REGIONAL ANATOMY
This muscle forms the majority of the anterior wall of the axilla and inserts onto the lateral lip of the intertubercular sulcus of the humerus.
Pectoralis major
This muscle is the primary flexor of the elbow regardless of forearm position because its insertion is on the radius.
Brachioradialis
This ligament prevents anterior displacement of the tibia relative to the femur and also limits hyperextension of the knee.
Anterior cruciate ligament (ACL)
This part of a long bone is the expanded end that articulates with another bone to form a joint.
Epiphysis
A patient falls on an outstretched hand and develops tenderness in the anatomical snuffbox. Which bone should be suspected?
Scaphoid
This carpal bone articulates directly with the radius and is the most frequently fractured carpal bone.
Scaphoid
Unlike most muscles crossing the hip, this muscle can produce both hip flexion and knee extension because it crosses both joints.
Rectus femoris
This ligament of the hip is considered the strongest ligament in the human body and helps prevent hyperextension of the hip.
Iliofemoral ligament
This anatomical feature is a narrow, constricted region of a long bone located between the epiphysis and diaphysis.
Metaphysis
A patient cannot actively extend the knee after trauma to the anterior knee. Which muscle group is primarily responsible for this movement?
Quadriceps femoris
This muscle passes through the lesser sciatic foramen and inserts onto the medial surface of the greater trochanter, functioning as a lateral rotator of the hip.
Obturator internus
This rotator cuff muscle initiates approximately the first 15° of shoulder abduction before the deltoid becomes the dominant abductor.
Supraspinatus
The annular ligament surrounds which portion of the radius and maintains it against the ulna during pronation and supination?
Head of the radius
A long bone contains a dense outer layer that provides most of its mechanical strength. Name this type of bone tissue.
Compact (cortical) bone
A patient has difficulty initiating shoulder abduction after a fall. MRI demonstrates a tear of the muscle occupying the supraspinous fossa. Identify the muscle.
Supraspinatus
This muscle originates from the anterior surfaces of the upper ribs, wraps around the lateral thoracic wall, and inserts along the medial border of the scapula.
Serratus anterior
A muscle with fibers running approximately perpendicular to its tendon generally produces greater force than a similarly sized parallel-fibered muscle. Name this architectural arrangement.
Pennate architecture
A positive anterior drawer test of the knee primarily indicates injury to which ligament?
ACL
Which type of bone cell is responsible for synthesizing new bone matrix and is particularly active during bone formation?
Osteoblast
A patient sustains a posterior dislocation of the hip. Which major nerve is particularly at risk because of its close relationship to the posterior hip?
Sciatic nerve
A lesion affecting the long thoracic nerve produces scapular winging. Identify the muscle whose paralysis produces this finding and explain the biomechanical consequence for overhead elevation.
Serratus anterior; loss of scapular protraction/upward rotation impairs normal scapulohumeral rhythm and elevation above the horizontal.
During forced expiration, this abdominal muscle is particularly important for increasing intra-abdominal pressure and compressing the abdominal viscera; its fibers run inferomedially.
Internal oblique
The shoulder is highly mobile but relatively unstable because the glenoid cavity is shallow. Name the fibrocartilaginous structure that deepens it and explain its contribution to stability.
Glenoid labrum; it deepens the glenoid socket, increases articular congruence, and contributes to static shoulder stability.
A patient has impaired bone remodeling. Identify the bone-resorbing cell, describe its origin, and explain how its activity differs from that of osteoblasts.
Osteoclast; a multinucleated cell derived from the monocyte/macrophage lineage that resorbs bone, whereas osteoblasts are mesenchymal-derived cells responsible for bone formation.
Following a midshaft humeral fracture, a patient develops wrist drop and sensory loss over the dorsal first web space. Identify the injured nerve and explain why the neurological deficit occurs at this anatomical level.
Radial nerve; it runs in close association with the radial groove on the posterior humerus and supplies the extensor compartment of the forearm through its distal branches.