Snell - Anatomy Chapter 2: Back Muscles

Questions and Answers

Which condition is characterized by the forefoot being adducted on the rear part of the foot?

Hallux valgus

Overriding toes

Metatarsus varus (correct)

Curly toes

What is the primary corrective measure for overriding toes?

Orthopedic shoes

Application of splints (correct)

Physical therapy

Surgery

In severe cases of curly toes, which procedure may be performed?

Amputation of the affected toe

Transplanting the flexor digitorum longus tendon into the extensor tendon (correct)

Insertion of a metal pin

Fusion of the toe joints

What does radiologic examination of the lower limb primarily focus on?

Bony structures Signup and view all the answers

Which statement about Shenton's line is correct?

It is an indicator of the hip joint's stability and should maintain a curved line. Signup and view all the answers

What is a common characteristic of ectromelia?

Partial absence of a lower limb Signup and view all the answers

Which of the following describes a commonly suggested cause for congenital hip dislocation?

Generalized joint laxity Signup and view all the answers

In which condition is hyperextension of the knee joint commonly found?

Genu recurvatum Signup and view all the answers

What is the primary treatment for congenital dislocation of the hip at birth?

Splinting in the position of abduction Signup and view all the answers

Which type of talipes involves the foot being dorsiflexed at the ankle joint?

Talipes calcaneovalgus Signup and view all the answers

What is metatarsus varus characterized by?

Adduction of the forefoot on the rear part of the foot Signup and view all the answers

Which statement is true regarding talipes?

It may be caused by muscle paralysis linked to spina bifida. Signup and view all the answers

Which condition is known to be particularly common in female children?

Congenital hip dislocation Signup and view all the answers

Which nerve exclusively supplies the trapezius muscle?

Spinal accessory nerve (cranial nerve XI) Signup and view all the answers

What forms the boundaries of the auscultatory triangle?

Latissimus dorsi, trapezius, rhomboid major Signup and view all the answers

Which is NOT a boundary of the lumbar triangle?

Rhomboid major Signup and view all the answers

Which of the following statements about the thoracolumbar fascia is TRUE?

The middle lamella is posterior to the deep muscles of the back. Signup and view all the answers

What is the primary function of the muscles forming the suboccipital triangle?

To allow significant motions at the atlanto-occipital and atlantoaxial joints Signup and view all the answers

In the cervical region, which vessels supply blood to the back?

Occipital vessels Signup and view all the answers

Which specific structure is contained within the suboccipital triangle?

Suboccipital nerve Signup and view all the answers

Which muscle is primarily associated with the lumbar triangle?

Latissimus dorsi Signup and view all the answers

What is the main function of the thoracolumbar fascia?

To enclose the erector spinae muscles Signup and view all the answers

Which of the following arteries is NOT associated with blood supply to the back in the sacral region?

Pulmonary artery Signup and view all the answers

Which of the following statements about the medial longitudinal arch is true?

The medial longitudinal arch is the biggest and most important clinically. Signup and view all the answers

What condition is characterized by a high medial longitudinal arch?

Pes cavus Signup and view all the answers

What happens to the ligaments when flatfoot persists over time?

They become permanently stretched. Signup and view all the answers

What primary anatomical change occurred to the head of the humerus in this case?

Displaced downward below the coracoid process Signup and view all the answers

Which nerves were primarily affected by the injury detailed in the case?

Axillary and Radial nerves Signup and view all the answers

What is bursitis in the lower limb primarily caused by?

Excessive friction or trauma. Signup and view all the answers

Which bursae are prone to inflammation?

Greater trochanter bursa and bursa over the ischial tuberosity. Signup and view all the answers

What was the main cause of the loss of shoulder curvature in this patient?

Displacement of the humerus medially Signup and view all the answers

During the development of the lower limb, when do limb buds appear?

During the 6th week of development. Signup and view all the answers

Which area of the arm showed severe sensory deficits?

Dorsal surface of the lateral three and a half fingers Signup and view all the answers

What is the anatomical relationship of the axillary nerve in the context of shoulder dislocation?

Encircles the humeral head laterally Signup and view all the answers

What is the primary function of the plantar ligaments?

To maintain the shape of the foot arches. Signup and view all the answers

In which part of the upper limb is the cubital fossa located?

