PT 701 Human Anatomy: The Leg PDF

The Leg 1 PT 701 Human Anatomy The Leg 1. Osteology a. Tibia i. Medial and lateral vi...

The Leg 1 PT 701 Human Anatomy The Leg 1. Osteology a. Tibia i. Medial and lateral vi. Shaft condyles vii. Anterior boarder and ii. Intercondylar eminence medial surfaces iii. Anterolateral tibial viii. Interosseus boarder tubercle (Gerdy’s ix. Soleal line tubercle) x. Medial malleolus iv. Tibial tuberosity xi. Fibular notch v. Facet for fibula b. Fibula i. Head iii. Lateral malleolus ii. Neck iv. Shaft c. Interosseus Membrane i. Syndesmoses between tibia and fibular (middle tibiofibular joint) d. Proximal and Distal tibiofibular joints i. Planar synovial joints ii. See notes on anterior and lateral leg for more details Section 1 The Leg 2 Section 1 The Leg 3 2. Fascia a. Crural Fascia i. Continuous with fascia lata ii. Surrounds the leg except along the medial surface of the tibia 1. Attaches to anterior and posterior margins of the tibia iii. Intermuscular septa  form anterior and lateral compartments iv. Retinacula: Prominent bands of the fascia in the distal leg that prevent the long tendons from bowstringing at the ankle 1. Superior and inferior extensor retinaculum 2. Flexor Retinaculum 3. Fibular Retinaculum Section 1 The Leg 4 b. Compartments of the Leg (four compartments) i. Compartments 1. Anterior compartment a. Bounded by Tibia, interosseus membrane, and anterior intermuscular septum 2. Lateral Compartment a. Bounded by anterior intermuscular septum, fibula, and posterior intermuscular septum 3. Deep Posterior Compartment a. Bounded by tibia, interosseus membrane and fibular anteriorly and the transverse septum posteriorly 4. Superficial Posterior Compartment a. Posterior to transverse septum ii. Clinical Relevance of the Compartments 1. Compartment Syndrome: soft tissue injury or edema or hemorrhage can quickly build up pressure in the injured compartment a.  Pressure on neurovascular structures in that compartment and can lead to nerve damage if not resolved b. This is a medical emergency and requires surgical release (an incision in the crurual fascia) to relieve the pressure 2. Chronic overuse injuries can also cause inflammation and increased pressure in selective compartments Section 1 The Leg 5 3. Superficial Posterior Compartment a. Overview i. Muscles of the posterior compartment are the more powerful plantar flexors ii. These muscles are crucial for walking, running, jumping iii. Planatris has little function and its tendon may be used for surgical repair of other strucutres iv. All three insert into the tendocalcaneus (Achilles tendon) b. Muscles of the Superficial Posterior Compartment Muscle Origin Insertion Nerve Action Plantar flexes Lateral head: lateral aspect ankle when knee of lateral condyle of femur is extended, raises Gastrocnemius Medial head: popliteal heel during surface of femur superior walking, flexes leg to medial condyle at knee joint Posterior Posterior aspect of head surface of and superior ¼ of posterior Plantar flexes calcaneus Tibial surface of fibula; soleal line ankle independent via calcaneal nerve S1,2 Soleus and middle 1/3 of medial of position of tendon border of tibia; and knee, steadies leg tendinous arch extending on foot between bony attachments Inferior end of lateral Weakly assists supracondylar line of gastroc in Plantaris femur; oblique popliteal plantarflexing ligament ankle Section 2 The Leg 6 c. Neurovascular i. Shares the posterior tibial artery and the tibial nerve with the deep posterior compartment (the neurovascular structures travel along the midline in the deep posterior compartment (see below for details) Section 2 The Leg 7 d. Clinical Considerations i. Achilles tendonitis/rupture 1. Tendonitis (and tendinosis) can develop due to improper training increases or impaired lower extremity biomechanics 2. Tendon rupture can lead to balling up of tendon in the calf  inability to plantarflex against gravity a. Typically requires surgical repair and extensive rehabilitation ii. Deep vein thrombosis and calf pump 1. Deep vein thrombosis (DVT) occurs when blood clots due to stasis 2. In individuals who are sedentary (especially on bed rest) this can happen in the posterior tibial veins (in the deep posterior compartment) 3. The triceps surae (calf muscles) can act as a muscle pump to help pump blood 4. PT’s are often involved in the care of individuals in acute care to help promote their use of active dorsi/plantarflexion to reduce risk of DVT Section 2 The Leg 8 4. Deep Posterior Compartment a. Overview i. Contains the long flexors of the foot and toes ii. These muscles function to control the foot during standing and gait b. Muscles