TBL 7

Question 1

Which mesoderm forms the shoulder and upper limb?

Answer 1

Chondroblasts and osteoblasts of the parietal layer of lateral plate mesoderm.

Question 2

Which mesoderm forms the hip bones and bones of the lower limb?

Question 3

What are the differences between morphogenesis of the upper and lower limbs?

Answer 3

There are TWO main differences in morphogenesis between upper and lower limbs:

1) Morphogenesis of the lower limbs is 1-2 days behind the upper limbs.
2) During the 7th week, upper limbs rotate 90 degrees laterally, placing the extensor muscles on the posterior/lateral surfaces and the thumb laterally. Whereas the** lower limb rotates 90 degrees medially, placing the extensor muscles on the anterior surface and the big toe medially**.

Question 4

From the vertebral column, where is the weight of the upper body transmitted and what structures are responsible for this transmission?

Answer 4

The weight of the upper body, which is centrally supported by the vertebral column, then gets divided and directed laterally to the sacrum and to the thick portions of the bilateral ilia via the sacroilliac joints.

Question 5

What structures stabilize the weight-bearing sacrum and ilia, and where are these structures located?

Answer 5

The rami of the pubis are joined centrally at the pubis symphysis to stabilize the weight-bearing sacrum and ilia.

Question 6

To what structures do the ilia transfer the body weight?

Answer 6

The ilia transfer the body weight to the femurs (specifically the heads and necks of the femur when standing)

Question 7

The fusion of what structures forms the hip bone? Which part of the hip bone articulates with the head of the femur?

Answer 7

The fusion of the ilium, pubis, and ischium form the hip bone. The acetabulum articulates with the head of the femur.

Question 8

What structures reinforce the joint capsule of the femur?

Answer 8

The iliofemoral, pubofemoral, and ishiofemoral ligaments reinforce the joint capsule of the femur.

Question 9

Explain the relationship between the ligaments of the femoral joint capsule and extension of the femur.

Answer 9

The ligaments (iliofemoral, pubofemoral, ischiofemoral) pass in a spiral fashion from the hip bones to the femur.

Extension of the femur causes the ligamentous spiral to become more tightly wound, which:

a) increases joints stability and
b) restricts extension to 10-20 degrees beyond the standing vertical position.

Question 10

Explain the relationship between the ligaments of the femoral joint capsule and flexion of the femur.

Answer 10

The ligaments (iliofemoral, pubofemoral, ischiofemoral) pass in a spiral fashion from the hip bones to the femur.

Flexion of the femur causes this ligamentous spiral to unwind, which:

a) increases joint mobility

and

b) allows flexion of the femur 90 degrees or more beyond standing vertical position.

Question 11

What is the common result of relative weakness in the ischiofemoral ligament?

Answer 11

Relative weakness in the ischiofemoral ligament typically results in hip dislocations most commonly in the posterior direction.

Question 12

When standing, how is overabduction and hyperextension of the hip joint prevented?

Answer 12

The iliofemoral ligament (anterior/superior) is arguably the strongest ligament of the body and prevents hyperextension by “screwing” the femoral head into the acetabulum via its spiral conformation.

The pubofemoral ligament (anterior/inferior) tightens during both extension and abduction, but mainly prevents overabduction of the hip joint.

Question 13

What forms the iliac crest and what are the attachment sites for tendons of the anterior thigh muscles?

Answer 13

The iliac fossa thickens at its superior border to form the iliac crest. The attachment sites for tendons of the anterior thigh muscles are the anterior superior iliac spine (ASIS) and the anterior inferior iliac spine.

Question 14

What are avulsion fractures of the hip bone?

Answer 14

Avulsion fractures of the hip bone typically occur during sports that require sudden acceleration or deceleration forces (sprinting or kicking in football, soccer, hurdles, bball, martial arts).

A small part of bone with a piece of a tendon or ligament attached is torn away (avulsed). These usually occur at apophyses (bony projections that lack secondary ossification centers).

Question 15

Identify structures A through F in the image below.

Answer 15

Question 16

Identify structures A through G in the image below.

Answer 16

Question 17

How do spiral fractures and comminuted fractures of the femur differ?

Answer 17

A spiral fracture of the femur is when the femur fragments override causing foreshortening of the bone.

A comminuted fracture of the femur is when the bone is broken into several pieces with the pieces displaced in various directions as a result of muscle pull.

Question 18

Identify structures A through F in the image below.

Answer 18

Question 19

What causes Osgood-Schlatter disease and what are its symptoms?

