BPK 326: Unit Test 2

Which nerve innervates the trapezius muscle?

The trapezius muscle is innervated by the spinal accessory nerve (CN XI).

What is the primary action of the superior (descending) part of the trapezius?

The superior part of the trapezius elevates the scapula.

What is the primary action of the inferior (ascending) part of the trapezius?

The inferior part of the trapezius depresses the scapula.

Which nerve innervates the latissimus dorsi muscle?

The latissimus dorsi is innervated by the thoracodorsal nerve (C6-C8).

Where do all parts of the latissimus dorsi insert on the upper limb?

All parts converge to insert onto the floor of the intertubercular (bicipital) groove of the humerus.

What are the primary actions of the latissimus dorsi on the humerus at the glenohumeral joint?

It adducts, medially rotates, and extends the humerus.

Which nerve provides innervation to the levator scapulae muscle?

The levator scapulae is innervated by the dorsal scapular nerve (C4-C5).

What action does the levator scapulae perform on the neck when the scapulae are fixed?

When the scapulae are fixed, the levator scapulae flexes the neck laterally.

How do the vertebral origins of rhomboid minor and rhomboid major differ?

Rhomboid minor originates from spinous processes C6-C7, whereas rhomboid major originates from spinous processes T2-T5.

What primary actions do the rhomboid muscles perform on the scapula?

The rhomboid muscles retract and elevate the medial border of the scapula.

What action does the serratus posterior superior perform during respiration?

The serratus posterior superior elevates ribs 2-5 to contribute to inhalation.

What action does the serratus posterior inferior perform during respiration?

The serratus posterior inferior depresses ribs 9-12 to contribute to exhalation.

From lateral to medial, what are the three muscle columns comprising the erector spinae group?

The three muscle columns from lateral to medial are iliocostalis, longissimus, and spinalis.

Which nerve innervates the clavicular part of the pectoralis major?

The clavicular part is innervated by the lateral pectoral nerve.

Which nerve innervates the sternocostal part of the pectoralis major?

The sternocostal part is innervated by the medial pectoral nerve.

What unique action is performed specifically by the clavicular part of the pectoralis major at the glenohumeral joint?

The clavicular part specifically flexes the arm at the glenohumeral joint.

What joint action is produced when both major heads of the pectoralis major contract together?

Acting together, both parts medially rotate and adduct the arm at the glenohumeral joint.

Where does the pectoralis minor muscle insert?

The pectoralis minor inserts onto the coracoid process of the scapula.

What actions does the pectoralis minor exert on the scapula?

The pectoralis minor depresses and protracts the scapula.

Which nerve innervates the serratus anterior muscle?

The serratus anterior is innervated by the long thoracic nerve of the brachial plexus.

What key scapular movements are performed by the serratus anterior?

The serratus anterior laterally rotates and stabilizes the scapula against the thoracic wall.

What three bony synovial joints constitute the shoulder complex?

The three synovial joints are the sternoclavicular, acromioclavicular, and glenohumeral joints.

What physiological joint couples the scapula to the thoracic cage?

The physiological coupling is provided by the scapulo-thoracic joint.

How is lateral rotation of the scapula defined anatomically?

Lateral rotation is defined by the lateral/upward movement of the inferior angle of the scapula relative to the thoracic cage.

At what vertebral level is the sternal angle (angle of Louis) located?

The sternal angle is located at the T4-T5 vertebral level.

At what vertebral level is the jugular (suprasternal) notch located?

The jugular notch is located at the T2-T3 vertebral level.

At what vertebral level is the xiphisternal joint positioned?

The xiphisternal joint is positioned at the T9 vertebral level.

Where is the midclavicular line positioned on the thoracic wall?

The midclavicular line descends vertically from the midpoint of the clavicle.

What structural and functional joint classifications apply to the 1st sternocostal joint?

The 1st sternocostal joint is structurally a synchondrosis (hyaline cartilage) and functionally a synarthrosis (immobile).

What structural joint classification applies to the 2nd through 7th sternocostal joints?

The 2nd through 7th sternocostal joints are classified as synovial plane joints.

What structural joint type characterizes the manubriosternal and xiphisternal joints?

Both the manubriosternal and xiphisternal joints are symphyses (fibrocartilaginous joints).

What four primary features define a typical rib (ribs 3-9)?

