TBL 8 Flashcards
What structures make up the sacrum?
The sacrum is composed of 5 fused sacral vertebrae and the vertebral canal continues into the sacrum as the sacral canal.
Where can the sacral hiatus be found, what structure serve as landmarks for its location? What is the reason for its existence?
The sacral hiatus is an inverted U-shaped opening at the end of the sacral canal.
The Sacral Cornua project inferiorly on both sides of the hiatus so they can serve as landmarks.
It exists because of the absence of the laminae and spinous process of S5.
What resides in the sacral canal, and what structures exit through the anterior and posterior sacral foramina?
The cauda equina resides in the sacral canal.
The anterior and posterior rami of spinal nerves S1-S4 exit through the anterior and posterior sacral foramina (S5 rami exit between vertebra S5 and the coccyx).
How is caudal epidural anesthesia performed and which spinal nerves are typically affected?
In a caudal epidural anesthesia is performed by injecting a local anesthetic agent into the fat of the sacral canal (typically through the sacral hiatus) that surrounds the proximal portions of the sacral nerves.
The S2-Co1 (coccygeal 1) spinal nerves of the cauda equina are typically affected.
Define the functions of the following structures:
a) Posterior & Anterior Sacroiliac ligaments
b) Sacrotuberous & Sacrospinous ligaments
a) Posterior & Anterior Sacroiliac ligaments
- hold the hip bones and sacrum together
b) Sacrotuberous & Sacrospinous ligaments
- connects the sacrum to the ischial tuberosity and ischial spine, respectively.
- both create the greater and lesser sciatic foramina
What is the purpose of the greater sciatic foramen?
The greater sciatic foramen is a conduit for structures passing between the pelvis and gluteal region.
What are the boundaries of the gluteal region?
The gluteal region encompasses the area inferior to the iliac crests and lateral to the greater trochanters of the femurs.
Name the largest and most superficial gluteal muscle.
What is its proximal attachment?
What is its distal attachment?
What is its innervation?
What is its function?
Gluteus Maximus
- proximal attachment* - superoposterior ilium & posterior sacrum
- distal attachment* - iliotibial tract
- innervation* - inferior gluteal nerve
- function* - extends thigh, especially from the flexed position (from sitting, walking up stairs)
The gluteus maximus covers most of muscle ___A___ , and muscle ___A___ covers the entire muscle ___B___.
1) What is the innervation of Muscle A & B?
2) What is the distal attachment of Muscles A & B?
3) What is the proximal attachment of Muscles A & B?
4) What is the function of Muscles A & B?
The Gluteus Maximus covers most of the Gluteus Medius, and the Gluteus Medius covers the entire Gluteus Minimus.
1) Both are innervated by the superior gluteal nerve.
2) Both distally attach to the greater trochanter of femur (lateral & anterior surface, respectively)
3) Both proximally attach to the external surface of the ilium.
4) Both abduct and medially rotate the thigh.
What are the main lesions that cause a positive Trendelenburg test?
A lesion of the superior gluteal nerve is a typical lesion that causes a positive Trendelenburg test.
It results in paralyis of the gluteus medius and minimus, which are usually responsible for keeping both sides of the pelvis balanced when lifting one foot off of the ground (as in walking). A positive Trendelenburg test results in descension of the unsupported side of the pelvis when lifting a leg.
Where is the safe area for intragluteal injections?
Intragluteal injections are only safe in the following places:
- superolateral quadrant of the buttocks
- superior to a line extending from the PSIS to the superior border of the greater trochanter (superior border of the gluteus maximus)
- in the triangular area between the fingers (when the index is placed on the ASIS and the fingers are spread posteriorly along the iliac crest until the tubercle of the crest is felt by the middle finger).
Tensor Fasciae Lata Muscle:
a) proximal attachment?
b) distal attachment?
c) innervation?
d) functions?
Tensor Fasciae Lata Muscle:
a) proximal attachment - ASIS
b) distal attachment - iliotibial tract
c) innervation - superior gluteal nerve
d) function - synergizes with stronger muscles during flexion of the thigh
Paralysis of which muscle activates hypertrophy of the tensor fascia lata?
The tensor fascia acts with the iliopsoas and rectus femoris. When the iliopsoas is paralyzed, the tensor fasciae undergoeas hypertrophy in an attempt to compensate for the paralysis.
Piriformis:
a) proximal attachment?
b) distal attachment?
c) what foramen does it mostly occupy?
Piriformis:
a) proximal attachment - anterior surface of the sacrum in the pelvis
b) distal attachment - greater trochanter of the femur
c) during its course from the pelvis to the greater trochanter, it occupies most of the greater sciatic foramen.
Quadratus Femoris:
a) proximal attachment?
b) distal attachment?
c) function?