Answer 19

Osgood-Shlatter disease is inflammation of the tibial tuberosity and chronic recurring pain caused by disruption of the epiphyseal plat at the tibial tuberosity.

Question 20

Describe the angulation of the femur and tibia, and what is the significance of this?

Answer 20

The adult femur has an angle (usually 126 degrees) between the neck of the femur and the shaft of the femur.

This angle allows the articulation of the femur and tibia (knees) to be closer to the axial line of the body and more directly inferior to the trunk, thus the center of gravity returns to the vertical axes of the supporting legs and feet, ideal for bipedal walking.

Question 21

Why is fracture of the neck of the femur more common in the elderly?

Answer 21

Fracture of the neck of the femur is more common in the elderly because the angle of inclination becomes more and more acute with increasing age. So with increasing age, there is increasing strain on the neck of the femur.

Question 22

Describe the minisci of the knee joint.

Answer 22

There are two, the lateral and medial menisci. They are incomplete rings of dense connective tissue paritally covering the articular surface of the tibial condyles.

Question 23

What is the most stable position of the knee joint?

Answer 23

The most stable position of the knee joint is when it is in the erect, extended position where contact of the articular surfaces is maximized and the primary ligaments of the knee are taut.

Question 24

What is the purpose of the lateral collateral ligament?

Answer 24

The lateral (fibular) collateral ligament (LCL) attaches the lateral epicondyle of the femur to the fibular head.

Question 25

What is the purpose of the medial collateral ligament?

Answer 25

The medial (tibial) collateral ligament attaches the medial epicondyle of the femur to the superomedial surface of the tibia.

Question 26

The tendon of _what muscle_ separates the lateral meniscus and LCL?

Answer 26

The tendon of the **popliteus muscle** separates the lateral meniscus and LCL.

Question 27

In the center of the knee joint, which two muscles cross each other obliquely like the letter X?

Answer 27

The **Anterior Cruciate Ligament** (**ACL**) and the **Posterior Cruciate Ligament** (**PCL**) cross each other obliquely in the center of the knee joint.

Question 28

What are the attachments of the PCL and what is its role?

Answer 28

The Posterior Cruciate Ligament (PCL) **arises from the posterior intercondylar area of the tibia** and **attaches anteriorly to the medial condyle of the femur**. The PCL **prevents anterior displacement of the femur on the tibia and hyperflexion of the knee**.

Question 29

What are the attachments of the ACL and what is it's role?

Answer 29

The Anterior Cruciate Ligament (ACL) **arises from the anterior intercondylar area of the tibia** and **attaches posteriorly to the lateral condyle of the femur**. The ACL **prevents posterior displacement of the femur on the tibia and hyperextension of the leg**.

Question 30

Which is stronger.. the PCL or ACL?

Answer 30

PCL

Question 31

How can twisting of the flexed knee create the "unhappy triad" injury?

Answer 31

Twisting of the knee in the flexed position **often sprains or disrupts the TCL (1/3)**, *which is directly connected to the medial meniscus*, thereby **often also tears and/or detaches the medial meniscus** from the joint capsule (2/3). *Also since the ACL is a pivot for rotary movements of the knee and is taut during flexion*, **the ACL is often concomitantly disrupted/torn,** which completes the "unhappy triad" of disrupted knee ligaments (3/3).

Question 32

What are the anterior and posterior drawing signs?

Answer 32

_Anterior Drawer Sign:_ The ACL prevents hyperextension of the knee and prevents the femur from sliding posteriorly on the tibia. Therefore, **if the ACL is torn, drawing the tibia anteriorly from the femur should be relatively easy**. _Posterior Drawer Sign:_ The PCL prevents the femur from sliding anteriorly on the tibia. Therefore, **if the PCL is torn, drawing the tibia posteriorly from the femur should be relatively easy.**

Question 33

Describe the tissue that makes up the sliding area of the knee joint.

Answer 33

The sliding area of the knee joint (articular cartilage) is **made of hyaline cartilage lacking perichondrium, which is a self-lubricating shock absorber with low friction properties.**

Question 34

What do the menisci provide for the knee joint?

Answer 34

The menisci are wedges of fibrocartilage known as articular discs that project into the synovial cavity and **provide shock absorption and load distribution**. They also lack perichondrium.

Question 35

What type of tissue lines the joint capsule of the knee and all joints of the upper and lower limbs, and what does it do?

