Limbs 1b - Overview of Anatomy of Upper and Lower LimbsAnil Chopra

1 Explain briefly the embryological development of the limbs2 Outline briefly the similarities and differences in the upper and lower limbs3 Explain briefly the difference between the segmental and peripheral nerve supply

of a limb4 Describe the essential structure of the upper and lower limbs, noting the

compartmentalised nature of the limbs and their neurovascular supply5 Outline the muscular compartments of the upper limb6 Describe the neurovascular patterns of the upper limb7 Outline the muscular compartments of the lower limb8 Describe the neurovascular patterns of the lower limb9 Explain the neurological components of neurological supply to a limb: motor,

sensory, reflex, autonomic and trophic10 Describe a method whereby the neurological features of nerve injury can be

evaluated using the pattern described above.

Embryology of the LimbsThe limbs grow out of the trunk along with the nerves that are going to supply them (C5-T1 for the arms and L2-S2 for the legs). The upper limbs do not rotate. The lower limbs however undergoes extension and internal rotation.Upper limb – flexors are anterior extensors are posterior Lower Limb – Extensors are anterior Flexors are posteriorThe limbs pick up their nerve supply before rotation

Compartments of the LimbsMuscles in the same compartment tend to perform the same role and have similar blood and nerve supplies.Upper Limb:1. Pectoral girdle muscles (chest)2. Intrinsic shoulder muscles3. Anterior upper arm muscles - flexors4. Posterior upper arm muscles - extensors5. Anterior forearm muscles - flexors6. Posterior forearm muscles - extensors7. Intrinsic hand musclesLower Limb:1. Hip abductors2. Hip extensors3. Hip flexors4. Anterior thigh muscles - extensors5. Medial thigh muscles6. Posterior thigh muscles - flexors7. Anterior leg muscles - extensors8. Lateral leg muscles

9. Posterior leg muscles - flexors10. Intrinsic foot muscles

Blood Supply to the Limbs

Upper Limb: Aorta Subclavian artery Axillary artery (as it passes into the limb) – has many branches. Brachial artery (as it enters the upper arm) – this then splits into the:

o Ulnar artery Common interosseous artery

Anterior interosseous artery Posterior interosseous artery

o Radial arteryo Anastomosis

Palmar carpal arch Dorsal palmar arch Metacarpal arteries Digital arteries

Veins generally follow the arteries There are 2 systems: superficial and deep

o Superficial system = cephalic and basilic vein which arise from the dorsal venous arch on the back of the hand

o The basilic vein runs on the medial (ulnar) aspect of the forearm and passes deep halfway to form the axillary vein

o The cephalic vein runs superficially on the lateral (radial) aspect of the forearm and upper arm and passes deep at the level of the shoulder to form the axillary vein

o Deep forearm veins pass from the forearm and drain into the basilic vein Venae comitantes pass alongside the brachial artery in the upper arm and drain

into the axillary artery The axillary vein passes from the upper arm into the axilla being a continuation of

the basilic vein where the cephalic and vena comitantes drain into it→ subclavian vein

During cold weather venous drainage is through deep veins During hot weather venous drainage is through superficial veins

Lower Limb: Common iliac arteries

o Internal iliac arteryo External iliac artery Femoral artery

Profunda femoris arteryo Superficial femoral arteryo Popliteal artery

Posterior tibial artery Anterior tibial artery Peroneal artery

o Plantar arch In the leg there are also superficial and deep venous systems Deep veins in the calf form the popliteal vein at the back of the knee → forms the

superficial femoral vein which runs alongside the superficial femoral artery → joined by the venae comitantes to form the femoral vein → passes beneath the inguinal ligament to form the external iliac vein → inferior vena cave

Superficial veins start as the dorsal venous arch → long saphenous vein arises from the medial aspect of the dorsum of the foot just anterior to the medial malleolus and runs up the medial sside of the limb, joining the femoral vein in the groin. The short saphenous vein arises from the lateral aspect of the dorsal venous arch, runs up the back of the leg and joins the popliteal vein in the back of the knee

Nervous Organisation of the LimbsThe innervation from the limbs comes from spinal nerves:o C5 – T1 for the armso L2 – S2 for the legsNerves form plexi of which in the:

Upper limb: anterior division supply the flexors and the posterior division supply to the extensors

Lower limb: posterior division supply the flexors and the anterior division supply the extensors

Segmental Innervation- Muscles are generally supplied by two adjacent segments of the spinal cord.- Muscles with the same action share the same nerve supply.- Opposing muscles are usually supplied by nerves two segments above or

below.- The more distal (outward) the joint in the limb, the more caudal (lower) the

spinal segment controlling that.

The Upper Limb

The Upper Limb

Shoulder

Abduction C5Adduction C678

External Rotation C5Internal Roatation C678

ElbowFlexion C56

Extension C78

ForearmSupination C6Pronation C78

WristFlexion C67

Extension C67

Long tendons to handFlexion C78

Extension C78

Intrinsic hand muscles T1

The Lower Limb

Lower Limb

Hip Knee AnkleL2

FlexionL3

ExtensionL4

Extension Dorsa FlexionL5

FlexionS1

Planta FlexionS2

Sensory Segmental SupplyEach segmental spinal nerve supplies sensation to a strip of skin. These do generally overlap – so when a single dermatome is lost it is not generally noticed.

C4 – infraclavicular regionC5 – lateral armC6 – lateral forearm and thumbC7 – middle fingerC8 – little finger and medial forearmT1 – medial armT2 – axilla and trunkT4 – nippleT10 – umbilicusT12 – lower abdomenL1 – suprapubic regionL3 – front of the thigh (L3 to knee)L4 – front of leg (L4 to floor)L5 – dorsum of great toeS1 – lateral aspect of footS2-S4 – perineum and perianal region

Segmental Reflexes: Either stretch reflexes or deep tendon reflexes and are monosynaptic Two main reflex arcs in the upper limb:

Biceps jerk (C6) Triceps jerk (C7)

Two main reflexes in the lower limb: Knee jerk (L3) Ankle Jerk (S1)

Autonomic segmental supply to the limbs:Sympathetic supply via T2-T6 for upper limbs and T11-L2

for lower limbsNo significant parasympathetic outflow to the limbs

Peripheral Nerve Supply to the Limbs:Peripheral innervation of the upper limb is derived from the

brachial plexus which is from the anterior rami of C5-T1 of the spinal nerves

Peripheral innervation of the lower limbs is from the lumbro-sacral plexus which is derived from the anterior rami of L2-S2

Most peripheral nerves are mixed, containing motor and sensory fibres.