BLOCK 12 WEEK 4 Flashcards

Question

Popliteal Fossa

Answer 1

The popliteal fossa is a diamond shaped area located on the posterior aspect of the knee. It is the main path by which vessels and nerves pass between the thigh and the leg. Diamond shaped 4 borders: - Superomedial – semimembranosus. - Superolateral – biceps femoris. - Inferomedial – medial head of the gastrocnemius. - Inferolateral – lateral head of the gastrocnemius and plantaris. Floor: posterior surface of the knee joint capsule, popliteus muscle and posterior femur. Roof: popliteal fascia and skin CONTENTS: - Popliteal artery - Popliteal vein - Tibial nerve - Common fibular nerve (common peroneal nerve)

Answer 2

The tibial and common fibular nerves are the most superficial of the contents of the popliteal fossa. They are both branches of the sciatic nerve. The common fibular nerve follows the biceps femoris tendon, travelling along the lateral margin of the popliteal fossa. The small saphenous vein pierces the popliteal fascia and passes between the two heads of gastrocnemius to empty into the popliteal vein. In the popliteal fossa, the deepest structure is the popliteal artery. It is a continuation of the femoral artery, and travels into the leg to supply it with blood.

Answer 3

The appearance of mass in the popliteal fossa usually is because of a bakers cyst or aneurysm of the popliteal artery. BAKERS CYST (popliteal cyst): - A Baker’s cyst (popliteal cyst) refers to the inflammation and swelling of the semimembranosus bursa – a sac-like structure containing a small amount of synovial fluid. It usually arises in conjunction with osteoarthritis of the knee. - Whilst it usually self-resolves, the cyst can rupture and produce symptoms similar to deep vein thrombosis.

Answer 4

Popliteal Aneurysm: - An aneurysm is a dilation of an artery, which is greater than 50% of the normal diameter. The popliteal fascia (the roof of the popliteal fossa) is tough and non-extensible, and so an aneurysm of the popliteal artery has consequences for the other contents of the popliteal fossa. - The tibial nerve is particularly susceptible to compression from the popliteal artery. The major features of tibial nerve compression are: - Weakened or absent plantar flexion - Paraesthesia of the foot and posterolateral leg An aneurysm of the popliteal artery can be detected by an obvious palpable pulsation in the popliteal fossa. An arterial bruit may be heard on auscultation.

Answer 5

A bursa is a sac-like structure containing a small amount of synovial fluid. It functions to decrease friction between tendons, bone, and skin during movement Knee bursae (4): - SUPRAPATELLAR BURSAE: located between the quadriceps femoris and the femur. - PREPATELLAR BURSAE: located between the apex of the patella and the skin. - INFRAPATELLAR BURSAE: split into deep and superficial. The deep bursa lies between the tibia and the patella ligament. The superficial lies between the patella ligament and the skin. - SEMIMEMBRANEOUS BURSAE: located posterior to the knee joint, between the semimembranosus muscle and the medial head of the gastrocnemius.

Answer 6

ALL: resists lateral rotation of the femur on the tibia - Commonly damaged with the ACL which causes long term rotational instability

Answer 7

-The tibial nerve is a major peripheral nerve of the lower limb. -It has several cutaneous and motor functions in the leg and foot. - Tibial Nerve Roots: L4-S3 SENSORY : Innervates the skin of the posterolateral leg, lateral foot and the sole of the foot. MOTOR: Innervates the posterior compartment of the leg and the majority of the intrinsic foot muscles.

Answer 8

The tibial nerve is a branch of the sciatic nerve, and arises at the apex of the popliteal fossa. It travels through the popliteal fossa, giving off branches to muscles in the superficial posterior compartment of the leg. Here, the tibial nerve also gives rise to branches that contribute towards the sural nerve, which innervates the posterolateral aspect of the leg. The tibial nerve continues its course down the leg, posterior to the tibia. During its descent, it supplies the deep muscles of the posterior leg. At the foot, the nerve passes posteriorly and inferiorly to the medial malleolus, through a structure known as the tarsal tunnel. Within this tunnel, branches arise from the tibial nerve to supply cutaneous innervation to the heel Immediately distal to the tarsal tunnel, the tibial nerve terminates by dividing into sensory branches, which innervate the sole of the foot.