Answer 35

Joint capsules in the upper and lower limbs are lined by a **synovial membrane (synovium), which consists of a simple cuboidal epithelium that produces synovial fluid for lubrication of the articular surfaces.**

Question 36

What is the pathogenesis of osteoarthritis?

Answer 36

_Osteoarthritis_ is the **most common form of arthritis** and it is primarily a disease of the articular cartilage with the following pathological characteristics which ultimately **leads to rapid deterioration of movement and function**: - *degradation of extracellular matrix (ECM) due to enhanced matrix metalloproteinase enzyme activity* * - decreased glycosaminoglycan content of the ECM* * - increased water content of the ECM* * - altered chondrocyte metabolism* * - loss of cartilage which results in bone-on-bone contact in synovial joints*

Question 37

What does the deep fascia of the thigh become as it travels inferiorly? What is the cause of the lateral thickening of the fascia lata?

Answer 37

The deep fascia of the thigh is continuous with the **deep fascia of the leg**. The fascia lata is thickened and reinforced by the **longitudinal fibers of the iliotibial tract**.

Question 38

Besides consolidating and sheathing the muscles of the leg, what other important role does the fasciae of the leg provide?

Answer 38

The fasciae of the legs **limit outward distension of contracting muscles**; thus, the contractile force "squeezes" veins of the lower limb to **assist blood flow against gravity toward the heart**.

Question 39

The union of what two veins forms the subcutaneous great saphenous vein? The union of what two veins forms the subcutaneous small saphenous vein?

Answer 39

_Great Saphenous Vein:_ **Dorsal Vein of the Big Toe + *Dorsal Venous Arch of the Foot*** _Small Saphenous Vein:_ **Dorsal Vein of the Little Toe + *Dorsal Venous Arch of the Foot***

Question 40

Describe the path of the Great Saphenous Vein (use landmarks).

Answer 40

*_The Great Saphenous Vein:_* **- ascends anterior to the medial malleolus** **- passes posterior to the medial condyle of the femur** **- anastomoses freely with the small saphenous vein** **- traverses the saphenous opening in the fascia lata** **- ultimately empties into the femoral vein.**

Question 41

Describe the path of the Small Saphenous Vein (use landmarks).

Answer 41

*_The Small Saphenous Vein:_* **- ascends posterior to the lateral malleolus as a continuation of the lateral marginal vein.** **- passes along the lateral border of the calcaneal tendon** **- inclines to the midline of the fibula and penetrates the deep fascia** **- ascends between the heads of the gastrocnemius muscle** **- ultimately empties into the popliteal vein in the popliteal fossa**

Question 42

What vessels accompany the great and small saphenous veins respectively, and where do these accompanying vessels drain into?

Answer 42

The **superficial lympatic vessels** accompany the great and small saphenous veins. The ones close to the _great saphenous vein_ drain into the **superficial inguinal lymph node**. The ones close to the _small saphenous vein_ drain into the **popliteal lymph node.**

Question 43

Identify the nerves that innervate regions A through G in the image below:

Answer 43

The **femoral cutaneous nerve, obturator cutaneous nerve, lateral cutaneous nerve, and posterior cutaneous nerve** innervate the anterior, medial, lateral, and posterior cutaneous regions of the thigh, respectively.

Question 44

Identify the nerves that supply sensory innervation to regions A through C in the image below:

Answer 44

Question 45

Why does the great saphenous vein or its tributaries often become varicose? Why can a deep vein thrombus in the lower limb be fatal?

Answer 45

Varicose veins are veins that dilated so that the cusps of their valves do not fully close. When this occurs in the great saphenous veins and its tributaries, **instead of only allowing blood flow in the superior direction, blood can now leak back down through the incomplete valves in the inferior direction due to gravity.**

Question 46

When is a saphenous cutdown required and where can sensory loss occur after the procedure?

Answer 46

A Saphenous Cutdown is **required whenever access to the venous circulation is too difficult as is often the case in infants, obese people, or in patients in shock whose veins are collapsed**. *This procedure allows access to the great saphenous vein by cutting the skin anterior to the the medial malleolus.* **Sensory loss can occur along the medial border of the foot** if the saphenous nerve, which accompanies the great spahenous vein anterior to the medial malleolus, is accidently cut.

Question 47

# _Fill in the blank:_ Muscles of the lower limb are derivatives of myoblasts in the ________ layer of ___________ mesoderm.

Answer 47

Muscles of the lower limb are derivatives of myoblasts in the **_parietal_** layer of **_lateral plate_** mesoderm.

Question 48

_For the iliopsoas muscle:_ a) What two muscles form it? b) what is the distal attachment? c) what is its function?