Quadratus Femoris:
a) proximal attachment - ischial tuberosity
b) distal attachment - intertrochanteric surface of the femur
c) function - synergistically rotates the thigh laterally
Semitendinosus & semimembranosus
a) proximal attachment?
b) distal attachment?
c) innervation?
c) function?
Semitendinosus & semimembranosus
- a) proximal attachment* - ischial tuberosity
- b) distal attachment* - superior tibia
- c) innervation* - tibial division of sciatic nerve
- d) function* - synergistically extend the thigh and flex the leg.
biceps femoris
- a) proximal attachment?*
- b) distal attachment?*
- c) innervation?*
- d) function?*
biceps femoris
a) proximal attachment
- ischial tuberosity for long head
- linea aspera for short head
b) distal attachment
- head of the fibula for both
c) innervation
- tibial division of sciatic nerve for long head
- fibular division of sciatic nerve for short head
d) function
- synergistically extends thigh and flexes leg
What vessels traverse the greater sciatic foramen superior and inferior to the piriformis muscle, respectively?
In the greater sciatic foramen, superior to the piriformis muscle:
- Superior Gluteal Nerve & Artery
In the greater sciatic foramen, inferior to the pirifomis muscle:
- Inferior Gluteal Nerve & Artery
What is the largest nerve in the body?
a) from what foramen does it emerge?
b) from what spinal cord segments does it arise?
Sciatic Nerve
a) it emerges from the greater sciatic foramen, inferior to the pirifomis
b) it arises from spinal cord segments L4-S3
What nerves does the sciatic nerve consist of?
Where does it completely branch into these separate nerves?
The sciatic nerve consists of loosely bound common fibular (peroneal) and tibial nerves that separate in the distal thigh.
What does the common fibular nerve innervate?
The common fibular (peroneal) nerve innervates muscles of the anterior and lateral leg.
Why are both heads of the biceps femoris not always paralyzed after nerve injury in the posterior thigh?
- The long head of the biceps femoris is innervated by the tibial division of the sciatic nerve.*
- The short head is innervated by the fibular division of the sciatic nerve.*
So both muscles are innervated by different nerves.
Why does complete section of the sciatic nerve, although uncommon, cause loss of ipsilateral lower limb function?
Loss of the ipsilateral lower limb function results from complete section of the sciatic nerve because the nerve supplies most of the muscles responsible for extension of the hip, flexion of the leg, and many ankle/foot movements.
Where does the posterior cutaneous nerve travel?
The posterior cutaneous nerve travels through the greater sciatic foramen, medial to the sciatic nerve.
What arteries branch from the internal iliac artery, and what muscles do they supply?
The gluteal arteries branch from the internal iliac artery and supplies the muscles of the gluteal region.
What muscles does the deep artery of the thigh?
The deep artery of the thigh supplies the hamstring muscles.
What vessels course through the center of the popliteal fossa?
What vesssels course along the lateral border of the fossa?
The tibial nerve and popliteal artery/vein course through the center of the popliteal fossa.
The common fibular (peroneal) nerve courses along the lateral border of the fossa.
Identify structures A in the image below. What usually surrounds these structures?
Popliteal lymphatic structures and neurovascular structures are usually surrounded by varying amounts of white fat.
Name the muscles that form the borders of the popliteal fossa:
- a) superomedial border*
- b) superolateral border*
- c) inferomedial border*
- d) inferolateral border*
Muscles of the popliteal border:
- a) superomedial border* - semimembranous
- b) superolateral border -* biceps femoris
- c) inferomedial border* - medial head of the gastrocnemius
- d) inferolateral border* - lateral head of the gastrocnemius
Popliteus muscle:
- a) what is its proximal attachment?*
- b) what is its distal attachment?*
- c) what two structural roles does it play?*
- d) what one functional role does it play?*
Popliteus muscle:
a) proximal attachment - lateral condyle of the femur
b) distal attachment - superoposterior tibia
c) Two structural roles:
1) forms part of the popliteal floor
2) separates the LCL and the lateral meniscus
d) One functional role:
1) when standing, releases the knee from its locked position by rotating the femur laterally 5 degrees to initiate the transition from standing to walking.
Where can the popliteal artery be found?
The popliteal artery resides on the floor of the popliteal fossa, deep to both the tibial nerve and popliteal vein.
What are the branches that anastomose around the knee joint to provide collateral circulation? What is the functional importance of this?
Popliteal, femoral, and anterior tibial arteries anastomose around the knee to provide collateral circulation.
This is functionally important when the knee joint has been maintained too long in a fully flexed position or when the vessels are narrowed or occluded.
What is the largest, most direct terminal branch of the popliteal artery? What muscles does this branch supply?
The Posterior tibial artery is the larger, more direct terminal branch of the popliteal artery and it supplies the posterior leg.