Answer 9

-The tibial nerve innervates the muscles of the posterior leg - the majority of the intrinsic foot muscles.# ALL of the muscles in the back of the leg are innervated by the tibial nerve deep and superficial. INTRINSIC MUSCLES: - The medial and lateral plantar branches of the tibial nerve provide innervation to all the intrinsic muscles of the foot (exept the extensor digitorum brevis, which is innervated by the deep fibular nerve).

Answer 10

In the popliteal fossa, the tibial nerve gives off cutaneous branches. These combine with branches from the common fibular nerve to form the sural nerve. This sensory nerve innervates the skin of the posterolateral side of the leg and the lateral side of the foot. The tibial nerve also supplies all the sole of the foot via three branches: -Medial calcaneal branches: These arise within the tarsal tunnel, and innervate the skin over the heel. -Medial plantar nerve: Innervates the plantar surface of the medial three and a half digits, and the associated sole area. -Lateral plantar nerve: Innervates the plantar surface of the lateral one and a half digits, and the associated sole area.

Answer 11

Nerve roots: L2-L4 Motor functions: Innervates the anterior thigh muscles that flex the hip joint (pectineus, iliacus, sartorius) and extend the knee (quadriceps femoris: rectus femoris, vastus lateralis, vastus medialis and vastus intermedius), Sensory functions: Supplies cutaneous branches to the anteromedial thigh (anterior cutaneous branches of the femoral nerve) and the medial side of the leg and foot (saphenous nerve).

Answer 12

- Arising from the lumbar plexus, the femoral nerve travels inferiorly through the psoas major muscle of the posterior abdominal wall. It supplies branches to the iliacus and pectineus muscles prior to entering the thigh - The femoral nerve then passes underneath the inguinal ligament to enter the femoral triangle - Approximately 4cm below the inguinal ligament, the femoral nerve divides into anterior and posterior divisions - The terminal cutaneous branch of the femoral nerve is the saphenous nerve. Saphenous nerve exits via the exits prior to the adductor hiatus. - The saphenous nerve innervates the medial aspect of the leg and the foot.

Answer 13

- The hip flexors and knee extensors are supplied by the femoral nerve

Answer 14

There are two main sensory branches that arise from the femoral nerve: - Anterior cutaneous branches – derived from the anterior division of the femoral nerve. They supply the skin of the anteromedial thigh. - Saphenous nerve – a continuation of the posterior division of the femoral nerve. It supplies the skin of the medial leg and foot.

Answer 15

The cutaneous branch of the obturator nerve supplies the skin of the middle part of the medial thigh. -Nerve roots: L2-L4 -Motor functions: Innervates the muscles of the medial compartment of the thigh (obturator externus, adductor longus, adductor brevis, adductor magnus and gracilis). -Sensory functions: Cutaneous branches of the obturator nerve innervate the skin of the medial thigh.

Answer 16

-Nerve roots: L4-S3. -Motor functions: Innervates the muscles of the posterior thigh (biceps femoris, semimembranosus and semitendinosus) and the hamstring portion of the adductor magnus (remaining portion of which is supplied by the obturator nerve). Indirectly innervates (via its terminal branches) all the muscles of the leg and foot. -Sensory functions: No direct sensory functions. Indirectly innervates (via its terminal branches) the skin of the lateral leg, heel, and both the dorsal and plantar surfaces of the foot.

Answer 17

-Nerve roots: L4 – S2 -Motor: Innervates the short head of the biceps femoris directly. Also supplies (via branches) the muscles in the lateral and anterior compartments of the leg. -Sensory: Innervates the skin of the lateral leg and the dorsum of the foot.

Answer 18

The common fibular nerve innervates the short head of the biceps femoris muscle Superficial fibular nerve: Innervates the muscles of the lateral compartment of the leg; fibularis longus and brevis. These muscles act to evert the foot. Deep fibular nerve: Innervates the muscles of the anterior compartment of the leg; tibialis anterior, extensor digitorum longus and extensor hallucis longus. These muscles act to dorsiflex the foot and extend the digits. It also innervates some intrinsic muscles of the foot.