At the elbow Signup and view all the answers

What causes the head of the talus to no longer be supported in flatfoot?

Lateral displacement and eversion of the forefoot. Signup and view all the answers

Which muscle group is primarily involved in maintaining shoulder curvature?

Deltoid and Subscapularis Signup and view all the answers

The adventitious bursae develop due to:

Abnormal and excessive friction. Signup and view all the answers

Which bursa is associated with the semimembranosus muscle?

Suprapatellar bursa. Signup and view all the answers

What type of joint is the glenohumeral joint?

Ball-and-socket joint Signup and view all the answers

What is the primary role of the plantar aponeurosis during walking?

To shorten the tie beams and heighten the longitudinal arches Signup and view all the answers

What condition is characterized by a collapsed medial longitudinal arch?

Pes planus Signup and view all the answers

Which of the following is true about the mechanism of running compared to walking?

Running uses a similar thrust mechanism as walking. Signup and view all the answers

What is the primary reason for pes cavus in most cases?

Muscle imbalance Signup and view all the answers

What is bursitis primarily caused by?

Infection and chronic trauma Signup and view all the answers

What happens to the ligaments during prolonged muscle fatigue?

They stretch, leading to pain Signup and view all the answers

Where in the lower limb is bursitis most likely to occur?

At the ischial tuberosity and greater trochanter Signup and view all the answers

What role do the lumbricals and interossei play during walking?

They keep the toes extended. Signup and view all the answers

What does pes planus lead to regarding the head of the talus?

It is no longer adequately supported. Signup and view all the answers

What is a common cause of an inflamed bursa?

Repeated friction against bony points Signup and view all the answers

Which structure is primarily responsible for tying the ends of the arch together?

Fibularis longus tendon Signup and view all the answers

What is the primary effect of standing immobile for long periods on the arches of the feet?

Fallen arches or flatfeet Signup and view all the answers

Which muscles were found to have no significant role in the static support of the arch during inactivity?

Tibialis anterior Signup and view all the answers

How does the body weight distribute when standing immobile?

Heel behind and heads of metatarsal bones in front Signup and view all the answers

Which muscle group becomes active during walking and running to support the arch?

Tibialis anterior and fibularis longus Signup and view all the answers

What occurs when a person is overweight and stands immobile for a long time?

Excessive strain on bones and ligaments Signup and view all the answers

What is the role of the fibularis Brevis in the context of transverse arch maintenance?

It suspends the arch from above Signup and view all the answers

Which of the following factors is emphasized as crucial for maintaining the arches of the feet?

Shape of bones, strong ligaments, and muscle tone Signup and view all the answers

Which structure serves as the keystone for the medial longitudinal arch?

Talus Signup and view all the answers

What is primarily responsible for maintaining the lateral longitudinal arch?

Shape of the calcaneum Signup and view all the answers

Which ligament is considered the most important for supporting the medial longitudinal arch?

Plantar calcaneonavicular ligament Signup and view all the answers

What method explains how the arches of the foot are supported similarly to a stone bridge?

Shape of bones shaped as wedges Signup and view all the answers

Which bones are part of the lateral longitudinal arch?

Cuboid and calcaneum Signup and view all the answers

What role do the plantar ligaments have in maintaining the medial longitudinal arch?

They tie the inferior edges of the bones together. Signup and view all the answers

What aspect of the medial longitudinal arch primarily allows for its suspension from above?

Support from muscles like tibialis anterior Signup and view all the answers

Which feature is NOT related to the arch support mechanisms described?

Use of steel reinforcements Signup and view all the answers

In terms of arch maintenance, what does the term 'keystone' refer to in the context of the foot?

The bone that is centrally positioned in the arch Signup and view all the answers

Which of the following correctly identifies the components of the transverse arch of the foot?

Bases of the metatarsal bones and cuneiforms Signup and view all the answers

What type of joint is the talocalcaneonavicular joint?

Plane joint Signup and view all the answers

Which ligament supports the head of the talus?

Plantar calcaneonavicular ligament Signup and view all the answers

What is the primary associated condition with hallux valgus?

Short first metatarsal bone Signup and view all the answers

Which movement is described as the sole of the foot facing medially?