Muscle Origin Insertion Nerve Action Weakly flexes knee Lateral surface of lateral and unlocks it by Posterior surface of tibia Tibial nerve Popliteus condyle of femur and rotating femur 5 superior to soleal line L4, L5. S1 lateral meniscus degrees on fixed tibia, Flexes great toe at Inferior 2/3 of posterior all joints, weakly Flexor surface of fibula, inferior Base of distal phalanx of Tibial nerve plantarflexes ankle, halluces part of interosseous great toe S2, 3 supports medial longus membrane longitudinal arch of foot Flexes lateral 4 Medial part of posterior Flexor digits plantar flexes surface of tibia inferior Bases of distal phalanges Tibial nerve digitorum ankle, supports to soleal line, bly broad of lateral 4 digits S2, 3 longus longitudinal arch of tendon to fibula foot Interosseous membrane; Tuberosity of navicular, posterior surface of tib, Tibialis cuneiform, cuboid and, Tibial nerve Plantar flexes and inferior to soleal line, posterior bases of 2nd 3rd and 4th L4. L5 inverts foot posterior surface of metatarsals fibula c. Neurovascular Section 3 The Leg 9 i. Innervation: Tibial nerve ii. Vascular: Posterior tibial artery (continuation of the popliteal artery as it descends from the popliteal fossa) d. Clinical/Functional Considerations i. Pure Inversion 1. Inversion of the foot is controlled by both the tibialis anterior and tibialis posterior. Working together these muscles can produce pure inversion. Working alone, the tibialis anterior produces inversion with dorsiflecion and the tibialis posterior produces inversion with plantarflexion. 2. Note that both muscles (although in different compartments with different peripheral nerves) receive the same spinal segments Section 3 The Leg 10 Section 3 The Leg 11 5. Anterior Compartment a. Overview i. The muscles of the anterior compartment are the dorsiflexors (extensors) of the ankle b. Muscles of the Anterior Compartment Proximal Muscle Distal Attachment Innervation Actions Attachment Lateral condyle Medial & inferior DF and inversion; and superior ½ of Deep fibular Tibialis Anterior surfaces of 1st (also draws the leg lateral surface of (peroneal) n; (TA) cuneiform and over the foot tibia, interosseous L4, 5 base of 1st MT. during gait) membrane Lateral condyle of Deep fibular Extensor tibia and superior Middle and distal Extends lateral (peroneal) n; digitorum longus ¾ of medial fibula phalanges of four digits and L4, L5 (EDL) and interosseous lateral 4 digits DF’s ankle membrane Middle part of Dorsal aspect, Deep fibular anterior surface of Extensor hallucis base of distal (peroneal) n; Extends great toe, fibula and longus (EHL) phalanx of great L4, L5 DF’s ankle interosseous toe membrane Inferior 2/3 of Deep fibular Fibularis anterior fibula and Dorsum of base of (peroneal) n; DF and eversion (Peroneus) tertius interosseous 5th MT L4, L5 membrane Section 4 The Leg 12 Section 4 The Leg 13 c. Muscles of the dorsal foot (short toe extensors) Muscle Origin Insertion Action Innervation Merge with Extensor Calcaneus (floor assist ext of toes Deep Fibular n L5 extensor Digitorum Brevis of tarsal sinus) at MTP jt S1 Tendons digits 2-4 Dorsal aspect Extensor Hallucis Calcaneus (floor assist ext of great Deep Fibular n L5 base of prox Brevis of tarsal sinus) toe at MTP jt S1 phalanx great toe Section 4 The Leg 14 d. Neurovascular i. Innervation: Deep fibular nerve (branch of common fibular) ii. Vascular: Anterior Tibial Artery 1. Becomes Dorsalis Pedis Artery as it crosses the ankle joint Section 4 The Leg 15 e. Clinical Considerations i. Anterior Shin Splints 1. Swelling and inflammation of the anterior compartment muscles (frequently due to increase in running/jumping activities too quickly) 2. May progress to compartment syndrome if inflammation/swelling is not controlled 3. May also include irritation/inflammation where the fascia attaches to the bone ii. Compartment Syndrome 1. See posterior leg notes iii. Foot Drop 1. Injury to deep fibular nerve (or common fibular)  paralysis of dorsiflexors of the ankle 2. As a result, the individual is unable to pull up his/her toes when stepping/walking  can lead to tripping and falling Section 4 The Leg 16 6. Lateral Compartment a. Overview i. Muscles of the lateral compartment evert the ankle ii. Primary function is to counteract the inversion actions of the dorsiflexors iii. Fibularis longus also plays a critical role in stabilizing/supporting the arches of the foot b. Muscles of the Lateral Compartment Proximal Muscle Distal Attachment Innervation Actions Attachment Superficial fibular Fibularis Head, superior 2/3 Base of 1st MT and Everts foot, weak (peroneal) n. (peroneus) longus of lateral fibula 1st cuneiform PF