Answer 19

- The nerve begins at the apex of the popliteal fossa, where the sciatic nerve bifurcates into the tibial and common fibular nerves. - CFN supplies the short head of the biceps femoris - Goes down in a lateral and inferior direction, over the lateral head of the gastrocnemius. At this point, the nerve gives rise to two cutaneous branches, which contribute to the innervation of the skin of the leg. - To enter the lateral compartment of the leg, the nerve wraps around the neck of the fibula, passing between the attachments of the fibularis longus muscle. Here, the common fibular nerve terminates by dividing into the SUPERFICIAL FIBULAR and DEEP FIBULAR nerves.

Answer 20

There are two cutaneous branches that arise directly from the common fibular nerve as it moves over the lateral head of the gastrocnemius: Sural communicating nerve – combines with a branch of the tibial nerve to form the sural nerve, which innervates the skin over the lower posterolateral leg. Lateral sural cutaneous nerve – innervates the skin over the upper lateral leg. In addition to these nerves The terminal branches of the common fibular nerve also have a cutaneous function: Superficial fibular nerve: Innervates the skin of the anterolateral leg, and dorsum of the foot (except the skin between the first and second toes). Deep fibular nerve: Innervates the skin between the first and second toes.

Answer 21

The common fibular nerve is most commonly damaged by a fracture of the fibula, or the use of a tight plaster cast. The anatomical course of the common fibular nerve causes it to wrap round the neck of the fibular, and so any fractures of the fibular neck can cause nerve palsy. Patients with common fibular nerve damage will lose the ability to dorsiflex the foot at the ankle joint. Hence the foot will appear permanently plantarflexed – known as footdrop. They may also present with a characteristic gait, as a result of the footdrop (for more information, see Walking and Gaits). There will also be a loss of sensation over the dorsum of the foot, and lateral side of the leg. Innervation is preserved on the medial side of the leg (supplied by the saphenous nerve, a branch of the femoral), and the heel and sole (supplied by the tibial nerve, a branch of the sciatic).

Answer 22

Nerve roots: L4-S1 Motor: Innervates the muscles in the lateral compartment of the leg (FIBULARIS LONGUS AND BREVIS) Sensory: Supplies the anterolateral aspect of the distal leg and the majority of the dorsum of the foot (apart from the webbing between the hallux and the second digit).

Answer 23

- The superficial fibular nerve is a terminal branch of the common fibular nerve. - It arises at the neck of the fibula, descending between the fibularis muscles and the lateral side of the extensor digitorum longus. Here, it gives rise to motor branches, which supply the fibularis longus and brevis. The nerve continues its descent, with a purely cutaneous function, providing sensory innervation to the anterolateral aspect of the lower leg. When the superficial fibular nerve reaches the lower third of the leg, it pierces the deep crural fascia and terminates by dividing into the medial and intermedial dorsal cutaneous nerves. These nerves enter the foot to innervate the majority of its dorsal surface.

Answer 24

Nerve roots: L4-S2 Motor function: Innervates the muscles in the anterior compartment of the leg (TIBIALIS ANTERIOR, EXTENSOR DIGITORIUM LONGUS and EXTENSOR DIGITORIUM BREVIS), as well as some of the intrinsic muscles of the foot Sensory function: Supplies the triangular region of skin between the 1st and 2nd toes.

Answer 25

Accompanied by the anterior tibial artery, it descends in a plane initially between the tibialis anterior and extensor digitorum longus, and then distally between the tibialis anterior and extensor hallucis longus. During its descent, the deep fibular nerve is initially lateral, then anterior and finally medial to the anterior tibial artery.

Answer 26

The lumbar plexus is a network of nerve fibres that supplies the skin and musculature of the lower limb. It is located in the lumbar region, within the substance of the psoas major muscle and anterior to the transverse processes of the lumbar vertebrae. The plexus is formed by the anterior rami (divisions) of the lumbar spinal nerves L1, L2, L3 and L4. It also receives contributions from thoracic spinal nerve 12.

Answer 27

The spinal nerves L1 – L4 form the basis of the lumbar plexus. At each vertebral level, paired spinal nerves leave the spinal cord via the intervertebral foramina of the vertebral column. Each nerve then divides into anterior and posterior nerve fibres. The lumbar plexus begins as the anterior fibres of the spinal nerves L1, L2, L3, and L4.