Inversion Signup and view all the answers

What is the type of joint for the calcaneocuboid joint?

Plane joint Signup and view all the answers

Which muscle pull exacerbates hallux valgus once the deformity is established?

Flexor hallucis longus Signup and view all the answers

How do the metatarsophalangeal and interphalangeal joints of the foot primarily resemble?

Those of the hand Signup and view all the answers

Which muscle is primarily responsible for performing eversion of the foot?

Fibularis longus Signup and view all the answers

What type of cartilage covers the articular surfaces of the talocalcaneonavicular joint?

Hyaline cartilage Signup and view all the answers

What is one significant disadvantage of having a foot composed of a single strong bone?

Inability to adapt to uneven surfaces Signup and view all the answers

What structure incompletely encloses the talocalcaneonavicular joint?

Capsule Signup and view all the answers

In examining a wet foot imprint, which area is least likely to be in contact with the ground?

Medial margin Signup and view all the answers

Which ligament attaches to the undersurface of the cuboid?

Long plantar ligament Signup and view all the answers

What arch of the foot involves the bases of the five metatarsals and the cuboid and cuneiform bones?

Transverse arch Signup and view all the answers

Which joint is involved in the inversion and eversion movements of the foot?

Talocalcaneonavicular joint Signup and view all the answers

Why does the foot appear flat in a young child?

Presence of subcutaneous fat Signup and view all the answers

What is the function of the dorsal and plantar ligaments in the cuneonavicular joint?

Strengthen the capsule Signup and view all the answers

Which two muscle groups assist the forward propulsion of the body during walking and running?

Gastrocnemius and soleus Signup and view all the answers

How is the foot's segmented structure beneficial for its function?

Enhances flexibility Signup and view all the answers

What is hallux rigidus primarily characterized by?

Pain and stiffness in the metatarsophalangeal joint Signup and view all the answers

Study Notes

Back Anatomy and Function

Muscle attachments vary in importance based on professional field; details are frequently omitted.
Superficial and intermediate back muscles primarily receive innervation from anterior rami of spinal nerves, except the trapezius, which is innervated by the spinal accessory nerve (cranial nerve XI).
Deep back muscles receive innervation from posterior rami of spinal nerves.

Muscular Triangles

Auscultatory Triangle: Important for auscultation of breath sounds; bordered by the latissimus dorsi, trapezius, and rhomboid major.
Lumbar Triangle: Potential site for lumbar hernia or infection; bordered by the latissimus dorsi, external oblique muscle, and iliac crest.
Suboccipital Triangle: Houses the suboccipital nerve and vertebral artery; bordered by the rectus capitis posterior major, obliquus capitis inferior, and obliquus capitis superior.

Thoracolumbar Fascia

Located between the iliac crest and 12th rib; serves as a strong aponeurosis for the erector spinae muscles.
Composed of three lamellae:
- Posterior Lamella: Covers deep back muscles; attached to lumbar spines.
- Middle Lamella: Attaches to transverse processes of lumbar vertebrae; lies anterior to deep muscles.
- Anterior Lamella: Attaches to the anterior surface of transverse processes; lies anterior to quadratus lumborum.

Blood Supply

Extensive vascular supply to the back, with branches connecting to the vertebral column from cervical and sacral regions.
Cervical supply originates from occipital vessels; sacral supply comes from iliolumbar and lateral sacral arteries.

Lower Limb Conditions

Metatarsus Varus: Adduction of the forefoot; corrected through manipulation and splinting.
Overriding Toes: Typically affects fourth/fifth toes; may require splinting.
Curly Toes: Affects toes that flex under neighbor; treated surgically in severe cases.

Radiographic Anatomy

Focus on bony structures of the lower limb; important landmarks include anterior inferior iliac spine, acetabulum, neck of the femur, and sacroiliac joint.

Foot Conditions

Ectromelia: Partial absence of a lower limb; similar condition described for upper limb.
Congenital Hip Dislocation: 10 times more common in females; suspicion arises in breech births or in families with shallow acetabula; treatment involves splinting.
Genu Recurvatum: Knee hyperextension in breech infants; typically resolves without treatment.