What is the proximal branch of the posterior tibial artery?
What muscles does it supply?
The proximal branch of the posterior tibial artery is the fibular artery, which supplies the following muscles:
- lateral side of the posterior leg
- fibularis longus and brevis muscles of the lateral leg
Where is the posterior tibial pulse palpated and why is its absence in people over 60 related to intermittent claudication?
The posterior tibial pulse is palpated between the posterior surface of the medial malleolus and the medial border of the calcaneal tendon.
Absence in people over 60 can be indicative of occlusive peripheral arterial disease, which can cause intermittent claudication (pain/cramps caused by inadequate blood supply) during walking. This is a result of narrowing or occlusion of the leg muscles.
Two heads of the gastrocnemius:
a) proximal attachment?
b) distal attachment?
c) function?
One head of the soleneus:
a) proximal attachment?
b) distal attachment?
c) function?
Two heads of the gastrocnemius:
a) proximal attachment - distal end of femur
b) distal attachment - common calcaneal tendon (achilles) attaches to the calcaneal tuberosity
c) function - plantarflex the foot during walking, running, jumping
One head of the soleneus:
a) proximal attachment - proximal fibula & tibia
b) distal attachment - common calcaneal tendon (achilles) attaches to the calcaneal tuberosity
c) function - plantarflex the foot during walking, running, jumping
Identify the muscles that attach at locations A through H in the image below.
*blue shaded region = distal attachment*
*red shaded region = proximal attachment*
What are the three tendons that join the calcaneal tendon and which of these can be used for grafting without compromising plantarflexion of the foot?
The gastrocnemius, soleus, and plantaris join the calcaneal tendon. The plantaris only weakly assists the other two and therefore can be used for grafting.
What muscles are immediately deep to the soleus on the lateral and medial sides, respectively? What nerve innervates these superficial and deep muscles of the posterior leg?
The flexor hallucis longus and flexor digitorum longus are immediately deep to the soleus.
The muscles of the posterior leg are innervated by the tibial nerve.
What deep muscle lies between the two flexor muscles (FHL & FDL)?
Where do the tendon of these deep muscles travel?
The tibialis posterior muscle lies between the FHL & FDL.
The tendons of these deep muscles course posterior to the medial malleolus.
After the plantarflexion lifts the heel, which muscle delivers the final thrust to propel the foot off the ground during walking, running, and jumping?
Where does the tendon of this muscle travel?
The Flexor Hallucis Longus delivers the final thrust to propel the foot after plantarflexion.
The flexor hallucis longus tendon travels posterior to the medial malleolus, crosses the sole of the foot deep to the tendon of the flexor digitorum and attaches to the distal phalanx of the big toe.
What muscle attaches to the distal phalanges of the lateral four toes?
What are the two functions of this muscle?
The flexor digitorum longus attaches to the distal phalanges of the lateral four toes.
FDL’s two functions:
1) flexes the toes
2) provides active support to the medial longitudinal arch during weight bearing.
Where does the tendon of the tibialis posterior attach to?
What this muscle’s main function and secondary function?
The tendon of the tibialis posterior attaches mainly to the navicular bone at the high point of the medial longitudinal arch.
Functions of the tibialis posterior:
main function - provide active support to the arch during weight
secondary function - works synergistically with the tibialis anterior to invert the foot when it is off the ground.
Identify structures A through F in the image below.
What articulations make up the ankle joint and what are the joint’s main movements?
Ankle Joint:
superior talus + medial malleolus of the tibia + lateral malleolus of the fibula
Functions:
1) Dorsiflexion by anterior compartment muscles
2) Plantarflexion by posterior compartment muscles
What are the three lateral ligaments of the ankle?
The three lateral ligaments of the leg are:
1) anterior talofibular ligament
2) Posterior talofibular ligament
3) Calcaneofibular ligament
What is the name of the medial ligament of the ankle and what structures does it connect?
The medial ligament is called the deltoid ligament and it attaches the medial malleolus of the tibia to the talus, calcaneus, and navicular bone.
Why is a Pott fracture-dislocation of the ankle erroneously called a trimalleolar fracture?
In a Pott fracture-dislocation of the ankle, the foot is forcibly everted, pulling on the extremely strong medial ligament (relative to the lateral ligament) and often tearing off the medial malleolus.
The parts that comprise the “trimalleolar fracture” are:
1) the medial malleolus of the tibia
2) the lateral malleolus of the fibula
3) the posterior margin of the distal end of the tibia
This is erroneous because it considers the entire distal end of the tibia a malleous, which is incorrect - only the medial end of the tibia and the lateral end of the fibula can be considered a “malleolus”
Why are ankle sprains almost always inversion injuries and which ligaments of the ankle are frequently torn?
An inversion injury is the twisting of the weightbearing plantarflexed foot. The person steps on an uneven surface and the foot is forcible inverted.