Answer 28

The anterior rami of the L1-L4 spinal roots divide into several cords. These cords then combine together to form the six major peripheral nerves of the lumbar plexus. These nerves then descend down the posterior abdominal wall to reach the lower limb, where they innervate their target structures. Branches: - Iliohypogastric Nerve - Ilioinguinal Nerve - Genitofemoral Nerve - Lateral Cutaneous Nerve of the Thigh - Obturator Nerve - Femoral Nerve

Answer 29

The sacral plexus is a network of nerve fibres that supplies the skin and muscles of the pelvis and lower limb. It is located on the surface of the posterior pelvic wall, anterior to the piriformis muscle. The plexus is formed by the anterior rami (divisions) of the sacral spinal nerves S1, S2, S3 and S4. It also receives contributions from the lumbar spinal nerves L4 and L5. In this article, we shall look at the anatomy of the sacral plexus – its formation and major branches.

Answer 30

The spinal nerves S1 – S4 form the basis of the sacral plexus. At each vertebral level, paired spinal nerves leave the spinal cord via the intervertebral foramina of the vertebral column. Each nerve then divides into anterior and posterior nerve fibres. The sacral plexus begins as the anterior fibres of the spinal nerves S1, S2, S3, and S4. They are joined by the 4th and 5th lumbar roots, which combine to form the lumbosacral trunk. This descends into the pelvis to meet the sacral roots as they emerge from the spinal cord.

Answer 31

The anterior rami of the S1-S4 spinal roots (and the lumbosacral trunk) divide into several cords. These cords then combine together to form the five major peripheral nerves of the sacral plexus. These nerves then descend down the posterior pelvic wall. They have two main destinations: Leave the pelvis via the greater sciatic foramen – these nerves enter the gluteal region of the lower limb, innervating the structures there. Remain in the pelvis – these nerves innervate the pelvic muscles, organs and perineum. BRANCHES: - Superior Gluteal Nerve - Inferior Gluteal Nerve - Sciatic Nerve - Posterior Femoral Cutaneous - Pudendal Nerve

Answer 32

RUPTURED CALCANEAL TENDON

Answer 33

- Bones of the foot are split into tarsals, metatarsals and phalanges

Answer 34

The tarsal bones of the foot are organised into three rows: proximal, intermediate, and distal. PROXIMAL: - TALUS - CALCANEUS INTERMEDIATE(1): - NAVICULAR DISTAL: - THE CUBOID - THREE CUNEIFORMS

Answer 35

The talus is the most superior of the tarsal bones. It transmits the weight of the entire body to the foot. It has three articulations: -Superiorly – ankle joint – between the talus and the bones of the leg (the tibia and fibula). -Inferiorly – subtalar joint – between the talus and calcaneus. -Anteriorly – talonavicular joint – between the talus and the navicular. The main function of the talus is to transmit forces from the tibia to the heel bone (known as the calcaneus). It is wider anteriorly compared to posteriorly which provides additional stability to the ankle. Whilst numerous ligaments attach to the talus, no muscles originate from or insert onto it. This means there is a high risk of avascular necrosis as the vascular supply is dependent on fascial structures.

Answer 36

The calcaneus is the largest tarsal bone and lies underneath the talus where it constitutes the heel. It has two articulations: -Superiorly – subtalar (talocalcaneal) joint – between the calcaneus and the talus. -Anteriorly – calcaneocuboid joint – between the calcaneus and the cuboid. It protrudes posteriorly and takes the weight of the body as the heel hits the ground when walking. The posterior aspect of the calcaneus is marked by calcaneal tuberosity, to which the Achilles tendon attaches.

Answer 37

Positioned medially, it articulates with the talus posteriorly, all three cuneiform bones anteriorly, and the cuboid bone laterally. On the plantar surface of the navicular, there is a tuberosity for the attachment of part of the tibialis posterior tendon.

