11 - Limb Organization and Anterior Medial Thigh

Question 1

division of ventral rami of spinal nerves destined for innervation of the limbs

Answer 1

ventral division:
-supply muscles that developed on the ventral side of the limb (flexors).

dorsal division:
-supply developmentally dorsal muscles (extensors).

Both divisions supply the skin

Question 2

dermatomeal vs. myotomal innervation

Answer 2

• More ventral rami contribute to the dermatomal innervation of a limb than to its myotomal innervation.
• Upper limb muscles are innervated by C5-T1 - Upper limb skin is innervated by C4-T2
• Lower limb muscles are innervated by L2-S3 - Lower limb skin is innervated by T12-S4

Question 3

cutaneous nerve patterns

Answer 3

more central dermatomes are represented distally

Question 4

muscular nerve patterns

Answer 4

proximal nerves innervate the more proximally positioned muscles (and vice versa)

Question 5

innervation of the skin of the hand

Answer 5

C6-C8

Question 6

innervation of the intrinsic muscles of the hand

Answer 6

C8, T1

Question 7

innervation of the skin of the foot

Answer 7

L4-S1

Question 8

innervation of the intrinsic muscles of the foot

Answer 8

S2, S3

Question 9

brachial plexus

Answer 9

Plexus formed from ventral rami
innervation of the upper limb.
originate from spinal cord levels C5-T1 (C4 and T2 are dermatomal only)

Question 10

lumbosacral plexus

Answer 10

• responsible for innervation of the lower limb

- originate from spinal cord levels T12 – S4 (T12, L1 and S4 are dermatomal only)

Question 11

innervation of developmentally dorsal muscles

Answer 11

dorsal division of nerves

Question 12

innervation of developmentally ventral muscles

Answer 12

ventral division of nerves

Question 13

organization of the limbs

Answer 13

• In the embryo, limbs develop from limb buds from the lateral side of the embryo –like a fish or salamander.
• Extensor muscles = dorsal side of the bud
• flexor muscles = ventral side
• ventral and dorsal musculature meet at the preaxial and postaxial borders of the limb. In adult, these borders marked by veins.

Question 14

rotation of limbs

Answer 14

• elbow faces posteriorly and knee faces anteriorly.
• developmentally ventral muscles are found in the anterior and medial compartments of the upper limb
• developmentally ventral mm found in posterior and medial compartments/ quadrants of the lower limb

Question 15

clavipectoral fascia

Answer 15

-lies deep to the Pectoralis major muscle, descends from the clavicle and encloses subclavius and pectoralis minor muscles.

Question 16

brachial fascia

Answer 16

deep fascia of the arm

Question 17

antebrachial fascia

Answer 17

deep fascia of the forearm

Question 18

palmar fascia

Answer 18

deep fascia of the hand

Question 19

intermuscular septa

Answer 19

• extend inward from the deep fascia of the arm and forearm to create fascial compartments of the upper limb
• each compartment is associated with its own nerve and contains muscles with similar actions
• in the forearm, the interosseous membrane assists in dividing the limb segment into compartments

Question 20

superficial fascia

Answer 20

loose connective tissue with fat, cutaneous nerves, lymphatics and veins

Question 21

great saphenous vein

Answer 21

• union of the dorsal venous arch with the dorsal vein of the great toe (hallux)
• runs in superficial fascia on medial aspect of the foot (anterior to the medial malleolus), leg & thigh
• ends by passing through saphenous opening in the deep fascia of the thigh (fascia lata)
• drain into femoral vein.

Question 22

small saphenous vein

Answer 22

arises from the union of the dorsal venous arch with the dorsal vein of the small toe. It runs in the superficial fascia on lateral side of foot (posterior to the lateral malleolus) and posterior aspect of the leg. It ends by draining into the popliteal vein in popliteal fossa (posterior aspect of the knee).

Question 23

perforating veins

Answer 23

connect the superficial veins (great and small saphenous veins and their tributaries) to deep companion veins. These valved perforating veins only allow blood flow from superficial to deep.

Question 24

lymphatic drainage

Answer 24

Superficial lymph follows the path of the great saphenous vein to reach the superficial inguinal nodes (from there it travels to the ext. iliac nodes). Lymph running with the deep veins go to the deep inguinal lymph nodes (then to external iliac nodes).

Question 25

saphenous cut-down

Answer 25

great saphenous vein is often used as a site for venous cut-down (for venous cannulation). For this procedure, the great saphenous vein is accessed about 2cm anterior and superior to the medial malleolus at the ankle.

