limbs 1b - overview of anatomy of upper and lower limbs

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Limbs 1b - Overview of Anatomy of Upper and Lower Limbs Anil Chopra 1 2 3 Explain briefly the embryological development of the limbs Outline briefly the similarities and differences in the upper and lower limbs Explain briefly the difference between the segmental and peripheral nerve supply of a limb 4 Describe the essential structure of the upper and lower limbs, noting the compartmentalised nature of the limbs and their neurovascular supply 5 Outline the muscular compartments of the upper limb 6 Describe the neurovascular patterns of the upper limb 7 Outline the muscular compartments of the lower limb 8 Describe the neurovascular patterns of the lower limb 9 Explain the neurological components of neurological supply to a limb: motor, sensory, reflex, autonomic and trophic 10 Describe a method whereby the neurological features of nerve injury can be evaluated using the pattern described above. Embryology of the Limbs The 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 posterior The limbs pick up their nerve supply before rotation Compartments of the Limbs Muscles 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 muscles 3. Anterior upper arm muscles - flexors 4. Posterior upper arm muscles - extensors 5. Anterior forearm muscles - flexors 6. Posterior forearm muscles - extensors 7. Intrinsic hand muscles Lower Limb: 1. Hip abductors 2. Hip extensors 3. Hip flexors 4. Anterior thigh muscles - extensors 5. Medial thigh muscles 6. Posterior thigh muscles - flexors 7. Anterior leg muscles - extensors 8. Lateral leg muscles

9. Posterior leg muscles - flexors 10. 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 artery o 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 artery o External iliac artery Femoral artery Profunda femoris artery o Superficial femoral artery o 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 Limbs The innervation from the limbs comes from spinal nerves: o C5 T1 for the arms o L2 S2 for the legs Nerves 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 LimbThe Upper Limb Shoulder Elbow Forearm Wrist Long tendons to hand Intrinsic hand muscles Abduction Adduction External Rotation Internal Roatation Flexion Extension Supination Pronation Flexion Extension Flexion Extension T1 C5 C678 C5 C678 C56 C78 C6 C78 C67 C67 C78 C78

The Lower LimbLower Limb Hip L2 L3 L4 L5 S1 S2 Flexion Extension Extension Flexion Planta Flexion Dorsa Flexion Knee Ankle

Sensory Segmental Supply Each 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 region C5 lateral arm C6 lateral forearm and thumb C7 middle finger C8 little finger and medial forearm T1 medial arm T2 axilla and trunk T4 nipple T10 umbilicus T12 lower abdomen L1 suprapubic region L3 front of the thigh (L3 to knee) L4 front of leg (L4 to floor) L5 dorsum of great toe S1 lateral aspect of foot S2-S4 perineum and perianal region

Segme lower li

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 limbs No 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.