PET 4340 Biomechanics: Upper Extremity, Lower Extremity, and Spine Review

Vocabulary practice flashcards covering the biomechanics, functional anatomy, kinematics, loads, and clinical conditions of the upper extremity, lower extremity, and spine for PET 4340 Exam 3 review.

Sternoclavicular (SC) Joint

A multiaxial arthrodial joint connecting the clavicle to the manubrium of the sternum, permitting $15^\circ$ of anterior protraction, $15^\circ$ of posterior retraction, $45^\circ$ of superior elevation, and $5^\circ$ of inferior depression.

Acromioclavicular (AC) Joint

An arthrodial joint between the acromion process and the clavicle that permits $20^\circ\text{ to }30^\circ$ of total gliding and rotational motion accompanying other shoulder movements.

Scapulothoracic Articulation

A functional, non-synovial articulation between the scapula and thorax that depends dynamically on muscular support to achieve $25^\circ$ of abduction-adduction, $60^\circ$ of upward-downward rotation, and $55^\circ$ of elevation-depression.

Trapezius Muscle

A three-region muscle of the shoulder girdle whose upper fibers elevate and upwardly rotate the scapula and extend/rotate the head; middle fibers elevate, upwardly rotate, and adduct; and lower fibers depress, adduct, and upwardly rotate the scapula.

Levator Scapulae Muscle

A posterior shoulder girdle muscle originating on the transverse processes of $C1\text{--}C4$ that elevates the medial margin of the scapula.

Rhomboid Muscles (Major and Minor)

Shoulder girdle muscles originating on the spinous processes of $C7\text{--}T5$ that work synergistically to adduct (retract), downwardly rotate, and slightly elevate the scapula.

Serratus Anterior Muscle

An anterolateral thoracic muscle originating on the upper nine ribs that abducts (protracts) the scapula and utilizes its longer lower fibers to draw the inferior angle outward, rotating the scapula upward.

Pectoralis Minor Muscle

A deep anterior chest muscle originating on ribs $3\text{ to }5$ and inserting on the coracoid process that performs scapular abduction (protraction), downward rotation, and depression.

Subclavius Muscle

A muscle originating on the superior aspect of the first rib and inserting into the inferior groove of the clavicle that stabilizes and protects the sternoclavicular joint while assisting in depression and abduction.

Glenohumeral Joint

A multiaxial ball-and-socket (enarthrodial) articulation between the glenoid fossa of the scapula and the head of the humerus that maximizes mobility at the expense of stability.

Glenohumeral Internal Rotation Deficit (GIRD)

A difference in internal rotation range of motion between an athlete\'s throwing and non-throwing shoulders, where a deficit exceeding $20\%$ represents a significantly elevated risk of shoulder injury.

Scapulohumeral Rhythm

A synergistic kinematic relationship between glenohumeral and scapulothoracic movement, generally exhibiting an accepted ratio of $2:1$ ($2^\circ$ of glenohumeral motion for every $1^\circ$ of scapular motion).

Loads on the Shoulder

The joint torque produced at the shoulder by each arm segment, calculated as the product of each segment\'s weight and its perpendicular moment arm from the joint axis.

Deltoid Muscle

A multi-pennate shoulder muscle whose anterior fibers perform abduction, flexion, horizontal adduction, and internal rotation; middle fibers perform abduction; and posterior fibers perform abduction, extension, horizontal abduction, and external rotation.

Pectoralis Major Muscle

An anterior chest muscle comprising an upper clavicular head (internal rotation, horizontal adduction, flexion, and abduction once elevated past $90^\circ$) and a lower sternal head (internal rotation, horizontal adduction, extension, and adduction).

Latissimus Dorsi Muscle

A broad back muscle inserting into the medial lip of the intertubercular groove of the humerus that performs humeral adduction, extension, internal rotation, and horizontal abduction.

Teres Major Muscle

A muscle originating on the inferior third of the lateral border of the scapula that executes internal rotation, adduction toward the midline, and extension, particularly from a flexed position.