Question 26

L1 dermatome

Answer 26

over inguinal ligament

Question 27

L2 dermatome

Answer 27

lateral aspect of thigh

Question 28

L3 dermatome

Answer 28

lower medial aspect of thigh

Question 29

L4 dermatome

Answer 29

medial side of hallux (big toe)

Question 30

L5 dermatome

Answer 30

lateral side of 2nd digit

Question 31

S1 dermatome

Answer 31

5th digit

Question 32

S2 dermatome

Answer 32

back of thigh

Question 33

S3 dermatome

Answer 33

skin over gluteal fold

Question 34

perforating veins

Answer 34

connect the superficial veins (great and small saphenous veins and their tributaries) to deep companion veins. These valved perforating veins only allow blood flow from superficial to deep.

Question 35

musculovenous pump

Answer 35

outward expansion of contracting muscles is limited by the taut deep fascia of the lower limb. Therefore, contracting muscles exert a compressive force on the deep veins, assisting in the propulsion of their contents cranially against gravity

Question 36

iliotibial tract/band

Answer 36

thickening of the lateral aspect of the fascia lata. It connects the iliac tubercle and proximal tibia. It is a sight of insertion for the gluteus maximus and tensor fasciae latae muscles.

Question 37

intermuscular septa

Answer 37

extend inward from the fascia lata and insert on the linea aspera of the posterior femur. They act to divide the thigh into anterior, posterior and medial compartments

Question 38

femoral sheath

Answer 38

composed of the inferior prolongations of the transversalis, iliopsoas and pectineal fasciae.

Three compartments in the femoral sheath:

• lateral compartment for the femoral artery
• intermediate compartment for the femoral vein - medial compartment for the femoral canal.

Question 39

femoral canal

Answer 39

contains loose connective tissue, fat and lymph. It s superior opening, which connects to the abdomen, is called the femoral ring.

Question 40

femoral hernias

Answer 40

occur through the femoral canal. Due to the rigid boundaries of the femoral ring, femoral hernias may become strangulated. These hernias are more common in females due to their wider pelves, larger femoral rings, and relatively smaller femoral vessels.

Question 41

femoral triangle

Answer 41

depression on the anteromedial aspect of thigh, inferior to the inguinal ligament and medial to the sartorius muscle. The apex of the femoral triangle points inferiorly and leads to adductor canal. The femoral TRIANGLE contains the femoral sheath and the femoral n.

Question 42

adductor canal

Answer 42

(a.k.a., subsartorial or Hunterian canal) extends from the apex of the femoral trangle to the adductor hiatus and liers deep to the sartorius m. The femoral vessels, saphenous nerve, and the nerve to vastus medialis travel through the adductor canal until it ends at the adductor hiatus.

Question 43

adductor hiatus

Answer 43

gap between the insertions of the two parts of the adductor magnus muscle. When the femoral vessels pass through the adductor hiatus, they appear on the posterior aspect of the thigh, in the popliteal region, as the popliteal artery and vein.

Question 44

where can femoral artery be palpated?

Answer 44

lies superficially as it passes through the femoral triangle. Its pulse can be palpated just inferior to the inguinal ligament midway between the anterior superior iliac spine and the pubic tubercle. It can be compressed against the femoral head in this same location.

Question 45

three arteries that enter the thigh

Answer 45

• femoral (common femoral)
• obturator
• inferior gluteal

Question 46

femoral artery

Answer 46

distal continuation of the external iliac artery, after the latter passes inferior to the inguinal ligament and enters the thigh. It changes it s name to Popliteal artery after it passes through the adductor hiatus.

Question 47

deep femoral artery

Answer 47

(a.k.a. profunda femoris) is a branch of the femoral artery and is primarily responsible for supplying the structures of the thigh (it is assisted by the obturator artery in the medial compartment and femoral artery in the anterior compartment).

Question 48

main branches of the profunda femoris artery are:

Answer 48

• Medial circumflex femoral
• Lateral circumflex femoral
• 3 or 4 perforating arteries

Question 49

obturator artery and vein

Answer 49

(branch of/tributary to the internal iliac) travel with the obturator nerve through the obturator canal to enter the thigh. They supply the head of the femur and medial compartment of the thigh along with the medial femoral circumflex vessels (branch of/tributary to the profunda femoris)

Question 50

inferior gluteal artery

Answer 50

branch of the Internal iliac that enters the gluteal region through the greater sciatic foramen. It has one branch that enters the thigh. We will discuss it with the gluteal region.