Answer 38

- Cuboid and 3 cuneiforms - Some cuneiforms are attachment points for muscles: -Medial cuneiform – tibialis anterior, (part of) tibialis posterior, and fibularis longus -Lateral cuneiform – flexor hallucis brevis

Answer 39

- The ankle joint (or talocrural joint) is a synovial joint located in the lower limb. - It is formed by the bones of the leg (tibia and fibula) and the foot (talus) - Functionally, it is a hinge type joint, permitting dorsiflexion and plantarflexion of the foot. -

Answer 40

The distal tibia and fibula articular portions together form the ankle mortice, which contains the body of talus bone

Answer 41

The medial ligament (or deltoid ligament) is attached to the medial malleolus (a bony prominence projecting from the medial aspect of the distal tibia). It consists of four ligaments, which fan out from the malleolus, attaching to the talus, calcaneus and navicular bones. The primary action of the medial ligament is to resist OVER-EVERSION of the foot.

Answer 42

The lateral ligament originates from the lateral malleolus (a bony prominence projecting from the lateral aspect of the distal fibula). It resists OVER_INVERSION of the foot, and is comprised of three distinct and separate ligaments: - Anterior talofibular – spans between the lateral malleolus and lateral aspect of the talus. -Posterior talofibular – spans between the lateral malleolus and the posterior aspect of the talus. -Calcaneofibular – spans between the lateral malleolus and the calcaneus.

Answer 43

A Pott’s fracture is a term used to describe a bimalleolar (medial and lateral malleoli) or trimalleolar (medial and lateral malleoli, and distal tibia) fracture. This type of injury is produced by forced eversion of the foot. It occurs in a series of stages: Forced eversion pulls on the medial ligaments, producing an avulsion fracture of the medial malleolus. The talus moves laterally, breaking off the lateral malleolus. The tibia is then forced anteriorly, shearing off the distal and posterior part against the talus.

Answer 44

The talocural joint is more stable in dorsiflexion. Anterior talus is held tightly in mortise

Answer 45

There are two distinct articulations that connect the talus and calcaneus: the anatomical subtalar (talocalcaneal) joint, located posteriorly, and the more anterior talocalcaneonavicular joint. Due to their simultaneous movement these joints are often considered as one collective functional unit in clinical practice, which is somewhat confusingly referred to as the (functional) subtalar joint. The talocalcaneonavicular joint is a form of ball and socket joint formed between three tarsal bones: the talus, calcaneus and navicular bones. Here, the convex head and plantar surface of the neck of talus articulate with a ‘socket’ formed by the calcaneus and navicular bone, in addition to the plantar calcaneonavicular and calcaneonavicular part of bifurcate ligament. There are three principal ligaments associated with this joint: the dorsal talonavicular ligament, plantar calcaneonavicular ligament and calcaneocuboid part of the bifurcate ligament. In the talocalcaneonavicular joint, the two types of movements (gliding and rotation) allow motions in 3 degrees of freedom: inversion/eversion, abduction/adduction, plantarflexion/dorsiflexion. These movements are affected by several adjacent joints, ligaments and periarticular tendinous tissue.

Answer 46

The foot has three arches: two longitudinal (medial and lateral) arches and one anterior transverse arch. They are formed by the tarsal and metatarsal bones, and supported by ligaments and tendons in the foot. Their shape allows them to act in the same way as a spring, bearing the weight of the body and absorbing the shock produced during locomotion. The flexibility conferred to the foot by these arches facilitates functions such as walking and running.

Answer 47

The transverse arch appears in the coronal plane and covers all five metatarsals, the cuboid bone, and the cuneiform bones.

Answer 48

There are two longitudinal arches in the foot – the medial and lateral arches. They are formed between the tarsal bones and the metatarsal heads The medial arch is the higher of the two longitudinal arches. It is formed by the calcaneus, talus, navicular, three cuneiforms and first three metatarsal bones. It is supported by: Muscular support: Tibialis anterior and posterior, fibularis longus, flexor digitorum longus, flexor hallucis, and the intrinsic foot muscles Ligamentous support: Plantar ligaments (in particular the long plantar, short plantar and plantar calcaneonavicular ligaments), medial ligament of the ankle joint. Bony support: Shape of the bones of the arch. Other: Plantar aponeurosis.

Answer 49

The lateral arch is the flatter of the two longitudinal arches, and lies on the ground in the standing position. It is formed by the calcaneus, cuboid and 4th and 5th metatarsal bones. It is supported by: Muscular support: Fibularis longus, flexor digitorum longus, and the intrinsic foot muscles. Ligamentous support: Plantar ligaments (in particular the long plantar, short plantar and plantar calcaneonavicular ligaments). Bony support: Shape of the bones of the arch. Other: Plantar aponeurosis.