Coracobrachialis Muscle

A muscle extending from the coracoid process to the medial middle humeral shaft that acts to flex, adduct, and horizontally adduct the humerus.

Rotator Cuff

A stabilizing musculotendinous group comprising the subscapularis (internal rotation), supraspinatus (abduction), infraspinatus (external rotation), and teres minor (external rotation) that maintains humeral head approximation within the glenoid fossa.

Humeroulnar Joint

The primary hinge joint of the elbow in which the humeral trochlea articulates within the trochlear fossa of the ulna.

Radioulnar Joints

Articulations between the radius and ulna consisting of proximal and distal pivot joints and a middle syndesmosis that permit forearm pronation and supination.

Lateral Epicondylitis

Commonly known as tennis elbow, an overuse pathology usually involving inflammation at the extensor digitorum origin on the lateral epicondyle from repetitive gripping and lifting activities.

Medial Epicondylitis

Commonly termed golfer\'s elbow, an injury involving the wrist flexor and pronator tendon origins near the medial epicondyle of the humerus.

Radiocarpal Joint

A condyloid articulation between the distal radius and three carpal bones where the majority of wrist flexion, extension, abduction, and adduction occurs.

Carpal Tunnel

A fibro-osseous canal formed by a three-sided carpal bone arch on the palmar side roofed by the transverse carpal and volar carpal ligaments, transmitting the median nerve and digital flexor tendons.

Carpometacarpal Joints

Articulations between carpal bones and metacarpals, categorized as a saddle joint at the thumb and gliding joints at digits two through five.

Metacarpophalangeal Joints

Condyloid articulations between the rounded distal heads of the metacarpals and the concave proximal phalanges that form the knuckles of the hand.

Pelvic Girdle

A bony structure consisting of two pelvic bones joined posteriorly by the sacrum, with each bone structurally composed of an upper two-fifths ilium, posterior and lower two-fifths ischium, and anterior and lower one-fifth pubis.

Acetabulofemoral Joint

An enarthrodial multiaxial ball-and-socket joint formed by the femoral head inserting into the acetabulum, providing high bony and ligamentous stability.

Iliofemoral Ligament ("Y" Ligament of Bigelow)

A strong anterior ligament of the acetabulofemoral joint that checks and limits excessive hip hyperextension.

Pubofemoral Ligament

An anteromedial and inferior hip joint ligament that limits excessive hip extension and abduction.

Ischiofemoral Ligament

A posterior ligament of the acetabulofemoral joint extending from the ischium to the trochanteric fossa of the femur that limits internal rotation.

Ligamentum Teres (Teres Ligament)

An intra-articular ligament running from deep inside the acetabular notch to the fovea capitis on the femoral head that slightly limits hip adduction.

Anterior Pelvic Rotation

Anterior tilting of the upper pelvis in the sagittal plane accompanied by lumbar spine extension and bilateral hip flexion.

Posterior Pelvic Rotation

Posterior tilting of the upper pelvis in the sagittal plane accompanied by lumbar spine flexion and bilateral hip extension.

Loads on the Hip Joint

The major compressive forces acting across the hip during stance, consisting of the overlying body segment weight ($\text{wt}$), abductor muscle tension ($F_m$), and the resultant joint reaction force ($R$).

Tibiofemoral Joint

The primary hinge articulation of the knee comprising dual condyloid joints between the medial and lateral condyles of the femur and tibia.

Patellofemoral Joint

The articulation between the patella and the femoral trochlea, which enhances the mechanical advantage of the quadriceps extensor mechanism by as much as $50\%$.

Menisci of the Knee

Crescent-shaped fibrocartilaginous discs positioned atop the tibial plateaus that distribute compressive loads across a wider surface area and absorb shock.

Cruciate Ligaments

Intracapsular knee ligaments (anterior and posterior) that cross obliquely within the intercondylar notch to stabilize anteroposterior translation of the femur relative to the tibia.

Patellofemoral Joint Compression

The compressive force ($C$) acting at the patellofemoral interface, determined as the vector sum of quadriceps tension ($F_m$) and patellar tendon tension ($F_t$), which increases sharply with knee flexion.