Clinical Notes on Foot Arches

Medial longitudinal arch is critical for balance and weight distribution; directly affected by muscle tone, ligaments, and bone shape.
Pes Planus (Flatfoot): Collapse of the medial longitudinal arch; leads to lateral displacement of the forefoot.
Pes Cavus (Claw Foot): High medial longitudinal arch; often related to muscle imbalances from conditions like poliomyelitis.

Bursitis in the Lower Limb

Inflammation of bursae due to various factors; may affect bursa around pelvic, knee, and ankle regions.
Key bursae prone to inflammation include those over the ischial tuberosity, greater trochanter, and near the knee.

Development of Lower Limb

Limb buds emerge in the 6th week; leg buds develop from lumbar and sacral segments.
Development involves localized mesenchymal proliferation leading to flattened paddles of limbs.

Walking and Running Mechanics

Walking involves a sequence of weight transfer through the foot, and muscular efforts to maintain stability and propel forward.
Running shifts weight onto the forefoot, eliminating heel contact; similar mechanisms of motion are utilized for propulsion.

Arch Support Mechanisms

Three arches in the foot supported by a combination of bone shape, muscle tone, and ligament strength; critical for function and stability during standing and movement.### Arch Support Mechanisms
Wedge-shaped stones support arches effectively; the keystone is crucial for stability.
Interlocking stones or binding them with metal staples prevents separation under weight.
Large bridges utilize tie beams to connect pillars, preventing sagging.
Suspension bridges rely on cables to support arches from above.

Medial Longitudinal Arch Maintenance

The sustentaculum tali holds the talus; the navicular bone accommodates talus' rounded head.
Plantar ligaments, particularly the plantar calcaneonavicular ligament, connect inferior edges of bones.
Tying ends of the arch involves multiple muscles and ligaments, including the plantar aponeurosis.
Tibialis anterior, tibialis posterior, and medial ligament of the ankle joint suspend the arch from above.

Lateral Longitudinal Arch Maintenance

Structure and function are similar to the medial longitudinal arch but focus on the lateral aspect.

Talocalcaneonavicular Joint

Anterior joint between talus, calcaneum, and navicular facilitates foot movement.
Articular surfaces of the joint consist of hyaline cartilage; classified as a plane joint.
The plantar calcaneonavicular ligament supports the talus' head and is reinforced with fibrocartilage.
Allows gliding and rotational movements.

Calcaneocuboid Joint

Articulates the calcaneum with the cuboid, also a plane joint.
Joint is secured by the bifurcated, long plantar, and short plantar ligaments.
The synovial membrane is present, enriching joint lubrication.

Movements in Subtalar, Talocalcaneonavicular, and Calcaneocuboid Joints

These joints are instrumental in foot inversion and eversion.
Inversion: sole of foot faces medially; eversion: sole faces laterally.
Inversion movements are generally more extensive than eversion.
Key muscles for inversion include tibialis anterior and posterior; for eversion, fibularis muscles are involved.

Cuneonavicular Joint

Connects the navicular to three cuneiform bones, categorized as a gliding-type joint.
Strengthened by dorsal and plantar ligaments; continuous joint cavity with other tarsal joints.

Clinical Notes

Hallux valgus is a common condition in women characterized by lateral deviation of the big toe.
Associated with poorly fitting shoes, leading to osteoarthritic changes in the first metatarsophalangeal joint.

Metatarsophalangeal and Interphalangeal Joints

Similar to hand joints; deep transverse ligaments connect toe joints.
Minimal abduction and adduction occur, centered around the second digit.

Foot as Functional Unit

The foot supports body weight and acts as a lever for movement.
Structure allows it to adapt to uneven surfaces despite being a weight-bearing lever.
Flexor muscles contribute significantly to propulsion alongside larger leg muscles.

Arches

The foot features three arches: medial longitudinal, lateral longitudinal, and transverse.
A child's foot appears flat due to subcutaneous fat; arches become more pronounced with weight-bearing.
Contact points on a wet foot imprint indicate how pressure is distributed across the foot.
The transverse arch's unique structure relies on the arrangement of metatarsals and tarsal bones, resembling a half-dome.

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Dive into Chapter 2 of Anatomy focusing on the back muscles' structure and nerve supply. This quiz assesses your understanding of the deep group muscles and their organization as discussed in the text. Test your knowledge on the anatomy essential for various professional fields.