Answer 50

Transverse Arch The transverse arch is located in the coronal plane of the foot. It is formed by the metatarsal bases, the cuboid and the three cuneiform bones. It has: -Muscular support: Fibularis longus and tibialis posterior. -Ligamentous support: Plantar ligaments (in particular the long plantar, short plantar and plantar calcaneonavicular ligaments) and deep transverse metatarsal ligaments. -Other support: Plantar aponeurosis. -Bony support: The wedged shape of the bones of the arch.

Answer 51

Pes cavus is a foot condition characterised by an unusually high medial longitudinal arch. It can appear in early life and become symptomatic with increasing age. Due to the higher arch, the ability to shock absorb during walking is diminished and an increased degree of stress is placed on the ball and heel of the foot. Consequently, symptoms will generally include pain in the foot, which can radiate to the ankle, leg, thigh and hip. This pain is transmitted up the lower limb from the foot due to the unusually high stress placed on the hindfoot during the heel strike of the gait cycle. Causes of pes cavus can be idiopathic, hereditary, due to an underlying congenital foot problem such as club foot, or secondary to neuromuscular damage such as in poliomyelitis. The condition is generally managed by supporting the foot through the use of special shoes or sole cushioning inserts. Reducing the amount of weight the foot has to bear, via overall weight loss can also improve the symptoms.

Answer 52

Pes planus is a common condition in which the longitudinal arches have been lost. Arches do not develop until about 2-3 years of age, meaning flat feet during infancy is normal. Because the arches are formed, in part, by the tight tendons of the foot, damage to these tissues through direct injury or trauma can cause pes planus. However in some people, the arches never formed during development. For most individuals, being flat-footed causes few, if any, symptoms. In children it may result in foot and ankle pain, whereas in adults the feet may ache after prolonged activity. Treatment, if indicated, generally involves the use of arch-supporting inserts for shoes.

Answer 53

The muscles acting on the foot can be divided into two distinct groups; extrinsic and intrinsic muscles. Extrinsic muscles: arise from the anterior, posterior and lateral compartments of the leg. They are mainly responsible for actions such as eversion, inversion, plantarflexion and dorsiflexion of the foot. Intrinsic muscles: are located within the foot and are responsible for the fine motor actions of the foot, for example movement of individual digits.

Answer 54

There are two intrinsic muscles located within the dorsum of the foot – the extensor digitorum brevis and extensor hallucis brevis. They assist the extrinsic muscles of the foot in extending the toes and are both innervated by the deep fibular nerve.

Answer 55

The extensor digitorum brevis is a small, thin muscle which lies underneath the long extensor tendons of the foot. Attachments: Originates from the calcaneus and inferior extensor retinaculum. It attaches onto the long extensor tendons of the medial four toes. Actions: Extension of the lateral four toes. Innervation: Deep fibular nerve.

Answer 56

The extensor hallucis brevis is often considered to be the medial part of the extensor digitorum brevis muscle, rather than a separate structure. Attachments: Originates from the calcaneus and inferior extensor retinaculum. It attaches to the base of the proximal phalanx of the great toe. Actions: Extension of the great toe. Innervation: Deep fibular nerve.

Answer 57

There are ten intrinsic muscles located in the plantar aspect (sole) of the foot. They act collectively to stabilise the arches of the foot and individually to control movement of the digits. They are innervated by the medial or lateral plantar nerves – which are branches of the tibial nerve. The muscles of the plantar aspect are arranged in four layers (superficial to deep):

Answer 58

The first layer contains three muscles. It is the most superficial and is located immediately underneath the plantar fascia. ABDUCTOR HALLUCIS The abductor hallucis muscle is located on the medial side of the sole, where it contributes to a small soft tissue bulge. Attachments: Originates from the medial tubercle of the calcaneus, the flexor retinaculum and the plantar aponeurosis. It attaches to the medial base of the proximal phalanx of the great toe. Actions: Abduction and flexion of the great toe. Innervation: Medial plantar nerve. FLEXOR DIGITORIUM BREVIS The flexor digitorum brevis muscle is located laterally to the abductor hallucis. It sits in the centre of the sole, sandwiched between the plantar aponeurosis and the tendons of flexor digitorum longus. Attachments: Originates from the medial tubercle of the calcaneus and the plantar aponeurosis. It attaches to the middle phalanges of the lateral four digits. Actions: Flexion of the lateral four toes at the proximal interphalangeal joints. Innervation: Medial plantar nerve. ABDUCTOR DIGIT MINIMI The abductor digiti minimi muscle is located on the lateral side of the foot. It is homologous with the abductor digiti minimi of the hand. Attachments: Originates from the medial and lateral tubercles of the calcaneus and the plantar aponeurosis. It attaches to the lateral base of the proximal phalanx of the 5th digit. Actions: Abduction and flexion of the little toe. Innervation: Lateral plantar nerve.

