Snell Anatomy Chapter 2: The Back

Questions and Answers

What is the primary action of the deep muscles of the back?

Elevation of the ribs

Extension of the vertebral column and skull (correct)

Lateral flexion of the vertebral column

Stabilization of the pelvis

Which group of muscles runs vertically from the sacrum to various points along the spine?

Transversospinalis group

Intermediate oblique running muscles

Superficial vertically running muscles (correct)

Deepest muscles

Which muscle group is considered the deepest among the deep back muscles?

Transversospinalis

Interspinales (correct)

Iliocostalis

Longissimus

What function do the spines and transverse processes serve in relation to the deep back muscles?

Levers facilitating muscle actions Signup and view all the answers

Which action can occur when the deep back muscles act unilaterally?

Abduction and/or rotation of the vertebrae and skull Signup and view all the answers

Which of the following muscles is NOT included in the intermediate oblique running muscles group?

Rectus capitis posterior major Signup and view all the answers

Which of these statements about the attachments of deep back muscles is true?

Overlapping attachments facilitate smooth movement of the vertebral column. Signup and view all the answers

Which of the following muscles primarily assists with the movement between adjacent vertebrae?

Intertransversarii Signup and view all the answers

Which muscle is exclusively innervated by the spinal accessory nerve?

Trapezius Signup and view all the answers

What is the anatomical boundary of the auscultatory triangle?

Rhomboid major, trapezius, latissimus dorsi Signup and view all the answers

Which lamella of the thoracolumbar fascia lies anterior to the quadratus lumborum?

Anterior lamella Signup and view all the answers

Which area provides arterial branches that supply the back?

Cervical and sacral regions Signup and view all the answers

What does the suboccipital triangle contain?

Suboccipital nerve and vertebral artery Signup and view all the answers

Which of the following muscles does NOT originate from the thoracolumbar fascia?

Obliquus capitis superior Signup and view all the answers

Which of these structures is NOT bound by the lumbar triangle?

Trapezius Signup and view all the answers

Which structure is a source of blood supply to the back from the cervical region?

Occipital vessels Signup and view all the answers

What typically occurs with bilateral cervical dislocations of the fifth or sixth cervical vertebrae?

Severe spinal cord injury Signup and view all the answers

What is the primary mechanism causing anterior compression fractures of the vertebral bodies?

Excessive flexion compression Signup and view all the answers

In which regions do vertical compression fractures primarily occur?

Cervical and lumbar regions Signup and view all the answers

What describes the typical injury associated with fracture dislocations of the vertebral column?

Combination of flexion and rotation Signup and view all the answers

Which type of fracture is associated with the hangman's fracture?

Cervical spine overextension injury Signup and view all the answers

What is the typical outcome if the upper cervical vertebrae are involved in a bilateral cervical dislocation?

Immediate respiratory paralysis resulting in death Signup and view all the answers

What effect do unilateral dislocations have on the spinal nerve?

Nipping of the spinal nerve in the foramen Signup and view all the answers

What accurately characterizes anterior compression fractures in terms of ligament status?

Posterior longitudinal ligament remains intact Signup and view all the answers

Which ligament primarily resists extension of the vertebral column?

Anterior longitudinal Signup and view all the answers

What is the movement primarily resisted by the supraspinous ligament?

Flexion Signup and view all the answers

Which ligament is involved in resisting contralateral abduction (lateral flexion)?

Intertransverse Signup and view all the answers

In which region of the vertebral column is flexion and extension considered limited?

Thoracic Signup and view all the answers

Which motion is not allowed at the atlanto-occipital joints?

Rotation Signup and view all the answers

What is the characteristic of rotation in the lumbar region?

Almost none Signup and view all the answers

Which ligament is specifically described as a cervical thickening of the interspinous and supraspinous ligaments?

Ligamentum nuchae Signup and view all the answers

Which type of movement occurs extensively in the cervical region due to the atlanto-axial joints?

Rotation Signup and view all the answers

What type of injury typically causes anterior compression fractures of the vertebral bodies?

Excessive flexion compression injury Signup and view all the answers

In the thoracic region, which structure mainly restricts the range of intervertebral movement?

Ribs and costal cartilages Signup and view all the answers

What is the most likely cause of the loss of normal shoulder curvature in this patient?

Displacement of the humerus medially Signup and view all the answers

Which nerves are primarily affected in the case of subcoracoid dislocation complicated by trauma?