L5, S1, S2 Dorsal surface of Superficial fibular Fibularis Inferior 2/3 of tuberosity on Everts foot, weak (peroneal) n. (peroneus) brevis lateral fibula lateral side, base PF L5, S1, S2 of 5th MT Section 5 The Leg 17 c. Neurovascular to Lateral Compartment i. Innervation: Superficial Fibular Nerve 1. Consider the course of the Superficial Fibular nerve: how could it be injured in a lateral ankle sprain? (more on that with the ankle!) ii. Vascular: Fibular Artery 1. Fibular artery does NOT run in the lateral compartment. It is a branch of the posterior tibial artery that runs in the deep posterior compartment 2. Perforating branches of the fibular artery traverse the posterior intermuscular septum to supply the fibularis muscles Section 5 The Leg 18 Section 5 The Leg 19 7. Overview of Neurovascular to the Leg a. Arterial Supply i. Blood supply derives from the popliteal artery which divides into anterior and posterior tibial arteries in the proximal leg ii. Anterior tibial artery supplies the anterior compartment and travels with the deep fibular nerve iii. Posterior tibial artery travels in the deep posterior compartment and gives of the fibular artery which travels near the fibula (also in the deep posterior compartment) Section 6 The Leg 20 b. Superficial Veins i. Great saphenous (medial) 1. From the dorsum of the foot  anterior to medial malleolus 2. Medial leg to medial thigh  merges with femoral vein ii. Small saphenous (posterior) 1. From lateral malleolus  posterior leg 2. Between heads of gastroc  joins popliteal vein in popliteal fossa Section 6 The Leg 21 c. Innervation Overview i. The tibial nerve travels in the deep posterior compartment near the posterior tibial artery ii. The deep fibular nerve travels in the anterior compartment with the anterior tibial artery iii. The superficial fibular nerve travels alone in the lateral compartment and then emerges superficially to provide cutaneous innervation over the distal lateral leg and dorsal foot Section 6 The Leg 22 d. Sensory to the Leg Section 6 The Leg 23 8. Arthrology of the Tibiofibular Joints a. Proximal Tibiofibular Joint i. Structure 1. Gliding Planar Joint 2. Between head of fibula and facet on proximal lateral tbia 3. Joint capsule may communicate with knee joint ii. Joint supports 1. Ligaments a. Proximal anterior tibiofibular ligament b. Proximal posterior tibiofibular ligament 2. Structures in close proximity a. Common peroneal nerve (runs around head of fibula) b. Biceps femoris and popliteus tendons c. IT band d. Origins of PL, EDL, Lateral Gastrocnemius and Soleus iii. Motions 1. Fibula glides superiorly and posteriorly with dorsiflexion (functional w/ ankle) iv. Neurovascular Supports 1. Innervation: common peroneal (fibular) nerve 2. Blood supply: Lateral genicular, anterior tibial, and recurrent tibial arteries Section 7 The Leg 24 B. Middle Tibiofibular Joint i. Structure 1. Syndesmosis: interosseus membrane b/t tibia and fibula 2. Fibers of IO membrane obliquely oriented to resist muscle pull and disperse forces (Fibula does not bear weight) ii. Motions 1. Accessory movement with ankle joint Section 7 The Leg 25 C. Distal Tibiofibular Joint i. Structure 1. Fibrous/Syndesmosis, but may be gliding planar 2. Fibula = convex, Tibia = concave surface ii. Joint supports 1. Ligaments a. Interosseus ligament (continuous with IO membrane) b. Distal Anterior Tibiofibular Ligament c. Distal Posterior Tibiofibular Ligament (very strong, more likely to avulse than tear) i. Deep portion = Transverse Tibiofibular Ligament (involved in “tri malleolar fx”) iii. Neurovascular Supports 1. Innervation: Deep peroneal (fibular), tibial, and saphenous nn 2. Blood supply: Perforating branches of peroneal, anterior and posterior tibial aa iv. Motions 1. Fibula glides superiorly and posteriorly with dorsiflexion (functions w/ ankle) Section 7 The Leg 26 9. Clinical Considerations for the leg a. Tibial fractures- heal slowly owing to a sparse muscular attachment to the tibia and thus poor blood supply. Tibial plateau fractures are particularly troublesome. b. Injuries to the common fibular nerve- on the neck of the fibula where it lies superficially and is prone to injury. This causes foot drop. c. Deep venous thrombosis and varicose veins- discussed in posterior leg. d. Compartment syndrome e. Shin splints: anterior and medial i. Anterior: see above ii. Medial shin splints: multiple theories implicating either tibialis posterior or the soleus along their attachments to the tibia f. Ankle reflex (ankle jerk) produced by tapping the tendo calcaneus tests the reflex pathways through spinal segments S1 and S2. It is performed similar to the knee jerk reflex. Section 7