Answer 48

_For the iliopsoas muscle:_ a) it is formed by the union of an abdominal muscle (**psoas major**) and a pelvic muscle (**iliacus**) b) It's distal attachment is the **lesser trochanter of femur.** c) it is the **chief flexor of the thigh when lifting the lower limbs for walking.**

Question 49

_For the sartorius muscle:_ a) what is its proximal attachment? b) what is its distal attachmen? c) what is its function?

Answer 49

_For the sartorius muscle:_ a) its *proximal attachment* is the **ASIS** (Anterior superior iliac spine) b) its *distal attachment* is to the **superomedial tibia** c) its *works synergistically* with other stronger muscles to **flex the hip and knee joints.**

Question 50

What is the strongest muscle of the body? What muscles form it and what does it do?

Answer 50

The strongest muscle of the body is the **quadriceps femoris**, formed by _FOUR_ muscles: * 1) Rectus femoris* * 2) Vastus lateralis* * 3) Vastus medialis* * 4) Vastus intermedius* It functions in actions that **extend the knee to lift or move the entire body weight such as squat lifts** or accelerating during running and jumping.

Question 51

What does the quadriceps tendon eventually become and attach to?

Answer 51

The quadriceps tendon eventually becomes the **patellar ligament that attaches to the tibial tuberosity.**

Question 52

Describe the physical orientation of the patella and define its function.

Answer 52

The patella is a **sesamoid bone embedded in the patellar ligament** and its function is... - to **provide a bony surface that is able to withstand the compression placed on the quadriceps tendon during kneeling and the friction occuring when the knee is flexed and extended during running.** - to provide additional leverage for the quadriceps in placing the tendon more anteriorly, farther from the joint's axis, **allowing it to approach the tibia from a position of greater mechanical advantage**.

Question 53

What is a unique function of the rectus femoris?

Answer 53

The rectus femoris is the only quadriceps muscle that attaches proximally to the anteriior inferior iliac spine so it **contributes to flexion of the thigh and extension of the legwhen the thigh is extended and the leg is flexed** (kicking a soccer ball)

Question 54

Where do the vastus lateralis, vastus intermedius, and vastus medialis attach proximally?

Answer 54

_Proximal Attachments:_ * Vastus lateralis* - **greater trochanter and lateral lip of linea aspera of femur** * Vastus medialis* - **Intertrochanteric line and medial lip of linea aspera of femur** * Vastus intermedius* - **Anterior and lateral surfaces of shaft of femur**

Question 55

What structure is the synovial cavity of the knee joint continuous with? What is the function of this structure?

Answer 55

The synovial cavity of the knee joint is continuous with the **_suprapatellar bursa_**, which **functions to cushion the qudriceps tendon as it extends the leg** by pulling lengthwise across the joint.

Question 56

How is suprapatellar bursitis related to popliteal (Baker) cysts?

Answer 56

Suprabursitis is caused by abrasions or penetrating wounds that allow bacteria to enter the suprapatellar bursa and cause an infection. Popliteal cysts are abnormal fluid-filled sacs of synovial membrane in the region of the popliteal fossa, usually a complication of chronic knee joint effusion.

Question 57

Envision abduction/adduction of the hip joint.

Answer 57

Here's some help:

Question 58

Where do the following muscles attach proximally: * a) adductor longus* * b)* adductor portion of the *adductor magnus* What is their common distal attachment?

Answer 58

_Proximal Attachments:_ * a) adductor longus* - **body of the pubis** * b)* adductor portion of the *adductor magnus* - **ishiopubic ramus** They both distally attach to the **linea aspera**.

Question 59

What does the medial portion of the adductor magnus contribute to?

Answer 59

The medial portion of the abductor magnus contributes to the **hamstring muscle** (to be studied later).

Question 60

_For the gracilis muscle:_ a) proximal attachment? b) distal attachment? c) function?

Answer 60

_For the Gracilis muscle:_ a) *proximal attachment* - **ischiopubic ramus** b) *distal attachment* - **superomedial tibia** c) *function* - _synergist_ with stronger muscles during **adduction of the thigh and flexion of the leg**

Question 61

Where is the gracilis muscle used for transplantation and why is lower limb function not noticeably compromised?

Answer 61

The gracilis can be used for transplantation because it **is a relatively weak member of the adductor group of muscles** so its absence is not very noticeable.

Question 62

Describe a "hip pointer".

