digitales plantares proprii → lat. 1,5 toes on plantar side + terminal phalanges (both sides) -
r. profundus + r. superficialis
- m. flexor hallucis brevis, caput lat.
- m. adductor hallucis
- m. quadratus plantae
- mm. lumbricales II, III, IV
- mm. interossei
- all mm. of pinky
4
What is special about n. pudendus?
Spinal origin?
Pathway + function.
forms own plexus pudendus (S2 - 4)
- through foramen infrapiriforme
- together w/ a. pudenda int. around spina ischiadica through foramen ischiadicum minus
- enters fossa ischioanalis, then on lateral wall in Alcock’s canal → there giving off branches
→ function of perineum, continence, sexual activity