Answer 59

Second Layer The second plantar layer contains two muscles – the quadratus plantae and the lumbricals. The tendons of the flexor digitorum longus (an extrinsic muscle) also travel through this layer. QUADRATUS PLANTAE The quadratus plantae is a flat, square-shaped muscle with two heads of origin. Attachments: Originates from the medial and lateral plantar surface of the calcaneus. It attaches to the tendons of flexor digitorum longus. Actions: Assists the flexor digitorum longus in flexion of the lateral four toes. Innervation: Lateral plantar nerve. Lumbricals There are 4 LUMBRICALS muscles in the foot. They are each located medial to their respective tendon of the flexor digitorum longus. Attachments: Originates from the tendons of flexor digitorum longus. Attaches to the extensor hoods of the lateral four digits. Actions: Flexion at the metatarsophalangeal joints and extension at the interphalangeal joints. Innervation: Medial lumbrical – medial plantar nerve. Lateral three lumbricals – lateral plantar nerve

Answer 60

FLEXOR HALLUCIS BREVIS The flexor hallucis brevis muscle is located on the medial side of the foot. It has two heads of origin. Attachments: Lateral head – originates from the plantar surfaces of the cuboid and lateral cuneiforms Medial head – originates from the tendon of the posterior tibialis tendon. The fibres converge into a single muscle belly, which attaches to the base of the proximal phalanx of the great toe. Actions: Flexion of the great toe at the metatarsophalangeal joint. Innervation: Medial plantar nerve. ADDUCTOR HALLUCIS The adductor hallucis muscle is located laterally to the flexor hallucis brevis. It consists of an oblique and transverse head. Attachments: Oblique head – originates from the bases of the 2nd, 3rd, and 4th metatarsals. Transverse head – originates from the plantar ligaments of the metatarsophalangeal joints. Both heads attach to the lateral aspect of the base of the proximal phalanx of the great toe. Actions: Adduction of the great toe. Supports the transverse arch of the foot. Innervation: Deep branch of lateral plantar nerve. FLEXOR DIGIT MINIMI BREVIS The flexor digiti minimi brevis muscle is located on the lateral side of the foot, underneath the metatarsal of the little toe. It resembles the interossei in structure. Attachments: Originates from the base of the fifth metatarsal and attaches to the base of the proximal phalanx of the fifth digit. Actions: Flexion of the little toe at the metatarsophalangeal joint. Innervation: Superficial branch of lateral plantar nerve.

Answer 61

The plantar and dorsal interossei comprise the fourth and final plantar muscle layer. The plantar interossei have a unipennate shape, while the dorsal interossei are bipennate. PLANTAR INTEROSSEI There are three plantar interossei, which are located between the metatarsals. Each arises from a single metatarsal. Attachments: Originates from the medial side of metatarsals three to five. Attaches to the medial sides of the phalanges of digits three to five. Actions: Adduction of the lateral three digits and flexion at the metatarsophalangeal joints. Innervation: Lateral plantar nerve. DORSAL INTEROSSEI There are four dorsal interossei, which are located between the metatarsals. Each arises from two metatarsals. Attachments: Originates from the lateral aspect of the metatarsals. The first muscle attaches to the medial side of the proximal phalanx of the second digit. The second to fourth interossei attach to the lateral sides of the proximal phalanxes of digits two to four. Actions: Abduction of the lateral four digits and flexion at the metatarsophalangeal joints. Innervation: Lateral plantar nerve.

Answer 62

HALLUX VALGUS - big toe points towards other toes HALLUX VARUS - big toe points away and goes away from other toes