Anatomy & Biomechanics Flashcards

The rotator cuff is composed of which four muscles?

Answer: Supraspinatus, infraspinatus, teres minor, subscapularis

The rotator cuff consists of supraspinatus, infraspinatus, teres minor, and subscapularis, remembered by the SITS acronym.

Which ligament primarily prevents anterior tibial translation relative to the femur?

Answer: Anterior cruciate ligament

The ACL is the primary restraint against anterior tibial translation and also limits internal tibial rotation.

The Q-angle is measured using which anatomical landmarks?

Answer: ASIS to center of patella to tibial tuberosity

The Q-angle is formed by lines from the ASIS to the patellar center and from the tibial tuberosity to the patellar center.

During normal walking gait, the center of mass follows which movement pattern?

Answer: A sinusoidal path in both vertical and lateral planes

The center of mass oscillates both vertically and laterally during walking, tracing a sinusoidal path in each plane.

Which structure provides the primary static restraint against inferior glenohumeral translation with the arm at the side?

Answer: Superior glenohumeral ligament

The superior glenohumeral ligament (SGHL) is the primary static stabilizer resisting inferior translation of the humeral head when the arm is adducted.

The iliotibial band (ITB) originates primarily from which structure(s)?

Answer: Iliac crest and tensor fasciae latae

The ITB originates from the iliac crest and the tensor fasciae latae, with additional contributions from the gluteus maximus.

Open kinetic chain (OKC) knee exercises differ from closed kinetic chain (CKC) exercises primarily because in OKC exercises:

Answer: The distal segment is free to move

In OKC exercises, the distal segment (foot) is free to move, whereas in CKC exercises the foot is fixed and proximal segments move.

Which muscle is the primary dynamic supporter of the medial longitudinal arch of the foot?

Answer: Tibialis posterior

The tibialis posterior is the primary dynamic stabilizer of the medial longitudinal arch, coursing beneath and supporting it during weight-bearing.

During the overhead throwing motion, which phase produces the greatest valgus stress on the medial elbow?

Answer: Late cocking

Late cocking generates the greatest valgus stress on the medial elbow as the shoulder reaches maximum external rotation and large deceleration forces build.

Femoral anteversion is measured as the angle between which two reference axes?

Answer: Femoral neck axis and the transcondylar axis of the femoral condyles

Femoral anteversion is the angle between the femoral neck axis and the transcondylar axis, reflecting the forward twist of the proximal femur.

Which type of muscle contraction generates the greatest force per unit of cross-sectional area?

Answer: Eccentric

Eccentric contractions generate more force per cross-sectional area than concentric or isometric contractions due to titin's passive contribution during muscle lengthening.

The pivot shift test evaluates which combination of tibial movements in an ACL-deficient knee?

Answer: Anterior translation and internal rotation

The pivot shift tests for anterior tibial translation combined with internal rotation, the coupled motion that the ACL primarily restrains.

The thoracolumbar fascia transmits forces diagonally by connecting which two muscles?

Answer: Latissimus dorsi to contralateral gluteus maximus

The thoracolumbar fascia creates a cross-body force couple connecting the latissimus dorsi to the contralateral gluteus maximus, stabilizing the lumbar spine.

Scapulohumeral rhythm describes which ratio of glenohumeral to scapulothoracic motion during arm elevation?

Answer: 2:1

Scapulohumeral rhythm is approximately 2:1, meaning for every 2° of glenohumeral motion, 1° of scapulothoracic upward rotation occurs.

Which nerve innervates the tibialis anterior and is vulnerable to traction injury during severe ankle inversion sprains?

Answer: Deep peroneal nerve

The deep peroneal nerve innervates the tibialis anterior and is susceptible to traction injury during severe ankle inversion.

The force couple producing scapular upward rotation involves which three muscles?

Answer: Upper trapezius, lower trapezius, and serratus anterior

Scapular upward rotation is produced by a three-muscle force couple: upper trapezius, lower trapezius, and serratus anterior.

Patellofemoral joint reaction forces are greatest during which activity?

Answer: Deep squatting

Deep squatting generates the highest patellofemoral joint reaction forces because the compressive load increases exponentially with knee flexion angle.

The Lisfranc joint complex consists of the articulation between which structures?

Answer: Cuneiforms and cuboid with metatarsal bases

The Lisfranc joint complex includes the tarsometatarsal articulations between the cuneiforms/cuboid and the bases of the five metatarsals.

Plantar flexion during heel rise represents which class of lever system?

Answer: Second-class lever

Heel rise is a second-class lever with the fulcrum at the metatarsal heads, the load (body weight) between the fulcrum and the gastrocnemius/soleus effort at the calcaneus.

The classic unhappy triad (O'Donoghue's triad) involves injury to which three structures?

Answer: ACL, MCL, and medial meniscus

O'Donoghue's unhappy triad classically involves the ACL, MCL, and medial meniscus, typically from a valgus-external rotation force to the knee.