The lateral ligament is most commonly affected since it is much weaker than the medial ligament and it has the responsibility of resisting inversion at the talocrural joint.
Particularly the anterior talofibular part of the lateral ligament is most vulnerable to inversion injury.
What is the structure that enables inversion and eversion of the foot?
What are the two different definitions of this structures and how do they differ?
The subtalar joint enables inversion and eversion of the foot.
Two definitions of the subtalar joint:
1) Anatomical Subtalar Joint - represents the single talocalcaneal articulation.
2) Surgical Subtalar Joint - used by orthopaedic surgeons and includes both the anatomical subtalar joint plus the talocalcaneal part of the talocalcaneonavicular joint.
What is the largest and strongest bone of the foot and what structure transmits the weight of the body to this strong bone?
The largest and strongest bone of foot is the calcaneus which receives the weight of the body from the subtalar joint.
Why are comminuted fractures of the calcaneus usually disabling?
Comminuted fractures of the calcaneus are usually debilitating because they disrupt the subtalar (talocalcaneal) joint.
Describe the three arches of the foot and explain their purpose.
Three arches of the foot:
1) Lateral Longitudinal Arch
- flatter arch of the foot, rests on the ground during standing
- made up of the calcaneus, cuboid, and lateral two metatarsals.
2) Medial Longitudinal Arch
- higher, more important arch of the foot
- made up of the calcaneus, talus, navicular, three cuneiforms, and three metatarsals.
3) Transverse Arch
- runs side to side between the lateral and medial archs
Purpose of the three archs:
- act as springboards to assist the flexor hallucis longus in propelling the foot during walking, running, and jumping.
Which structures provide passive support to the medial longitudinal arch?
Which structures provide active support to the medial longitudinal arch?
Passive support
- plantar calcaneonavicular ligament (spring ligament)
Active support
- tendons of the tibialis posterior and flexor digitorum longus
What is characteristic about the deep fascia of the sole of the foot (plantar fascia)?
The plantar fascia thickens centrally to form the plantar aponeurosis which functions as a superficial ligament that assists passive support of the medial arch by the spring ligament.
What causes acquired flatfeet and how do they differ from rigid flatfeet?
Acquired flatfeet
- “fallen arches” caused by disfunction of the tibialis posterior (active support of the medial longitudinal arch) owing to trauma, degeneration with age, or denervation.
- the plantar calcaneonavicular ligament (passive support of the medial longitudinal arch) can no longer support the head of the talus, which then falls inferomedially resulting in flattening of the medial part of the longitudinal arch along with lateral deviation of the forefoot.
Rigid Flatfeet
- flat foot even when not bearing weight (as opposed to “flexible flatfeet” which is flat only when bearing weight).
- results from loose or degenerated intrinsic ligaments (inadequate passive arch support)**.
- usually resolves with age as the ligaments mature
When is pain from Plantar Fasciitis most severe, when does it dissipate, and how is it exacerbated?
Plantar fasciitis is pain caused by an overuse mechanism usually resulting from running and high-impact aerobics, especially when inappropriate footwear is worn. It is the most common hindfoot problem in runners.
Pain is felt on the plantar surface of the foot and heel where the aponeurosis proximally attaches to the medial tubercle/surface of the calcaneus
Pain is most severe after sitting and when beginning to walk in the morning.
Pain usually dissipates after 5-10 minutes of activity and often returns following rest.
Pain is exacerbated if there is a calcaneal spur (abnormal bony process) protruding from the medial tubercle of the calcaneus. A bursa often develops at the end of this spur which can become inflamed and tender.
What nerve bifurcates posterior to the medial malleolus and what does it bifurcate into?
The tibial nerve bifurcates into the medial and lateral plantar nerves which innervate the respective halves of the plantar surface of the foot.
Identify the nerves that innervate regions 1, 2, 3, and 6 in the image below.
Why can injury of the sciatic nerve in the gluteal region cause loss of sensation from the foot?
The sciatic nerve (largest nerve in the body) supplies no structures in the gluteal region, instead it supplies the posterior thigh muscles, ALL leg and foot muscles, and supplies the skin of most of the leg and foot.
What artery travels posterior to the medial malleolus?
What does this artery bifurcate into and what do these branching arteries supply?
The posterior tibial artery travels posterior to the medial malleolus and bifurcates into the medial and lateral plantar arteries which supply those respective regions.
Describe the path of lymph vessels from the medial foot.
Describe the path of lymph vessels from the lateral foot.
Lymph vessels from the medial foot join those following the great saphenous vein, which ultimately drain into the superficial inguinal lymph nodes
Lymph vessels from the lateral foot join those following the small saphenous vein, which ultimately drain into the popliteal lymph nodes then superficial inguinal lymph nodes.
