Hindlimb Blood, Lymph, and Nerve Supply (Week 3, Mod 7)

What is the main unit that provides the nerve supply to the hind limbs? What nerves branch from it?

The lumbosacral plexus supplies the nerves for the hindlimbs

Emerging peripheral nerves to the hind limb:

• Gluteal nerve

• Obturator

• Femoral nerve

• Sciatic

  • Tibial / fibular / peroneal branches

Describe the route of the gluteal nerve… what muscles does it supply? What then, is its function? Does it provide cutaneous sensation?

Route:

• Runs over the dorsal surface of the BODY of the ilium

Supplies the gluteal muscles

• Are hindlimb ABDUCTORS 

  • (hind limb retractor / hip extensor in equine)

Does not supply cutaneous sensation 

Describe the route of the obturator nerve… what muscles does it supply? What then, is its function? Does it provide cutaneous sensation?

Route:

• Passes through the OBTURATOR FORAMEN 

  • Is a short route, passes to medial thigh

Supplies the GAPE muscles (gracilis, adductor, pectineus, and external obturator)

• Hind limb ADDUCTORS

Does not provide cutaneous sensation

What is a common problem in dairy cattle that could cause damage to the obturator nerve? What would then happen as a result of this?

Obturator nerve could become damaged in cows during parturition

• Due to medial pathway of the nerve; caused by birthing of OVERSIZED CALVES

• Have difficulty standing up; “doon coo”

Is not a problem in horses; typically don’t have oversized foals

Describe the route of the femoral nerve… what muscles does it supply? What then, is its function? Does it provide cutaneous sensation?

Route:

• Short route to cranial thigh

Supplies the cranial thigh muscles 

• Iliopsoas 

• Sartorius 

• Quandriceps (all heads)

Therefore act as hip FLEXORS, limb PROTRACTORS, and stifle EXTENSORS

Gives sensory supply to the entire medial aspect of the hind limb 

What branch of the femoral nerve is responsible for cutaneous sensation on the inside of the hind limb?  What specific anatomical region does it pass through?

The saphenous branch

• Passes through the FEMORAL TRIANGLE 

  • Region in the upper, medial thigh where the femoral nerve, femoral artery, and femoral vein all pass through

What nerve is responsible for the “patellar reflex”? If this nerve is damaged, what happens to the hindlimb?

The FEMORAL NERVE is responsible for the patellar reflex (hammer to knee test)

• Should cause involuntary extension to the stifle upon impact 

If femoral nerve is damaged, P will be unable to extend stifle (loss of patellar reflex)

• Cannot weight bear

• No compensatory muscles 

Describe the route of the sciatic nerve… what muscles does it supply? What then, is its function? Does it provide cutaneous sensation?

Route:

• Dorsal surface of ilium → passes CAUDAL to hip (very close to hip joint) → runs DEEP to biceps femoris 

Supplies the CAUDAL thigh muscles:

• Biceps femoris 

• Semitendinosus 

• Semimembranous 

Therefore functions as hip EXTENSORS / limb RETRACTORS, and stifle FLEXORS

What are the two branches of the sciatic nerve?

1) Tibial nerve

2) Peroneal / Fibular nerve 

Describe the route of the tibial nerve (branch of sciatic)… what muscles does it supply? What then, is its function? Does it provide cutaneous sensation?

Supplies the caudal TIBIAL muscles:

• Gastrocnemius 

• Superficial digital flexor 

• Deep digital flexor 

Therefore acts as a hock EXTENSOR and digital FLEXORS 

DOES supply cutaneous sensation

• To the caudal / plantar aspect of the limb

Describe the route of the peroneal / fibular nerve (branch of sciatic)… what muscles does it supply? What then, is its function? Does it provide cutaneous sensation?

Supplies the CRANIAL tibial muscles:

• Cranial tibial 

• Peroneus group 

• Long Digital Extensor 

Therefore, acts as a hock FLEXOR and a digital EXTENSOR 

DOES provide cutaneous sensation:

• Cranial / dorsal aspect of limb

• Also lateral thigh 

How can the sciatic nerve become damaged? What happens to the hindlimb as a result? Are there any compensatory muscles that would help the limb still function?

Sciatic Nerve damage may result from

• Hip trauma / surgery

• Femoral fractures

Lose supply to: 

• Hip extensors/ stifle flexors

• Hock extensors/ digital flexors

• Hock flexors/ digital extensors

• Cutaneous sensation

Still possible to:

• Abduct (Gluteals)

• Adduct (Obturator N)

• Protract limb / flex hip / extend stifle (Femoral N)

** CAN get isolated sciatic nerve damage 

As the tibial and peroneal / fibular nerves descend down the EQUINE hindlimb, what nerves do they branch into?

Tibial Nerve:

• Plantar nerves → become plantar digital nerves (1)

• Plantar metatarsal nerves  (2)

Peroneal / Fibular nerve:

• Dorsal metatarsal nerves (3)

Describe the ARTERIAL blood supply of the hindlimb… how is it similar to the blood supply of the forelimb?

ALSO runs as one single major blood vessel, changes names with the region of the hind limb:

• External iliac artery leaves abdominal aorta →

• Femoral artery runs through the thigh region →

• Popliteal artery supplies the distal limb, branches from here 

** ALSO crosses the flexor angle of joints 

Distal limb ALSO well-vascularized:

The farther you go down the limb, the more the artery branches off, and the thinner the branches get and the more that are produced.

- This is why foot injuries bleed like crazy , because there’s so much vascularization 

Describe the VENOUS drainage system of the hind limb… how is it similar to the forelimb?

Has a DEEP and SUPERFICIAL system as well:

• Deep system -

  • Follows arterial blood supply

  • Vein, artery, and nerve all run together; has the same name as artery

• Superficial system -

  • Consists of the lateral saphenous and medial saphenous veins

    • Lat. → prominent in dogs; access to circulation

    • Med. → prominent in cats and horses; access to circulation

What exactly is the femoral triangle, and what are its contents / boundaries?

• Contents:

• Femoral Vein Artery & Nerve

  • Pulse – Femoral Artery

  • Intravascular catheters – Femoral vein

  • Femoral nerve = saphenous branch

• Boundaries:

  • Caudal - Pectineus (& Adductor) 

  • Cranial - Sartorius 

What is the main hind limb lymph node of the dog? Of the cow? Describe how they are clinically significant.

Dog - POPLITEAL

• Caudal to stifle

Cow - PREFEMORAL

• Cranial to femur

Clinical significance:

• Becomes enlarged in response to INFECTION

  • Can be used to differentiate between localized / systemic diseases 

• Important in large animals for meat inspection