Axillary and radial nerves Signup and view all the answers

What region of the body corresponds to the sensory deficits observed in this patient?

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

What is the primary function of the upper limb?

To maneuver the hand for object manipulation Signup and view all the answers

Which muscle's pull is primarily responsible for the further displacement of the humeral head in this injury?

Pectoralis major muscle Signup and view all the answers

What anatomical structure is the head of the humerus displaced relative to in this injury?

Coracoid process of the scapula Signup and view all the answers

Which bones comprise the appendicular skeleton of the upper limb?

Clavicle, scapula, humerus, ulna, radius Signup and view all the answers

In assessing this patient's injury, which aspect must the clinician understand regarding the axillary nerve?

Its role in innervating the deltoid muscle Signup and view all the answers

Which characteristic is unique to the hand in the context of upper limb anatomy?

Manipulation of objects using a pincer-like action Signup and view all the answers

What is the role of the clavicle in the upper limb?

Connects the upper limb to the thorax and allows for mobility Signup and view all the answers

Which bone's anatomy is essential for understanding the mechanics of shoulder dislocations?

Humerus Signup and view all the answers

Which area is specifically mentioned as receiving particular attention for injuries?

Wrist and hand Signup and view all the answers

What condition is characterized by the head of the humerus displacing below the coracoid process?

Subcoracoid dislocation Signup and view all the answers

Which of the following accurately describes the clavicle's ossification?

It is the first bone to begin ossification. Signup and view all the answers

What condition is commonly associated with injuries in the shoulder region?

Fractures and dislocations Signup and view all the answers

Which compartment is NOT part of the upper limb structure?

Palmar region Signup and view all the answers

What injury is specifically characterized by disruption of the atlas ring in the cervical region due to excessive vertical force?

Jefferson's fracture Signup and view all the answers

Which condition involves the anterior slippage of the L5 vertebra due to degeneration of intervertebral discs?

Degenerative spondylolisthesis Signup and view all the answers

How is a hangman's fracture typically caused?

Severe extension injury of the neck Signup and view all the answers

Which group of back muscles are primarily involved with movements of the thoracic cage?

Intermediate group Signup and view all the answers

What is a potential effect of congenital spondylolisthesis?

Loss of restraining influence from articular processes Signup and view all the answers

Which injury can result from falls or blows to the head, particularly affecting the odontoid process?

Odontoid process fracture Signup and view all the answers

What common condition results in compression injury to the spinal cord due to excessive mobility of the odontoid fragment?

Odontoid process fracture Signup and view all the answers

In which type of fracture does the vertebral body break up and protrude fragments posteriorly into the vertebral canal?

Vertical compression fracture Signup and view all the answers

What is the primary role of the deep group of back muscles?

Support movement of the vertebral column and skull Signup and view all the answers

What is a significant risk factor for nontraumatic vertical compression fractures?

Severe disease states like osteoporosis Signup and view all the answers

Which structure is primarily responsible for the attachment of the conoid ligament on the clavicle?

Conoid tubercle Signup and view all the answers

What is the primary function of the clavicle in relation to the upper limb?

Act as a strut, holding the arm laterally Signup and view all the answers

Which characteristic pertains specifically to the scapula?

It lies between the second and seventh ribs. Signup and view all the answers

What causes the most common type of clavicle fracture?

Fall on an outstretched hand Signup and view all the answers

Which feature of the scapula accommodates the suprascapular artery and nerve?

Scapular notch Signup and view all the answers

Which muscle is responsible for pulling the medial end of a fractured clavicle upward?

Sternocleidomastoid Signup and view all the answers

What defines the medial border of the scapula?

It is closest to the vertebral column. Signup and view all the answers

Which condition might arise due to narrowing between the clavicle and the first rib?

Thoracic outlet syndrome Signup and view all the answers

What connects the medial end of the clavicle to the sternum?

Sternoclavicular joint Signup and view all the answers

Which bony process is not considered a defining feature of the scapula?

Conoid tubercle Signup and view all the answers

What is the anatomical significance of the inferior angle of the scapula?

It can be palpated easily and aligns with the seventh rib. Signup and view all the answers

Which structure is located at the apex of the glenoid cavity?

Supraglenoid tubercle Signup and view all the answers

What demarcates the supraspinous fossa from the infraspinous fossa on the scapula?

The spine of the scapula Signup and view all the answers

What is the classification of the glenoid labrum?

