11 - Limb Organization and Anterior Medial Thigh Flashcards
division of ventral rami of spinal nerves destined for innervation of the limbs
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
dermatomeal vs. myotomal innervation
- 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
cutaneous nerve patterns
more central dermatomes are represented distally
muscular nerve patterns
proximal nerves innervate the more proximally positioned muscles (and vice versa)
innervation of the skin of the hand
C6-C8
innervation of the intrinsic muscles of the hand
C8, T1
innervation of the skin of the foot
L4-S1
innervation of the intrinsic muscles of the foot
S2, S3
brachial plexus
Plexus formed from ventral rami
innervation of the upper limb.
originate from spinal cord levels C5-T1 (C4 and T2 are dermatomal only)
lumbosacral plexus
- responsible for innervation of the lower limb
- originate from spinal cord levels T12 – S4 (T12, L1 and S4 are dermatomal only)
innervation of developmentally dorsal muscles
dorsal division of nerves
innervation of developmentally ventral muscles
ventral division of nerves
organization of the limbs
- 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.
rotation of limbs
- 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
clavipectoral fascia
-lies deep to the Pectoralis major muscle, descends from the clavicle and encloses subclavius and pectoralis minor muscles.
brachial fascia
deep fascia of the arm
antebrachial fascia
deep fascia of the forearm
palmar fascia
deep fascia of the hand
intermuscular septa
- 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
superficial fascia
loose connective tissue with fat, cutaneous nerves, lymphatics and veins
great saphenous vein
- 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.
small saphenous vein
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).
perforating veins
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.
lymphatic drainage
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).
saphenous cut-down
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.
L1 dermatome
over inguinal ligament
L2 dermatome
lateral aspect of thigh
L3 dermatome
lower medial aspect of thigh
L4 dermatome
medial side of hallux (big toe)
L5 dermatome
lateral side of 2nd digit
S1 dermatome
5th digit
S2 dermatome
back of thigh
S3 dermatome
skin over gluteal fold
perforating veins
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.
musculovenous pump
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
iliotibial tract/band
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.
intermuscular septa
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
femoral sheath
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.
femoral canal
contains loose connective tissue, fat and lymph. It s superior opening, which connects to the abdomen, is called the femoral ring.
femoral hernias
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.
femoral triangle
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.
adductor canal
(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.
adductor hiatus
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.
where can femoral artery be palpated?
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.
three arteries that enter the thigh
- femoral (common femoral)
- obturator
- inferior gluteal
femoral artery
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.
deep femoral artery
(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).
main branches of the profunda femoris artery are:
- Medial circumflex femoral
- Lateral circumflex femoral
- 3 or 4 perforating arteries
obturator artery and vein
(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)
inferior gluteal artery
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.