Tibiotalar Joint

The anatomical ankle hinge joint formed by the articulation of the concave distal tibia with the convex superior dome of the talus.

Plantar Fascia

Thick fibrous connective tissue bands covering the plantar surface of the foot that store mechanical strain energy during stance and release it to assist with push-off.

Spinal Motion Segment

The fundamental biomechanical and functional unit of the spine, consisting of two adjacent vertebrae and the intervertebral disc and soft tissues interconnecting them.

Atlas (C1)

The first cervical vertebra, which lacks a true vertebral body and spinous process and features superior articular facets that articulate with the occipital condyles.

Axis (C2)

The second cervical vertebra, distinguished by the dens (odontoid process) projecting superiorly to form a pivot joint with the anterior arch of the atlas.

Facet Joints (Zygapophysial Joints)

Paired diarthrodial gliding joints on the posterior vertebral arch that direct regional spinal range of motion and sustain up to $30\%$ of spinal compressive loads, especially in hyperextension.

Facet Joint Orientations

Regional variations in facet angulation relative to transverse and frontal planes: cervical ($45^\circ$ transverse, $0^\circ$ frontal), thoracic ($60^\circ$ transverse, $20^\circ$ frontal), and lumbar ($90^\circ$ transverse, $45^\circ$ frontal).

Annulus Fibrosus

The dense outer concentric ring of fibrocartilage surrounding an intervertebral disc that behaves mechanically as a coiled spring to hold adjacent vertebral bodies together.

Nucleus Pulposus

The colloidal gel core of an intervertebral disc possessing high fluid content that behaves mechanically like a ball bearing over which vertebrae roll during bending.

Intervertebral Disc Mechanical Analogy

The biomechanical model where the outer annulus fibrosus functions as a tensile coiled spring and the central nucleus pulposus functions as a pivot ball bearing.

Primary Spinal Curves

Anteriorly concave thoracic and sacral curvatures of the vertebral column that are present at birth.

Secondary Spinal Curves

Posteriorly concave cervical and lumbar curvatures that develop as an infant learns to sit up, stand, and hold the head upright.

Lordosis

An abnormal or exaggerated anterior convex curvature of the lumbar region of the vertebral column.

Kyphosis

An abnormal or exaggerated posterior convex curvature of the thoracic region of the vertebral column.

Scoliosis

An abnormal lateral deviation or curvature of the vertebral column.

Erector Spinae Muscles

A major posterior spinal extensor column comprising the iliocostalis (lateral), longissimus (middle), and spinalis (medial) layers, acting to extend, laterally flex, and ipsilaterally rotate the trunk and head.

Sternocleidomastoid Muscle

An anterior neck muscle that bilaterally extends the head at the atlantooccipital joint and flexes the cervical spine, while unilaterally producing ipsilateral lateral flexion and contralateral rotation.

Quadratus Lumborum Muscle

A deep posterior abdominal muscle that stabilizes the lumbar spine and pelvis, extends the lumbar spine, and causes ipsilateral lateral flexion and contralateral lateral pelvic rotation.

Transversus Abdominis Muscle

The deepest muscle layer of the abdominal wall that compresses the abdominal contents and assists in forced expiration by pulling the abdominal wall inward.

Torque at the L5-S1 Joint

The flexor moment generated about the $L5\text{--}S1$ joint center by the weights of the head, trunk, arms, and lifted load multiplied by their respective horizontal moment arms, totaling $10{,}790\,\text{N}\cdot\text{cm}$ in trunk flexion.

Third Lumbar (L3) Disc Loading

The relative compressive load on the $L3$ disc across postures, defined as $100\%$ during upright standing, markedly reduced when supine, and substantially elevated when sitting or bending forward.

Spondylolysis

A unilateral or bilateral stress fracture or defect occurring in the pars interarticularis of the neural arch of a vertebra.

Spondylolisthesis

A bilateral fracture of the pars interarticularis with subsequent anterior displacement or slipping of a vertebral body relative to the subjacent vertebra.