A fibrocartilage ring Signup and view all the answers

Which part of the scapula is primarily responsible for forming the acromion?

Spine Signup and view all the answers

What is the primary function of the glenoid cavity?

To articulate with the head of the humerus Signup and view all the answers

Which anatomical feature is located immediately inferior to the glenoid cavity?

Infraglenoid tubercle Signup and view all the answers

Which bone articulates distally with the trochlear notch of the ulna?

Humerus Signup and view all the answers

What does the lateral (axillary) border represent on the scapula?

The thickened edge closest to the axilla Signup and view all the answers

Which muscle group is primarily responsible for the stabilization of the shoulder joint known as the 'rotator cuff'?

Supraspinatus, Infraspinatus, Teres Minor, Subscapularis Signup and view all the answers

What is the primary function of the anatomical snuffbox?

It provides a site for the radial artery and a landmark for scaphoid bone fracture. Signup and view all the answers

Which anatomical structure is primarily affected in carpal tunnel syndrome?

Median nerve Signup and view all the answers

Which boundary defines the axilla and its primary contents?

Humerus, Scapula, Thoracic wall Signup and view all the answers

What is the main function of the lumbrical muscles in the hand?

To assist in extension of the fingers at the metacarpophalangeal joints Signup and view all the answers

Which structure is NOT considered a component of the carpal tunnel?

Extensor Digitorum tendon Signup and view all the answers

Which major artery supplies the upper limb, branching from the subclavian artery?

Axillary artery Signup and view all the answers

Which movement is primarily facilitated by the pronator teres muscle?

Pronation of the forearm Signup and view all the answers

What is defined as the four compartments within the upper limb, which contain muscles with similar functions?

Fascial compartments Signup and view all the answers

Which structure primarily facilitates lymphatic drainage in the upper limb?

Axillary nodes Signup and view all the answers

Study Notes

Back Muscle Nerve Supply

Back muscles are mainly innervated by anterior rami of spinal nerves except the trapezius, which is innervated by the spinal accessory nerve.
Deep muscle groups receive innervation from posterior rami of spinal nerves.

Muscular Triangles

Auscultatory Triangle: Best location for listening to breath sounds, bordered by the latissimus dorsi, trapezius, and rhomboid major.
Lumbar Triangle: A site for potential lumbar hernia or pus emergence; borders include latissimus dorsi, external oblique, and iliac crest.
Suboccipital Triangle: Contains the suboccipital nerve and vertebral artery, bordered by the rectus capitis posterior major and the obliquus capitis muscles.

Deep Fascia (Thoracolumbar Fascia)

Located between the iliac crest and the 12th rib, offering strong aponeurosis.
Encloses erector spinae muscles and provides origins for transversus abdominis, internal abdominal oblique, and latissimus dorsi.
Divided into three lamellae: posterior, middle (attached to transverse processes), and anterior (anterior to quadratus lumborum).

Back Blood Supply

Extensive and intricate blood supply connects vertebral structures to various vascular sources.
Arterial Supply: Occipital branches in cervical region, iliolumbar, and lateral sacral arteries in sacral region.
Venous Supply: Comprised of branches from the internal iliac artery.

Deep Back Muscles

Categorized into superficial, intermediate, and deep groups based on their location and function.
Deep muscles are primarily responsible for vertebral column extension and rotation.

Vertical Compression Fractures

Occur in cervical and lumbar regions due to high vertical forces.
Jefferson's fracture disrupts the atlas, while lumbar fractures may cause vertebral body damage and posterior fragment protrusion.

Odontoid Process of Axis Fracture

Relatively common due to falls or head impacts, with potential for spinal cord injury from fragment mobility.

Hangman's Fracture

Resulting from severe neck extension, usually due to car accidents or similar trauma.
Enlarge vertebral canal but rarely compress spinal cord due to forward displacement of the axis.

Spondylolisthesis

Characterized by anterior slippage of L5 vertebra on the vertebra below or sacrum, resulting from structural defects or degenerative changes.

Back Muscle Groups

Superficial Group: Includes trapezius, latissimus dorsi, levator scapulae; functionally linked to upper limb.
Intermediate Group: Contains serratus posterior superior/inferior, involved in thoracic cage movements.
Deep Group: Complex muscle arrangement for vertebral column, rib, and skull movement.