Answer 62

_"hip pointer"_ - this sports injury referes to a **contusion of the iliac crest that usually occurs at its anterior part where the sartorius attaches to the ASIS**. *One of the most common sports injuries to the hip region.*

Question 63

Describe a "charley horse".

Answer 63

_"charley horse"_ - this sports injury refers to the **cramping of an individual thigh muscles because of ischemia or refers to a contusion and rupture of blood vessels sufficient enough to form a hematoma**. *Usually the consequence of tearing fibers of the rectus femoris (sometimes the quadriceps tendon is also partially torn).*

Question 64

Describe a "groin pull".

Answer 64

_"groin pull"_ - this sports injury refers to the **strain, stretching, and likely tearing of the proximal attachments of the anteromedial thigh muscles**. *Usually involves the flexor and adductor thigh muscles whose proximal attachment is the inguinal region (groin). Usually occurs in sports requiring quick starts (sprinting) or stretching (gymnastics).*

Question 65

What structure forms the superior boundary of the femoral triangle?

Answer 65

The superior boundary of the femoral triangle is formed by the **inguinal ligament**, *which extends between the ASIS and body of the pubis*.

Question 66

What forms the lateral and medial boundaries of the femoral triangle?

Answer 66

The _lateral boundary_ is formed by **the sartorius muscle**. The _medial boundary_ is formed by **the adductor longus muscle**.

Question 67

_For the Femoral Nerve:_ a) from where does it originate? b) what specific site does it enter in the femur? c) what does it innervate? d) what is its terminal branch?

Answer 67

_For the Femoral Nerve:_ a) it *originates* from spinal cord segments **L2-L4** b) it leaves the abdominopelvic cavity and *enters* the **lateral aspect of the femoral triangle** c) it *innervates* the **anterior thigh muscles** d) the **saphenous nerve** is its *terminal branch*

Question 68

What lesions might cause diminution or loss of the patellar tendon reflex?

Answer 68

*Tapping the ligament activates muscle spindles in the quadriceps. Afferent impulses from the spindles travel in the femoral nerve to the L2-L4 segments of the spinal cord. From here, efferent impulses are transmitted via motor fibers in the femoral nerve to the quadriceps, resulting in a jerk-like contraction of the musle and extension of the leg at the knee joint ("knee jerk").* Diminution or absense of the patellar tendon reflex may result from **any lesion that interrupts the innervation of the quadriceps** (ex: peripheral nerve disease)

Question 69

_For the Obturator Nerve:_ a) from where does it originate? b) where does it travel in relation to the femoral nerve? c) from what site does it exit the abdominopelvic cavity? d) what does it innervate?

Answer 69

_For the Obturator Nerve:_ a) it *originates* from spinal cord segments **L2-L4** b) it *travels* **parellel to the femoral nerve on the posterior abdominal wall** c) it *exits* the abdominopelvic cavity **via the obturator foramen** d) it *innervates* the **medial thigh muscles**

Question 70

What does the deep fascia of the iliopsoas muscle extend under and what is its role in this area?

Answer 70

The deep fascia of the iliopsoas muscle **extends under the inguinal ligament as the femoral sheath.** This sheath **surrounds the femoral artery and vein in the femoral triangle allows them to glide under the inguinal ligament during movements of the hip joint**.

Question 71

_For the Femoral Canal:_ a) what forms it? b) what vessels travel through it? c) what is the purpose of the small oval femoral ring at the base of the canal

Answer 71

_For the Femoral Canal:_ a) it is formed by the **femoral sheath** b) **lymphatic vessels from the inguinal lymph nodes** travel through it c) the small oval femoral ring **enables the lymph vessels to enter the abdominopelvic cavity** where they drain into resident lymph nodes.

Question 72

The femoral artery is a continuation of what artery? What does the femoral artery supply?

Answer 72

The femoral artery is a continuation of the **external iliac artery and it supplies the anterior and anteromedial thigh**.

Question 73

Where does the obturator artery travel?

Answer 73

The obturatory artery **follows the course of the obturator nerve into the medial thigh.**

Question 74

Where does the deep artery of the thigh originate from and what other artery usually branches from it?

Answer 74

The deep artery of the thigh (profunda femoris artery) originates from the **femoral artery**. The **medial circumflex femoral artery** usually arises from the deep artery of the thigh.

