Week 4 - Clinical Anatomy of the Wrist and Hand Assignment

Specify the anatomical structures involved in mallet or baseball finger

In mallet finger the portion of the extensor hood that attaches to the distal phalanx is torn or avulsed, usually as a result of jamming the fingertip against a hard surface. In this injury the patient is unable to extend his/her distal interphalangeal joint

Explain the clinical significance of the anatomical snuff box.

The anatomical snuffbox is an important landmark for several structures but is especially significant with respect to the scaphoid bone. The scaphoid is the most frequently fractured carpal bone and is also one of the bones most susceptible to osteonecrosis. Pain felt deep within the snuff box indicates a fracture of the scaphoid. -Abductor Pollicis Longus -Extensor Pollicis Brevis -Extensor Pollicis Longus (EPL). The 'roof' of the snuff box is a nerve - the superficial radial nerve which innervates the back of the hand.

Specify the mechanism of injury and bones involved in the following common fractures of the hand and wrist: boxer's

fracture of the fifth (sometimes fourth) metacarpal. As its name implies, this fracture is the result of punching something hard with a closed and abducted fist.

Explain the anatomical basis of Dupuytren's contracture.

a pathological condition of the palmar fascia and aponeurosis that results in its progressive shortening, thickening and fibrosis. More typically seen in men over the age of 50, the condition is characterized by a partial flexion of the ring and little fingers, similar in appearance to the "claw hand" associated with ulnar nerve injuries.

Specify the actions and innervations of the dorsal interossei

abduction of digits at MCP deep branch of the ulnar n.

Specify the innervation of the thenar

abductor pollicis brevis adductor pollicis opponens pollicis flexor pollicis brevis innervated by recurrent branch of the median n.

Specify the actions and innervations of the palmar interossei

adduction of digits at MCP deep branch of the ulnar n.

Specify the common sites of injury to the following nerves and list the primary functional deficits associated with each: POSTERIOR INTEROSSEOUS, recurrent median; explain how the sensory (if applicable) and motor functions of each of these nerves are assessed clinically

compression of the posterior interosseous nerve where it passes through the radial tunnel. This may result in paresis or paralysis of the digital and thumb extensor muscles, resulting in an inability to extend the thumb and fingers at their metacarpophalangeal joints. ON BACK OF FOREARM/HAND

Specify the innervation of the hypothenar

deep branch of the ulnar n.

Specify the common sites of injury to the following nerves and list the primary functional deficits associated with each: RADIAL; explain how the sensory (if applicable) and motor functions of each of these nerves are assessed clinically

depends where injury is located above elbow: interferes with functions of the posterior compartment muscles and the distal cutaneous branches BOTH below elbow: -deep branch only: posterior forearm motor deficits only -superficial branch only: only sensory deficits over the 1st dorsal webspace "Hook-em horns"

Specify the actions and innervations of the lumbricals

1st and 2nd - median n. 3rd and 4th - deep branch of the ulnar n.

Explain the anatomical basis and common symptoms of carpal tunnel syndrome.

Carpal tunnel syndrome results from any lesion that compromises the space within the carpal tunnel The compression of the median nerve that is associated with this condition may result in tingling and and/or impaired sensation of the lateral three and a half digits and lateral palm, as well as functional weakness of the thumb and lateral fingers. Because the palmar cutaneous branch of the median nerve arises proximal to, and does not pass through, the carpal sensation in the central palm remains unaffected.

Specify the common sites of injury to the following nerves and list the primary functional deficits associated with each: RECURRENT MEDIAN; explain how the sensory (if applicable) and motor functions of each of these nerves are assessed clinically

Damaged with lacerations of the radial-sided wrist and proximal palm. Results in loss of thumb flexion, opposition, and abduction without sensory or other motor deficits.

Specify the mechanism of injury and bones involved in the following common fractures of the hand and wrist: Colle's

Distal end of the radius is displaced posteriorly; usually osteoporotic women

Specify the location and contents of Guyon's (ulnar) canal.

Located b/w the Pisiform and the Hook of Hamate anterior carpal bone Its contents include: Ulnar nerve and ulnar artery

Specify the common sites of injury to the following nerves and list the primary functional deficits associated with each: ULNAR; explain how the sensory (if applicable) and motor functions of each of these nerves are assessed clinically

Lower trunk injury (C8,T1) when chest forcibly widens weakness of hand/GRIP and sensory deficits of the medial aspect of the hand ulnar canal syndrome, the ulnar nerve is compressed where it passes within the ulnar (Guyon's) canal, common symptoms of this condition include hypoesthesia of the medial one-and one-half digits and weakness of the intrinsic hand muscles.

Explain the role of the triangular cartilage of the radiocarpal joint.

Ulna does not touch carpal bones This serves as a connection between the ulna and carpal bones AND allows for greater flexibility/adduction on the ulnar side than on the radial side.

List the ten structures that pass through the carpal tunnel.

i. Median Nerve ii. 4 tendons from Flexor Digitorum Superficialis (FDS) iii. 4 tendons from Flexor Digitorum Profundis (FDP) iv. 1 tendon from the Flexor Pollicis Longus (FPL) All wrapped in synovial sheath

Specify the common sites of injury to the following nerves and list the primary functional deficits associated with each: ANTERIOR INTEROSSEOUS; explain how the sensory (if applicable) and motor functions of each of these nerves are assessed clinically

innervates the deep digital flexors of the thumb, index and middle fingers and the pronator quadratus muscle. Anterior interosseous nerve palsy refers to injury of the anterior interosseous branch of the median nerve. indicated by the pinch posture. As the anterior interosseous nerve has no cutaneous distribution, there are no cutaneous sensory deficits associated with this injury median nerve gives rise to the anterior interosseous nerve between pronator heads

Specify the mechanism of injury and bones involved in the following common fractures of the hand and wrist: scaphoid

more common in younger individuals and are particularly problematic given the poor blood supply to the scaphoid bone. Therefore, this bone is susceptible to necrosis upon suffering a fracture.

Specify the common sites of injury to the following nerves and list the primary functional deficits associated with each: MEDIAN; explain how the sensory (if applicable) and motor functions of each of these nerves are assessed clinically

weakness of wrist and finger flexion and motions of the thumb and sensory deficits over the thumb and first 3 digits...THUMB SIDE OF PALM Entrapment of the median nerve between the two heads (humeral and ulnar) of the pronator teres muscle can result in pronator syndrome. Compromise of the median nerve at this location typically presents as pain and tenderness in the forearm with sensory deficits in hand/palm