Vertebral Column Dislocations

Dislocations typically occur at cervical vertebrae due to non-interlocked articular processes.
Unilateral dislocations press spinal nerves causing severe pain, while bilateral can lead to spinal cord injury and respiratory failure.

Vertebral Column Fractures

Anterior compression fractures are often caused by flexion-compression injuries at mobility junctions, with the vertebral body crushed but ligaments intact.

Major Vertebral Column Ligaments

Ligament	Location	Movement Resisted
Anterior longitudinal	Anterior vertebral bodies	Extension
Posterior longitudinal	Posterior vertebral bodies	Flexion
Ligamenta flava	Adjacent laminae	Flexion
Intertransverse	Between transverse processes	Contralateral abduction
Interspinous	Between spinous processes	Flexion
Supraspinous	Tips of adjacent spinous processes	Flexion
Ligamentum nuchae	Cervical interspinous thickening	Flexion

Regional Intervertebral Movements

Cervical: Extensive flexion/extension and rotation; atlanto-axial joints allow significant movement.
Thoracic: Limited flexion, with minimal rotation due to rib restrictions.
Lumbar: Extensive flexion/extension; minimal rotation; primarily allows circumduction and pelvic tilting.

Upper Limb Clinical Case

64-year-old woman diagnosed with subcoracoid dislocation and nerve damage after a fall, highlighting the importance of shoulder anatomy knowledge for effective diagnosis and treatment.

Upper Limb Anatomy Overview

Comprehensive details include osteology, nerve supply (e.g., brachial plexus), vasculature, muscular relationships, and joint structure.
Learning objectives focus on identifying bones, muscles, and nerve relationships, including the mechanism and significance of upper limb functions in clinical practice.### Lymphatic Drainage of the Upper Limb
The upper limb lymphatic drainage primarily flows into the axillary lymph nodes, which are crucial for immune response.
The axillary nodes receive lymph from the breast via the lateral quadrant and the upper limb.
Intrinsic drainage patterns link upper limb lymphatics to the neck and thoracic duct, emphasizing interconnectivity for potential metastasis.

Bony Components of Joints

The shoulder joint consists of the clavicle, scapula, and humerus, allowing a wide range of motion and manipulation.
The elbow is formed by the humerus, radius, and ulna, primarily facilitating flexion and extension.
The wrist comprises the radius, ulna, carpal bones, metacarpals, and phalanges, allowing complex movements including flexion, extension, and circumduction.

Major Ligaments and Structures

Shoulder: Key ligaments include the glenohumeral ligaments and the coracohumeral ligament, providing stability.
Elbow: The ulnar collateral ligament is critical for stability during movement.
Wrist: The triangular fibrocartilage complex supports the ulnar side of the wrist and allows for extensive articulation among carpal bones.

Characteristic Features of Major Traumas

Shoulder injuries often involve dislocation or rotator cuff tears, impacting the range of motion.
Elbow fractures often result from falls, particularly in children, leading to “nursemaid’s elbow.”
Wrist injuries frequently involve scaphoid fractures or carpal tunnel syndrome, affecting grip strength and motor function.

Medical Imaging of the Upper Limb

Standard medical images include X-rays, MRIs, and CT scans, depicting bone fractures, soft tissue injuries, and joint spaces.
Key landmarks are visible in imaging: the acromion in the shoulder, the capitulum and trochlea at the elbow, and carpal bones in the wrist.
A thorough understanding of anatomical landmarks is vital for accurate diagnosis and treatment planning.

Surface Projections and Palpation Points

The clavicle is palpable along its length, serving as a reference point in surface examination.
The acromion process can be easily located at the tip of the shoulder, indicating the shoulder joint's position.
The medial and lateral epicondyles of the humerus are key palpation points for assessing the elbow joint.
The anatomical snuffbox, formed by the scaphoid and trapezium bones, is significant for assessing wrist injuries.

Functionality of the Upper Limb

The upper limb is designed for a range of functions, including gross and fine motor skills, critical for tasks such as gripping and manipulation.
The opposable thumb allows for pincer grip, enhancing dexterity and functionality in hand movements.
Each compartment of the arm, forearm, and hand houses specific muscles responsible for coordinated actions.

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Description

Explore the intricacies of the back muscles and their nerve supply in this quiz based on Chapter 2. Learn about the innervation of back muscles, with a specific focus on the trapezius and the deep muscle groups. Additionally, discover the importance of muscular triangles such as the auscultatory triangle and its clinical relevance.