Question 75

_What are the distributions of:_ * a) the deep artery of the thigh* * b) the medial circumflex femoral artery*

Answer 75

a) the _deep artery of the thigh_ supplies muscles in the: **- medial compartment** **-** **posterior compartment** **- lateral part of the anterior compartment**. b) the _medial circumflex femoral artery_: **- supplies most of the blood to the head and neck of femur** **- its *transverse branch* takes part in cruciate anastomosis of thigh** **- its *ascending branch* joins inferior gluteal artery**

Question 76

Why can aseptic vascular necrosis of the displaced femoral head occur after femoral neck fractures?

Answer 76

In a femoral neck fracture, **the retinacular arteries which arise from the medial circumflex artery and supply the head of the femur often get severed,** leaving only the artery to the ligament of the femoral head as the main source of blood flow to the femoral head, which is usually inadequate.

Question 77

What are compartment syndromes and how are prolonged symptoms relieved?

Answer 77

_Compartment syndromes_ arise **when there is hemorrhage, edema, or inflammation of muscles resulting in increased intracompartmental pressure**. Since muscles are usually contained within a strong compartment of septa and deep fascia, when the muscle's size is abnormally increased (due to inflammation for example), it pushes against the surrounding fascia and increases the intracompartmental pressure. **An increase in intracompartmental pressure can compress vital structures in the compartment such as small blood vessels or nerves, resulting in loss of motor function or blood supply**. _The treatment is a **fasciotomy**_, which is an incision of overlying fascia or septum to relieve pressure.

Question 78

How are tibialis anterior muscle strains and deep fibular nerve entrapment distinguished by their symptoms?

Answer 78

Tibialis anterior muscle strain (shin splints) and deep fibular nerve entrapment both are associated with pain/tenderness in the anterior compartment of the leg, only **shin splints has usually milder pain in the anterior compartment of the leg**.

Question 79

Visualize inversion and eversion of your foot. Visualize dorsiflexion and plantarflexion of your foot.

Answer 79

Good job.

Question 80

_For the Tibialis Anterior:_ a) what is the proximal attachment? b) what is the distal attachment? c) what innervates it? d) what is its function?

Answer 80

_Tibialis Anterior:_ a) proximal attachment - **tibia** b) distal attachment - **plantar surface (sole) of the medial foot** c) innervation - **deep fibular nerve** d) function - **dorsiflexes ankle and inverts foot**

Question 81

_For the *Extensor Digitorum Longus* and *Extensor Hallicus Longus*:_ a) name their proximal attachments. b) name their distal attachments. c) what innervates them? d) what is their function?

Answer 81

_For the *Extensor Digitorum Longus* and *Extensor Hallicus Longus*:_ a) proximal attachment - **tibia** b) distal attachment - **dorsum of the toes** c) innervation - **deep fibular nerve** _EDL function -_ **extends lateral four digits & dorsiflexes ankle** _EHL function -_ **extends great toe & dorsiflexes ankle**

Question 82

_For *Fibularis Longus* and *Fibularis Brevis*:_ a) proximal attachment? b) distal attachment? c) innervation? d) function?

Answer 82

_For *Fibularis Longus* and *Fibularis Brevis*:_ a) proximal attachment - **fibula** b) distal attachment - **plantar surface & lateral side of foot, *respectively*** c) innervation - **superficial fibular nerve** d) function - **everts foot and weakly plantarflexes ankle**

Question 83

Describe the evolution of the femoral artery as it travels inferiorly down the lower limb (what arteries does it become?).

Answer 83

The femoral artery diagonally crosses the distal femur and **becomes the popliteal artery** that in the proximal leg, **bifurcates into the anterior tibial artery and posterior tibial artery**.

Question 84

What does the anterior tibial artery become?

Answer 84

The anterior tibial artery, which supplies the anterior and lateral leg, **continues onto the dorsum of the foot as the dorsal pedis artery** that extends to the first interosseous space to provide digital arteries to the big toe.

Question 85

Why is the common fibular nerve frequently injured and what are the symptoms after its injury?

Answer 85

The common fibular nerve is commonly injured **because it is in a superficial position and it winds subcutaneously around the fibular neck**, leaving it vulnerable to direct trauma. It is also commonly severed in a femoral neck fracture, and commonly stretched in a knee joint injury or dislocation. _Symptoms_ are **flaccid paralysis of all muscles in the anterior and lateral compartments of the leg** (dorsiflexors of ankle and evertors of foot). Most famously, **foot drop**, due to loss of dorsiflexion and retention of inversion.

Question 86

Where is the dorsal pedis pulse palpated and what is the most common cause of its dimunition or absence?

Answer 86

The dorsal pedis pulse is palpated as seen in the image below, with the feet slightly dorsiflexed.