A typical rib consists of a head, neck, tubercle, and shaft (body).

Which numerical pairs of ribs are categorized as atypical ribs?

Ribs 1, 2, 11, and 12 are classified as atypical ribs.

What is the anatomical function of the costal groove located along the inferior internal surface of a rib?

The costal groove protects and houses the intercostal neurovascular bundle (vein, artery, and nerve).

What unique structural feature distinguishes cervical vertebrae from all other regional vertebrae?

Cervical vertebrae possess a foramen transversarium within each transverse process.

What structural characteristics define typical thoracic vertebrae?

Thoracic vertebrae feature heart-shaped bodies, circular vertebral foramina, long sloping spinous processes, and costal facets for rib articulation.

What are the 3 structural features distinguish typical lumbar vertebrae?

1. massive,kidney-shaped bodies

2. triangular vertebral foramina,

3. short, broad, blunt spinous processes.

What key bony elements are completely absent in atlas (C1)?

The atlas lacks both a vertebral body and a spinous process.

What prominent vertical bony projection distinguishes axis (C2)?

The axis is distinguished by the odontoid process, or dens, projecting superiorly from its body.

What anatomical movement is permitted by the atlanto-occipital joint?

The atlanto-occipital joint permits flexion and extension, producing the nodding 'yes' motion.

What primary movement is permitted by the three atlanto-axial joints working together?

The atlanto-axial joints permit rotational movement of the head (the 'no' motion) around the pivot of the dens.

What structural break defines a 'Hangman's fracture'?

A Hangman's fracture involves fracture of the dens (odontoid process) away from the vertebral body of C2 due to abrupt hyperextension.

Which bony structures articulate to form a costovertebral joint at the head of a rib?

The head of the rib articulates with the superior costal demifacet of its corresponding vertebra and the inferior demifacet of the vertebra superior to it.

Which anatomical structures articulate to form a costotransverse joint?

The articular facet of the rib tubercle articulates with the costal facet on the transverse process of the same-numbered vertebra.

What mechanical movement occurs in the upper ribs (1-6) during deep inhalation?

Upper ribs undergo a 'pump-handle movement' that rotates the sternum anteriorly to increase anteroposterior thoracic diameter.

What mechanical movement occurs in the lower ribs (7-10) during deep inhalation?

Lower ribs undergo a 'bucket-handle movement' that glides the lateral rib margins superiorly to increase transverse thoracic diameter.

Why do upper costotransverse joints produce rotational pump-handle movement while lower joints produce gliding bucket-handle movement?

Convex tubercles fitting into concave transverse processes in upper ribs permit rotation, whereas flat matching surfaces in lower ribs permit gliding.

What outer structural component forms the fibrous circumference of an intervertebral disc?

The outer ring is formed by the anulus fibrosus, consisting of concentric fibrocartilage lamellae.

What structural component forms the gelatinous core of an intervertebral disc?

The inner core is the nucleus pulposus, a high-water gelatinous tissue that absorbs mechanical shock.

What structural failure occurs during an intervertebral disc herniation?

Degeneration or structural rupture of the anulus fibrosus allows bulging or extrusion of the nucleus pulposus.

At which two specific spinal junction levels do herniated discs most commonly occur?

Herniated discs occur most frequently at the L4-L5 or L5-S1 spinal levels.

Term: Dermatome

Definition: An area of skin supplied by cutaneous sensory nerve fibers originating from a single specific spinal cord segment.

Term: Myotome

Definition: A collection of skeletal muscles innervated by motor nerve fibers arising from a single specific spinal nerve root.

What clinical condition results when multiple adjacent ribs are fractured in two places, creating a paradoxically moving segment?

This unstable chest wall condition is known as flail chest.

Where does the splenius capitis muscle insert?

The splenius capitis inserts onto the mastoid process of the temporal bone.

What are the actions of the deep multifidus muscle group?

Multifidus extends and laterally flexes the spine, assists in rotational movement, and provides proprioceptive feedback.

Between which thoracic rib boundaries does the bed of the female breast extend vertically?

The bed of the female breast extends vertically from the 2nd rib through the 6th rib.

Which back muscles act together as the primary retractors of the scapula?

Scapular retraction is primarily performed by the middle trapezius and the major and minor rhomboids.